Field

The present application relates to improvements for a cycle, and in particular to a crank assembly, a derailleur assembly, and a cycle.

Background

With the exception of track bikes, almost all of the commercially available cycles employ mechanisms that require a user to perform certain functions by hand, as well as a variable-ratio bicycle gearing system comprising a drive chain connecting the front and rear sprocket sets.

For example, a user may select an appropriate gear for a suitable cadence using a mechanical shifter or to apply braking by squeezing a brake lever mounted on a handlebar. Not only the force applied by the user can be considerable, but the use of such hand-operated shifters and brake levers may also prevent the user from maintaining a firm grip on the handlebar. Furthermore, the actuating force is commonly transferred by Bowden cables that run externally from the handlebar, along the length of the bicycle frame to a rear derailleur, or a rear brake. Not only they are unsightly, but loose cables may also get caught, or knotted up, during riding and transportation. This problem is particularly prominent in collapsible or foldable cycles that are frequently carried around during crowded commutes.

Similarly, derailleurs for shifting the drive chain from one sprocket to another typically consist of a moveable chain guide operable by a Bowden cable that is attached to a gear lever. Upon actuating the gear lever, the change in cable tension moves the chain guide in a direction perpendicular to the rear axle, thus derailing the chain onto different sprockets in the sprocket set. A conventional derailleur typically comprises a single derailleur frame that holds an upper guide sprocket and a lower tensioner sprocket. Together the two sprockets guide the chain in an S-shaped pattern to the sprocket set. By a parallelogram mechanism, the frame is configured to simultaneously displace in both the vertical and horizontal directions, and is spring-loaded and pivotable about the rear axle to take up any slack in the chain. Such an arrangement maintains a constant separation between the upper guide sprocket and the different-sized sprockets in the sprockets set over the range of movement. However, such conventional derailleurs typically extend downwardly from the rear axle and require substantial ground clearance to accommodate the vertically extending derailleur frame. Whilst these derailleurs are perfectly acceptable for use in ordinary bicycles where the rear wheels are at least 26 inches in diameter, they often preclude the use of wheels that are measured less than 16 inches in size. Thus, the use of such derailleurs presents a challenge when reducing the overall height of a bicycle. For example, in collapsible bicycles, the overall height of the bicycle is often dictated by their wheel sizes.

Furthermore, commercially available collapsible cycles are commonly arranged to fold sideways to convert into a collapsed configuration, in which the axes of the front and rear wheels do not usually align. Therefore it is difficult to manoeuvre a folded cycle on both of its wheels. To aid their manoeuvrability, these collapsible cycles are often provided with additional miniature support wheels at the rear of their frames, but their small sizes make the cycles difficult to manoeuvre on rough and bumpy surfaces.

Therefore, an improved crank assembly, derailleur assembly and folding mechanism for addressing these problems are highly desirable.

Summary

The present invention offers a crank assembly at which a user may effect gear selection and/or braking by foot. Advantageously, by reducing or eliminating the need for hand operations, the user may maintain a firm grip on the handlebar at all times, thereby improving the safety and quality of cycling. Moreover, the use of an electronically operated sensor arrangement for gear selection and/or braking may eliminate the use of Bowden cables.

According to a first aspect of the presently-claimed invention, there is provided a crank assembly for a cycle, comprising: a crank arm having a first proximal end attachable to a crank axle for driving rotational movement in the crank axle about a first axis; a pedal attached to a second distal end of the crank arm, the pedal is rotatable about a second axis parallel to the first axis, and is slidingly movable relative to the second distal end of the crank arm along the second axis; and a sensor arrangement arranged to sense an axial position of the pedal along the second axis, and therefrom generating a signal corresponding to the axial position of the pedal. The cycle may be any pedal-powered cycle, for example monocycles, bicycles, tricycles, quadricycles, cargo cycles and recumbent cycles.

Using a bicycle as an example, the crank axle may be referred to as a driving axle that is installed at a bottom bracket of the bicycle. The crank axle may be rotatable about the first axis, or otherwise known as a crank axis, that extends perpendicularly to the longitudinal axis of the bicycle. The crank axle may rotate with one or more front sprockets coaxially mounted thereon, for driving rotational motion in a corresponding rear sprocket set by a chain or a belt.

The pedal may comprise a spindle defining a second axis parallel to the crank axis. The pedal may be rotatably attached to the second distal end of the crank arm by the spindle. Thus, the rider may push on the pedal perpendicularly to the second axis to crank the crank axle in order to drive a forward movement of the cycle.

In conventional cycles, the pedal may only rotate about the second axis whilst movement in any other direction is constrained, e.g. the spindle in a conventional pedal only permits rotational movement in the pedal. This ensures all of the pedalling forces are precisely translated to crank the crank axles. In contrast, the spindle according to the present invention is configured to slidingly move through an aperture at the second distal end of the crank arm, thereby allowing the pedal to move relative to the crank arm along the second axis. Advantageously, such an arrangement may allow the rider to perform additional functions by foot in addition to conventional pedalling, and thereby removing the need for conventional Bowden cable connections.

The sensor arrangement may detect the sliding movement in the pedal as it slides along the second axis.

In some embodiments, the sensor arrangement may comprise a magnetic sensor and a magnet each attachable to one of the cycle and the pedal. For example, a reed switch may be installed on the cycle frame for sensing the proximity of a rare earth magnet that is attached to the pedal, e.g. at an end of the slidable spindle. For example, the reed switch may sense a weakened magnetic field when the pedal is put in an axial position furthest away from the cycle frame, e.g. a default position, or otherwise referred to as a first axial position, during normal pedalling, and thus it does not generate a signal. Once the rider moves the pedal towards the cycle frame along the second axis to perform a particular function, the magnetic field as sensed by the reed switch strengthens, and once it exceeds a predetermined threshold the reed switch generates a signal to be transmitted to a controller or other electronic devices for carrying out the said function.

In some embodiments, other magnetic sensors such as Hall effect sensors may be used, particularly in applications where the precise pedal position along the second axis is required. In some other embodiments, the reed switch or magnetic sensors may be installed on the pedal for sensing the proximity of a rare earth magnet attached to the cycle frame, wherein the signal may be transferred to a controller or other electrical devices wirelessly or by physical wiring.

In some embodiments, the sensor arrangement comprises a switch at the pedal for sensing the axial position of the pedal along the second axis. For example, the pedal may comprise one or more contact switches at respective pedal positions along the second axis. More specifically, the or each contact switch may generate a signal when it comes into contact with a part of the pedal.

In some embodiments, the sensor arrangement may comprise other sensors such as optical sensors, infrared sensors and ultrasound sensors.

Optionally, the sensor arrangement comprises a signal emitter at the pedal and a signal receiver at the cycle for wirelessly communicating the signal therebetween. The signal emitter may receive the signal from the switch, the magnetic sensor or the said other sensors and subsequently relay the signal wirelessly to the signal receiver.

Optionally, the signal is wirelessly communicable between the signal emitter at the pedal and the signal receiver at the cycle optically or by radiowaves. The said wireless communication may be a one-way communication from the signal emitter to the signal receiver, or it may be two-way communication between the two.

In some embodiments, the pedal is provided with an infrared emitter for emitting the signal, e.g. infrared rays, to one or more infrared receivers arranged at the frame. Advantageously, due to its longer wavelengths in comparison to visible light, the use of infrared waves for signal transmission offers less scattering and absorption, and thus it is particularly suitable for use in dusty environments.

In some other embodiments, the pedal is provided with a Bluetooth emitter for broadcasting the signal to one or more Bluetooth receivers arranged at the frame. Such an arrangement may advantageously allow the transmitted signal to be encoded to the particular Bluetooth emitter/receiver pairing, thus reducing the likelihood of interference with other wireless devices in the vicinity.

Optionally, the signal emitter is configured to emit the signal only when the pedal is away from a first axial position, e.g. furthest away from the second distal end of the crank arm. As the first axial position may typically be adopted for normal riding, the signal emitter may be switched off to reduce power consumption.

Optionally, the pedal comprises an electrical generator for energising one or more electrical components at the pedal, wherein the electrical generator generates electricity by the rotational movement of the pedal about the second axis, and optionally the pedal comprises a capacitor for storing electrical energy generated by the electrical generator. The electrical generator may be a dynamo that rotatably connects between the pedal and the spindle and may configure to generate a DC power supply for charging the capacitor, e.g. a rechargeable battery, or directly energising the electrical components, e.g. the one or more of the contact switches, the infrared emitter and the Bluetooth signal emitter. In turn, the capacitor may discharge stored energy for energising the electrical components when the pedal is stationary relative to the spindle.

Optionally, the signal is configured to control a gear selector, wirelessly or by physical wires, thereby allowing gear selection to be controlled by the movement of the pedal along the second axis. The gear selector may comprise an electronic derailleur for the front and/or rear sprocket sets. Upon receiving the signal, the electronic derailleur may displace the drive chain, in a direction parallel to the first axis, to a plurality of gear positions each of which corresponds to a sprocket of the sprocket sets.

Optionally, the signal is configured to control a brake actuator, thereby allowing braking to be controlled by the movement of the pedal along the second axis. The brake actuator may comprise an electronic brake actuator for the front and/or rear brakes of the cycle, wirelessly or by physical wires. Upon receiving the signal, the electronic brake actuator may apply a braking force to a rim of the wheel or a brake disc to slow down the cycle. In some embodiments, the braking force may correspond to the amount of sliding movement in the pedal along the second axis.

Optionally, the pedal is moveable between a first axial position and one or more further axial positions along the second axis. More specifically, the sensor may sense the pedal position at each of the first axial position and the further axial positions, and thereby generate a signal accordingly.

Optionally, the pedal is biased towards the first axial position by a biasing means. For example, the first axial position may be a default pedal position adopted during normal pedalling where the rider does not require to perform a function, thus, the biasing means may aid the pedal to be retained at the first axial position. In order to move the pedal from the first axial position to other further axial positions, the rider may overcome the biasing force to drive sliding movement in the pedal along the second axis. In a preferred embodiment, a compression spring may coextend inside the spindle and biases against the second distal end of the crank arm. Thus the biasing force may bias the pedal away from the second distal end of the crank arm, and towards the first axial position during normal pedalling.

Optionally, the pedal is sequentially moveable between the first axial position and the plurality of further axial positions along the second axis, wherein the crank assembly further comprises an indexing arrangement for movably retaining the pedal at each of first axial position and the one or more further axial positions. For example, the first axial positional and the plurality of further axial positions may each correspond to a particular derailleur position. Thus, sequential gear selection may be achieved by moving the pedal through the various axial positions in the pedal.

Optionally, the indexing arrangement may comprise a sprung ball retainer at the second distal end of the crank arm. The sprung ball retainer may configure to movably retain the pedal at the desired axial position by a notch provided at each of the first axial position and the plurality of further axial positions at the spindle. The retaining force imposed by the sprung ball retainer may be sufficient to overcome the biasing force from the biasing means, i.e. if a biasing means is also provided, and it may be overcome by the rider when a force is applied to move the pedal along the second axis.

