The present invention falls within the field of mechanics applied to race bicycles or mountain bikes, and is related in particular to a bicycle equipped with a system for laterally sliding the chain.

The invention radically modifies the existing prior art in the manual mechanical system for the speed gear ratio of race bicycles or mountain bikes, which is based on one or more front crowns placed axial with the central movement and a pinion pack placed axial with the rear wheel, with chain-type traction which operates by moving obliquely to the bicycle axis .

In the prior art, there are no solutions similar to that of the present invention.

Object of the present invention is removing the following prior art limitations: traction chain obliqueness - need of a minimum number of two front crowns with derailing device and related speed gear;

- maximum number of 11 ratios on rear pinion;

- impossibility of regularly using all ratios being present;

- speed gear of the long rod type, necessary for reaching minimum ratios lower than 0.70.

The above and other objects and advantages of the invention, as will result from the following description, are obtained with a bicycle equipped with a system for laterally sliding the chain as claimed in claim 1. Preferred embodiment and non-trivial variations of the present invention are the subject matter of the dependent claims.

It is intended that all enclosed claims are an integral part of the present description.

It will be immediately obvious that numerous variations and modifications (for example related to shape, sizes, arrangements and parts with equivalent functionality) could be made to what is described, without departing from the scope of the invention, as will appear from the enclosed claims.

The present invention will be better described by some preferred embodiments thereof, provided as a non-limiting example, with reference to the enclosed drawings, in which:

- Figure 1 shows a plan view of a first preferred embodiment of the system according to the present invention;

- Figure 2 shows a longitudinally sectioned view of the system of Figure 1;

- Figure 3 shows two sectional views, where the dashed parts show the displacement of the mobile crown with respect to the tracks, provided to enable the lateral sliding movement and the withdrawal of the system;

- Figure 4 shows an exploded view of the system of Figure 1;

- Figure 5 shows a plan view of the system of Figure 1 applied to a bicycle;

- Figure 6 shows a side view of the system of Figure 1 applied to a bicycle;

- Figure 7 shows a perspective view of the system of Figure

6; - Figure 8 shows a plan view of a second preferred embodiment of the system according to the present invention;

- Figure 9 shows a longitudinally sectioned view of the system of Figure 8;

- Figure 10 shows an exploded view of the system of Figure 8; - Figure 11 shows a plan view of the system of Figure 8 applied to a bicycle;

- Figure 12 shows a side view of the system of Figure 8 applied to a bicycle; and

- Figure 13 shows a perspective view of the system of Figure

12.

The above listed limitations are removed by a system of the lateral sliding type, which provides for the insertion of a suitable mechanism which generates the automatic lateral displacement of the transmission chain, coupled with the displacement of the chain on the rear pinion ratios. The mechanism of the present Application is inserted between the pedal area and the pinion pack. All standard bicycle sizes are kept unchanged, together with the distances between central movement and pinion axis, wheels and pedals. The system can therefore be installed on all bicycles and mountain bikes with a simple modification to the frame, which will necessarily have to provide for the upward translation of the lower forks of the rear carriage. The enclosed drawings show, only as a demonstration of the global functionalities of the invention, a hypothetical bicycle frame which, being based on a traditional scheme with triangles, has infinite solutions for the frame. The lateral sliding mechanism of the chain has an industrial application, since it can be easily manufactured and assembled. The system is based on the lateral sliding of a mobile crown, which moves on rails placed longitudinally to the sliding axis, and follows the lateral displacement of the chain on the rear pinion of the bicycle. The lateral sliding of the mobile crown therefore automatically occurs, due to the lateral force transmitted by the displacement of the rear speed gear coupled with the rotation movement of the system, in addition to the tensioning of the chain produced by the spring of the chain tightening device of the speed gear itself; these factors therefore produce the alignment action of the chain in a smooth and regular way. For the system operation, the subdivision of the traction chain is provided: the first chain operates from the front crown to the fixed crown (or double crown in case of mountain bike) of the mechanism (direct traction) , the second chain from the mobile laterally sliding crown of the mechanism to the pinion pack (indirect or dragging traction) .

