Drive system for a bicycle bottom bracket, bottom bracket, and bicycle comprising such a drive system

Abstract

The invention relates to a drive system for a bicycle bottom bracket, comprising: - a crank (110) comprising a means (111) for securing to a shaft (A); - a drive arm (120) extending along a longitudinal axis and comprising a first means for pivot connection to the crank (110), the connection means extending along an axis transverse to the longitudinal axis, the longitudinal axis and the transverse axis together defining a drive plane (PE); and - a static footrest (130) comprising a means for attachment to the drive arm (120) and a flat surface defining a plane (PA) for supporting a foot, the connection means being at a first predetermined distance (d1) from the securing means (111), the attachment means being at a second predetermined distance from the connection means, and the drive and support planes (PE, PA) intersecting at a predetermined angle (α).

Description

[0001] TITLE: DRIVE SYSTEM FOR CYCLE CRANKSET, CRANKSET AND CYCLE INCLUDING SUCH A DRIVE SYSTEM.

[0002] 1. Technical field

[0003] The field of the invention is that of cycles. More specifically, the invention relates to the design and implementation of a drive system for a crankset.

[0004] The present invention finds particular application in cycling, both competitive and recreational. Furthermore, the present invention aims to make cycling accessible to people with reduced mobility. The present invention also finds application in the medical field, particularly for the rehabilitation and / or muscle strengthening of a patient.

[0005] 2. Prior art

[0006] A cycle generally refers to a bicycle, which is a two-wheeled vehicle that moves by turning its rear wheel using the muscular power of the rider's legs. The rider's force is transferred to the rear wheel via a transmission system (pedals, cranks, chainring, drive chain, etc.) so that the rear wheel turns and the cycle moves forward. These physical and bodily components thus define a mechanical chain that propels the cycle.

[0007] To increase cycle speed, while maintaining or minimizing the user's muscular effort, it is known to modify anatomical propulsion and / or material propulsion.

[0008] Modifying anatomical propulsion involves adapting the user's pedaling posture. Depending on the situation and / or type of cycle, it is not always possible or easy to influence this parameter.

[0009] Modifying the material propulsion involves adapting the structural specificities of the cycle by perfecting all or part of the mechanical parts of the transmission system.

[0010] To achieve this, in addition to electric assistance solutions, there are numerous mechanical solutions for improving bicycle transmission components to increase crankset torque and thus bicycle performance. For example, the use of elliptical or oval chainrings, weighted pedals, independent cranks, etc., is well-known.

[0011] However, existing mechanical solutions do not allow users to reach their respective maximum power output when pedaling and / or are sometimes relatively complex to implement.

[0012] Moreover, these mechanical solutions do not adapt, or adapt with difficulty, to the individual needs of users, according to their abilities and the contexts of use.

[0013] 3. Summary of the invention

[0014] The proposed technique aims in particular to provide an effective solution to at least some of these different problems.

[0015] To achieve this, the proposed technique relates, in its first aspect, to a bicycle crankset drive system comprising:

[0016] - a crank arm with a means of attachment to a bottom bracket shaft,

[0017] - a drive arm extending along a longitudinal axis and having a first pivot connection means to the crank, the first connection means extending along an axis transverse to the longitudinal axis, the longitudinal axis and the transverse axis defining a drive plane,

[0018] - a static footrest intended to receive a user's foot, the footrest having a first means of attachment to the drive arm and a foot reception surface, the first means of attachment being partially disposed in the drive plane, the flat surface defining a support plane intersecting the drive plane, the first means of connection of the drive arm to the crank being located at a first distance, named "di", predetermined from the means of securing the crank to the bottom bracket shaft, the first means of attachment of the footrest to the drive arm being located, along the longitudinal axis, at a second distance, named "d2", predetermined from the first means of connection of the drive arm to the crank, and the drive and support planes being intersecting at a predetermined angle, named "a".Such a drive system, through the management of the parameters "di", "d2", and "a", allows for increased pedaling performance for the user of a bicycle equipped with this system. Indeed, unlike traditional pedaling devices that impose a circular foot trajectory, a drive system conforming to the proposed technique allows for a deformation of this trajectory, which can be oval, for example. Furthermore, this deformation of the foot trajectory is determined by taking into account the user's muscular capabilities in order to maximize the power transmitted to the crankset. In other words, the proposed technique makes it possible to increase pedaling power thanks to optimized kinematics (because it is personalized according to the user and their biomechanical measurements).A training system conforming to the proposed technique therefore makes it possible to optimize the pedaling kinematics in order to best exploit the user's joint torques and ensure maximum power transmission to the crankset.

