This invention relates to improvements in responsiveness of bicycle drive mechanisms. This invention particularly relates to a clutch system to provide positive drive to a hub of a bicycle, although it will be appreciated that the invention may be used with any manually-driven vehicle.

This invention relates to the field of manually-driven vehicles and particularly bicycles. Throughout the document, use of the word "bicycle" refers to bicycles, tricycles and all other manually-driven vehicles.

The present invention relates to wheel hubs and primarily bicycle-type wheel hubs with clutches where the hub is freewheeling when torque is not being applied to the hub through a sprocket that is linked by a chain to a pedal-operated drive arrangement, and will engage to transfer torque to a wheel hub when torque is applied to the drive arrangement.

Generally, hubs for bicycles have a one-way ratchet locking mechanism. When power is transmitted, the dog teeth or pawls lock to a hub outer body giving drive. When freewheeling, the dog teeth or pawls run over the hub outer body causing a noise.

Such wheel hubs have clutches capable of freewheeling and will engage when a torque is applied to the rear driven wheel hub through a chain linked to a pedal- operated drive arrangement mounted on a drive shaft on the bicycle frame. Such bicycles can be directly driven through a drive arrangement incorporating a single sprocket or multiple sprockets. One such earlier design is a ratchet-type design that includes an annular ring gear having its outer circumference secured to the inner wall of a hub body and includes teeth or notches formed around the ring gear inner circumference that slope in the direction of turning of the hub body when it is freewheeling, and includes pawls that are spring biased and are connected to extend outwardly at spaced intervals from around a pedal assembly that each have a tooth end. In freewheeling operations, the outwardly biased pawl tooth ends will each travel up the slope of each ring gear tooth or annular notch, and with the spring biasing to extend each pawl tooth end to cause the pawl end to travel down the tooth or annular, notch face and engage the next tooth or annular notch face. Thereby, when the pedal-operated drive arrangement is turned, that turning will be against the

slope of the ring gear teeth or annular notch, and the pawl tooth ends will engage and bind against the ring gear teeth faces or annular notches, transmitting an applied torque through the ring gear and into the wheel hub body to drive the wheel.

However, such ratchet means have a delay in action until the pawl tooth ends engage the ring gear teeth or annular notches. Such delay causes a delay in the applied force being effective and can give rise to the cyclist making errors of judgement to try to compensate for the delay. This can result in loss of balance in cornering, as the weight of the rider can be incorrectly positioned due to the error in delayed effect of the driving force. The need for the cyclist to compensate for the error is an undue burden, particularly in road racing.

Other earlier systems have employed ball bearing assemblies for power transfer through a hub to turn a wheel, the assemblies having a series of spaced pockets that each incorporates a sloping side configuration and require a ball in each pocket to bear both a radial load, that is applied perpendicular to the bearing assembly, and axial loads as are transmitted through the axle. The balls are readily deformed and become an efficient drive mechanism quite quickly.

It is therefore desirable to provide an improved bicycle drive mechanism to overcome or at least ameliorate the problems of the prior art.

It is also an object of the invention to provide an improved hub and clutch design to provide immediate drive action.

It is also desirable to provide an improved bicycle drive mechanism which is relatively cheap and easy to manufacture, install and use and which provides a good weight to strength ratio.

In accordance with the present invention there is provided a bicycle drive mechanism for mounting on a wheel axle, the mechanism comprising a hub having a coaxially arranged bore to accommodate the wheel axle and including the central structure of a wheel in the form of spaced discs made integral with the outer ends of the hub, said discs including holes for receiving spokes to form a spoked wheel able to rotate freely on the wheel axle; a drive axle fixed coaxially to the hub and extending laterally from one of its ends, the drive axle including a smooth cylindrical outer surface for receiving a combination of needle roller bearing and needle roller clutch in a common cage, the combination of needle roller bearing and needle roller

clutch in a common cage including two internal sets of rollers such that a first allows free wheeling in one direction and the second provides an instant gripping and direct drive in the opposite direction; and a sleeve having an inner surface for mounting on the combination of needle roller bearing and needle roller clutch in a common cage and an outer surface shaped to receive an engagement means such as a sprocket or cluster of sprockets for connection and driving through a chain and drive means such as a pedal-operated drive arrangement operated by the rider; wherein the engagement means can freewheel or when driven in the appropriate direction through the chain and drive means cause immediate drive of the hub and, thereby, drive of the wheel of the bicycle.

