Strong wear-resistant bicycle chain wheel pair and chain wheel cassette freewheel with such bicycle chain wheel pair

Abstract

The invention relates to a bicycle rear wheel sprocket pair for positively engaging with a bicycle roller chain in a force transmitting manner, wherein the rear wheel sprocket pair is rotatable about a sprocket shaft, wherein the sprocket shaft defines an axial direction along the sprocket shaft, a radial direction orthogonal to the sprocket shaft and a circumferential direction around the sprocket shaft, wherein the rear wheel sprocket pair comprises a larger sprocket and a coaxial smaller sprocket axially adjacent to the larger sprocket, the smaller sprocket being connected to the larger sprocket for jointly rotating without slippage about the sprocket shaft, wherein the larger sprocket has an even number of teeth equal to or smaller than 22, and wherein the difference in the number of teeth between the larger sprocket and the smaller sprocket is exactly two teeth.

Description

Technical Field

[0001] This invention relates to a bicycle rear wheel sprocket pair for force-transmitting engagement with a bicycle roller chain. The rear wheel sprocket pair is rotatable about a sprocket shaft, wherein the sprocket shaft defines an axial direction, a radial direction orthogonal to the sprocket shaft, and a circumferential direction around the sprocket shaft. The rear wheel sprocket pair includes a larger sprocket and a smaller sprocket coaxially adjacent to the larger sprocket in the axial direction, the smaller sprocket being connected to the larger sprocket to rotate together about the sprocket shaft in a slip-free manner. Background Technology

[0002] EP 1 188 658B1 discloses a rear sprocket cassette with seven sprockets. The tooth count of the sprockets, from the outermost smallest sprocket to the innermost largest sprocket, is 11–13–15–17–21–25–29–33. That is, known sprocket cassettes only have sprockets with an odd number of teeth. The outermost sprocket is the one furthest from the longitudinal center plane of the bicycle (orthogonal to the sprocket axis). Correspondingly, the innermost sprocket is the one closest to the longitudinal center plane of the bicycle.

[0003] Similarly, a bicycle roller chain engaging in a ring on the rear sprocket has been disclosed, having multiple chain rollers arranged longitudinally along the chain at predetermined chain spacing and chain plates connected to these chain rollers. The links of a known conventional bicycle roller chain are formed by pairs of chain plates, where inner and outer chain plate pairs alternate longitudinally along the chain. Since the bicycle roller chain is constructed in a closed loop, this longitudinal direction is also the chain's ring direction. The end regions of the outer chain plate pairs overlap with the end regions of the inner chain plate pairs in a known manner, such that the end regions of the inner chain plate pairs are arranged between the end regions of the outer chain plate pairs and the chain rollers held between these end regions; specifically, one inner chain plate end region is arranged on each of the two end sides of the chain rollers. Therefore, the inner width between the two inner chain plates of the inner chain plate pair, measured along the chain width direction, that is, parallel to the roller axis of the chain roller, is smaller than the inner width between the two outer chain plates of the outer chain plate pair. The inner width of the chain link pair defines the meshing space for the sprocket teeth to engage with the roller chain. Therefore, as a link type, narrow links defined by the inner chain link pair and wide links defined by the outer chain link pair alternate on the roller chain. Because the inner and outer chain link pairs alternate in the chain's circumferential direction, a bicycle roller chain always has an even number of links. Hereinafter, the bicycle roller chain will also be simply referred to as a "bicycle chain" or "chain".

[0004] For convenience, sprockets with an odd number of teeth will be referred to as "odd-numbered sprockets" in the following text, and sprockets with an even number of teeth will be referred to as "even-numbered sprockets".

[0005] The disadvantage of odd-numbered sprockets is that the meshing relationship between the same tooth and a type of link changes with each cycle of the bicycle chain. Therefore, the same tooth alternately meshes with narrower inner link plates and wider outer link plates in successive cycles of the bicycle chain. Consequently, each tooth of an odd-numbered sprocket must be able to mesh with narrow links.

