SYSTEM FOR MOTORIZED ACTION OF A BICYCLE BY MEANS OF FRICTION WITH A REMOVABLE DRIVE UNIT

Description

Domaine de l'invention

[0001] This patent application relates to the field of bicycles and more particularly to systems for motorized assistance of a bicycle by friction which includes a removable motor housing. Etat de la technique

[0002] It is known to equip a bicycle with a system for motorized assistance which includes an electric motor housed in a casing and a drive mechanism which is powered by the electric motor.

[0003] The drive mechanism of the motorized assistance system generally drives the axle of the rear wheel or the front wheel of the bicycle, or the axle of the bicycle's bottom bracket, to transmit a driving torque to assist the bicycle user in their pedaling effort.

[0004] Such a system, like the one described and shown in document US7568714B2, suffers from a certain complexity of implementation on the bicycle and requires a complex drive mechanism.

[0005] An alternative is to equip the bicycle with a system for motorized assistance of a friction cycle.

[0006] This type of friction drive system typically consists of a housing mounted on the bicycle that houses an electric motor powered by an electrical energy source, such as a battery. The motor also includes a cylindrical drive roller that rotates around a transverse drive shaft.

[0007] The drive roller is designed to drive a bicycle wheel by friction on a tread of a tire fitted to the wheel.

[0008] Document US2019291815A1 describes and illustrates such a system for motorized assistance of a cycle by friction. Document EP 3 543 104 A2 shows the preamble to claim 1.

[0009] This type of friction-based system makes it possible to provide assistance to a bicycle at a moderate cost and with a relatively limited additional mass carried on the bicycle.

[0010] However, this type of friction system according to the prior art is not suitable for easy assembly and disassembly. Exposé de l'invention

[0011] The present invention aims, in particular, to overcome the drawbacks of the aforementioned prior art. This objective, as well as others that will become apparent from the following description, is achieved with a system for the motorized assistance of a bicycle, comprising a support mast which includes at least one arm extending from a base intended to be attached to a bicycle, to a free end forming a transverse locking finger perpendicular to said arm, and the system comprising a removable motor housing adapted to be mounted on said mast and which includes: a cylindrical drive roller which is powered by an electrical power source and which is driven in rotation about a transverse drive axis, said drive roller being intended to drive the cycle wheel by friction on a tread of a tire fitting said wheel, a locking housing for the casing on the mast, which extends tangentially to the drive roller along a casing insertion axis, from an inlet forming a channel, and a locking cleat which is arranged in the locking housing and which has a stop notch intended to cooperate with the locking finger of the mast to lock the casing on the mast, and which delimits a bearing face extending tangentially to the drive roller, said bearing face being intended to cooperate with a first side of the mast arm.

[0012] According to the present invention, the housing is capable of being driven, in a locking movement directed towards the base of the mast tangentially to the drive roller, from a free position in which the housing is detached from the mast, to a working position in which the housing is blocked in translation along the arm of the mast in a first direction and a second direction opposite, respectively by the locking finger which is in contact with the stop notch of the cleat and by the drive roller which is in contact with the pneumatic, and in which the housing is blocked in pivoting around a transverse axis materialized by the locking finger, in the direction of rotation of the drive roller, by the arm of the support mast which is in contact with said support face provided for this purpose.

[0013] The system according to the invention allows for the manual mounting and dismounting of a motorized unit for pedal assistance of a cycle.

[0014] Furthermore, the system takes advantage of the elastic properties of the tire to allow the motor housing to reach its operating position, in which it is locked onto the mast. Other optional features of the invention, taken alone or in combination, include: The cleat is mounted to slide within the housing, tangentially to the drive roller, between a plurality of positions in each of which the cleat can be immobilized by a locking device. This allows adjustment of the housing's distance from the tire when the housing is in its operating position, thereby regulating the pressure exerted by the drive roller on the tire. Adjusting the pressure exerted by the roller on the tire ensures adequate friction between the drive roller and the tire to minimize the risk of roller slippage. The cleat locking device includes at least one automatic cleat locking mechanism, which cooperates with the mast by shape compatibility to automatically lock the cleat when the housing tilts into its operating position. This feature ensures that the drive roller is always correctly positioned relative to the tire. Therefore,The automatic locking device for the cleat allows for less precise positioning of the support mast on the cycle; the cleat locking device includes a spring to elastically return the cleat against the mast locking finger. The spring allows the cleat to follow the locking finger; the cleat defines a cam track designed to cooperate with the mast locking finger and which successively presents, along the insertion axis of the housing, a first portion and a second portion forming two opposing slopes, the second portion being formed at least in part by the stop notch, and during said locking movement, the following locking finger slides on said first portion of the cam track so that the housing slides towards the tire along the mast until the drive roller presses and deforms the tire of the cycle wheel and then, successively,The locking finger slides on said second portion of the cam track, causing the housing to pivot around the locking finger and resulting in a partial release of the pressure exerted by the drive roller on the tire, until the housing reaches its operating position. The channel is designed to guide the mast during the locking movement of the housing, and the channel includes a wall adapted to bear against a second side of the mast arm, when the housing is in its operating position, to oppose the pivoting of the housing around a transverse axis formed by the locking finger, in a direction opposite to the direction of rotation of the drive roller; the mast is designed to extend in a direction perpendicular to the axis of the cycle wheel; the mast has two arms extending parallel to each other from a first end forming said mast base.up to a second end connected to said locking finger; the mast is mounted on a second support fork comprising a first leg and a second leg which are designed to extend on either side of said bicycle wheel.