The hub and the drive axle can both include respective axial ly-arranged bores and the drive axle can be mounted to the hub such that the hub and drive axle both can in unison rotate freely on the wheel axle of the bicycle.

The mounting of the drive axle to the hub can be by one lateral inner side of the hub at the end of its coaxial bore including a stepped annular collar having an internal screw thread and the drive axle having at one end a complementary external thread for engaging the internal thread of the hub and being fixed to the hub and supported thereby. To provide a strong attachment, the end of drive axle abuts the inner lateral end of the hub when the drive axle is screwed into the internal screw thread of the hub.

Lock-up or drive-point occurs when the drive axle abuts or screws up and locks to the hub to obtain final drive from the clutch bearing.

The drive axle can include a coaxially-arranged, shaped internal surface for receiving an Allen key or other complementary-shaped driving means sized to fit neatly within the shaped internal surface of the drive axle and employed to assist in tightening of the screw thread of the drive axle into the complementary thread of the hub. Preferably, the shaped internal surface is located at the same end of the drive axle as the external thread.

The mounting of the drive axle to the hub can be by splines provided on the outer surface of the drive axle and the inner surface of the coaxial bore of the hub.

Therefore, the attachment of the hub can be in three configurations depending on the model:

1. the drive axle is screwed into the hub at a set depth to a lock up/drive point.

2. the drive axle is pressed into the hub then side screws used to obtain lock up/drive. 3. an outer drive axle and the hub have, respectively, male and female splines which press together to achieve lockup/drive, and alignment is then achieved by the positioning of a second, close fitting inner drive axle within the coaxial bores of the outer drive axle and hub and the screwing of a thread on the end of the inner drive axle into a complementary thread of the hub.

The drive axle can include bearing means to support it while allowing free rotation of the drive axle on the wheel axle.

The outer end of the drive axle can include an end shoulder extending radially larger than the smooth cylindrical outer surface for receiving the combination of needle roller bearing and needle roller clutch in a common cage so as to retain the combination of needle roller bearing and needle roller clutch in a common cage in position. The end shoulder can be formed by a screw end cap having a central opening for receiving the end of the wheel axle. The screw end cap can have a threaded engagement to the wheel axle. The handing of the threaded engagement is preferably opposite to the freewheeling direction of the hub, so as to decrease the chance of accidental unthreading.

The screw end cap can include a bearing mounting for allowing support of the drive axle in free rotation on the wheel axle.

The invention provides a mounting system on a hub of a bicycle enabling use of a combination of needle roller bearing and needle roller clutch in a common cage including three internal sets of rollers such that two outer sets allow freewheeling in one direction and the third inner set provides an instant gripping and direct drive in the opposite direction, the mounting system including mounting of a drive axle to the hub and able to receive the combination of needle roller bearing and needle roller clutch in a common cage in operative connection. The mounting system can include a shaped sleeve for engaging between the combination of needle roller bearing and

needle roller clutch in a common cage and a sprocket or plurality of sprockets of a chain-driven, geared bicycle.

The shaped sleeve can be appropriately shaped to receive the required plurality of sprockets. Also in accordance with the invention, there is provided an improved bicycle drive mechanism comprising in combination a drive shaft laterally attachable to a hub of a bicycle, a combination of needle roller bearing and needle roller clutch in a common cage mounted on the drive shaft, and a sleeve encircling the combination of needle roller bearing and needle roller clutch in a common cage and engageable with a gear cluster body, wherein the combination allows free wheeling of the drive shaft in one direction and in the second direction provides an instant gripping and direct drive in the opposite direction.

It is therefore clear the improved bicycle drive mechanism provides an improved combination of features and improved interconnection which overcome the problems of the prior art.

Unlike earlier wheel hub designs, the bicycle drive mechanism of the invention will allow the drive axle to lock up on the combination of needle roller bearing and needle roller clutch in a common cage when load is applied, thereby transmitting drive to the wheel and to run on the outer bearings of the combination of needle roller bearing and needle roller clutch in a common cage at freewheel making no noise.