[0019] Furthermore, such a training system allows for the design of more efficient cycles, or the adaptation of existing cycles, that are suitable for individuals with different anthropometric profiles.

[0020] A training system conforming to the proposed technique can be transposed in a versatile way, to meet the needs of individuals ranging from everyday users to athletes, and extend its potential benefits to people suffering from motor impairments, in a case of rehabilitation for example.

[0021] According to a particular feature of the proposed technique, the first distance, the second distance and the angle are determined based on anthropometric data of said user.

[0022] Using the user's anthropometric data allows for a personalized determination of the values ​​for the first distance "di", the second distance "d2", and the angle "a". This results in an improvement in the torque of the crankset equipped with such a drive system, and therefore in the performance of the cyclist.

[0023] According to another particular feature of the proposed technique, the anthropometric data include at least one user data from among: mass, height, femoral region length, crural region length and foot length.

[0024] Such anthropometric data are most significant in the personalized determination of the values ​​of the first distance "di", the second distance "d2", and the angle "a". This therefore makes it possible to limit the computing resources required to implement the associated determination process while ensuring that the training system parameter values ​​are efficient.

[0025] According to another particular feature of the proposed technique, at least one of the first distance, second distance and angle is adjustable.

[0026] Adjusting all or part of the first distance "di", the second distance "d2", and the angle "a" allows the training system to be used by various successive users. Such an adjustable training system is particularly well-suited to medical devices used by multiple users, for example, in rehabilitation centers.

[0027] According to another particular feature of the proposed technique, the crank has a plurality of second means of connection, complementary to the first means of connection of the drive arm, the first and second means of connection being assembled in a reversible manner.

[0028] According to another particular feature of the proposed technique, the drive arm has a plurality of second means of attachment, complementary to the first means of attachment of the footrest, distributed along the longitudinal axis, the first and second means of attachment being assembled in a reversible manner.

[0029] According to another particular feature of the proposed technique, the first footrest fixing means is configured to cooperate with a second drive arm fixing means, the first and second fixing means having complementary grooves.

[0030] According to another particular feature of the proposed technique, the training arm and the footrest are made as a single unit.

[0031] Such a structure, known as an invariant design, makes it possible to limit the number of components in the drive system and therefore the associated connecting elements. This results in a reduction in the mass of the drive system and an improvement in its mechanical strength.

[0032] The present invention also relates, according to a second aspect, to a cycle crankset comprising a bottom bracket shaft, each longitudinal end of said shaft carrying, in an opposite manner, a drive system as described above.

[0033] The present invention relates finally, according to a third aspect, to a cycle comprising a frame carrying a crankset as described above.

[0034] 4. List of figures

[0035] Other features and advantages of the invention will become apparent from the following description of embodiments, given by way of simple illustrative and non-limiting examples, and the accompanying drawings, among which:

[0036] - [Fig.1A] to [Fig.1E]: Figures IA to 1E illustrate, from different views, a partial example of a crankset for a cycle equipped with a drive system conforming to a first embodiment of the invention;

[0037] - [Fig.lA]: Figure IA illustrates the pedal assembly from a perspective view;

[0038] - [Fig.lB]: Figure IB illustrates the pedal assembly from a front view;

[0039] - [Fig.lC]: Figure IC illustrates the pedal assembly from a first side view;

[0040] - [Fig.lD]: Figure 1D illustrates the pedal assembly from a second side view;

[0041] - [Fig.lE]: Figure 1E illustrates the pedal assembly from a top view;

[0042] - [Fig.2]: Figure 2 is a simplified functional diagram of a process for determining custom parameters of the training system for figures IA to 1E;

[0043] - [Fig. 3A] and [Fig. 3B]: Figures 3A to 3B illustrate, from front and side views respectively, a partial example of a bicycle crankset equipped with a drive system according to a second embodiment of the invention; and

[0044] - [Fig.4A] and [Fig.4B]: Figures 4A and 4B illustrate, from different side views, a partial example of a crankset for a cycle equipped with a drive system according to a third embodiment of the invention.