[0006] The shifting conditions required to move a bicycle chain from one sprocket to the next smaller sprocket can weaken the sprocket itself. As is well known, this shifting is achieved via a derailleur on a rear cassette, where the chain guide rollers, which guide the bicycle chain in the correct direction, are arranged coplanar with the sprocket that receives the chain after the shift, via a power transmission mechanism, such as mechanically via a cable drive or electrically via a "shift-by-wire" system. Thus, the chain moves from the sprocket currently guiding the chain to the sprocket about to guide it.

[0007] On the sprocket, a recessed structure in the form of a planar recess belonging to this end side is constructed on the end side facing the next smaller sprocket. The chain plates (usually the outer chain plates) of the bicycle chain can be at least partially submerged in these recessed structures to move the chain axially closer to the larger sprocket, thereby assisting the shifting process. Specifically, there are upshifting recessed structures that assist the chain in shifting from the larger sprocket to the next smaller sprocket during upshifting, and downshifting recessed structures that assist the chain in shifting from the adjacent smaller sprocket to the larger sprocket during downshifting. During the corresponding shifting process, when the sprocket pair consisting of the larger sprocket and the adjacent smaller sprocket is viewed axially from the outside, that is, when the smaller sprocket is closer to the observer, the shape and / or radial inner boundary of the recessed structure follows the direction of the bicycle chain in the transition region between the smaller and larger sprockets. This means that the upshift recess and / or its radially inner edge generally approach the smaller sprocket from a radially outer position on the larger sprocket in a counterclockwise radial direction, and the downshift recess and / or its radially inner edge generally approach the smaller sprocket from a radially outer position on the larger sprocket in a clockwise radial direction.

[0008] On a sprocket, some teeth are typically configured as output teeth. When shifting to the next smaller sprocket, these output teeth act as the last teeth to engage between the chain links' sprocket pairs before the chain leaves the larger sprocket and moves towards the smaller sprocket. In the normal drive rotation direction of the rear sprocket, that is, clockwise from the outside along the sprocket shaft reference view, the output teeth are typically adjacent to their corresponding upshift recesses clockwise, such that the chain engaging the output teeth passes laterally from beside the teeth that follow the output teeth counterclockwise, making full use of the upshift recesses as a movement space.

[0009] Similarly, for the downshifting process, receiving teeth are constructed on the larger sprocket. These receiving teeth should engage as the first teeth with the bicycle chain that needs to be moved to the larger sprocket. Here, the bicycle chain is axially approached to the larger sprocket, making full use of the downshifting recess as a movement space. The chain first passes laterally, radially outward, next to the teeth located clockwise in front of the receiving teeth, making full use of the upshifting recess as a movement space. Finally, the receiving teeth can engage as the first teeth of the sprocket into the meshing space between the two chain plates. Therefore, the receiving teeth are adjacent to their corresponding downshifting recesses counterclockwise.

[0010] The output and receiving teeth have bodies different from the other teeth of the sprocket to perform corresponding engagement tasks during the corresponding gear shifting process. These output and receiving teeth may be equipped with tooth height measured radially, and / or tooth width measured circumferentially, and / or tooth thickness measured axially, and / or tooth tip shape, and / or the profile of at least one tooth surface, and / or the position of one or two tooth flanks relative to the nearest sprocket flank, and / or tooth camber about an inclined axis orthogonal to the radial projection direction of the tooth, and / or tooth camber about an inclined axis parallel to the radial projection direction of the tooth, so as to serve as the last engaging teeth during upshifting or as the first engaging teeth during downshifting.

[0011] The chain is typically received on the larger sprocket of a sprocket pair based on the larger meshing space on the outer sprocket pair. Furthermore, the outer sprockets and outer sprocket pairs are closer to the sprocket in the system-related axial direction than the inner sprocket pair, because the outer sprocket facing the larger sprocket of the chain looping on the smaller sprocket is always axially closer to the larger sprocket than the inner sprocket facing the larger sprocket.