Optionally, the crank assembly comprises a second crank arm attached to the crank axle opposite to the crank arm, wherein a second pedal is rotatably attached to a second end of the second pedal, and is moveable relative to the second distal end of the second crank arm along a third axis parallel to the first and second axes. Such crank assembly may resemble a conventional crank assembly where two crank arms are provided on each side of the crank axle, and are substantially opposite to each other when viewed along the first axis. However, in contrast to conventional crank assemblies, such an embodiment may allow two different functions to be independently performed when the rider moves each of the pedal and the second pedal along respectively the second and third axes.

Optionally, the pedal and the second pedal are configured to control gear selection in opposite directions. For example, in a preferred embodiment, the pedal and the second pedal may each have a first axial position away from the cycle frame adoptable during normal pedalling, and a second axial position proximal to the cycle frame for effecting gear selection. Thus, the rider may opt to shift up by sliding the pedal from its first axial position to its second axial position, and to shift down by sliding the second pedal from its first axial position to its second axial position, or vice versa. The said gear shifting may be accomplished only by foot, and not relying on hand-operated shifter and Bowden cable connections as found on conventional bicycles.

Optionally, the axial movements of the pedal and the second pedal are each configured to control gear selection at one of the front and rear gear sprockets or brake actuators of the cycle. More specifically, the pedal and the second pedal may be sequentially moveable between the various axial positions along their respective second and third axes, whereby the sliding movement in the pedal and the second pedal may allow the rider to effect gear selection respectively at a rear derailleur and a front derailleur, or vice versa. Alternatively, the axial movement in the pedal and the second pedal may allow the rider to apply a corresponding braking force, respectively at the front brake actuator and rear brake actuator, or vice versa.

According to a second aspect of the presently-claimed invention, there is provided a crank assembly for a cycle, comprising: a crank axle rotatable about a first axis, the crank axle is configured to drive forward movement of the cycle when rotating in a first direction; a freewheel comprises an inner rotor and an outer rotor coextending along the first axis, the freewheel is mounted on the crank axle by the inner rotor and is connectable to a brake actuator by the outer rotor, wherein the outer rotor is configured to disengage from the inner rotor when the crank axle rotates in the first direction, and to engage with the inner rotor when the crank axle is forced to rotate in a second direction opposite the first direction, thereby applying an actuating force to the brake actuator.

The freewheel may be any freewheel commonly used in rear sprockets set in cycle drivetrains, e.g. at the rear axle. The freewheel according to the present invention may be a freewheel provided on the crank axle and may only engage in a rotational direction opposite to the rotational direction that engages the rear axle freewheel. Thus, according to the present invention, the freewheel at the crank axle may only engage when the crank axle is forced to rotate in the second direction opposite the first direction, and thereby translating the rotation force in the second direction to an actuating force applicable to the brake actuator.

The brake actuator may be a rear brake actuator and/or a front brake actuator, thus in some embodiments, the rotation force applied at the crank axle in the second direction may be translated into a braking force applicable to the front and/or rear brakes of the cycle. The brake actuator may comprise a brake calliper for a rim brake or a disc brake.

Advantageously, such as arrangement may utilise a reversed pedal movement for controlling the braking of the cycle, thus reducing, or eliminating the need to apply braking force by hand via conventional Bowden cable connections. Not only a larger braking force may be applied by a more powerful muscles group, e.g. quadriceps and hamstrings in the rider’s upper legs in comparison to the rider’s fingers, but the rider may also maintain a firm grip on the handlebar at all times.

In some embodiments, the outer rotor of the freewheel may be mechanically connectable to the brake actuator by one or more of a chain, a cable or a hydraulic system. In a preferred embodiment, the outer rotator comprises a sprocket that is connectable to the rear brake actuator by a chain. As the crank axle and the outer rotator is forced to rotate in the second direction, it tensions the chain and thereby translating the rotating force into an actuating force at the brake actuator. A larger rotating force inputted in the second direction at the crank axle may result in a proportionally larger actuating force at the brake actuator.

Alternatively, the crank assembly comprises a sensor arrangement arranged to sense engagement between the outer and inner rotor, and therefrom generating a signal for controlling the amount of actuating force applicable to the brake actuator. The sensor arrangement may sense engagement between the outer and inner rotor by sensing the angular displacement of the outer rotor and/or measuring the force applied on the crank axle in the second direction. Thus, in these embodiments, the outer rotor of the freewheel may not be mechanically connected to the brake actuator.

The sensor arrangement may be configured to generate a signal for controlling the amount of actuating force applicable to the brake actuator. For example, the sensor arrangement may comprise a load cell configured to measure the rotational force applicable in the second direction at the crank axle or the outer rotor. Alternatively, it may comprise other sensors for monitoring the angular displacement in the outer rotor, such as optical sensors. The signal may be received by a front or rear electronic brake actuator for applying an actuating force at the brakes.

In some embodiments, the amount of actuating force applicable by the electronic brake actuator may not be proportional to the force acting on the crank axle in the second direction. For example, the actuating force may be uniform regardless of the magnitude of the force acting on the crank axle or the degree of angular displacement of the outer rotor in the second direction.

Alternatively, and preferably, the amount of actuating force applicable by the brake actuator increases with increasing force acting on the crank axle or increasing angular displacement of the outer rotor in the second direction. Optionally, the amount of actuating force applicable by the brake actuator is proportional, or non-proportional, to the force acting on the crank axle or the angular displacement of the outer rotor in the second direction. Thus, the user may pedal in a reversed direction, e.g. the second direction, to effect braking at the front and/or rear brakes, without the need for applying braking by hands. Optionally, the signal is communicable between the sensor and the brake actuator by wire. Optionally, the signal is wirelessly communicable between the sensor and the brake actuator. For example, the use of a sensor arrangement may allow the signal to be received by an electronic front/rear brake actuator, by wire or wirelessly. That is, since the front and/or rear brake actuators are distally positioned from the freewheel, such an arrangement is particularly suitable for controlling the brake actuators without the use of a mechanical connection. Furthermore, such an arrangement may advantageously allow the simultaneous application of front and rear brakes by means of reverse pedalling, and therefore reducing the need for rider input. In some embodiment, the actuating force applicable by the front and rear electronic brake actuators, based on the same degree of reverse pedalling, may be the same, or different to each other.

Optionally, the crank assembly further comprises a biasing means for biasing the outer rotor in the first direction, such that the brake actuator ceases applying the actuating force once the force acting on the crank axle in the second direction is removed.

The biasing means may be directly connected to the outer rotor, or by the mechanical connection, e.g. the chain, to bias the outer rotor in the first direction, the biasing means may release the tension in at least a part of the mechanical connection between the outer rotor and the brake actuator when no force is applied at the crank axle in the second direction.

In the case where a sensor arrangement is employed, the biasing means may disengage the outer rotor from the inner rotor once the force acting on the crank axle in the second direction is removed, and thereby promptly returning it to its default position. The sensor, upon sensing the disengagement of the outer rotor from the inner rotor, signals the brake actuator to cease applying the actuating force at the front and/or rear brakes. Advantageously, such an arrangement may promptly ease the brake actuator as soon as the rider removes the force in the second direction.

The present invention also offers a derailleur assembly having a guide sprocket that may only traverse in a horizontal plane when guiding the chain to the desired sprocket in the sprocket set. Advantageously, by removing the parallelogram commonly used in conventional bicycles, the guide sprocket is no longer required to displace in the vertical plane, thus substantially reducing the overall height of, and ground clearance required by, the derailleur assembly. Moreover, the guide sprocket and the tensioner sprocket in the derailleur assembly may move relative to each other, thus allowing the tensioner sprocket to be arranged with greater ground clearance in comparison to the conventional derailleurs. In addition, such an arrangement may allow the derailleur assembly to be more readily concealed in a monocoque frame.

According to a third aspect of the presently-claimed invention, there is provided a derailleur assembly for a cycle, the cycle having a multi-stage sprocket assembly rotatable about an axis, the derailleur assembly comprising: a guide rail extending substantially in a horizontal plane and angled to the axis; a chain guide mounted on the guide rail, the chain guide is slidingly moveable between a plurality of positions along the guide rail each corresponds to a drive sprocket of the multistage sprocket assembly; a guide sprocket rotatably supported on the chain guide, the guide sprocket is configured to guide displacement of a drive chain parallel to the axis, wherein the separation between the guide sprocket and the corresponding drive sprocket is substantially the same at each of the positions; and an electronic actuator, the electronic actuator is configured to receive a signal from a gear selector to drive sliding movement in the chain guide.

The cycle may be any cycle comprising a multi-stage sprocket assembly in its drive train. The multi-stage sprocket assembly may commonly be referred to as a cassette, which may be the rear sprocket set and/or the front sprocket set of the cycle. For example, the guide sprocket is configured to guide displacement of a drive chain parallel to the axis corresponding to a rear axle or a crank axle of the cycle. Therefore, the sprockets in the rear sprocket set may coaxially extend along a rear axis about which the rear axle rotates. Similarly, the sprockets in the front sprocket set may coaxially extend along a crank axis about which a crank axle rotates. Namely, the axis extends perpendicularly to the longitudinal axis of the cycle.

The guide rail may extend in a plane substantially parallel to the horizon when the cycle is set on levelled ground, i.e. in the horizontal plane, and the horizontal plane may be substantially parallel to a line extending through the front and rear axle of the bicycle.

In most cases, the sizes of the sprockets in the multi-stage sprocket assembly may incrementally change with each sprocket. This provides a gradual change in gear ratio as the chain sequentially shifts through the different sprockets. For example, a nominal line may extend in the horizontal plane and joins the apexes, or leading teeth aligned at the horizontal plane, of all of the sprockets. In other words, the nominal line corresponds to the tapered side profile of the multi-stage sprocket assembly. The guide rail may extend parallel to the said nominal line, and therefore, the guide rail extends at an angle to the axis. The guide rail may linearly extend at an angle between 30° to 70° to the axis, or between 40° to 60° to the axis, or between 45° to 55° to the axis, or in a preferred embodiment substantially 50°, to the axis, and/or it may extend parallel to the nominal line.

Alternatively, in some multi-stage sprocket assemblies, the sizes of sprockets in the multi-stage sprocket assembly may not change propotionally with each sprocket. For example, the sprockets corresponding to the highest gears may decrease in size in a non-linear manner, which may result in a higher achievable top speed, or the sprockets corresponding to the lowest gears may increase in size in a non-linear manner, which may allow for more rapid acceleration. In these cases, the guide rail may non-linearly extend in the horizontal plane and complements the profile of the multi-stage sprocket assembly. For example, the guide rail may comprise, along its length, a curvature or plural consecutive segments extending at different angles to the axis, complementary to a curved or angled side profile of the multi-stage sprocket assembly.

Such arrangements may ensure the separation between the apexes (e.g. the opposing teeth that face each other) of the guide sprocket and the corresponding drive sprocket is substantially the same at each of the positions as the chain guide slides along the guide rail, and therefore reducing the amount of chain rattle, as well as the risk of accidental derailment.

The derailleur assembly comprises an electronic actuator, the electrical actuator is configured to receive a signal from a gear selector, or shifter, to drive sliding movement in the chain guide. Optionally, the derailleur assembly comprises a rack and pinion gearing for translating a rotational motion of the electrical actuator to the sliding movement in the chain guide.