[0045] 5. Detailed description of the invention

[0046] We then illustrate different embodiments of the invention with the aid of figures that directly or indirectly refer to a bicycle crankset. The term

[0047] "Cycle" should be understood in its broadest sense. It includes, in particular, bicycles (racing, mountain, hybrid), tricycles, quadricycles, ergocycles, pedal boats, etc. The invention can therefore be applied to any vehicle comprising a crankset.

[0048] In the description of the figures, the same elements will be designated by the same reference numerals on the different figures of the same particular embodiment. From one embodiment to another, these elements will be designated by a reference numeral retaining the same last two digits, but whose hundreds digit will correspond to the particular embodiment.

[0049] 5.1 Description of illustrative embodiments

[0050] Figures IA to 1E illustrate, from different views, a partial example of a bicycle crankset equipped with a drive system according to a first embodiment of the invention. Figure 2 is a simplified functional diagram of a method for determining the customized parameters of this drive system.

[0051] In this first embodiment, the 100 drive system for a cycle crankset comprises:

[0052] - a crank 110, extending along a longitudinal axis Xno, fixed to a bottom bracket shaft A,

[0053] - a drive arm 120, extending along a longitudinal axis X120, mounted to rotate freely on the crank 110, and

[0054] - a static footrest 130, intended to receive a user's foot (not shown), fixed to the drive arm 120.

[0055] The footrest 130 is described as "static" in that it has no movement relative to the drive arm 120 that supports it. In other words, and unlike previous solutions, the footrest 130 lacks a pivot connection with the drive arm 120. By eliminating such a pivot connection, the drive system 100 imposes a single optimal kinematic path for the user's foot. This results in improved power transmission to the crankset. Without the implementation of such a static footrest 130, a continuum of possible pedaling trajectories would exist, failing to guarantee a single pedaling method or the optimality of the drive system according to the proposed technology.

[0056] The crank 110 has, near one longitudinal end, a fastening means 111 designed to cooperate with a complementary fastening means provided on one end of the bottom bracket shaft A. The fastening means 111 of the crank 110 extends along a transverse axis Yno to the longitudinal axis Xno and is adapted to immobilize the crank 110 on the shaft A.

[0057] The drive arm 120 has, near one longitudinal end, a first connecting means 121 configured to cooperate with a second complementary connecting means 112 provided on the crank 110. The first connecting means 121 of the drive arm 120 extends along a transverse axis Y120 to the longitudinal axis X120 and is configured to allow rotation of the drive arm 120 relative to the crank 110, along the transverse axis Y120. The longitudinal axis X120 and the transverse axis Y120 of the drive arm 120 define a drive plane P E .

[0058] The footrest 130 has a first fastening means 131 configured to cooperate with a second complementary fastening means 122 provided on the drive arm 120. The fastening means 122 and 131 of the drive arm 120 and the footrest 130, respectively, are partially arranged in the drive plane P Eof the 120 training arm.

[0059] The footrest 130 also has a flat surface 132, called the receiving surface, defining a support plane P for the user's foot on the footrest 130.

[0060] The crank 110 and the footrest 130 are located on either side of the drive arm 120 and substantially opposite each other. In other words, the drive arm 120 has a first lateral surface and a second lateral surface, opposite the first lateral surface. The crank 110 is attached to the drive arm 120 near one end of its first lateral surface, while the footrest 130 is attached to the same drive arm 120 near one end of its second lateral surface. The crank 110 and the drive arm 120 therefore move in parallel planes (not shown).

[0061] The first linkage means 121 of the drive arm 120 to the crank 110 is located, along the longitudinal axis Xno, at a first predetermined distance "di" from the means of securing the crank 111 to the shaft A of the crankset.

[0062] The first means of fixing 131 of the footrest 130 to the drive arm 120 is located, along the longitudinal axis X120, at a second predetermined distance "d2" from the first means of connecting 121 of the drive arm 120 to the crank 110.

[0063] Finally, the support plane P intersects the training plane P E according to an angle "a" of a predetermined value.

[0064] In this embodiment, the values ​​of the first distance "di", the second distance "dî" and the angle "a" are determined based on anthropometric data DAi, DA2, DA X of the user of the training system 100.

[0065] For this purpose, a DT processing device, visible in figure 2, separate from the drive system 100, is implemented.