The crowns of the mechanism rotate around their central axis, and the force of the first crown (fixed) is transmitted to the second crown (mobile) by means of the sliding rails. For the mountain bike version, since ratios included between 4.0 and 0.67 are necessary, the system is equipped with a double fixed crown with derailing device, in which the smaller crown operates as multiplier and the bigger crown as reducer. The derailing device is placed in the lower part of the fixed double crown and operates on the "unloaded chain", in the space included between chain and rear wheel. The chain tightening device is placed as edge to the front crown with upwards tensioning rotation, as can be seen in Figures 11 and 12.

The lateral sliding of the mobile crown occurs on rails with round head, on which the round saddles of the mobile crown are housed; roundness guarantees the minimum contact surface between the parts, reducing friction and removing contrary effect to sliding, generated by the compression of the tensioned chain which pushes on the crown and on the sliding rails. The side thrust force is decidedly greater than the friction force and sliding is further enabled by the rotary action of the system. The saddles of the mobile crown provide for a detachment from the rails of about 0.2 mm (see Figure 3, section 1).

In the mountain bike version, the detachment between saddles and rails can be further limited to 0.05 mm to avoid phenomena of excessive small vertical jumps or side movements.

The sliding rails, being a single body with the fixed traction crown, smoothly and homogeneously transfer the rotation force to the mobile crown. Figure 5 shows the distances from mechanical components, such as wheel spokes, from the rotation radius of the pedal, from the cyclist's foot movement. The distance of the mechanism axis from the rear wheel axis changes due to the frame sizes, and consequently the crank length: in the drawing, the distance of mechanical components from the rotation radius of the crank is about 20 mm (see Figure 6) .

In order to reduce to a minimum the sliding mechanism sizes, the lateral stroke of the crown is sized by computing an axle displacement of the chain, only on the two extreme ratios of 6 mm, equal to 4% of obliqueness (or, in case of a mountain bike, of 4.5 mm, equal to 3.5% of obliqueness), which guarantees the absence of lateral friction on the chain.

The mobile crown has a lateral stroke of 43 mm (mountain bike: 38 mm) , computed for a rear pinion, with 12/14 speeds; naturally, the stroke could be increased or reduced by inserting pinions with a greater or smaller number of crowns, or to reduce or completely remove the obliqueness also on the 2 extreme ratios (see Figures 5 and 11) . The mechanism measures a total depth as plan of 61 mm, 55 mm measured from the fastening bracket to the frame (Figures 1, 5 and 8), of 75 mm (mountain bike: 84.5 mm) from the bicycle axis, and its placement corresponds to the central area of a foot plant, area with smallest interference with the foot itself in its rotary movement.

As regards the version for race bicycle, the mechanism, having also a multiplication function, uses on its central movement a small sized crown, which produces on the traction chain a quite greater force due to the reduction of the negative arm, and consequently the pickup will be higher and more direct.

For example, the 32-type front crown with an intermediate fixed 11-type crown, which has a multiplication function and which passes the force on the 16-type crown, corresponds to a front 47-type crown: therefore, the pickup obtained with a 47- type crown, whichever the rear ratio, is decidedly lower than the one obtained with a 32-type one. The mobile crown can be replaced by extracting it from the sliding rails, simply unscrewing the fastening screws of the external ring nut of the stroke stopper, therefore allowing to modify the available range of ratios in an extremely simple way. Te insertion of a number of rear ratios (14 or more) provides for the widening of the abutment of the small fork on the rear hub: a 150/162 mm hub will therefore have to be assembled, while the central movement can also be of the standard 68 mm type. Figures 2-3 show the longitudinal section and the cross sections of the mechanism, with related dimensioning of the components. As regards the part related to ratios which can be obtained from the system, only as an example the following are reached:

- 32-type front crown, 11-type fixed, 16-type mobile, pinion pack 9/36 = range of ratios 5.17/1.29. - 32-type front crown, 11-type fixed, 15-type mobile, pinion pack 9/32 = range of ratios 4.84/1.36

- 33-type front crown, 12-type fixed, 16-type mobile, pinion pack 9/31 = range of ratios 4.88/1.41 - 33-type front crown, 12-type fixed, 15-type mobile, pinion pack 9/31 = range of ratios 4.58/1.33.