The gear selector may comprise an electronic shifter operable by hand or other means, and is configured to send a signal wirelessly, or by wire, to the electronic actuator for effecting gear selection. For example, the signal may be a signal for selecting a higher gear or a lower gear sequentially in the sprocket assembly, or for direct selection of any gear. The electronic actuator may be an electrical motor that is fixedly attached to the frame of the cycle. Upon receiving the signal, the electronic actuator may configure to drive rotational movement in a pinion gear, which in turn delivers linear motion in a corresponding rack gear to cause sliding movement in the chain guide.

In some other embodiment, a worm gear or other suitable gearing systems may be used in lieu of the rack and pinion gearing. In some other embodiment, a Shape Memory Alloy actuator or other direct-drive linear motors may be used for driving the sliding movement in the chain guide without the need for a gearbox.

In contrast to conventional derailleurs, the chain guide according to the present invention may only move in the horizontal plane. Advantageously, such an embodiment may substantially reduce the clearance required to accommodate the vertical displacement that is otherwise required in conventional derailleurs, thus resulting in a more vertically compact derailleur assembly.

Optionally, the guide rail comprises retaining means for movably retaining the chain guide at each of the positions. For example, the retaining means may be an indexing arrangement such as a notch provided at each of the positions.

Optionally, the derailleur assembly further comprises an optical switch in communication with the electronic actuator, the optical switch configured to project optical radiation, e.g. infrared radiation, towards the chain guide, wherein the chain guide comprises a slot or a protrusion at each of the positions for allowing or disrupting the said optical radiation, so as to cease the sliding movement of the chain guide at each of the positions.

Optionally, the guide sprocket is configured to guide displacement of the drive chain parallel to the axis corresponding to a rear axle or a crank axle of the cycle. Optionally, the movement of the chain guide along the angled guide rail is greater than the displacement in the drive chain along the axis. Since the guide rail extends at an angle to the axis, any movement in the chain guide would result in a relatively smaller translation in the drive chain parallel to the axis. Advantageously, such an arrangement may allow the displacement in the drive chain to be more precisely controlled. Optionally, the guide rail having a first end fixedly attachable to a structure of the cycle proximal to, or forward to, the multi-stage sprocket assembly and a second end fixedly attachable to the structure at a position forward of a rear wheel of the cycle. For example, when used for changing gear in a rear sprocket set, the first end of the guide rail may be attached to a fork end at the rear of the cycle frame commonly known as the derailleur hanger. The second end of the guide rail may be attached to, or at a location near, the bottom bracket of the cycle or other parts of the frame forward of the cycle’s rear wheel. Thus, the derailleur assembly may utilise a space that is otherwise left unoccupied in conventional cycles.

According to a fourth aspect of the presently-claimed invention, there is provided a derailleur assembly for a cycle, the cycle having a multi-stage sprocket assembly rotatable about an axis, the derailleur assembly comprising: a chain guide moveable to a plurality of positions each corresponds to a drive sprocket of the multi-stage sprocket assembly; a guide sprocket rotatably supported on the chain guide, the guide sprocket is configured to guide displacement of a drive chain parallel to the axis, wherein the separation between the guide sprocket and the corresponding drive sprocket is substantially constant at each of the positions; and a tensioner sprocket rotatably mounted on a tensioner member, the tensioner sprocket is configured to engage and tension the drive chain, wherein the tensioner member is moveable relative to the chain guide.

Optionally, the tensioner member is fixedly attached to the chain guide. Such an arrangement may resemble the derailleur frame as used in conventional derailleurs.

Alternatively, and preferably, the derailleur assembly further comprises a tensioner sprocket rotatably mounted on a tensioner member, the tensioner sprocket is configured to engage and tension the drive chain, wherein the tensioner member is moveable relative to the chain guide. The tensioner member may be moveable relative to the chain guide along the vertical plane. That is, in contrast to conventional derailleurs where the tensioner sprocket and the guide sprocket are mounted on a single derailleur frame, the derailleur assembly according to the present invention comprises an additional tensioner member for housing the tensioner sprocket. By the relative movement between the tensioner member and the chain guide, the tensioner sprocket may also move relative to the guide sprocket. Such an arrangement may advantageously decouple the two functions in the derailleur assembly, e.g. chain tensioning and chain guidance. Thus, the vertical displacement as observed in conventional tensioner sprockets may be significantly reduced or eliminated. Moreover, since the movement in the chain guide is decoupled from the tensioner member, the biasing force that is required for chain tensioning no longer acts directly upon the chain guide. Advantageously, less input force may be required from the rider, or the electronic actuator, to effect gear shifting.

Optionally, the derailleur assembly further comprises a biasing means connected between a structure of the cycle and the tensioner member, the biasing means is configured to apply a biasing force on the tensioner member so as to tension the drive chain. In contrast to conventional derailleurs where the biasing means is connected between a fixed portion and a moveable portion of the derailleur, the biasing means in the present invention is configured to connect directly between the tensioner member and a structure of the cycle, e.g. the bicycle frame. For example, the biasing means may comprise a tension spring, and wherein the derailleur assembly may further comprise one or more pulleys attached to the structure of the cycle for routing the tension spring around the axis, e.g. a rear axle of the cycle. Advantageously, such an arrangement may allow the biasing means to be routed around the axis, thereby offering sufficient ground clearance when smaller wheels, e.g. less than 16 inches in size, are used.

Optionally, the tensioner member is arranged at a vertical position below the chain guide and an apex of the largest sprocket in the multi-stage sprocket assembly. More specifically, the tensioner member is positioned below the lowest tooth of the largest sprocket so as to provide sufficient clearance therebetween.

Optionally, the tensioner member is configured to be suspended by the biasing force applied by the biasing means and the tension in the drive chain. That is, the tensioner member may not fixedly attach to the frame of the cycle. Rather, it may be suspended by the biasing means and the drive chain. Thus, the tensioner member may move in any direction and around any axes.

Optionally, the tensioner member is moveable in a direction parallel to the axis by the displacement in the drive chain. More specifically, since the tensioner member is not fixedly attached to the frame, it may trail the drive chain in a direction parallel to the axis. Advantageously, such an arrangement may allow the tensioner sprocket to maintain adequate alignment with the guide sprocket, and thus minimising rattle and resistance during pedalling.

According to a fifth aspect of the presently-claimed invention, there is provided a derailleur assembly for a cycle, the cycle having a multi-stage sprocket assembly rotatable about an axis, the derailleur assembly comprising: a chain guide, the chain guide is moveable between a plurality of positions each corresponds to a drive sprocket of the multi-stage sprocket assembly; a guide sprocket supported on the chain guide, the guide sprocket is configured to guide displacement of a drive chain parallel to the axis; an electronic actuator, the electronic actuator is configured to receive a signal from a gear selector to drive movement in the chain guide; a chain movement sensor for sensing movement of the drive chain; a gear position sensor for sensing the position of the chain guide; wherein the electronic actuator is operable in a mode to aid acceleration from a standstill in which, upon sensing the onset of drive chain movement and sensing the chain guide corresponds to a position other than the largest sprocket of the multi-stage sprocket assembly, the electronic actuator moves the chain guide to a position corresponds to the largest sprocket in absence of a user input.

The derailleur assembly may resemble a commonplace derailleur assembly operable by an electronic actuator, or the derailleur assemblies of the third or fourth asepcts, except it may further comprise the chain movement sensor and gear position sensor. The multi-stage sprocket assembly may be a rear sprocket of the cycle and therefore the largest sprocket may correspond to a sprocket that drives the cycle at the slowest speed, e.g. a first gear sprocket.

The chain movement sensor may sense the movement of the drive chain directly, or it may sense the rotational movement in the sprocket set. The gear position sensor may sense the relative position between the chain guide and the frame or other components of the cycle. It may sense each of the positions of the chain guide, or it may comprise a single contact switch to sense the chain guide is not in a position corresponding to the largest sprocket. Advantageously, such an arrangement may allow the drive chain to automatically shift to the lowest gear upon starting from a standstill, thereby reducing the effort required by the rider.

Optionally, the derailleur assembly comprises a speedometer for sensing the movement of the cycle, and wherein the electronic actuator is only operable in the mode when the cycle accelerates from a standstill. Advantageously, such an arrangement prevents the drive chain from automatically shifting to the lowest gear when the cycle is coasting at speed.

According to a sixth aspect of the presently-claimed invention, there is provided a method of operating the derailleur assembly of the fifth aspect, comprising the steps of: sensing, by the chain movement sensor, the onset of drive chain movement; sensing, by the gear position sensor, the chain guide corresponds to a position other than the largest sprocket of the multi-stage sprocket assembly; moving, by operating the electronic actuator in the mode to aid acceleration from a standstill, the chain guide to a position corresponds to the largest sprocket in absence of a user input.

Optionally, the method further comprises the step of: sensing, by the speedometer, the cycle is accelerating form a standstill; and enabling the electronic actuator in the said mode.

According to a seventh aspect of the present invention, there is provided a cycle, comprising the crank assembly of first aspect or second aspect, and/or the derailleur assembly of any one of the third to sixth aspects.

According to an eighth aspect of the presently-claimed invention, there is provided a monocoque frame that forms a load-bearing structure to which a rear wheel of the cycle is mounted onto, the monocoque frame at least partially encloses a gear selector and other drivetrain components that drives the rear wheel; the monocoque frame comprises a channel extending along the longitudinal axis of the monocoque frame; a subassembly to which a front wheel of the cycle is mounted onto, the subassembly having a guide frame slidably received inside the channel of the monocoque frame for varying the overall length of the cycle; and a seat post, the seat post is arranged to extend through, and angled to, the channel of the monocoque frame in a ridable configuration, and is configured to be stowed in the channel parallel to the guide frame in a collapsed position.

The present invention also offers a cycle having a frame and a subframe pivotably connected to the frame, wherein in a collapsed configuration the frame and subframe may remain aligned in the same plane. In the collapsed configuration the cycle may be manoeuvred on its rear wheel, or both the front and rear wheels, which are substantially larger than the miniature support wheels commonly featured in known collapsible cycles. Advantageously, the single point of contact at the rear wheel may allow the cycle to be easily manoeuvrable when collapsed.

According to a ninth aspect of the presently-claimed invention, there is provided a cycle, comprising: a frame to which a rear wheel of the cycle is mounted onto; and a subframe to which a front wheel of the cycle is mounted onto, the subframe is pivotably connected to, and rotatable about the frame to convert the cycle between an extended configuration and a collapsed configuration, wherein in both the extended and collapsed configurations the frame and the subframe extend in the same plane, wherein the plane extends vertically along a longitudinal axis of the cycle, wherein the subframe pivots towards the rear wheel when converting to the collapsed configuration and thereby reducing the overall length of the cycle.

The cycle may be powered by the user alone, or by a combination of user input and a motor, e.g. an electric bike. The cycle may otherwise be referred to as a collapsible cycle where the frame may refer to a rear load-bearing structure having a seat and drivetrain components attached thereto. On the other hand, the subframe may be connected to a fork and a handlebar.

The frame and the subframe may be pivotally connected by means of a hinged connection or a pivot joint. The hinged connection or the pivot joint may be located towards the bottom end of the frame. Thus, the subframe may pivot towards the rear wheel when converting to the collapsed configuration and thereby reducing the overall length of the cycle. More specifically, the frame and the subframe may rotate towards each other whilst remaining in the same plane, wherein the said plane may extend vertically along a longitudinal axis of the cycle. Such an arrangement may be distinct from known collapsible cycles where the frame and subframe are folded sideway which, in the collapsed configuration, causes the two to extend in different planes.