[0066] This DT processing device, including a processor and memory, receives the anthropometric data DAi, DA2, DA X of the user (input data) and outputs the values ​​of the first distance "di", the second distance "d2" and the angle "a" of the drive system 100 (output data).

[0067] This DT processing device is configured to implement a computer program product comprising program code instructions for implementing a method for determining the values ​​of the first distance "di", the second distance "d2" and the angle "a" of the drive system 100.

[0068] This determination process includes:

[0069] - an optimization phase aimed at finding the best solution to a problem by mimicking the process of natural selection; and

[0070] - a nonlinear problem solver from an algorithmic differentiation tool. Such a solver is a relatively flexible and efficient way to express and solve complex problems.

[0071] This determination method also takes into account anatomical and anthropometric constraints CAi, CA2, CA X (input data) in order to propose realistic and implementable values ​​in a training system 100% compliant with the invention. The anatomical and anthropometric constraints CAi, CA2, CA XConsidered, for example, are the maximum joint torques of the hip, knee, and ankle, which depend on the position and speed of the joint in question. Optimizing and constraining the angular position and speed of the knee and hip joints allows for maximum exploitation of these maximum joint torques to produce the maximum average crank power.

[0072] Obviously, the values ​​of the first distance "di", the second distance "d2" and the angle "a" can be determined by other processes which implement different or additional algorithms and / or tools and / or parameterization data, such as structural constraints related to the adjustment mechanisms (detailed later).

[0073] In this first embodiment, the anthropometric data DAi, DA2, DA XThe factors taken into consideration to determine the values ​​of the first distance "di", the second distance "d2" and the angle "a" of the 100 drive system are, for a particular user: mass, height, femoral region length, crural region length and foot length.

[0074] The accuracy of the values ​​for the first distance "di", the second distance "d2", and the angle "a" is correlated with the number of anthropometric data points, particularly those of the legs, taken into account by the determination process. High accuracy of these parameter values ​​results in better calibration of the 100 drive system. This allows the user to more easily reach their maximum power output, and therefore improve the crankset's torque.

[0075] However, it is possible to determine the values ​​of the parameters "di", "d2", and "a" using a limited number of anthropometric data points, such as mass and / or height. This simplified implementation is particularly useful when the user's anthropometric data are likely to change within a relatively short timeframe, as is the case for a user who is still growing.

[0076] In this first embodiment, the first distance "dl", the second distance "d2", and the angle "a" are adjustable via step-by-step mechanisms. In other words, the positions of the drive arm 120 and footrest 130 can be changed as needed, for example, when the user of the cycle equipped with the drive system 100 changes. The adjustment of the first distance "dl" is achieved by changing the position of the drive arm 120 along the crank 110.

[0077] To achieve this, several identical secondary connecting means 112 are distributed along the crank 110 along the longitudinal axis Xno to define alternative mounting positions for the drive arm 120. The first connecting means 121 of the drive arm 120 is coupled to one of the secondary connecting means 112 according to the value of the first predetermined distance "di". One of the connecting means 112, 121 is removable and configured to reversibly attach the drive arm 120 to the crank 110.

[0078] Similarly, the adjustment of the second distance "d2" is achieved by changing the position of the footrest 130 along the drive arm 120.

[0079] Again, several identical secondary mounting means 122 are distributed along the drive arm 120 along the longitudinal axis X120 to define alternative mounting positions for the footrest 130. The first mounting means 131 of the footrest 130 is coupled to one of the secondary mounting means 122 according to the value of the second predetermined distance "dî". One of the mounting means 122, 131 is removable and configured to reversibly attach the footrest 130 to the drive arm 120.

[0080] The adjustment of angle "a" is obtained by varying the inclination of the receiving surface 132 of the footrest 130 relative to the drive arm 120.

[0081] To do this, the footrest 130, made in one piece (monobloc), has on its first fixing means 131 grooves configured to cooperate with complementary grooves, extending along the transverse axis Y120, provided in the second fixing means 122 of the drive arm 120.

[0082] Each of these step-by-step mechanisms is relatively robust and is therefore particularly suited to the 100 drive system on which significant forces are likely to be applied by the user.

[0083] In the illustrated example, the crank 110, made of aluminum, has an oblong shape. This design eliminates any sharp angles that could potentially harm the user's physical integrity in the event of an impact. Near one longitudinal end of the crank 110, there is a square-section slot extending along the transverse axis Yuo. This square slot forms the means 111 for attaching the crank 110 to the bottom bracket shaft A. This slot shape ensures a robust mounting of the crank and an efficient distribution of forces on the bottom bracket shaft.