[0015] The invention also relates to a cycle which includes at least one wheel equipped with a tire, characterized in that it is equipped with a system for motorized assistance of the type described above. Brève description des dessins

[0016] Other features, purposes and advantages of the invention will become apparent from the detailed description that follows, for understanding of which reference should be made to the accompanying drawings in which: [ Fig. 1 ] is a schematic profile view of a bicycle equipped with a motorized assistance system comprising a removable motor housing that cooperates by friction with the front wheel of the bicycle, according to the invention; Fig. 2 ] is a schematic front view of the bicycle of the figure 1 , without the engine housing; [ Fig. 3 ] is a perspective view of the engine casing of the figure 1 ; Fig. 4 [ ] is a schematic longitudinal sectional profile view of the engine housing of the system of the figure 1 at the beginning of a locking movement of the motor housing onto the support mast; [ Fig. 5 ] is a schematic longitudinal sectional profile view of the engine housing of the figure 1 during the locking movement of the motor housing onto the support mast, in a first intermediate position; [ Fig. 6 ] is a schematic longitudinal sectional profile view of the engine housing of the figure 1 during the locking movement of the motor housing onto the support mast, in a second intermediate position; [ Fig. 7 ] is a schematic longitudinal sectional profile view of the engine housing of the figure 1 in a motor housing operating position locked onto the mast; [ Fig. 8 ] is a schematic top view in cross-section along axis 8-8 of the figure 9 illustrating the mechanism for locking the engine housing in its operating position; [ Fig. 9 ] is a schematic cross-sectional view along axis 9-9 of Fig. 8, illustrating the locking device for the motor housing in its operating position; Fig. 10 ] is a schematic cross-sectional view along axis 10-10 of Figure 13, illustrating the device for locking the motor housing in its operating position, according to an alternative embodiment of the invention; [ Fig. 11 ] is a schematic top view in cross-section along axis 12-12 of the figure 10 illustrating the engine housing locking device during the engine housing locking movement, according to the variant embodiment of the invention of the figure 10 ; Fig. 12 ] is a schematic top view in cross-section along axis 12-12 of the figure 10 illustrating the device for locking the engine housing in its operating position, according to the variant embodiment of the invention of the figure 10 ; Fig. 13 ] is a schematic profile view in longitudinal section along axis 13-13 of the figure 10 illustrating the device for locking the engine housing in its operating position, according to the variant embodiment of the invention of the figure 10 .

[0017] In the description and claims, the longitudinal, vertical and transverse terminology will be adopted without limitation with reference to the L, V, T trihedron shown in the figures, considering that the cycle adopts a vertical position of use and moves longitudinally forward.

[0018] Also, the expressions "superior", "inferior" and "lower", "high" will be used, without limitation, to refer to the upper and lower parts respectively of the figure 1 .

[0019] Throughout all these figures, identical or similar elements are identified by identical or similar reference symbols. Description détaillée

[0020] We represented in figure 1 a system 10 for the motorized assistance of a cycle 12.

[0021] Cycle 12 is a bicycle which has a front wheel 14 and an associated hub 15, which are mounted freely in rotation on a first fork 16 of cycle 12, around a first transverse axis A of rotation.

[0022] In addition, cycle 12 has a rear drive wheel 18 which is mounted freely in rotation on the frame of cycle 12, around a second transverse axis B of rotation.