As regards the mountain bike version, the mutually axial front crown and the chain tightening device are preferably placed in line with the centre of the two fixed crowns, the axis displacement of the traction chain being 2.5 mm, equal to

1% of obliqueness on the traction, namely practically null. The technical solution, which is innovative in this field, applied to the system, allows obtaining ratios of 4.09/0.66 by arranging a simple 9/28 pinion pack with 12 ratios, making therefore possible to apply a speed gear with very short rod, which therefore allows increasing the distance from ground of the speed gear mechanism.

As regards the part related to ratios which can be obtained, as an example the following are reached: - 27-type front crown, 11-type and 22-type fixed, 15-type mobile, pinion pack 9/28 = range of ratios 4.09/1.31 - 2.04/0.66. The enclosed drawings verify the system by using standard, commonly marketed components, such as the tread width equal to 62 mm, the abutment of the small fork on the rear carriage, which needs a 142/150 mm hub, while the central movement can be standard.

With reference now to Figures 4 and 10, the major mechanical component of the system of the invention will be described, the version applied to a mountain bike being different from the one applied to a race bicycle only regarding exterior parts, for components 2 and 8.

The exploded view of Figures 4 and 10 shows all single pieces: the mechanism is blocked on a central pin (3) , preferably made of steel whose diameter is 10 mm, which is screwed onto the supporting bracket of the bicycle frame. The length of the central pin which works as a shelf is preferably only of 55 mm, as guarantee of the stiffness and absence of possible bending.

The whole mechanism rotates on the central pin through the two ball or roller bearings (4) placed at its ends, as guarantee of the perfect rotation and friction reduction; the housing tubular device of the bearings made of steel or light alloy to reduce its weight is divided into two parts mutually screwed and fastened by a blocking screw, can also be made in a single body; on part of the tubular device (7) the fixed crown (or double crown) (8) is screwed, on the other part (5) the sliding rails (5b) of the mobile crown (6) are housed.

The tubular device can therefore b unscrewed and easily assembled and disassembled for cleaning or replacing the bearings. The bearings are tightened on the suitable internal seat of the tubular device, by the nut made of steel (9) which, being screwed onto the central pin, enables the complete blocking of the mechanism. The mechanism is fastened to the frame through an Allen key with external stopper spring (11) to the bracket of the frame or any other blocking system.

The fixed crown (8) is fastened to the tubular device (7) of the mechanism through screwing till the end of stroke. The mobile crown (6) and the sliding rails (5b) are preferably made of steel or light alloy as guarantee of a greater smoothness and endurance. The mobile crown (6) slides with a distance from the tubular device of 2.5 mm, and the sliding rails transfer the rotation force on the saddles of the mobile crown (6a), pushing on the saddle recess. The stroke stopper in the internal side (5a) is part of the rails themselves, while in the external side is exerted by the removable lock nut made of steel (2), fastened through screws (1) screwed to the five rails. The maximum spunto and traction force transferred by the front chain to the fixed crown is transmitted in the sturdier part next to the system fastening bracket. The rotation speeds of the mechanism during a race reach 180/300 revolutions/minute, and the tangential acceleration force present on the mechanism rails will tend to completely eliminate deposits of water or dirt.