The frame and subframe may be removably retained in either the extended configuration or the collapsed configuration by a suitable fastening mechanism, preferably a quick-release fastener such as a toggle latch and a snap-fit latch. The fastening mechanism may be provided adjacent to the hinged connection or the pivot joint, or it may be in any suitable location at the frame and the subframe.

In the extended configuration, the frame and the subframe may be substantially aligned along the longitudinal axis of the cycle. More specifically, the cycle is extended to its full length in the extended configuration with the front and rear wheels separated to the greatest extent. That is, the cycle in the extended configuration resembles a commonplace cycle for normal riding.

The frame and the subframe may abut each other at a location towards the top end of the cycle in the extended configuration during use. Thus, advantageously, such an arrangement may provide multiple points of contact between the frame and the subframe in the extended configuration, thereby increasing the rigidity of the cycle.

Optionally, the frame comprises a handlebar connected to the front wheel, wherein in the collapsed configuration the cycle is manoeuvrable on its rear wheel, or both the rear and front wheels, by the handle bar, e.g. by pulling on the handle bar. The handlebar may be connected to the front wheel by conventional steering mechanisms. By lifting the front end of the collapsed cycle, the rear wheel forms a single point of contact with the ground. Thus, advantageously, the larger size of the rear wheel provides the collapsed cycle with better manoeuvrability in comparison to the conventional collapsible cycles.

In some embodiments, the frame may be formed from plural tubular frame sections similar to conventional bicycles. For example, the frame may resemble a triangle to provide the necessary structural support. In these embodiments, the gear selector and other drivetrain components that drive the rear wheel are exposed.

Alternatively, and preferably, the cycle may comprise a monocoque frame that forms a loadbearing structure to which a rear wheel of the cycle is mounted onto, the monocoque frame at least partially encloses a gear selector and other drivetrain components that drive the rear wheel. In a preferred embodiment, the monocoque frame completely encloses the entire gear selector and other drivetrain components that drive the rear wheel. The monocoque frame may generally be defined as an exoskeleton frame and may form from two monocoque shells. The monocoque frame may shield the drivetrain components including the front and rear sprocket sets, as well as the drive chain that connects the two sprocket sets. Thus, not only the monocoque frame helps conceal the drivetrain components thus offering an additional layer of protection, it may shield the user from the grease and grit commonly associated with a bicycle drivetrain system.

Optionally, in the collapsed configuration the front wheel is at least partially, or fully, received in the monocoque frame. That is, the monocoque frame may comprise a slot or a recess for receiving the front wheel. Advantageously, when it is partially received in the monocoque frame, the sway in the front wheel is restricted and therefore, such an arrangement may aid manoeuvrability and handling of the collapsed cycle. Furthermore, the front wheel may be shielded from the external environment in the monocoque frame.

Features from any one of the first to the nineth aspects of the present invention may be applicable with any other feature from the other aspects.

Brief Description of the Drawings

Certain embodiments of the presently-claimed invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a side view of a bicycle in an extended configuration according to a first embodiment of the present invention;

Figure 2 is a side view of the bicycle of Figure 1 in a collapsed configuration;

Figures 3 and 4 are respectively a side view and a plan view of a crank assembly according to a second embodiment of the present invention as fitted to the bicycle as shown in Figures 1 and 2; Figure 5 is a plan view of a crank assembly adopting a different pedal position to that as shown in 4;

Figure 6 is a plan view of a crank assembly showing the pedal of Figure 4 being put into a collapsed configuration;

Figures 7a and 7b are plan views of a pedal in respectively a first axial position and a second axial position according to a third embodiment of the present invention;

Figures 8a and 8b are plan views of a pedal in respectively a first axial position and a second axial position according to a fourth embodiment of the present invention;

Figures 9 and 10 are cross-sectional plan views of a derailleur assembly according to a fifth embodiment of the present invention;

Figure 11 is a flow diagram of a method of operating the derailleur assembly of Figures 9 and 10;

Figure 12 is a side view of a freewheel mounted to a crank axle according to a sixth embodiment of the present invention;

Figures 13 A and 13B are respectively a side view and plan view of a brake actuating system where a braking force is applied;

Figures 14A and 14B are respectively a side view and plan view of brake actuating system of Figures 13 A and 13B where the braking force is removed;

Figure 15 is a side view of a derailleur assembly according to a seventh embodiment in which the drive chain engages the largest sprocket in the rear sprocket set;

Figure 16 is a side view of the derailleur assembly of Figure 15 in which the drive chain engages the smallest sprocket in the rear sprocket set; Figure 17 is a side view of a bicycle in a ridable configuration according to an eighth embodiment of the present invention; and

Figure 18 is a side view of the bicycle of Figure 17 in a collapsed configuration.

Detailed Description

Collapsible bicycle comprising a monocoque frame

Figures 1 and 2 are side views of a bicycle 10 in respectively an extended configuration and a collapsed configuration according to a first embodiment of the present invention. The bicycle 10 is a collapsible bicycle where it may adopt an extended configuration for normal riding as shown in Figure 1, as well as being put into a collapsed configuration as shown in Figure 2 during transportation.

Towards the front of the bicycle 10 there is provided a subassembly 22, comprising a front wheel 34 rotatably mounted onto a fork 24 by a front axle 36. The fork 24 having a steerer tube at its top end that extends through a headtube 26, wherein bearings are provided in the headtube 26 to aid relative rotation between the said steerer tube and the headtube 26. The steerer tube of the fork 24 is coupled to a handlebar stem 25 fixed attached to a handlebar (not shown). The handlebar stem 25 is partly enclosed in a stem sleeve 27 extending upwardly from the headtube 26. Thus, a rider may rotate the handlebar about the headtube 26 to steer the bicycle 10 into the desired direction.

The subassembly 22 further comprises an elongated subframe 28 welded to the headtube 26. The subframe 28 extends in a horizontal plane along the longitudinal axis of the bicycle 10, and comprises a pivot arm 28b angled from a mid-section of the subframe 28. The subframe 28 and the pivot arm 28b are of conventional tubular frame construction and may form from any suitable material, such as stainless steel, aluminium or titanium alloys, or carbon fibre. The phrase horizontal plane generally refers to a plane parallel to the horizon when the bicycle 10 is set on levelled ground as shown in Figure 1, and may be substantially parallel to a line extending through the front and rear axle of the bicycle.

The stem sleeve 27 is configured to pivot about a hinge 29 to convert between the extended configuration and the collapsed configuration. More specifically, in the extended configuration, the handle stem 25 extends at an angle to the longitudinal axis of the bicycle 10 and is locked in position by a hinged lever. On the other hand, as shown in dotted line, the handle stem 25 is substantially parallel to the subframe 28 when the stem sleeve 27 of the bicycle 10 is put into the collapsed configuration. Such an arrangement reduces the overall length of the bicycle when it is collapsed.

Referring to Figure 1, a rearward portion of the bicycle 10 comprises a monocoque frame 12 rotatably supported on a rear wheel 30 by a rear axle 32. The monocoque frame 12 forms a load-bearing structure of the bicycle 10 that is configured to distribute some of the weight of the rider (not shown) and the bicycle 10 to the rear axle 32. That is, the monocoque frame 12 is the only load-bearing member connected between a seat post 16 and a crank axle 200 of the bicycle 10 to the rear axle 32. The monocoque frame 12 may be formed from any suitable material such as stainless steel, aluminium and titanium alloys and other composite materials such as firbreglass and a carbon fibre composite. The rear wheel 30 and the front wheel 34 are compact bicycle wheels each having an overall diameter of less than 350mm, commonly referred to as 12 or 14 inches wheels.

The monocoque frame 12 is formed from two monocoque shells joint together along a longitudinal centreline of the bicycle 10. As shown in Figure 1, the monocoque frame 12 fully encloses a rear sprockets set 40, a front sprockets set 50 and their respective derailleurs, as well as the drive chain 42 connecting the sprockets sets 40, 50.

In the extended configuration, as shown in Figure 1, an end of the subframe 28 abuts an upper end of the monocoque frame 12 to provide additional structural support. The pivot arm 28b of the subframe 28 is pivotally connected to monocoque frame 12 by a pivot 13. The pivot 13 is located towards a forward leading edge at the bottom portion of the monocoque frame 12. By the pivot 13, the subframe 28 is rotatable about the monocoque frame 12 to convert the bicycle 10 between the extended configuration of Figure 1 and the collapsed configuration of Figure 2. In the collapsed configuration, the end of subframe 28 is free from the monocoque frame 12.

More specifically, in contrast to conventional collapsible cycles where the front and rear sections of the bicycles are sideway pivotable, the subframe 28 and the monocoque frame 12 of the present invention are pivotable in a plane extending vertically along the longitudinal axis of the bicycle. That is, the monocoque frame 12 and the subframe 28 are arranged to rotate towards each other whilst remaining in the same plane. During converting, the front and rear wheels 30, 34 move towards each other in the vertical plane until they make contact in the collapsed configuration, in which the bicycle 10 is supported by both the front and rear wheels 30, 34 on the ground. Thus, the overall length of the bicycle 10 is significantly reduced. In some embodiments, the front and rear wheels may not contact each other in the collapsed configuration. Furthermore, the front wheel 34 is partially enclosed in the monocoque frame 12 in the collapsed configuration, thereby restricting its sway.

The bicycle 10, in the collapsed configuration, is manoeuvrable on its rear wheel 30 by pulling on the handle bar. More specifically, by lifting the handle bar, a rider may tilt the front end of the collapsible cycle 10 upwardly and lifts the front wheel 34 off the ground. Alternatively, the rider may manoeuvre the collapsed bicycle 10 on both the front and rear wheels 30, 34 without lifting up its front end.

One or more toggle latches (not shown) are provided to removably retain the subframe 28 in place in both the collapsed configuration and the extended configuration.

In the collapsed configuration, a majority of the seat post 16 is received into the monocoque frame so as to reduce the overall height of the bicycle 10 when it is put into the collapsed configuration.

Referring back to Figure 1, the front sprocket set 50 is mechanically connected to the rear sprocket set 40 by the drive chain 42. In use, a rider may push on a pedal 121 to rotate the crank axle 200 and the front sprocket set 50 in a first rotational direction 202. By the drive chain 42 and the rear sprocket set 50, the driving force is transferred to rear wheel 30 for driving forward motion in the cycle 10.

The drive chain 42 loops around a sprocket in each of the rear and front sprocket sets 40, 50, as well as engaging with a guide sprocket 70 and a tension sprocket 90 in a rear derailleur assembly. In the illustrated embodiment, the front sprocket set 50 comprises a single sprocket whilst the rear sprocket set 40 comprises four sprockets of different sizes, thus only the rear derailleur assembly is featured. In other embodiments, the front and rear sprocket sets may have any number of sprockets as required and may feature an additional front derailleur. The guide sprocket 70 is configured to move in a direction parallel to the rear axle 32 so as to displace the drive chain 42 to other sprockets in the rear sprocket set 40. The tension sprocket 90, biased by a biasing means, is configured to maintain the tension in the drive chain as it loops around the various sprockets of the rear sprocket set 40.