[0023] According to the figure 2 , the system 10 according to the invention comprises a second support fork 20 which includes a first leg 22a and a second leg 22b which extend radially on either side of the front wheel 14, each from a lower section 24a, 24b respectively mounted on the hub 15 of the front wheel 14, to a transverse junction portion 26 which connects the first leg 22a to the second leg 22b.

[0024] The junction portion 26 of the second fork 20 is extended by a mast 28 which is intended for the support of a removable motor housing 30.

[0025] For this purpose, the mast 28 has an inverted U shape comprising a first arm 32a and a second arm 32b which extend generally vertically respectively from a first base 34a and a second base 34b connected on the junction portion 26 of the second fork 20, to a free end forming a transverse locking finger 36 which connects the first arm 32a and the second arm 32b of the mast 28.

[0026] By way of non-limitation, the mast 28 for the support of the engine housing 30 can be fixed directly onto accessory fixing nuts which are sometimes originally present on the first fork 16 of the cycle 12, and which are generally intended for the fixing of a mudguard or a front luggage rack.

[0027] As can be seen in figures 2 And 9 , the locking finger 36 has a curved loop shape.

[0028] Preferably, the mast 28 extends globally vertically and radially with respect to the front wheel 14 of the cycle 12.

[0029] Furthermore, according to the figures 1 And 2 , the second fork 20 has a first branch 38a and a second branch 38b which are connected to the first fork 16 of the cycle 12, to lock the second fork 20 in rotation on the first fork 16.

[0030] By way of non-limitation, the second fork 20 may have only one arm 38a which is connected to one of the legs 22a, 22b or directly to the frame of the cycle 12 above the front wheel 14.

[0031] With reference to the figure 3 The motor housing 30 includes a casing 40 which carries a motor roller 42. The casing 40 is flanked by a first cheek 44a and a second cheek 44b between which a handle 45 extends transversely.

[0032] The drive roller 42 is a cylinder designed to drive the front wheel 14 of the cycle 12 by friction on a tread of the front wheel 14's tire 46, as illustrated in the figure 7 .

[0033] For this purpose, the drive roller 42 is associated with an electric motor (not visible in the figures) which is supplied with electrical energy by a battery (not shown) and which drives the drive roller 42 in rotation around a transverse drive axis C.

[0034] Also, in reference to the figure 4 , the housing 30 delimits a housing 48 for locking the housing 30 on the mast 28, which extends tangentially to the drive roller 42 along a vertical insertion axis D of the housing 30, from an inlet forming a guide channel 50 for the mast 28.

[0035] The D axis of insertion of the housing is parallel to the mast 28 and it generally represents the direction to follow to insert the housing 30 onto the mast 28.

[0036] As can be seen in figures 4 And 8 , the channel 50 is delimited longitudinally by a vertical front wall 52 and by a vertical rear wall 54, and it is delimited transversely by a first vertical cheek 56a and by a second vertical cheek 56b opposite.

[0037] Furthermore, channel 50 has a chamfered mouth 58 visible at figures 4 And 9 , designed to guide the mast 28 and facilitate the insertion of the mast 28 into the locking housing 48.

[0038] Additionally, the housing 30 includes a locking lug 60 which is arranged in the locking housing 48.

[0039] The cleat 60 delimits a front bearing face 62 which extends vertically and tangentially to the drive roller 42, the bearing face 62 being intended to cooperate with a first front side of each of the arms 32a, 32b of the mast 28.

[0040] Also, the cleat 60 has an outgrowth 64 which projects longitudinally backwards from the bearing face 62.

[0041] With reference to figures 4 And 9 , the protrusion 64 has a notch forming a stop 66 which is intended to cooperate with the locking finger 36 of the mast 28, to lock the housing 30 onto the mast 28.

[0042] The locking notch 66 has an inverted U-shape that complements the shape of the locking finger 36, as can be seen in the figure 9 .

[0043] In addition, the cleat 60 delimits a cam path 68 which is intended to cooperate with the locking finger 36 of the mast 28 during the insertion of the mast 28 into the housing 48.

[0044] As can be seen at the figure 4 , the cam track 68 presents successively, from bottom to top along the axis D of insertion of the housing 30, a first lower portion 70 which forms a ramp inclined towards the rear with respect to the support face 62, and a second upper portion 72 which forms a ramp inclined towards the front.

[0045] The second portion 72 of the cam track 68 is formed by the stop notch 66 of the cleat 60.

[0046] According to another feature of the invention, the cleat 60 is mounted to slide in the housing 48, in a vertical direction tangential to the drive roller 42, between a plurality of positions (only one of which is shown in the figures) in each of which the cleat 60 is able to be immobilized by a locking device 74.