[0012] As mentioned above, in odd-numbered sprockets, the correspondence between a tooth and a type of chain link that meshes with it alternates with each rotation of the sprocket. Therefore, in known sprocket cassettes, the way the chain transfers to the larger sprocket is related to the number of rotations the smaller sprocket guiding the chain has made until the shifting process. To reliably receive the chain without any undesirable delay (i.e., the time interval between the rider initiating the shifting process and the actual shifting on the sprocket), the larger sprocket has two receiving teeth that are circumferentially adjacent to each other, such that at least one receiving tooth engages with the outer chain plate during downshifting to receive the chain.

[0013] This applies similarly to the output teeth when shifting up.

[0014] To facilitate engagement with chains that are not yet fully or no longer fully looping around larger sprockets, the receiving and output teeth are constructed to be finer compared to other teeth that do not perform the tasks of receiving and output teeth. This further weakens the overall structure of the receiving and output teeth and the sprocket.

[0015] Compared to the chain drive disclosed in EP 1 188 658B1, electric-assisted modern bicycle drivetrains can transmit a greater amount of torque more consistently. Furthermore, with electric assistance in the bicycle drivetrain, the gear difference—the difference in the number of teeth between the largest and smallest sprockets on the cassette divided by the number of teeth on the smallest sprocket—is increased. In addition, the riding and shifting behaviors of electric-assisted bicycles also differ compared to bicycles driven solely by human power.

[0016] Due to the larger gear shifts compared to the past, a larger number of sprockets must be fitted to the rear cassette to meet riders' expectations for reduced gear shift jumps between adjacent sprockets. In the case of a bicycle driven solely by human power without electric assistance, minimal gear shift jumps are always necessary, meaning a smaller difference in the number of teeth between the sprocket pair and the smaller sprocket. As tires tend to become larger and chainstays tend to become shorter, relatively smaller chainrings are typically used on the pedal cranks. Consequently, the speed range of electric assist allowed by most road traffic regulations is increasingly shifting towards the smaller rear sprocket. In Germany, the maximum permissible speed for electric assist is, for example, 25 km / h, while in other countries it ranges from 20 km / h to a maximum of 30 km / h. Therefore, the smaller sprocket of the cassette is particularly at risk of increased wear. Summary of the Invention

[0017] In view of this, the purpose of the present invention is to improve the bicycle rear wheel chainring described at the beginning of this document, so as to make it more stable without increasing the structural space requirements, and thus be used for work with greater mechanical loads.

[0018] The solution of this invention to achieve the above-mentioned objective is that the larger sprocket of the bicycle rear wheel sprocket pair described at the beginning of this document has an even number of teeth, equal to or less than 22, wherein the difference in the number of teeth between the larger and smaller sprockets is exactly two teeth. Therefore, both sprockets in the sprocket pair have an even number of teeth, such that the correspondence between each sprocket tooth and the type of chain link it meshes with does not change during the engagement of the sprocket with the bicycle chain. That is, if a tooth engages with an outer link in a cycle, then that tooth engages with an outer link in every cycle of the sprocket.

[0019] The larger sprocket has a shifting region along a section of its circumference on its end side facing the smaller sprocket, which includes a shifting recess. As described above, the shifting region is constructed and arranged to enable the engagement transition of the bicycle roller chain from the larger to the smaller sprocket on the rear wheel sprocket pair that rotates clockwise around the sprocket axis.

[0020] Typically, only the upshift zone allows the chain to shift up to a smaller sprocket. Similarly, typically only the downshift zone allows the chain to shift down from a smaller sprocket to a larger sprocket.

[0021] In this application, when clockwise and counterclockwise are used as directional designations for a sprocket pair, it always refers to an axial reference view of the sprocket pair or a sprocket cassette containing the sprocket pair, in which the smaller sprocket of the sprocket pair is closer to the observer than the larger sprocket. Because the smaller sprocket is farther from the longitudinal center plane of the bicycle on the rear wheel of the bicycle carrying the sprocket, and thus "more outward" compared to the larger sprocket, the axial reference view is also referred to below as an "external" axial view.