Upon first inspection, it would appear this design would not work. This appears to be the reason that no-one has previously proceeded along this path. In particular it might appear that: 1. the combination of needle roller bearing and needle roller clutch in a common cage would not take the weight and drive forces of a cyclist;

2. the combination of needle roller bearing and needle roller clutch in a common cage could not be locked in place to secure drive due to its shape;

3. the free wheeling load and RPM from a cyclist wheel would be too great for the outer roller bearing in the combination of needle roller bearing and needle roller clutch in a common cage;

4. the finished product would be too heavy to achieve the strength required;

5. the combination of needle roller bearing and needle roller clutch in a common cage has no sealing capabilities and, exposed to the elements, would fatigue too quickly.

However these problems have been at least ameliorated by the arrangement of the new bicycle drive mechanism of the invention.

Conventional rear hubs having a ratchet locking mechanism have power transmitted to the dog teeth or pawls to lock to the hub outer body giving drive. At freewheel, the dog teeth or pawls run over the hub outer body causing a noise. However, in the present invention, the drive axle locks up on the clutch bearing when load is applied, thereby transmitting drive to the wheel, and runs on the outer bearings in the clutch bearing cage at freewheel making no noise.

Further in accordance with a novel improvement of the invention, there is provided a bicycle drive mechanism for mounting on a wheel axle, the mechanism comprising in combination a drive shaft, hub and combination of needle roller bearing and needle roller clutch in a common cage with the drive shaft freely mountable on the wheel axle of a bicycle and fitting within the hub of a bicycle and engageable at a lateral end with a sprocket cluster body, the combination of needle roller bearing and needle roller clutch in common cage mounted on the drive shaft within the hub and engageable thereto, wherein the combination allows freewheeling of the drive shaft in one direction and in the second direction provides an instant gripping and direct drive.

It can be seen that there is no need for a long drive axle and the responsiveness of the bicycle drive mechanism is substantially improved.

In order that the invention is more readily understood, a particular embodiment thereof will now be described by way of example only with reference to the accompanying drawings wherein:

Figure 1 is a longitudinal cross-sectional view of an improved bicycle drive mechanism, according to a first embodiment of the invention;

Figure 2 is a longitudinal cross-sectional view of an improved bicycle drive mechanism, according to a second embodiment of the invention.

With reference to Figure 1, there is shown a bicycle drive mechanism 11 for mounting on a wheel axle 12 of a bicycle. The mechanism 11 includes a bicycle hub

15, a drive axle 20, a combination needle roller bearing and needle roller clutch in a common cage 25 and a sleeve 26 to receive an engagement means 27 to support a sprocket or cluster of sprockets (not shown) for connection and driving of the bicycle by a drive means (not shown) such as a chain driven by the rotation of pedals by the rider.

The bicycle hub 15 is a variation of a standard hub and has a coaxial bore 18 allowing its mounting on the bicycle wheel axle 12, the hub including spaced parallel discs 16 integral with the outer side of the hub near its lateral ends and including holes 17 for receiving spokes (not shown) to form the central structure of a spoked wheel (not shown) able to rotate freely on the wheel axle 12.

The drive axle 20 is a hollow, substantially cylindrical element able to be mounted on the hub 15 and to extend laterally from and coaxial with the hub 15 with its coaxial bore 21 extending coaxially with the coaxial bore 18 of the wheel axle 12. The drive axle 20 includes a smooth cylindrical outer surface 22 for receiving a combination of needle roller bearing and needle roller clutch in a common cage 25 mounted on the smooth cylindrical outer surface of the drive axle. The combination of needle roller bearing and needle roller clutch in a common cage 25 includes three internal sets of rollers such that a first and second outer set allows freewheeling in one direction and a third central set provides an instant gripping and direct drive in the opposite direction.

The sleeve 26 has inner surface 26a for mounting on the combination of needle bearing and needle roller clutch in a common cage 25 and outer surface 26b shaped to receive an engagement means 27 to support a sprocket or cluster of sprockets (not shown) for connection and driving by a drive means (not shown) such as a chain driven by the rider. Therefore the sprocket or cluster of sprockets can freewheel and when driven in one direction cause immediate drive of the hub and, thereby, drive of the wheel of the bicycle.

As stated, the hub 15 and the drive axle 20 both include respective coaxial bores and the drive axle can be mounted to the hub such that the hub and drive axle both in unison rotate freely on the wheel axle 12 of the bicycle.