[0047] To that end, as can be seen in the figure 8 , the cleat 60 comprises a first rail 76a and a second rail 76b which extend vertically on either side of the cleat 60, following a vertical sliding direction.

[0048] The first rail 76a and the second rail 76b are mounted to slide in a first groove 78a and a second groove 78b of guidance respectively, which are delimited by the housing 48. The locking device 74 of the cleat 60 includes, by way of example, a vertical screw 80 comprising an adjustment head 82 which rests on an upper wall 84 of the housing 48 and a body 86 which extends vertically through a passage hole 88 provided in the upper wall 84 of the housing 48 and which is screwed into the cleat 60.

[0049] Thus, screw 80 allows the cleat 60 to be locked in sliding and also allows the cleat 60 to be raised and lowered by screwing and unscrewing screw 80 respectively.

[0050] It is understood that the screw can rotate on itself, but that the screw head 82 always remains in contact with the upper wall 84, at the risk of the screw going up and down, taking the lug 60 with it, which would impair the adjustment.

[0051] Preferably, the housing 48 is delimited by a cartridge 90 which is mounted removably in the housing 30, in particular to facilitate access to the locking device 74, in order to adjust the position of the stop 60.

[0052] As will be seen in more detail later, adjusting the position of the cleat 60 allows for adjusting the spacing of the housing 30 relative to the tire 46.

[0053] The removable housing 30 is capable of being driven, in a locking movement directed from top to bottom along the mast 28, from a free position in which the housing 30 is detached from the mast 28, to an operating position illustrated in figures 7 , 8 et 9 in which the housing 30 is locked onto the mast 28 and blocked in translation along the mast 28.

[0054] In its operating position, the housing 30 is blocked in translation on the mast 28 along the transverse, longitudinal and vertical axes, and it is blocked in rotation on the mast 28 around these same axes.

[0055] More specifically, the housing 30 is blocked in vertical upward translation by the locking finger 36 which is in contact with the stop notch 66 of the lug 60.

[0056] Conversely, the housing 30 is blocked in vertical downward translation by the drive roller 42 which is supported on the pneumatic 46.

[0057] In addition, the housing 30 is blocked in transverse translation and in rotation around a longitudinal axis, by the arms 32a, 32b of the mast 28 which cooperate with the stop notch 66 of the cleat 60 and which also cooperate with the first cheek 56a and the second cheek 56b of the channel 50.

[0058] Also, the housing 30 is blocked in longitudinal translation forward by a first side of the mast 28 which is supported on the support face 62 of the cleat 60, and backward by a second side of the mast 28 which is supported on the rear wall 54 of the guide channel 50 of the mast 28.

[0059] Similarly, the housing 30 is blocked from rotation around a transverse axis materialized by the locking finger 36, along the direction of rotation of the drive roller 42 and in a direction opposite to the direction of rotation of the drive roller 42, by the arms 32a, 32b of the mast 28 which are in contact with the support face 62 provided for this purpose, and by the rear wall 54 of the guide channel 50 of the mast 28.

[0060] The transition of the housing 30 from its free position to its position of use is described below, in chronological order.

[0061] With reference to the figure 4 , during the locking movement of the housing 30, the locking finger 36 is guided by the chamfered mouth 58 of the channel 50 to enter the housing 48.

[0062] Next, as can be seen on the figures 4 And 5 The user inserts the housing 30 onto the mast 28; the locking finger 36 slides downwards along the first portion 70 of the cam track 68, so that the housing 30 translates downwards parallel to the first portion 70 of the cam track 68, until the drive roller 42 makes contact with the tire 46 of the wheel of the cycle 12, as illustrated in the figure 5 .

[0063] To continue the locking movement of the housing 30 towards its operating position, the user presses the handle 45 of the housing; the drive roller 42 presses and deforms the pneumatic tire 46, which allows the locking finger 36 to continue its travel against the pneumatic tire 46, until it reaches the second portion 72 of the cam track 68, as illustrated in the figure 6 .

[0064] Finally, the locking finger 36 slides on the second portion 72 of the cam track 68, causing a slight tilt of the housing 30 around the locking finger 36 in a counterclockwise direction of pivoting corresponding to the direction of rotation of the drive roller 42.

[0065] The tilting of the housing 30 causes a partial release of the pressure exerted by the drive roller 42 on the tire 46, until the housing 30 reaches its operating position illustrated in the figure 7 .