With the above described solution, the invention therefore deals, with reference to Figures 1 to 7, in a first preferred embodiment, with a race bicycle comprising:

- a supporting frame;

- a pedal assembly connected to the supporting frame, composed of two pedals and a first toothed wheel interposed therebetween, around which a first chain is operatively placed;

- a pinion pack connected to the supporting frame, composed of at least two second toothed wheels around which a second chain is operatively placed, the displacement of the second chain on one of the toothed wheels occurring through a speed gear; at least one laterally sliding system placed between the pedal assembly and the pinion pack, wherein the laterally sliding system is composed of a mechanism equipped with:

- at least one third toothed wheel (8) around which the first chain is operatively placed;

- at least one fourth toothed wheel (6) around which the second chain is operatively placed, the fourth toothed wheel (6) being integrally rotating with the third toothed wheel (8) ; and

- at least one rail (5a, 5b) to which the fourth toothed wheel (6) is operatively connected, the rail (5a, 5b) having a longitudinal axis which is parallel to the rotation axis of the first, second, third and fourth toothed wheels (8, 6), the fourth toothed wheel (6) being adapted to slide along the rail (5a, 5b) following the displacement of the second chain on one of the second toothed wheels after a speed change operation, in order to keep the rotation plan of the second chain substantially parallel to the plane of the supporting body.

Innovatively , the fourth toothed wheel (6) is adapted to automatically laterally slide, due to the lateral force transmitted by the displacement of the rear speed gear, coupled with the rotary movement of the system, in addition to the tensioning of the second chain produced by the spring of the chain tightening device of the speed gear itself; these factors therefore produce the alignment action of the second chain, in a smooth and regular way.

Moreover, the fourth toothed wheel (6) is adapted to laterally slide on two rails with round head (5a, 5b), in which the round saddles (6a) of the fourth toothed wheel (6) are housed, the roundness guaranteeing the minimum contact surface between the parts, reducing friction and the effect of the contrary force to sliding, due to compression of the tensioned second chain which pushes on the fourth toothed wheel (6) and on the sliding rails (5a, 5b) . In particular, the laterally sliding system is further composed of a mechanism blocked on a central pin (3) made of steel, adapted to be screwed onto the supporting bracket of the bicycle frame, the whole mechanism rotating on the central pin (3) through at least two ball bearings (4), the housing tubular device of the bearings (4), preferably made of steel or light alloy for reducing its global weight, being divided into two parts mutually screwed and fastened by a blocking screw, the third toothed wheel (8) being screwed on a first part (7) of the tubular device, the sliding rails (5b) of the fourth toothed wheel (6) being housed on a second part (5) of the tubular device, the mechanism being fastened to the frame with at least one stopper spring (11) external to the bracket of the frame, the third toothed wheel (8) being fastened to the first part (7) of the tubular device of the mechanism through screwing till the end of stroke, the fourth toothed wheel (6) and the sliding rails (5a, 5b) being preferably made of steel or light alloy, the stroke stopper in the internal side of a rail (5a) being part of the rails themselves, while in the external side it is exerted by a removable lock nut (2), fastened through screws (1) screwed to the rails. With the above described solution, the invention further deals, with reference to Figures 8 to 13, in a second preferred embodiment, with a bicycle of the mountain bike type comprising:

- a supporting frame;

- a pedal assembly connected to the supporting frame, composed of two pedals and a first toothed wheel interposed therebetween, around which a first chain is operatively placed; and

- a pinion pack connected to the supporting frame, composed of at least two second toothed wheels around which a second chain is operatively placed, the displacement of the second chain on one of the toothed wheels occurring through a speed gear;

Innovatively, the bicycle further comprises at least one laterally sliding system placed between the pedal assembly and the pinion pack, such laterally sliding system being composed of a mechanism equipped with:

- at least one third toothed wheel (8) around which the first chain is operatively placed;