The mounting of the drive axle 20 to the hub 15 is by one lateral inner side of the hub at the end of its coaxial bore 18 including a stepped annular collar 19 having

an internal screw thread on the surface 19b coaxial with coaxial bore 18. The drive axle 20 has at one end an external thread 22a for engaging the internal thread 19b of the hub 15 and being supported thereby. The thread is such as to provide a strong attachment. Also to provide a strong attachment, the end of drive axle 20b abuts the inner lateral end 19a of the hub 15 when the drive axle 20 is screwed into the collar 19. Lock-up or drive-point occurs when the drive axle abuts or screws up and locks to the hub to obtain final drive from the clutch bearing.

The drive axle 20 includes a shaped internal surface 23 a for receiving an Allen key or other complementary-shaped driving means that is sized to fit neatly within the shaped internal surface of the drive axle 20 and is employed to assist in tightening of the screw thread of the drive axle 20 into the complementary thread of the hub 15. The shaped internal surface 23a is on opposing internal sides and the same end as the external thread 22a at the one end of the drive axle 20.

However, in equipment for use in competitive cycling activities, the major consideration in construction is weight versus strength. The lighter the better with adequate strength is the rule and there has always been a compromise between the two. Therefore, using suitable material, the thickness of material between the external thread 22a of the drive axle 20 and the shaped internal surface 23 to receive an Allen key or the like can be made approximately three millimetres while the remaining portion of the drive shaft can be made approximately two millimetres thick.

The outer end of drive axle 20 incorporates a bearing housing 9 accommodating bearing 14 which supports the drive axle while allowing it free rotation on the wheel axle. The bearing housing is larger in diameter than the smooth cylindrical outer surface of the drive axle for receiving the combination of needle roller bearing and needle roller clutch in a common cage 25 and acts to retain the combination of needle roller bearing and needle roller clutch in a common cage in position.

The end shoulder may be formed by a screw end cap 31 having a central opening for receiving the end of the wheel axle. The screw end cap 31 has a threaded engagement to the end of the wheel axle and is larger in diameter than the smooth cylindrical outer surface for receiving the combination of needle roller

bearing and needle roller clutch in a common cage 25 and acts to retain the combination of needle roller bearing and needle roller clutch in a common cage in position. The handing of the threaded engagement of the screw end cap with the end of the wheel axle is preferably opposite to the freewheeling direction so as to decrease chance of accidental unthreading. The thread of the screw end cap and end of the wheel axle is such as to provide a strong attachment.

The end cap 31 optionally includes a bearing mounting (not shown) which accommodates a bearing (not shown) to support the drive axle 20 and allow it free rotation on the wheel axle 12. As previously stated, in equipment for use in competitive cycling activities, the major consideration in construction is weight versus strength. The lighter the better with adequate strength is the rule and there has always been a compromise between the two.

When a final design had evolved, various material were tested for suitability, commencing with the lightest material and progressing towards heavier, stronger materials.

1. The first drive axle was made from aluminium which provided a very good weight factor. However, with a hardness of approximately only 15 Rockwell, within 20 kilometres of riding the axle wore out due to the effects of the locking load from the clutch bearing of the combination needle roller bearing and needle roller clutch in a common cage.

2. A drive axle was made from aluminium with a chromium coating, giving a surface hardness of approximately 65 Rockwell. Similarly, the locking load tore off the chromium coating within 20 kilometres of riding. 3. A further drive axle was made from titanium with a hardness of approximately 35 Rockwell. This showed an unsatisfactory rate of wear after 90 kilometres of riding. 4. The titanium drive axle was remanufactured with a nitrided coating, giving a surface hardness of approximately 85 Rockwell. This showed an unsatisfactory rate of wear after 110 kilometres of riding. Further use of the same design resulted in the drive axles snapping at the lock up/drive point of the hub, due to brittleness.

5. A drive axle was then made in tool steel case hardened 65 Rockwell. This provided a satisfactory level of strength, but was very heavy.

6. A final designed was then evolved for the drive axle, with the locking point changed from being at the end of the stepped threaded axle section to the front face. The material used was EN36A steel, case hardened and wall thickness were reduced to reduce weight. The design was tested over approximately 5,000 kilometres of riding without any experience of breakage or wear.

In accordance with one particular embodiment, the drive axle is manufactured according to the following characteristics:

1. Material = EN36A steel, case hardened

2. Design as depicted in the figures.

3. Applications:

A. To transfer the drive from the clutch of the combination of needle roller bearing and needle roller clutch in a common cage to the hub.