[0084] The second connecting means 112, from the crank 110 to the drive arm 120, are formed by identical circular slots, five in the illustrated example, provided on the crank 110 along axes parallel to the transverse axis Yuo of the securing means 111 to the bottom bracket shaft A. The circular slots 112 are distributed linearly and at constant intervals along the crank 110 along its longitudinal axis Xuo.

[0085] The drive arm 120, also made of aluminum and oblong in shape, has, on one side and near one longitudinal end, a cylindrical rod projecting along the transverse axis Yuo. The cylindrical rod 121 forms the first means of connecting the drive arm 120 to the crank 110. The cylindrical rod 121 is thus mounted, reversibly and pivotally, in one of the circular slots 112 of the crank 110. The rod 121 is held in position within the circular slot 112 by removable locking means (not shown).

[0086] The second fixing means 122, of the drive arm 120 to the footrest 130, are formed by identical grooved slots, five in the illustrated example, provided on the drive arm 120 along axes parallel to the transverse axis Yuo of the first connecting means 121 to the crank 110. The grooved slots 112 are distributed, in a linear manner and at a constant distance, on the drive arm 120 along its longitudinal axis X o.

[0087] The footrest 130, also made of an aluminium material, has essentially the shape of a flat parallelepiped with a grooved projection on one side of its edge forming the first means of attachment 131.

[0088] Naturally, the greater the number of circular lights (112) and fluted lights (112), the more precise the adjustments of the first and second distances "di" and "d2". The same applies to the number of flutes for adjusting angle "a". The number of steps is therefore likely to vary depending on the requirements.

[0089] Depending on the requirements, it may also be possible to distribute the circular lights 112 and / or the fluted lights 112 at varying intervals. For example, the spacing values ​​can be determined to correspond to a normal distribution of the adjustment positions preferred by a user group. This notably improves the granularity of the adjustment of the first and second distances "di" and "dî".

[0090] An experiment, including a virtual simulation, of the 100 training system was conducted with data from two distinct individuals.

[0091] The first individual, designated M1, is a 34-year-old man, 189 cm tall and weighing 90 kg. His femur length is 47.5 cm, his thigh length is 44 cm, and his foot length is 30.5 cm. The second individual, designated Fl, is a 49-year-old woman, 160 cm tall and weighing 60 kg. Her femur length is 38 cm, her thigh length is 39 cm, and her foot length is 24.3 cm.

[0092] All or part of this data was entered into the determination process described above. Then, the first and second distances "di" and "d2" and the angle "a" of the drive system 100 were set according to the values ​​generated by this same determination process.

[0093] After experimentation, it was found that the average power produced by the first individual, M1, was 866 W with a cycle equipped with the drive system conforming to the proposed technique, compared to 750 W with a traditional cycle. The average power produced by the second individual, Fl, was 400 W with a cycle equipped with the drive system conforming to the proposed technique, compared to 354 W with a traditional cycle.

[0094] The proposed technique would therefore allow for a significant improvement in the average power output for each individual (15.1% for Ml and 12.8% for Fl) compared to a traditional cycle architecture without this training system. Naturally, those skilled in the art will understand that the amount of improvement in average power is specific to each individual. Furthermore, it was observed that the heel trajectory obtained after optimization for the two individuals differs with respect to the limits set for the parameters and is slightly different between the two individuals.

[0095] Figures 3A and 3B illustrate, from different views, a partial example of a cycle crankset equipped with a drive system according to a second embodiment of the invention.

[0096] This second embodiment differs from the first embodiment only in the type of mechanism for adjusting the value of the angle "a" between the drive plane P E and the support plane P. For reasons of clarity and conciseness in particular, the common and identical elements between the first embodiment and the second embodiment will not be described.

[0097] In this second embodiment, the drive system 200 features a mechanism for continuously adjusting the angle "a" between the drive plane P E and the support plan P A .

[0098] More specifically, in the illustrated example, the first attachment means 231 for the footrest 230 is formed by a cylindrical rod, while the second attachment means 222 for the drive arm 220 are each formed by a complementary cylindrical slot. The footrest 230 is therefore rotationally movable relative to the drive arm 220.