[0022] According to the invention, on the larger sprocket, the upshift recess is configured with exactly one output tooth, which, due to its shape and orientation, is designed to be the last tooth engaged between the chain plates of the bicycle roller chain link during the upshifting process from the larger sprocket to the smaller sprocket, in conjunction with the end-side upshift recess. Typically, only this specially configured output tooth, and no other teeth, engage with the chain as the last tooth of the larger sprocket during upshifting.

[0023] The advantages of having only one output tooth in each upshift zone are twofold: First, the chain, in terms of its link sequence, transfers to the smaller sprocket in a defined orientation, because unlike the prior art described above, there are no longer two teeth that are circumferentially consecutive and each of them can be used as the last engaging tooth due to its shape and orientation. The output tooth typically engages with the outer chainring link because, in the reference view, the next inner chainring link in the counterclockwise direction is more easily passed by the tooth that follows the output tooth in the counterclockwise direction due to its narrower size and slides radially inward on the end of the larger sprocket facing the smaller sprocket. Second, only this one output tooth needs to be constructed. As mentioned above, the output tooth is typically thinner axially than the teeth of conventional non-output teeth, allowing the bicycle chain to move axially toward the smaller sprocket. This reduces the number of teeth on the larger sprocket that are structurally weakened due to the reduced thickness.

[0024] As a supplement or alternative, the larger sprocket has a downshifting region along its circumference on its end side facing the smaller sprocket, which includes a downshifting recess. As described above, the downshifting region is configured to achieve the engagement transition of the bicycle roller chain from the smaller to the larger sprocket on the rear wheel sprocket pair that rotates clockwise around the sprocket axis.

[0025] As a supplement or alternative, on the larger sprocket, the downshift recess is configured with exactly one receiving tooth. This receiving tooth, due to its shape and orientation, is designed to be the first tooth to engage between the chain plates of the bicycle roller chain link during the downshifting process from the smaller sprocket to the larger sprocket, in conjunction with the end-side downshift recess. Typically, only the receiving tooth is adapted to be the first tooth to engage with the chain link when downshifting to the larger sprocket.

[0026] With the described technical solution, where the downshift recess has only one corresponding receiving tooth, the chain is received by the larger sprocket in a defined manner in terms of its link sequence when downshifting from a smaller sprocket to a larger sprocket. Based on the technical solution and orientation, the receiving tooth will only engage with the chain shifted to the larger sprocket if the link at the circumferential position of the receiving tooth is an outer link that provides a larger engagement space than the inner link. For whatever reason, if the link at that position of the receiving tooth is an inner link, the chain will be pushed away. Furthermore, the same applies here: a construction scheme with only one receiving tooth per downshift recess reduces the number of teeth that would structurally weaken the receiving function.

[0027] The larger sprocket of the sprocket pair of the present invention may have only upshifting recess construction with exactly one corresponding output tooth and downshifting recess construction with exactly one corresponding receiving tooth, or particularly advantageously have both features, so as to receive the chain from the smaller sprocket of the gear pair and transfer the chain to the smaller sprocket in a clear orientation.

[0028] The basic functional correspondence between the output tooth and the upshift recess that works in conjunction with it is generally a spatial correspondence, because when a bicycle chain shifts up, the chain rollers following the counterclockwise engaging output tooth typically bend towards the smaller sprocket, wherein at least one of the chain links following the output tooth counterclockwise is axially submerged in the upshift recess. The upshift recess is a groove on the end side facing the smaller sprocket, which provides axial movement space for the chain. Therefore, the output tooth preferably follows the upshift recess in the clockwise direction. Consequently, it is preferable that there are no other teeth between the upshift recess and the output tooth in the clockwise direction.