[0066] When the housing 30 moves into its operating position and locks onto the mast 28, it emits a characteristic and reassuring click for the user.

[0067] Conversely, moving the housing 30 from its working position to its free position involves pulling on the handle 45 of the housing 30, so that the locking finger 36 slides on the second portion 72 of the cam track 68, causing a slight tilting of the housing 30 around the locking finger 36 by lever action, in a clockwise direction, and so that the drive roller 42 presses and deforms the pneumatic 46 until the locking finger 36 leaves the second portion 72 of the cam track 68 and slides upwards on the first portion 70 of the cam track 68 to allow the housing 30 to be removed.

[0068] Thus, the housing 30 of system 10 for the motorized assistance of cycle 12 is adapted to be easily mounted and dismounted on cycle 12 by a simple movement, without requiring any special tools.

[0069] It will be understood that the height of the adjustment of the cleat 60 allows the gap between the housing 30 and the tire 46 to be advantageously adjusted, in order to adjust the pressure exerted by the drive roller 42 on the tire 46 to an ideal value which allows the drive roller 42 to drive the front wheel 14 of the cycle 12 by friction, without slipping.

[0070] According to an alternative embodiment of the invention illustrated in figures 10 à 13 , the locking device 74 of the cleat 60 includes a first lock 92a and a second lock 92b for automatic clamping of the cleat 60.

[0071] According to this embodiment, as described previously, the cleat 60 comprises a first rail 76a and a second rail 76b extending on either side of the cleat 60, each following a vertical sliding direction, and which are mounted to slide in a first guide groove 78a and a second guide groove 78b respectively, each delimited by the housing 48. As can be seen in the figure 13 , the cleat 60 forms a cornice 94 which projects longitudinally from the bearing face 62 delimited by the cleat 60, to cooperate with the locking finger 36 of the mast 28.

[0072] In addition, the locking device 74 includes a spring 96 which is interposed vertically between the cornice 94 attached to the cleat 60 and a bottom wall 98 of the housing 48, to elastically recall the cleat 60 against the locking finger 36 of the mast 28.

[0073] The first lock 92a and the second lock 92b for automatic clamping of the cleat 60 each form a wedge which extends longitudinally from front to back, from the bearing face 62 delimited by the cleat 60 and which has a decreasing section towards the rear.

[0074] Also, the first lock 92a and the second lock 92b of automatic jamming are delimited transversely by a first cheek 100a and a second cheek 100b respectively and by a first ramp 102a and a second ramp 102b respectively.

[0075] The first cheek 100a and the second cheek 100b are supported transversely on a first lateral wall 104a and on a second lateral wall 104b respectively of housing 48.

[0076] The first ramp 102a and the second ramp 102b are arranged to cooperate with the first arm 32a and the second arm 32b of the mast 28, so that when the housing 30 moves from its free position illustrated to the figure 10 , to its position of use illustrated in the figure 11 The first arm 32a and the second arm 32b of the mast 28 slide longitudinally on the first ramp 102a and the second ramp 102b of the first lock 92a and the second lock 92b, respectively. These locks are then spread apart and pushed transversely against the first side wall 94a and the second side wall 94b of the housing 48, thus causing the cleat 60 to become wedged by friction. According to this embodiment, the cleat 60 is slid along by the locking finger 36 against the spring 96 until the drive roller 42 makes contact with the pneumatic tire 14.

[0077] Next, the locking finger 36 slides on the second portion 72 of the cam track 68, causing a slight rocking of the housing 30 around the locking finger 36 and simultaneously, the first arm 32a and the second arm 32b of the mast 28 spread apart the first lock 92a and the second lock 92b respectively, which lock the cleat 60 in the housing 48.

[0078] Advantageously, the automatic locking device 74 allows the system 10 according to the invention to adapt to tires of different thicknesses.

[0079] Naturally, the invention described above is by way of example. It is understood that a person skilled in the art is capable of carrying out different embodiments of the invention without departing from its scope.