- at least one fourth toothed wheel (6) around which the second chain is operatively placed, the fourth toothed wheel (6) being integrally rotating with the third toothed wheel (8) ; - at least one rail (5a, 5b) to which the fourth toothed wheel (6) is operatively connected, the rail (5a, 5b) having a longitudinal axis which is parallel to the rotation axis of the first, second, third and fourth toothed wheels (8, 6), the fourth toothed wheel (6) being adapted to slide along the rail (5a, 5b) following the displacement of the second chain on one of the second toothed wheels after a speed change operation, in order to keep the rotation plan of the second chain substantially parallel to the plane of the supporting frame;

- at least one fifth toothed wheel, whose diameter is lower than the third toothed wheel (8) and placed adjacent to the third toothed wheel (8), the fifth toothed wheel operating as speed multiplier, the third toothed wheel

(8) operating as speed reducer;

- at least one sixth toothed wheel as chain tightening device placed in contact with the first chain, placed between the first toothed wheel and the third/fifth toothed wheel (8) and having an upwards tensioning rotation; and

- a derailing element placed between the third/fifth toothed wheel (8) and the sixth toothed wheel as chain tightening device, in order to get in contact with the lower stroke of the first chain when the first chain is in an unloaded status, namely free from tension.

In particular, the fourth toothed wheel (6) is adapted to automatically laterally slide, due to the lateral force transmitted by the displacement of the rear speed gear, coupled with the rotary movement of the system, in addition to the tensioning of the second chain produced by the spring of the chain tightening device of the speed gear itself, factors which generate therefore the alignment action of the second chain. Moreover, the fourth toothed wheel (6) is adapted to laterally slide on two rails with round head (5a, 5b) , on which the round saddles (6a) of the fourth toothed wheel (6) are housed, the roundness guaranteeing the minimum contact surface between the parts, reducing friction and the effect of the contrary force to sliding, due to compression of the tensioned second chain which pushes on the fourth toothed wheel (6) and on the sliding rails (5a, 5b) .

Preferably, the laterally sliding system is further composed of a mechanism blocked on a central pin (3) made of steel, adapted to be screwed onto the supporting bracket of the bicycle frame, the whole mechanism rotating on the central pin (3) through at least two ball bearings (4), the housing tubular device of the bearings (4), preferably made of steel or light alloy to reduce its weight, being divided into two parts mutually screwed and fastened by a blocking screw, the third and the fifth toothed wheel (8) being screwed on a first part (7) of the tubular device, the sliding rails (5b) of the fourth toothed wheel (6) being housed in a second part (5) of the tubular device, the mechanism being fastened to the frame with at least one stopper spring (11) external to the bracket of the frame, the third and the fifth toothed wheel (8) being fastened to the first part (7) of the tubular device of the mechanism through screwing till the end of stroke, the fourth toothed wheel (6) and the sliding rails (5a, 5b) being preferably made of steel or light alloy, the stroke stopper in the internal side of a rail (5a) being part of the rails themselves, while in the external side it is exerted by a removable lock nut (2), fastened through screws (1) screwed to the rails (5a, 5b) . The benefits deriving from the above described laterally sliding system are as follows:

- eliminating the chain obliqueness;

- inserting 12/14 or more ratios on the pinion pack;

- using a single crown on the central movement: therefore, without the front speed gear, the stroke operation is modular, facilitated and progressive;

- using all ratios which can be applied on the rear pinion; - transmitting the force with a chain always axial with the cycle;

- having more pickup power due to a small front crown;

- reducing the distance between the pedals Q factor, much below what has been so far possible;

- eliminating the chain jumping with the inconvenience of the chain dislodgement in front;

- for the mountain bike, applying a "short rod" speed gear, which allows increasing the distance from ground of the apparatus, reducing the chance of damaging the speed gear itself;

- for the mountain bike, inserting the derailing device into the lower part of the chain, with the "unloaded chain zone" which creates a smaller lateral friction;

- for the mountain bike, obtaining a range of ratios 4.09/0.66 using a 9/28 pinion with short rod speed gear;

- for the mountain bike, being able to insert rear wheels with tread increased to 70/80 mm on standard 142 mm rear hubs.