Slidable pedal in combination with a magnetic sensor arrangement

In conventional bicycles, a rider only pushes on the foot pedals to drive forward motion in the bicycle, and relies on a hand-operated gear selector for selecting an appropriate gear, or a handoperated brake lever for slowing down the bicycle. In a second embodiment of the present invention, a crank assembly is provided which allows the rider to select gear or to apply braking when sliding the foot pedals sideways to the bicycle.

Figures 3 and 4 are respectively a side view and a plan view of a crank assembly according to a second embodiment of the present invention. The crank assembly is shown installed onto the collapsible bicycle 10 of Figures 1 and 2 as an example. However, such a crank assembly is also applicable to any suitable cycle. Figure 4 shows a truncated view of a crank axle 200 extending through the monocoque frame 12 along a first axis 60 and is rotatably supported on the monocoque frame 12 by suitable bearings (not shown). In relation to a conventional bicycle, the crank assembly can also be mounted onto a bottom bracket.

The crank assembly comprises a crank arm 100 having a first proximal end 102 and a second distal end 104 opposite to the first proximal end 102. The first proximal end 102 of the crank arm 100 comprises a square tapered aperture through which an end of the crank axle 200, having a complementary profile, extends and is coupled thereto. Thus, the crank arm 100 may pivot about the first axis 60 to drive rotation movement in the crank axle 200. For simplicity, Figures 3 and 4 do not show a front sprocket set but it is nevertheless coaxially installed onto the crank axle 200.

The second distal end 104 of the crank arm 100 comprises a fork end defining a space in which a pivot block 108 is inserted. The pivot block 108 is pivotally connected to the fork end by a guide pin 106, which extends through both the fork end and the pivot block 108. Such an arrangement allows the pivot block 108 to rotate about the guide pin 106. The pivot block 108 comprises a pivot block aperture through which a spindle 122 of a pedal assembly 120 extends. The spindle 122 defines a second axis 62 parallel to the first axis 60. The pedal assembly 120 further comprises a pedal 121 rotatably mounted on the spindle 122 by suitable bearings (not shown). Thus, similar to conventional crank assemblies, a rider may push on the pedal 121 in a direction perpendicular to the second axis 62 to rotate the crank axle 200, so as to drive forward motion in the bicycle 10.

By the pivoting movement in the pivot block 108, the pedal assembly 120 is pivotable about the guide pin 106 in a plane parallel to the second axis 62. The pivoting motion allows the pedal assembly 120 to convert between an extended configuration as shown in Figure 4 and a collapsed configuration as shown in Figure 6. More specifically, in the rideable configuration, the spindle 122 extends substantially parallel to the first axis 60 so as to allow the rider to push on the pedal 121 to drive rotation in the crank axle 200. In contrast, in the collapsed configuration, the spindle 122 is oriented perpendicularly to the first axis 60. This feature is particularly beneficial for collapsible bicycles as the collapsed pedal in the collapsed configuration reduces their overall widths.

The crank arm 100 further comprises an internal sprung latch mechanism 150 for securing the pivot block 108 in the rideable configuration. That is, the sprung latch mechanism 150 comprises a spring-loaded latch receivable in a notch formed on pivot block, such that during normal pedalling the spindle 122 is kept parallel to the first axis 60. To convert the pedal assembly to the collapsed configuration, the rider may slide a toggle button 152 along the crank arm 100 to counteract the biasing force, thereby retracting the spring-loaded latch from the notch to free up the pivot block 108.

In contrast to conventional crank assemblies, the pedal assembly 120 is configured to slide from a first axial position to at least a second axial position along the second axis 62. More specifically, by the sliding movement, the rider may perform certain functions when the pedal assembly is put into the second axial position.

Referring to Figure 4, a guide slot 126 is opened through the spindle 122 along the second axis 62. The guide pin 106, which extends through the pivot block 108, also extends through the guide slot 126. Thus, by the relative sliding movement between the guide pin 106 and the guide slot 126, the pedal assembly 120 may slide through the pivot block aperture along the second axis 62.

The guide slot 126 generally defines the extent of the sliding movement in the pedal assembly 120. As shown in Figure 4, where the pedal assembly 120 is positioned at a first axial position, e.g. it is furthest removed from the monocoque frame 12, the guide pin 106 abuts one end of the guide slot 126. The first axial position may be referred to as a default pedalling position.

When the pedal assembly 120 slides towards the monocoque frame 12 to a second axial position as shown in Figure 5, the guide pin 106 abuts an opposite end of the guide slot 126 where further movement along the second axis 62 is prohibited. The stroke of the sliding movement in the given example ranges from 10 - 15mm, but the stroke may be different in other embodiments. For example, the stroke of the sliding movement may correspond to a range of displacement in the corresponding derailleur or brake actuator.

In the illustrated embodiment, the spindle 122 comprises a hollow tube in which a compression spring 124 is provided. More specifically, one end of the compression spring 124 abuts a closure member 130 and biases against the guide pin 106 at the other end. Thus, the compression spring 124 biases the pedal assembly 120 away from the monocoque frame 12. Such an arrangement ensures the pedal assembly 120 is always biased towards the first axial position during normal pedalling.

The closure member 130 is a screw threadedly installed in the hollow tube. By turning the closure member 130 it can reposition along the second axis relative to the hollow tube, and thereby varying the amount of biasing force applicable by the compression spring 124. More specifically, the force required to move the pedal assembly 120 from the first axial position to the second axial position may be adjusted by turning the closure member 130 relative to the spindle 122. Alternatively, the closure member 130 may be a stopper fixedly attached to the hollow tube.

In some other embodiments, the pedal is sequentially moveable between the first axial position and a plurality of further axial positions along the second axis. For example, the plurality of further axial positions may comprise at least a second axial position and a third axial position each corresponding to a sprocket of the front sprocket set or the rear sprocket set. The crank assembly may further comprise an indexing arrangement for removably retaining the pedal at each of first axial position and the one or more further axial positions. Thus, sequential gear selection may be achieved by moving the pedal sequentially through the various axial positions.

Moreover, in these embodiments, the indexing arrangement may comprise a sprung ball retainer at the guide pin. The sprung ball retainer may configure to removably retain the pedal at desired axial positions by a notch provided at each of the first axial position and the plurality of further axial positions at the guide slot. The retaining force exerted by the sprung ball retainer may be sufficient to overcome the biasing force from the biasing means, i.e. if a biasing means is also provided, and it may be overcome by the rider when a force is applied to move the pedal along the second axis.

The spindle 122 further comprises a flange washer 128 arranged between the pedal 121 and the pivot block 108. As shown in Figure 5, the pedal assembly 120 may slide towards the monocoque frame 12 until the flange washer 128 makes contact with the pivot block 108, thereby it acts as an end stop that limits the axial movement of the pedal assembly 120. The flange washer 128 may be threadedly attached to the spindle 122 so that its axial position may be adjusted for varying the extent of movement in the pedal assembly 120.

In the illustrated embodiment, the crank assembly comprises a sensor arrangement 140,142 arranged to sense the axial position of the pedal 121 along the second axis 62. The sensor arrangement comprises a reed switch 142 that is installed on the monocoque frame 12 for sensing the proximity of a rare earth magnet 140 attached to a proximal end of the spindle 122. As shown in Figure 4, the reed switch 142 is arranged at a position on the monocoque frame 12 such that it aligns with the rare earth magnet 140 along the second axis 62 once in every crank revolution. The reed switch 142 is shown positioned on an exterior surface of the monocoque frame 12 in Figure 4, but it can be attached inside the monocoque frame in other embodiments.

As shown in Figure 4, when the pedal 121 is put in the first axial position during normal pedalling, e.g. the axial position that is furthest away from the monocoque frame 12, the reed switch 142 is put in an ‘off position and therefore it does not generate a signal. In order to perform a particular function, the rider may slide the pedal towards the monocoque frame 12 to the second axial position as shown in Figure 5. As such, the magnetic field as sensed by the reed switch 142 strengthens, and once it exceeds a predetermined threshold the reed switch 142 is put in an ‘on’ position and thus generates a signal to a controller or an electronic device for carrying out the said function. As the rider ceases applying force in the pedal 121 along the second axis 62, the compression spring 124 biases the pedal 121 back towards its first axial position suitable for normal pedalling.

In some other embodiments, the reed switch may be installed on the spindle for sensing the proximity of a rare earth magnet attached to the monocoque frame, wherein the signal may be transferred to a controller wirelessly, e.g. by a Bluetooth connection, or by physical wiring. In these embodiments, the reed switch may be energised by a battery or a capacitor, or by the rotating motion in the pedal assembly.

The use of the reed switch 142 is sufficient for monitoring the pedal movement across two axial positions, e.g. the first axial position as shown in Figure 4 and the second axial position as shown in Figure 5. For applications that require detection at more than two axial positions, or when the precise pedal position along the second axis is required, other magnetic sensors such as Hall effect sensors may be used in lieu of the reed switch. In some other embodiments, the sensor arrangement may comprise other sensors such as optical sensors, infrared sensors and ultrasound sensors.

In the illustrated embodiment, the signal is configured to control an electronic gear selector (not shown) such as a front electronic derailleur and/or a rear electronic derailleur respective for the front and/or rear sprocket sets. Thus, in contrast to known examples, the present invention allows gear selection to be controlled by the movement of the pedal 121 along the second axis 62. Upon receiving the signal, the electronic front and/or rear derailleur displaces the drive chain, in a direction parallel to the first axis 60, to a plurality of gear positions, each of which corresponds to a sprocket of the respective sprocket sets.

In the present example, a second crank arm (not shown) is attached to an end of the crank axle 200 opposite to the crank arm 100, wherein a second pedal (not shown) is rotatably attached to a second end of the second pedal, and is sliding moveable relative to the second distal end of the second crank arm along a third axis parallel to the first and second axes. More specifically, two crank arms are provided on each side of the crank axle 200, and are substantially opposite to each other when viewed along the first axis 60. Thus, the sliding movements in the pedal 121 and the second pedal along their respective second axis 62 and third axis allow two different functions to be independently performed.

In the illustrated embodiment, the pedal 121 and the second pedal are configured to control gear selection in opposite directions. For example, the pedal 121 and the second pedal may each have a first axial position distal to the monocoque frame 12 adoptable during normal pedalling, and a second axial position proximal to the cycle frame for effecting gear selection. That is, the rider may upshift by sliding the pedal from its first axial position to its second position, and downshifts by moving the second pedal from its first axial position to its second position.

In some other embodiments, the pedal 121 and the second pedal are each configured to control gear selection at one of the front and rear derailleurs. More specifically, the pedal 121 and the second pedal are sequentially moveable between a plurality of axial positions along their respective second and third axes, where each of the plurality of axial positions corresponds to a sprocket in the respective front and rear sprocket sets.

In some other embodiments, the signal is configured to control an electronic brake actuator, thereby allowing braking to be controlled by the movement of the pedal and/or the second pedal along their respective second and/or third axes. The electronic brake actuator may control the front and/or rear brakes of the cycle. Upon receiving the signal, the electronic brake actuator may apply a braking force to the rim of the wheel or a brake disc to slow down the bicycle. In some embodiments, the braking force applicable may correspond to the amount of axial movement in the pedal and/or the second pedal along their respective second axis and third axis.