[0099] The adjustment of the angle "a" of inclination of the receiving surface 232 of the footrest 230 is achieved by selectively locking the rotational movement of the footrest 230 relative to the drive arm 220.

[0100] To achieve this, the footrest 230 includes, between the receiving surface 232 and the first fastening means 231, a cylindrical roller 233. In other words, the first fastening means 231 and the receiving surface 232 are supported on either side of the roller 233.

[0101] On the roller 233 is provided an arched groove 234 which is configured to receive a locking lug 240 which fits into the drive arm 220.

[0102] Such a mechanism allows, in particular, a better precision in adjusting the value of angle "a". Figures 4A and 4B illustrate, from different views, a partial example of a bicycle crankset equipped with a drive system according to a third embodiment of the invention.

[0103] This third embodiment differs from the first embodiment only in the absence of a mechanism for adjusting the first distance "di" and the second distance "d2". Again, for reasons of clarity and conciseness, the common and identical elements between the first and third embodiments will not be described.

[0104] In this third embodiment of the drive system 300, the crank 310 and the drive arm 320 have a single second means of connection 312 and of fixing 322 respectively.

[0105] In other words, the value of the first distance "di", between the first connecting means 321 of the drive arm 320 to the crank 310 and the means 311 of securing the crank 310 to the bottom bracket shaft A, is invariable. Similarly, the value of the second distance "d2", between the first attachment means 331 of the footrest 330 to the drive arm 320 and the first connecting means 321 of the drive arm 320 to the crank 310, is invariable.

[0106] In this third embodiment, only the value of the angle "a", between the training planes P E and support P, is adjustable.

[0107] This configuration limits stress concentrations near the openings in the crank and drive arm. This results in improved mechanical strength of the drive system. A drive system conforming to this third embodiment is particularly well-suited for applications such as off-road bicycles.

[0108] Since the values ​​of the distances "di" and "d2" are fixed, such a tailor-made training system is particularly intended for competitors whose anthropometric data do not change, or change negligibly.

[0109] 5.2 Other embodiments and variants not shown

[0110] In the illustrated embodiments, the user's anthropometric data is used to determine the values ​​of the first distance "di", the second distance "d2", and the angle "a" of the drive system. According to another embodiment, not shown, other personal data of the user (age, gender, etc.) are taken into account, in addition to or instead of all or part of the anthropometric data, to determine the values ​​of the first distance "di", the second distance "dî", and the angle "a". In yet another embodiment, not shown, the user's anthropometric data is used to determine the value of at least one other additional parameter of the drive system, such as the dimensions of the footrest's landing surface. Such configurations allow for further improvement in the power output of the user.

[0111] In the illustrated embodiments, the drive arm and footrest are separate components joined together in a reversible manner to modify the values ​​of the second distance "d2" and / or the angle "a". According to another embodiment, not shown, the drive arm and footrest are made as a single unit, i.e., manufactured as a monobloc (for example, by 3D printing or molding). Such a monobloc configuration requires determining, prior to the manufacturing of the drive system, the values ​​of the second distance "d2" and the angle "a" for a specific individual. Since these values ​​are fixed, such a custom-made drive system is essentially intended to equip the bicycle of a cyclist (competitive rider) whose anthropometric data does not change, or changes only negligibly.Such a structure, known as an invariant design, makes it possible to limit the number of components in the drive system and therefore the associated connecting elements. This results in a reduction in the mass of the drive system and an improvement in its mechanical strength.

[0112] In the illustrated examples, the dimensions of the drive system components (crank, drive arm, and footrest) are not specified. These dimensions are determined based on requirements, as they depend on various factors, such as the bicycle's architecture (and more specifically the overall dimensions of the associated crankset), the bicycle's operating environment, and / or the values ​​of the first distance "di", the second distance "d2", and the angle "a".

[0113] In the examples shown, the crank, drive arm, and footrest are made of aluminum. Of course, other materials can be considered depending on the needs and / or intended use of the drive system. For example, for road use, all or part of these components are made of carbon fiber to reduce the weight of the drive system. In another example, for off-road use, all or part of these components are made of steel to increase the mechanical strength of the drive system.

[0114] In the examples shown, the crank and drive arm are each oblong. Of course, other shapes are possible. For example, the drive arm could be rectangular to simplify its design and manufacture.