B. To allow overrun of the clutch of the combination of needle roller bearing and needle roller clutch in a common cage during freewheeling of the hub.

C. To support a floating axle bearing which, in turn, supports the hub during freewheeling.

D. To provide alignment of the combination of needle roller bearing and needle roller clutch in a common cage, wheel axle and hub.

The material should be harder than 65 Rockwell.

With reference to Figure 2, there is shown a second embodiment of the invention wherein there is provided a bicycle drive mechanism 56 for mounting on a wheel axle 24, the mechanism comprising in combination a hub 1 with radial flanges 16 formed at each end including holes 17 for receiving the upset ends of spokes (not shown), wheel axle 24, drive axle 47, combination of needle roller bearing and needle roller clutch in a common cage 29, shaped sprocket carrier 27, end caps 41, 43 and bearing retainer 50. Threaded end 28 of said drive axle is screwably engaged and tightened into threaded bore 46 provided in the inner end of said sprocket carrier, parts of the coaxial bores of said drive axle and said sprocket carrier being shaped to

allow the engagement with them of suitable tools employed to facilitate said threaded engagement and tightening. Said sprocket carrier is rotationally supported on wheel axle 24 on bearing 30 accommodated in recess 32 formed in the outer end of said sprocket carrier, said bearing being retained in place in its accommodating recess by end cap 43 secured to wheel axle 24 by engagement and tightening of its threaded bore 53 with thread 52 formed on the end of said wheel axle, shaped recess 44 being provided in said end cap to accommodate a suitable tool employed to facilitate said threaded engagement and tightening. Drive axle 47 is rotationally supported in hub 1 on bearing 33 accommodated in recess 34 formed in the end of said hub adjacent said sprocket carrier and running on surface 45 of said drive axle, and on bearing 35 accommodated in recess 36 formed in the end of said hub remote from said sprocket carrier and running on surface 38 of said drive axle. Said drive axle is retained in place in said hub by engagement and tightening of its threaded end 48 with threaded bore 49 provided in bearing retainer 50. Said bearing retainer abuts and retains bearing 35 in place in its said accommodating recess. The end of wheel axle 24 remote from said sprocket carrier is rotationally supported on bearing 39 accommodated in recess 40 formed in bearing retainer 50. Bearing 39 is retained in place in its said accommodating recess by end cap 41 secured to wheel axle 24 by engagement and tightening of its threaded bore 55 with thread 54 formed on the end of said wheel axle, shaped recess 42 being provided in said end cap to accommodate a suitable tool employed to facilitate said threaded engagement and tightening. Combination of needle roller bearing and needle roller clutch in a common cage 29 is pressed in an interference fit into recess 51 formed in said hub, freewheeling on said drive axle when said hub is displaced in one rotational sense, and its needle roller- type sprag elements immediately engaging surface 37 of said drive axle when said hub is rotationally displaced in the opposite rotational sense.

In preferred embodiments of the present invention, said combination of needle roller bearing and needle roller clutch in a common cage takes the form of drawn cup roller clutch and bearing assemblies of the type exemplified by any of Timken/Torrington Types FC, FCS, FCL-K, RC-FS, or RC.

Obviously, said wheel axle of the various embodiments of the present invention may be made hollow for the purpose of reducing weight.

Obviously, a sleeve of a suitable strong, hard material (depicted as 26 in Figure 1) may be provided to surround said combination of needle roller bearing and needle roller clutch in a common cage in the embodiment depicted in Figure 2.

Obviously, the needle roller bearing and needle roller clutch components of said combination of needle roller bearing and needle roller clutch in a common cage may be made separate and one or more of said needle roller bearing components may be used with one or more needle roller clutch components.

Obviously, the bearing retainer and sprocket carrier depicted in Figure 2 may also be fixed to said drive axle by pressing the ends of said drive axle into complementary recesses in said bearing retainer and said sprocket carrier and retaining said ends in position by installing and tightening of suitable screw fastenings passing more or less radially through said bearing retainer and said sprocket carrier; or by pressing the splined ends of said drive axle into complementary splined recesses provided in said bearing retainer and said sprocket carrier. It should be evident from the description hereinabove that the present invention provides an improved bicycle hub which avoids most, if not all of the disadvantages of the prior art. Of course many modifications to the above described embodiment may be readily envisaged by persons skilled in the art and such are included in the scope of the invention.