Advantageously, the sliding movement in the pedal 121 along the second axis 62 may be used for controlling braking and/or gear selection in a bicycle 10, thus reducing or eliminating the need for hand-operations from the rider.

Slidable pedal in combination with a contact switch

Figures 7A and 7B are plan views of a pedal assembly 220 having a pedal 221 in respectively a first axial position and a second axial position according to a third embodiment of the present invention. For conciseness, the details of the sliding mechanism are omitted in Figures 7A and 7B but they are nevertheless present. The pedal assembly 220 is structurally similar to the pedal assembly 120 of the second embodiment, in that the pedal 221 is slidable relative to a spindle 222 along the second axis 62. In contrast, the axial position of the slidable pedal 221 is not sensed by a magnetic sensor. Instead, its axial position is detected by a contact switch 270 triggerable at the second axial position.

Referring to Figure 7A, the pedal assembly 220 comprises a Bluetooth signal emitter 260 concealed inside the pedal 221. The Bluetooth signal emitter 260 is configured to communicate wirelessly with a corresponding Bluetooth signal receiver 262 shielded inside a monocoque frame 12. The proximity between the signal emitter 260 and the signal receiver 262, as well as openings and gaps at the monocoque frame 12, ensure adequate wireless transmission even if the monocoque frame 12 is formed from metal.

The Bluetooth signal is encoded to the specific emitter/receiver pairing. Thus the signal does not interfere with other Bluetooth devices in the vicinity of the bicycle. In some other embodiments, other types of radio signals may be used for wirelessly transmitting the signal in lieu of the Bluetooth signal.

The signal emitter 260 and the signal receiver 262 are each provided with a power source. More specifically, the signal emitter 260 is energised by a rechargeable battery 272 that is concealed in the pedal, which in turn is energised or charged by a dynamo (not shown) located between the spindle 222 and the pedal 221 that converts the rotational movement in the pedal 221 into electrical current.

The signal emitter 260 and the battery 272 are switchably connected by the contact switch 270. That is, when the pedal 221 is in the first axial position as shown in Figure 7A, the contact switch is opened and therefore the signal emitter 260 is not energised. When the pedal 221 is slid to a second axial position as shown in Figure 7B, a protrusion 274 circumferentially provided on the spindle 222 pushes onto the contact switch 270, thereby closing the circuit to establish wireless communication between the signal emitter/receiver 260, 262. The signal receiver 262 then relays the received signal to a controller or other electronic devices for carrying out gear changes or braking. In some other embodiments, the signal emitter may not be switched on/off by the contact switch. Instead, the signal emitter may be continuously energised during use. In these embodiments, the contact switch may be electrically connected to the signal emitter such that, upon detecting the pedal is slid into the second axial position, the signal generated by the contact switch may be transmitted from the signal emitter to the signal receiver.

Figures 8 A and 8B are plan views of a pedal assembly 320 having a pedal 321 in respectively a first axial position and a second axial position according to a fourth embodiment of the present invention. For conciseness, the details of the sliding mechanism are omitted in Figures 8A and 8B but they are nevertheless present. The pedal assembly 320 is structurally similar to the pedal assembly 220 of the third embodiment, in that the axial position of the pedal 321 is detected by a contact switch 370 triggerable at the second axial position. In contrast, the signal generated by the contact switch 370 may be transmitted optically between an Infrared (IR) emitter 382 and an IR receiver 384.

The pedal assembly 320 comprises an IR controller 380 concealed inside the pedal 321. The IR controller 380 is in electrical connection with, and controls the operations of, a plurality of IR emitters 382. The IR emitters are positioned on a sidewall of the pedal 321 facing the monocoque frame 12, and are configured to project IR waves or light signals through an opening 12b at the monocoque frame 12. The IR receiver 384 is provided inside the monocoque frame 12b and positioned behind the opening 12b for receiving the IR signals emitted from the IR emitters 382. In some embodiments, there may be a plurality of IR receivers and respective openings distributed around the crank axle for receiving the IR waves emitted by the IR emitters, as the pedal assembly 220 rotates around the crank axle during normal use. In some other embodiments, other optical transmission devices may be used in lieu of the IR emitter/receiver, e.g. laser and/or visible light.

Similar to the pedal assembly 220 of the third embodiment, the IR controller 380 and the IR receiver 384 are each provided with a power source. More specifically, the IR controller 380 is energised by a rechargeable battery 372 that is concealed in the pedal 321, which in turn is energised or charged by a dynamo (not shown) located between the spindle 322 and the pedal 321 that converts the rotational movement in the pedal 321 into electrical current. The IR controller 380 and the battery 372 are switchably connected by the contact switch 370. That is, when the pedal 321 is in the first axial position as shown in Figure 8 A, the contact switch 370 is opened and therefore the IR controller 380 is not energised. When the pedal 321 is slid to a second axial position as shown in Figure 8B, a protrusion 374 circumferentially provided on the spindle 322 pushes onto the contact switch 370, thereby closing the circuit to energise the IR controller 380 and the IR emitter 382 to emit the IR signals. Through the opening 12b the IR signals are received by the IR receiver 384 which is then relayed to a controller or other electronic devices for carrying out gear change or braking.

In some other embodiments, the IR controller may not be switched on/off by the contact switch. Instead, the IR controller and the IR emitters may be continuously energised during use. In these embodiments, the contact switch may be electrically connected to the IR controller such that, upon detecting the pedal is slid into the second axial position, an IR signal that is specific to the second axial position (e.g. the said IR signal corresponding to the second axial position may be modulated differently to that specific to the first axial position) may be generated by the IR emitter to indicate a change in the axial position of the pedal.

Electronically controlled derailleur assembly

In conventional electronically controlled derailleurs, the guide sprocket is arranged to displace in both the vertical plane and the horizontal direction by moving a chain guide with an electronic actuator. More specifically, the chain guides in known examples only move upon receiving a user input. According to the present invention, there is provided an electronic actuator that is configured to operate in a mode that automatically shifts the drive chain to the lowest gear upon accelerating from a standstill.

Figures 9 and 10 are cross-sectional plan views of a derailleur assembly according to a fifth embodiment of the present invention, taken across a horizontal plane through the rear axle 32. Figures 9 and 10 respectively shows the drive chain 42 engages with the largest sprocket 40d and the smallest sprocket 40a in the rear sprocket set 40.

The derailleur assembly as shown in Figure 9 is a rear derailleur assembly installed at the rear axle 32 of the bicycle 10, but it may also serve as a front derailleur for the crank axle in other embodiments. In the illustrated embodiment, the derailleur assembly is installed onto the collapsible bicycle 10 as shown in Figures 1 and 2 as an example, but the derailleur assembly may nevertheless be used with any suitable cycle.

As shown in Figure 9, the rear axle 32 is rotationally mounted onto the monocoque frame 12 by suitable bearings (not shown). The rear axle 32 defines a rear axis 64 having the rear sprocket set 40, the rear wheel 30, and a brake disc 226 coaxially mounted thereon. The rear sprocket set 40 is connected with the front sprocket set 50 by the drive chain 42.

The rear sprocket set 40 comprises a series of four sprockets 40a-40d that incrementally increase in diameter, or size. For example, the sprockets 40a, 40b, 40c and 40d respectively having 14, 17, 20, 24 teeth provided around their circumferences. As the drive chain 42 sequentially shifts through the sprockets 40a-40d they result in a gradual change in pedalling cadence. Due to the differences in the sprockets sizes, the rear sprocket set 40 have a generally tapered side profile, represented by a dotted nominal line 44 extending across the apexes (or leading teeth aligned in the horizonal plane) of all of the sprockets 40a-40d. The nominal line 44 extends at an angle a to the rear axis 64. In this particular example, the angle a is 50°.

In some other embodiments, the rear sprocket set may comprise any plural number of sprockets each having different sizes, resulting in a change in the gradient of the nominal line. Thus, the angle a in these embodiments may range between 30° to 70°, or between 40° to 60°, or between 45° to 55° to the rear axis.

The derailleur assembly comprises a guide rail 80 extending substantially in the horizontal plane and at an angle a to the rear axis 64. More specifically, the guide rail extends parallel to the nominal line 44 and thus it is separated to the teeth of all of the sprockets 40a-40d by substantially the same gap. In the illustrated embodiment, the guide rail 80 extends diagonally across the longitudinal axis 66 of the bicycle 10, and fixedly mounts onto opposite sides of the monocoque frame 12 by suitable brackets. The brackets are suitably sized to offset the position of the guide rail 80 along the longitudinal axis 66, so as to provide sufficient clearance between the guide rail 80 and the rear sprocket set 40.

In some other embodiments, in particular ones that feature a conventional bicycle frame, the guide rail may not extend across the longitudinal axis, but instead, the first end of the guide rail may attach to a fork end of the frame that mounts the rear axle, and the second end attached to a bottom bracket of the bicycle.

The guide rail 80 is positioned forward of the rear wheel 30, and is shielded from grit by a mudguard 34 surrounding the rear wheel 30. Such an arrangement utilises a space that is normally left unoccupied in conventional bicycles.

As shown in Figure 9, a chain guide 72 is slidably mounted on the guide rail 80 by suitable bearings (not shown). The chain guide 72 comprises arms 73 towards one end onto which the guide sprocket 70 is rotatably mounted. The guide sprocket 70 is aligned with a vertical plane and is rotatable about an axis parallel to the rear axis 64. In some embodiments, the guide sprocket is sandwiched between a pair of chain shields (not shown) when it is installed onto the arms 73. The chain shields may have a diameter larger than, or substantially equal to that of the guide sprocket so as to prevent the chain from derailing from the chain sprocket.

The chain guide 72 is slidingly moveable between a plurality of positions along the guide rail 80 each corresponds to a sprocket 40a-40d of the rear sprocket set 40. For example, the chain guide 72 as shown in Figure 9 is at a position corresponding to the largest sprocket 40d, and at a position corresponding to the smaller sprocket 40a as shown in Figure 10. Thus, at each of the positions, the guide sprocket 70 is parallel to, and separated by a substantially constant gap to, the corresponding sprocket 40a-40d. More specifically, the parallelity between the guide rail 80 and the tapered side profile of the rear sprocket set 40, e.g. the nominal line 44, maintains a substantially constant separation through the range of sliding movement and advantageously minimises rattling and the risk of chain derailment.

As shown in Figures 9 and 10, the movement of the chain guide 72 along the angled guide rail 80 is greater than the displacement in the drive chain 42 parallel to the rear axis 64. More specifically, since the guide rail 80 extends at an angle to the axis, any movement in the chain guide 72 parallel to the nominal line 44 would result in a relatively smaller displacement in the drive chain 42. Advantageously, such an arrangement may allow the displacement in the drive chain 42 to be more precisely controlled.