[0115] In the illustrated examples, the footrest has roughly the shape and dimensions of a traditional pedal designed to accommodate a portion of the user's foot. Of course, other footrest designs can be considered depending on the needs and / or uses of the drive system. In another example, not shown, the footrest has roughly the shape of a sole whose dimensions closely match those of the user's foot.

[0116] In the first and second illustrated embodiments, each of the distances "di" and "d2" is adjustable via a step-by-step mechanism. According to another embodiment, not shown, each of the distances "di" and "d2" is adjustable via a continuous mechanism. For example, to achieve this, the drive arm is supported by a sliding block that moves in a groove in the crank. Similarly, the footrest is supported by a sliding block that moves in a groove in the drive arm. In such a configuration, reversible locking means are provided to secure the slides in the desired positions.

[0117] Obviously, the invention is not limited to the embodiments and variants described above and provided solely by way of example. It encompasses various modifications, alternative forms, and other variants that a person skilled in the art might consider within the scope of the present invention, and in particular all combinations of the different modes of operation described above, which may be taken separately or in combination.

[0118] Depending on the embodiments chosen, the invention offers various advantages, including: improving the power output of a user on a bicycle crankset; customizing the drive system settings; providing a solution that can be used alternately by different users; offering a solution adaptable to an existing cycle; limiting the mass of the drive system; ensuring long life; limiting manufacturing costs; etc.

Claims

DEMANDS

1. Drive system (100, 200, 300) for bicycle crankset comprising: - a crank (110, 210, 310) having a means of attachment (111) to a bottom bracket shaft (A), - a drive arm (120, 220, 320) extending along a longitudinal axis (X120) and having a first connecting means (121) pivoting to said crank (110), said first connecting means (121) extending along a transverse axis (Y120) to said longitudinal axis (X120), said longitudinal axis (X120) and said transverse axis (Y120) defining a drive plane (P E ), - a static footrest (130, 230, 330) intended to receive a user's foot, said footrest (130) having a first means of attachment (131) to said drive arm (120) and a receiving surface (132) for said foot, said first means of attachment (131) being partially disposed in said drive plane (P E), said flat surface (132) defining a support plane (P) intersecting said drive plane (PE), said first connecting means (121) of said drive arm (120) to said crank (110) being located at a first predetermined distance (di) from said securing means (111) of said crank (110) to said bottom bracket shaft (A), said first fixing means (131) of said footrest (130) to said drive arm (120) being located, along said longitudinal axis (X120), at a second predetermined distance (d2) from said first connecting means (121) of said drive arm (120) to said crank (110), and said drive planes (P E ) and support (P A ) being intersecting at a predetermined angle (a).

2. A training system (100, 200, 300) according to claim 1, characterized in that said first distance (di), said second distance (d2) and said angle (a) are determined based on anthropometric data (DAi, DA2, DA X ) of said user.

3. Training system (100, 200, 300) according to claim 2, characterized in that said anthropometric data (DAi, DA2, DA X ) include at least one user data point from: mass, height, femoral region length, crural region length and foot length.

4. Drive system (100, 200, 300) according to any one of claims 1 and 3, characterized in that at least one of said first distance (di), second distance (dî) and angle (a) is adjustable.

5. Drive system (100, 200) according to claim 4, characterized in that said crank (110, 210) has a plurality of second connecting means (112, 212), complementary to said first connecting means (121, 221) of said drive arm (120, 220), said first and second connecting means (112, 212, 121, 221) being assembled reversibly.

6. Drive system (100, 200) according to claim 4, characterized in that said drive arm (120, 220) has a plurality of second fastening means (122, 222), complementary to said first fastening means (131, 231) of said footrest (130, 230), distributed along said longitudinal axis (X120), said first and second fastening means (122, 222, 131, 231) being assembled reversibly.

7. Drive system (100) according to claim 4, characterized in that said first fastening means (131) of said footrest (130) is configured to cooperate with a second fastening means (122) of said drive arm (120), said first and second fastening means (131, 122) having complementary grooves.

8. Drive system (100, 200, 300) according to any one of claims 1 to 3, characterized in that said drive arm and said footrest are made in one piece.

9. Crankset for a cycle comprising a crankshaft (A), each longitudinal end of said shaft (A) carrying, in an opposite manner, a drive system (100, 200, 300) according to any one of claims 1 to 8.

10. Cycle comprising a frame carrying a crankset according to claim 9.

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