Claims

1. System (10) for motorised assistance of a cycle (12), characterised in that it includes a support post (28) that comprises at least one arm (32a, 32b) extending from a base (34a, 34b) provided to be connected onto a cycle (12) to a free end forming a transverse locking finger (36) perpendicular to said arm (32a, 32b), and the system (10) including a removable motor unit (30) that is adapted to be mounted on said post (28) and which includes: - a cylindrical drive roller (42) which is powered by a source of electric energy and which is driven in rotation about a transverse drive axis (C), said drive roller (42) being provided to drive a wheel (14) of the cycle (12) by friction on a tread of a tyre (46) with which said wheel (14) is provided, - a housing (48) for locking the unit (30) on the post (28), which extends tangentially to the drive roller (42) along an axis (D) of insertion of the unit (30), from an inlet forming a channel (50), and - a locking lug (60) which is arranged in the locking housing (48) and which includes a stop notch (66) provided to cooperate with the locking finger (36) of the post (28) to lock the unit (30) on the post (28), and which defines a bearing face (62) extending tangentially to the drive roller (42), said bearing face (62) being intended to cooperate with a first side of the arm (32a, 32b) of the post (28), and in that the unit (30) is capable of being driven, in a locking movement directed towards the base of the post (28) tangentially to the drive roller (42), from a free position in which the unit (30) is detached from the post (28), to a position of use in which the unit (30) is locked in translation along the arm (32a, 32b) of the post (28) in opposite first and second directions, respectively by the locking finger (36) which bears on the stop notch (66) of the lug (60) and by the drive roller (42) which bears on the tyre (46), and wherein the unit (30) is blocked from pivoting about a transverse axis embodied by the locking finger (36), in the direction of rotation of the drive roller (42), by the arm (32a, 32b) of the support post (28) which bears against said bearing face (62) provided for this purpose.

2. System (10) for motorised assistance of a cycle (12) according to claim 1, characterised in that the lug (60) is mounted to slide in the housing (48), tangentially to the drive roller (42), between a plurality of positions in each of which the lug (60) is capable of being immobilised by a locking device (74), to allow adjustment of the distance of the unit (30) from the tyre (46) when the unit (30) occupies its position of use, in order to adjust the pressure exerted by the drive roller (42) on the tyre (46).

3. System (10) for motorised assistance of a cycle (12) according to claim 2, characterised in that the device (74) for locking the lug (60) includes at least one lock (92a, 92b) for automatically locking the lug (60), which cooperates with the post (28) by shape cooperation to automatically lock the lug (60) when the unit (30) tilts into its position of use.

4. System (10) for motorised assistance of a cycle (12) according to claim 3, characterised in that the device for locking the lug includes a spring for elastically returning the lug against the locking finger 36 of the post 28.

5. System (10) for motorised assistance of a cycle (12) according to any one of the preceding claims, characterised in that the lug (60) defines a cam path (68) which is provided to cooperate with the locking finger (36) of the post (28) and which successively has, along the axis (D) of insertion of the unit (30), a first portion (70) and a second portion (72) forming two opposite slopes, the second portion (72) being formed at least partly by the stop notch (66), and in that during said locking movement, the follower locking finger (36) slides on said first portion (70) of the cam path (68) so that the unit (30) slides towards the tyre (46) along the post (28) until the drive roller (42) presses and deforms the tyre (46) of the wheel (14) of the cycle (12) then, successively, the locking finger (36) slides on said second portion (72) of the cam path (68), causing the unit (30) to tilt about the locking finger (36) and causing the partial release of the pressure exerted by the drive roller (42) on the tyre (46), until the unit (30) reaches its position of use.

6. System (10) for motorised assistance of a cycle (12) according to any one of the preceding claims, characterised in that the channel (50) is designed to guide the post (28) during the locking movement of the unit (30), and in that the channel (50) includes a wall (54) which is adapted to bear on a second side of the arm (32a, 32b) of the post (28), when the unit (30) occupies its position of use, to oppose the pivoting of the unit (30) about a transverse axis embodied by the locking finger (36), in a direction opposite to the direction of rotation of the drive roller (42).

7. System (10) for motorised assistance of a cycle (12) according to any one of the preceding claims, characterised in that the post (28) is provided to extend along a direction perpendicular to the axis (A) of the wheel (14) of the cycle (12).

8. System (10) for motorised assistance of a cycle (12) according to any one of the preceding claims, characterised in that the post (28) includes two arms (32a, 32b) which extend in parallel, each from a first end forming said base (34a, 34b) of the post (28) to a second end connected to said locking finger (36).

9. System (10) for motorised assistance of a cycle (12) according to any one of the preceding claims, characterised in that the post (28) is mounted on a second support fork (20) comprising a first leg (22a) and a second leg (22b) which are provided to extend on either side of said wheel (14) of the cycle (12).

10. Cycle (12) which includes at least one wheel (14) equipped with a tyre (46), characterised in that it is equipped with a system (10) for motorised assistance according to any one of claims 1 to 9.