The relative sliding movement between the chain guide 72 and the guide rail 80 is driven by a motor 78 (e.g, an electronic actuator) in combination with a rack 76a and pinion 76b gearing. The motor 78 is fixed attached to the monocoque frame 12. The pinion gear 76b is mounted onto an output shaft of the motor 78, and is configured to engage the corresponding rack 76a that is fixed attached to the chain guide 72. This allows the rotational movement at the output shaft to be converted to a linear sliding movement in the chain guide 72. For example, upon receiving an upshift or a downshift signal from an electronic shifter (not shown), the output shaft of the motor 78 rotates in a direction corresponding to the signal. By the rack and pinion gearing 76a, 76b, the chain guide 72 slides along the guide rail 80 to a different position corresponding to the desired sprocket 40a-40d in the rear sprocket set 40. This causes the guide sprocket 70 to displace the drive chain 42 onto the desired sprocket and provides the rider with a suitable cadence.

In the illustrated embodiment, the derailleur assembly comprises an optical switch 79 fixedly connected to a part of the cycle, e.g. the frame 12. In the illustrated embodiment the optical switch 79 is a through-hole slotted optical switch. The optical switch 79 is electronically communicable with the motor 78 (or electronic actuator). The optical switch 79 comprises an optical emitter and a corresponding optical receiver provided on respective sides of the chain guide 72. The optical emitter is configured to vertically project optical radiation, e.g. an IR beam, towards the chain guide and the optical receiver. The chain guide 72 comprises a slot 74 at each of the positions for allowing or disrupting the said optical radiation, so as to cease the sliding movement of the chain guide 72 at each of the positions. For example, when the chain guide 72 has traversed to one of the positions, the slot opened at the said position allows the IR beam to pass therethrough and be sensed by the optical receiver. As such, once the chain guide has reached the required position the optical switch 79 signals the motor 78 to cease the sliding movement of the china guide 72, and thereby retains the chain guide 72 at the said position.

Alternatively, the chain guide may be provided with a protrusion, e.g. a finger, at each of the positions for disrupting the optical radiation when the chain guide has traversed to the said position. Upon sensing a blockage of IR beam, the optical switch signals the motor to cease the sliding movement of the china guide, and thereby retains the chain guide at the said position.

In some other embodiments, a sprung ball indexing arrangement may be provided to movably retain the chain guide at each of the positions. For example, the guide rail may be provided with a notch at each of the positions for receiving a sprung ball mechanism that is fitted to the chain guide. This advantageously may allow the chain guide to be physically retained, by the biasing force from the sprung ball mechanism, at each of the positions when the motor is not actuated. In order to initiate sliding movement in the chain guide, the motor would have to first overcome the biasing force to dislodge the sprung ball mechanism from the notch and thereby freeing up the chain guide.

The derailleur assembly further comprises a chain movement sensor (not shown) that senses the rotational movement in the rear sprockets set 40. Since the drive chain 42 is engaged with one of the sprockets 40a-d in the rear sprockets set 40, any rotational movement in the rear sprockets set 40 also reflects movement in the drive chain 42. Specifically, the onset of the drive chain 42 movements can be sensed when the rear sprockets set 40 starts rotating.

The derailleur assembly further comprises a gear position sensor (not shown) that senses the position of the chain guide 72 with respect to the guide rail 80. In the simplest form, the gear position sensor comprises a single contact switch at a position along the guide rail 80 in which the drive chain 42 engages with the largest sprocket 40d.

Referring to Figure 11, the electronic shifter is configured to operate in a mode in which it automatically moves chain guide 72 to a position corresponding to the largest sprocket 40d (e.g. as shown in Figure 9) in absence of user input 430 upon: sensing, by the chain movement sensor, the onset of drive chain movement 400; and sensing, by the gear position sensor, the chain guide corresponds to a position other than the largest sprocket of the multi-stage sprocket assembly 420.

The chain guide 72 may move along the guide rail 80 only when there is a movement in the drive chain 42. This helps the drive chain 42 to derail from an engaged sprocket 40a-c and to subsequently engage with the largest sprocket 40d.

The derailleur assembly further comprises a speedometer (not shown) to sense the bicycle’s actual speed. More specifically, the speedometer is configured to at least sense the bicycle is accelerating from a standstill 410, thereby enabling the electronic shifter to operate in the mode. Thus, the optional inclusion of speedometer reading safeguards the electronic shifter from engaging the lowest gear when the bicycle is coasting at speed. In some other embodiements, the derailleur assembly may employ an alternative chain guide, for example, the chain guide may form part of a parallelogram commonly used in a commonplace derailleur assembly.

Foot actuated brake actuator

In conventional bicycles, a rider may push a pedal in the forward and downward directions to rotate the crank axle in a first rotational direction, so as to drive forward motion in the bicycle. During coasting, a freewheel installed at the rear axle decouples the rotation in the rear wheel from the rear sprocket set, thereby allowing the rider to cease pedalling whilst the bicycle is still in motion. That is, the freewheel at the rear axle only engages when the crank axle is rotating in the first rotational direction. However, the provision of the freewheel at the rear axle also means the rider cannot slow down the bicycle by simply pedalling in a reverse direction. As a result, most of the commercially available bicycles rely on the use of a hand-operated brake lever via Bowden cables to effect braking.

The present invention offers an inventive solution to allow the rider to control a brake actuator when applying force in a reversed pedalling direction, thereby reducing, or eliminating the need for hand-operated brake levers. More specifically, the present invention provides a second freewheel at the crank axle connectable with a brake actuator, which only engages when the crank axle is forced to rotate in a second rotational direction opposite the first rotational direction.

Figure 12 shows a freewheel 210 provided in a crank assembly according to a sixth embodiment of the present invention, using the bicycle 10 of Figures 1 and 2 as an example. However, such a crank assembly is also applicable to any suitable cycle. In relation to a conventional bicycle, the crank axle of the crank assembly can also be mounted onto a bottom bracket.

The freewheel 210 comprises an inner rotor 212 and outer rotor 214 coaxially mounted onto a crank axle 200. More specifically, since the inner rotor 212 is mounted onto the crank axle 200 by a spline connection, the inner rotor 212 rotates with the crank axle 200 when the latter rotates in both the first rotational direction 202 and the second rotational direction 204. In contrast to the freewheels fitted on rear axles of conventional bicycles, the freewheel 210 only engages when the crank axle rotates in the second rotational direction 204, e.g. when the rider applies force in a reversed pedalling direction.

More specifically, during normal pedalling where the crank axle 200 rotates in a first rotational direction 202, the freewheel 210 disengages so that the inner rotor 212 and the crank axle 200 rotates relative to the outer rotor 214. That is, the outer rotor 214 is substantially stationary relative to the first axis 60. On the other hand, when the crank axle 200 rotates in the second rotational direction 204, the freewheel 210 engages, causing the outer rotor 214 to rotate with the inner rotor 212 and the crank axle 200.

In the illustrated example, the outer rotor 214 is a sprocket. The sprocket comprises a plurality of teeth for engaging with a chain. In some other embodiments, the outer rotor may be any type of rotor such as a pulley for engaging a cable.

Figures 13A and 13B show respectively a side view and a plan view of an activated brake actuation system according to the sixth embodiment of the present invention. Whereas Figures 14A and 14B show respectively a side view and a plan view of a deactivated brake actuation system according to the sixth embodiment of the present invention.

As shown in the figures, the freewheel 210 is mechanically connected to a rear brake actuator 220 by a chain 230. More specifically, the chain 230 having a first end connected to the monocoque frame 12, winds around the outer rotor 214 of the freewheel 210 and engages with the teeth of the said outer rotor 214, with its other end connected to a brake caliper 222 of the brake actuator 220.

As shown in Figures 13 A and 13B, when the rider applies a force to crank the crank axle 200 in the second rotational direction 204, the outer rotor 214 engages with the inner rotor 212 and thus it is forced to rotate in the second rotational direction. By the teethed engagement, the rotational movement in the outer rotor 214 tensions the chain 230, and thereby applies an actuation force at the brake caliper 222. In response, the brake caliper 222 compresses a pair of brake pads 224 against the surface of a brake disc 226 to effect braking in the bicycle 10. Thus, the force applied to rotate the crank axle 200 in the second rotational direction 204 is translated to the braking force for slowing down the bicycle 10. Moreover, by the mechanical connection, the braking force applied to the brake actuator 220 is substantially proportional to the force applied at the crank axle 200 in the second rotational direction 204.

In some other embodiments, the brake pads 224 may instead be compressed against the rim of the rear wheel 30 during braking.

The brake pads 224 are configured to disengage from the brake disc 226 when the rider ceases applying force at the crank axle 200 in the second rotational direction 204, e.g. when braking is no longer required. As shown in Figures 14A and 14B, a biasing means 232 is provided to bias the outer rotor 214 to rotate in the first rotational direction 202 to facilitate a prompt disengagement. More specifically, the biasing means 232 is a tension spring having an end connected to the chain at a connection point 234 between the freewheel 210 and the brake actuator 220, and another end connected to the monocoque frame 12 of the bicycle 10. Essentially, the connection point 234 divides the chain 230 into a leading section 236 extending between the connection point 234 and the freewheel 210, and a trailing section 238 extending between the connection point 234 and the brake actuator 220.

The tension spring 232 is configured to apply a biasing force at the connection point 234 with a force component acting towards the brake actuator 220. The tension spring may extend substantially along the chain 230, or it may be angled to or offset to the chain to provide clearance. As such, the biasing force removes the tension in the trailing section 238 of the chain 230, thereby allowing the brake pads 224 to promptly disengage from brake disc 226.

By the biasing force imposed at the connection point 234, the leading section 236 of the chain 230 tensions and therefore biases the outer rotor to rotate in the first rotational direction 202.

In some other embodiment, the tension spring may directly connect between the outer rotor 214 and the monocoque frame 12 to bias the outer rotor in the first rotational direction 202. In these embodiments, the entire section of the chain 230 extending between the freewheel 210 and the brake actuator 220 may slack when the force acting on the crank axle 220 in the second direction is removed. In some embodiments, the biasing means may be other suitable springs such as a torsion spring. During normal pedalling, e.g. when the rider cranks the crank axle in a first rotational direction as shown in Figures 14A and 14B, the outer rotor 214 remains stationary relative to the first axis 60 during normal pedalling. Thus, no actuating force is applied to the brake caliper 220.

In some other embodiments, the crank assembly may comprises a sensor arrangement arranged to sense engagement between the outer and inner rotor, and therefrom generating a signal for controlling the amount of actuating force applicable to the brake actuator. That is, the brake actuators in these embodiments are electronic brake actuator electronically communicable with the sensor arrangement, thus there requires no mechanical connection between the electronic brake actuators and the outer rotors. The sensor arrangement may sense engagement between the outer and inner rotor by sensing the angular displacement of the outer rotor and/or measuring the force applied on the crank axle in the second direction.

For example, the sensor arrangement may comprise a load cell configured to measure the rotational force applicable in the second direction at the crank axle or the outer rotor. Alternatively, it may comprise other sensors for monitoring the angular displacement in the outer rotor, such as optical sensors. The signal may be received by a front and/or a rear electronic brake actuator for applying an actuating force at the brakes. Preferably, the amount of actuating force applicable by the electronic brake actuator increases with and/or proportional to increasing force acting on the crank axle or increasing angular displacement of the outer rotor in the second direction. Thus, the user may pedal in a reversed direction, e.g. the second direction, to effect braking at the front and/or rear brakes, without the need for applying braking by hands.

Advantageously, the freewheel allows braking to be achieved by a reversed pedalling input, thus reducing or eliminating the need for hand-operations from the rider.

Decoupled tensioner member and chain guide

A conventional derailleur typically comprises a single derailleur frame that holds both the guide sprocket and the tensioner sprocket, and therefore the two sprockets move in unison along in both vertical and horizontal directions during a gear change.

In a derailleur assembly according to a seventh embodiment of the present invention, the guide sprocket and the tensioner sprocket are rotatably mounted on respective chain guide and tensioner member, and wherein the chain guide and the tensioner member are moveable relative to each other. Such an arrangement may advantageously decouple the two functions, chain tensioning and chain guidance, in the derailleur assembly. Thus, the vertical displacement as observed in conventional tensioner sprockets may be significantly reduced or eliminated. Moreover, since the movement in the chain guide is decoupled from the tensioner member, the biasing force that is required for chain tensioning no longer acts directly upon the chain guide. Advantageously, less input force may be required from the rider, or the electronic actuator, to effect gear shifting.

Figures 15 and 16 show an enlarged side view of the bicycle 10 of Figures 1 and 2 in combination with the horizontally moveable chain guide 72 of Figures 9 and 10. For simplicity reasons, the guide rail and other components are not shown again. Figures 15 and 16 respectively shows the drive chain 42 engages with the largest sprocket and the smallest sprocket in the rear sprocket set 40.

As shown in Figure 15, the chain guide 72 and tensioner member 92 are distinct elements and are connected by the drive chain 42. More specifically, the drive chain 42 sequentially routes through the tensioner sprocket 90 at tensioner member 92 and the guide sprocket 70 at the chain guide 72 before feeding to a sprocket of the rear sprocket set 40.

A biasing means, in this example a tension spring 94, is fixedly attached between the monocoque frame 12 at fixing point 98 and the tensioner member 92. The monocoque frame also comprises a plurality of tensioner pulleys 96a, 96b are rotatably mounted thereon and are distributed around the rear axle 32. The tension spring 94 is routed through the plurality of tensioner pulleys 96a, 96b such that it is wound around the rear axle 32. Advantageously, this allows a relatively long tension spring 94 to be neatly concealed in the monocoque frame 12, as shown in Figures 15 and 16, as well as providing increased ground clearance to cater for smaller wheels.

The length of the tensioner spring and the number of tensioner pulleys may vary across different embodiments. For example, in some embodiments, more tensioner pulleys may be provided for routing a lengthier tensioner spring, e.g. to provide a larger overall biasing force or to utilise longer tension springs with lower spring constants. In some embodiments, to reduce complexity a shorter length of tension spring may be used which accordingly reduces the number of tensioner pulleys required. This reduces the complexity of the derailleur assembly. In some other embodiments, shorter coil springs or torsion springs with higher spring constants may be used to provide the required biasing force, without the need for any tensioner pulley, e.g. the coil spring or the torsion spring may directly connect between the monocoque frame and the tensioner member.

The tensioner spring 94 is configured to bias the tensioner member 92 away from the front sprocket set 50 and therefore tensions the drive chain 42 to reduce or eliminate slack in the drive chain 42. The tensioner member 92 is suspended by the biasing force in the tensioner spring 94 and the tension in the drive chain 42, and therefore it is moveable in all directions and about all axes.

For example, when shifting the drive chain 42 from the largest sprocket in Figure 9 to the smallest sprocket in Figure 10, the tensioner spring 94 pulls the tensioner member 92 further away from the front sprocket set 50 in order to maintain sufficient tension in the drive chain 42 to eliminate slack, e.g. the tensioner member 92 moves along the longitudinal axis of the bicycle 10.

Since the movement in the chain guide 72 is decoupled from the tensioner member 92, the biasing force that is required for chain tensioning no longer acts directly upon the chain guide 72. Advantageously, less input force may be required from the rider, or the electronic actuator, to effect gear shifting.

The displacement in the drive chain 42 along the rear axis 64 during shifting also displaces the tensioner member 92 horizontally. More specifically, since the tensioner member 92 is not fixedly attached to the frame, it trails the drive chain 42 and the chain guide 72 in a direction parallel to the rear axis 64. For example, in the illustrated embodiment where four sprockets are featured in the rear sprocket set 40, the tensioner member may displace up to 20mm in a direction parallel to the rear axis 64 as it displaces the drive chain 42 through the four sprockets. Advantageously, such an arrangement may allow the tensioner sprocket to maintain adequate alignment with the guide sprocket, and thus minimising rattle and resistance during pedalling.

As shown in Figures 15 and 16, the tensioner member 92 is arranged at a position below the chain guide and an apex of each of the sprockets in the multi-stage sprocket assembly. More specifically, the tensioner member is positioned below the bottom teeth of the largest sprocket in the rear sprocket set 40 so as to provide sufficient clearance when it trails the drive chain 42 in a direction parallel to the rear axis 64.

As shown in Figure 15, one of the tensioner pulley 96b is mounted at a position on the monocoque frame 12 such that a section of the tension spring 94 extends substantially parallel to the section of the drive chain 42 connecting the tensioner sprocket 90 and the front sprocket set 50. Thus, during shifting the tensioner member 92 moves along the direction of the drive chain 42. This advantageously minimises vertical displacement in the tensioner member 92 during a gear change. In some embodiments, the tensioner pulley is positioned such that a section of the tension spring and the section of the drive chain connecting the tensioner sprocket and the front sprocket set extend parallel to the horizontal plane. Thus, during shifting the tensioner member moves only in the horizontal direction.

Advantageously, the vertical displacement as observed in conventional tensioner sprockets may be significantly reduced or eliminated.

Collapsible bicycle comprising a monocoque frame

Figures 17 and 18 are side views of a bicycle 510 in respectively a ridable configuration and a collapsed configuration according to an eighth embodiment of the present invention. The bicycle 510 is a collapsible bicycle where the overall length of the bicycle 510 can be varied to suit riders of different sizes in a ridable configuration as shown in Figure 17, as well as being put into a collapsed configuration as shown in Figure 18 during transportation. The collapsible bicycle 510 is similar to the collapsible bicycle 10 as shown in Figures 1 and 2 and thus for conciseness, like features are not described again.

Towards the front of the bicycle 510 there is provided a subassembly 522, comprising a front wheel 34 rotatably mounted onto a fork 524 by a front axle 36. The fork 524 having a steerer tube at its top end that extends through a headtube 526, wherein bearings are provided in the headtube 526 to aid relative rotation between the said steerer tube and the headtube 526. The steerer tube of the fork 524 is coupled to a handlebar stem 525 fixed attached to a handlebar (not shown). The handlebar stem 525 is partly enclosed in a stem sleeve 527 extending upwardly from the headtube 526. Thus, a rider may rotate the handlebar about the headtube 526 to steer the bicycle 510 into the desired direction. The stem sleeve 527 is configured to pivot about a hinge 529 to convert between the ridable configuration and the collapsed configuration. More specifically, in the rideable configuration, the handle stem 525 extends at an angle to the longitudinal axis of the bicycle 510 and is locked in position by a hinged lever. On the other hand, the handle stem 525 is substantially parallel to the longitudinal axis of the bicycle 510 when the stem sleeve 527 of the bicycle 510 is put into the collapsed configuration. Such an arrangement reduces the overall height of the bicycle when it is collapsed.

The subassembly 522 further comprises an elongated guide frame 528 welded to the headtube 526. The guide frame 528 extends in a horizontal plane along the longitudinal axis of the bicycle 510. The guide frame 528 is of conventional tubular frame construction and may form from any suitable material. The phrase horizontal plane generally refers to a plane parallel to the horizon when the bicycle 510 is set on levelled ground, and may be substantially parallel to a line extending through the front and rear axle of the bicycle.

Referring to Figure 17, a rearward portion of the bicycle 510 comprises a monocoque frame 512 rotatably supported on a rear wheel 30 by a rear axle 32. The monocoque frame 512 forms a load-bearing structure of the bicycle 510 that is configured to distribute some of the weight of the rider (not shown) and the bicycle 510 to the rear axle 32. That is, the monocoque frame 512 is the only load-bearing member connected between a seat post 516 and a crank axle 200 of the bicycle 510 to the rear axle 32. The monocoque frame 512 may be formed from any suitable material such as steel, aluminium, and other composite materials such as a carbon fibre composite. The rear wheel 30 and the front wheel 34 are compact bicycle wheels each having an overall diameter of less than 350mm, commonly referred to as 12 or 14 inches wheels.

The monocoque frame 512 is formed from two monocoque shells joint together along a longitudinal centreline of the bicycle 510. As shown in Figure 17, the monocoque frame 512 fully encloses a rear sprockets set 40, a front sprockets set 50 and their respective derailleurs, as well as the drive chain 42 connecting the sprocket sets 40, 50.

The monocoque frame 512 further comprises a guide channel 514 extending along the longitudinal axis of the bicycle 510 and in the same horizontal plane as the guide frame 528. In the illustrated embodiment, the guide channel 514 extends internally through a front and rear opening of the monocoque frame 512. In some other embodiments, the guide channel 514 only extends through the front opening of the monocoque frame 512 whilst the rear end of the monocoque frame 512 is sealed, e.g. the guide channel 514 does not extend all the way through the monocoque frame in these embodiments.

The guide channel 514 is configured to slidingly receive the guide frame 528. The guide channel 514 has a cross-sectional profile complementary to that of the guide frame 528. The cross-section profiles of the guide channel 514 and the guide frame 528 are non-circular to prevent relative rotation between the subassembly 522 and the monocoque frame 512. By the sliding connection, the monocoque frame 512 joints the subassembly 522 to form the bicycle 510.

The overall length of the bicycle 510 can be adjusted by sliding the guide frame 528 along the guide channel 514 within a movement range to suit riders of different sizes. Furthermore, the guide channel 514 comprises a retaining means for movably retaining the guide frame 528 at any desired position within the said movement range.

For example, to suit a taller rider, the bicycle may be lengthened to its greatest extent by sliding the guide frame 528 towards a first end of the movement range, e.g. towards the front of the monocoque frame 512. On the other hand, as shown in Figure 18, the bicycle 510 may be put into the collapsed configuration by sliding guide frame 528 towards a second end of the movement range, which significantly shortens the overall length of the bicycle. To suit shorter or smaller riders, the guide frame 528 may slide to a position between the two ends of the movement range.

As shown in Figure 18, the seat post 516 is configured to be inserted into the guide channel 514 through a rear opening of the monocoque frame 512 when the bicycle 510 is put into the collapsed configuration. More specifically, the seat post 514 may be received in, and coextends with, both the guide channel 514 and the guide frame 528. Such an arrangement reduces the overall height of the bicycle 510 when it is put into the collapsed configuration.

The bicycle 510 further comprises a support wheel 538 rotatably supported at the rear end of the monocoque frame 512. The support wheel 538 extends in the same plane as the front wheel 34 and the rear wheel 30, and is positioned upward of the rear wheel 30 as shown in Figures 17 and 18. When the bicycle 510 is put into the collapsed configuration as shown in Figure 18, the bicycle 510 may be pivoted about the rear axle 32 and be supported on both the rear wheel 30 and the support wheel 538. Thus, the rider may transport the bicycle 510 with relative ease by the support wheel 538 and the rear wheel 30.