[0029] In sprockets with no more than 22 teeth, the larger sprockets have exactly one upshifting zone along their entire circumference. This upshifting zone has only one upshifting recess and therefore only one output tooth. When the upshifting process begins, it occurs within one revolution of the sprocket. This is a delay that is acceptable to the rider. By constructing only one upshifting recess and one output tooth, the weakening of the sprocket caused by the upshifting process is minimized.

[0030] The description of the output teeth above applies similarly to the receiving teeth. First, using the downshift recess structure, which is constructed as an axial groove in the end side, the chain is axially brought close to the larger sprocket receiving the chain. Then, the receiving teeth receive the chain by engaging with the chain link shape and guide it to the larger sprocket. Therefore, the functional correspondence between the receiving teeth and the downshift recess structure is also a spatial correspondence. Preferably, the receiving teeth follow the downshift recess structure immediately in the counterclockwise direction. Thus, it is preferable that there are no other teeth between the downshift recess structure and the receiving teeth in the counterclockwise direction.

[0031] In terms of the maximum shift delay per revolution of the sprocket, under the condition of minimal weakening of the largest sprocket caused by the downshifting process, the larger sprocket can only have exactly one upshifting area along its entire circumference, and therefore can only have exactly one receiving tooth.

[0032] Experiments show that maximizing the distance between the receiving tooth and the output tooth in a clockwise direction, starting from the output tooth, is beneficial to the wear marks on the larger sprocket and thus its service life. Similarly, to achieve this maximum distance in the clockwise direction, it is advantageous to construct only one output tooth and one receiving tooth. While adhering to the boundary conditions required for shifting between the larger and smaller sprockets, a larger distance in the clockwise direction can be achieved by: starting from the output tooth, having k teeth arranged clockwise between the output tooth and the receiving tooth, where k = T – d, where T is the number of teeth on the larger sprocket, and d is equal to 5 or 7. The output and receiving teeth are not included in this calculation. This only applies to teeth arranged clockwise between the output and receiving teeth. Preferably, the number of teeth on the larger sprocket, T, is divisible by 6, and d is preferably equal to 5. In this case, if the number of teeth on the larger sprocket, T, is not divisible by 6, then d is preferably equal to 7. However, it should be noted that if the number of teeth on the larger sprocket, T, is divisible by 6, then d can theoretically also be equal to 7.

[0033] Similarly, in order to maximize the distance between the receiving tooth and the output tooth of the larger sprocket in the clockwise direction, the larger sprocket can be constructed such that there are 3 or 5 teeth between the receiving tooth and the output tooth in the clockwise direction, starting from the receiving tooth, where the receiving tooth and the output tooth are not included in the calculation.

[0034] According to an advantageous but non-mandatory improvement, if the number of larger sprockets is divisible by 6, then there are 3 teeth clockwise between the receiving and output teeth; and if the number of larger sprockets is not divisible by 6, then there are 5 teeth clockwise between the receiving and output teeth.

[0035] To provide sufficient mobility for the bicycle chain even with a small axial distance between the smaller and larger sprockets, the tooth following the output tooth in the clockwise direction can be configured as an upshifting drive tooth. This drive tooth's tooth face, facing away from the smaller sprocket, is closer to the smaller sprocket than the tooth face of the next tooth following it in the clockwise direction. This drive tooth typically engages with an inner link and, when engaged, provides axial clearance towards the smaller sprocket for that link. The tooth face of this drive tooth facing the smaller sprocket is typically not axially offset compared to the next tooth following it in the clockwise direction; therefore, this drive tooth is thinner than the next tooth in the clockwise direction.

[0036] As a supplement or alternative, to improve the axial mobility of the chain, the tooth following the receiving tooth in the counter-clockwise direction can be configured as a downshifting drive tooth. The drive tooth's tooth surface facing away from the smaller sprocket is closer to the smaller sprocket than the tooth surface of the next tooth following this drive tooth in the counter-clockwise direction. This drive tooth typically engages with an inner link and, when engaged, provides axial clearance towards the smaller sprocket for this inner link. The tooth surface of this drive tooth facing the smaller sprocket is typically not axially offset compared to the next tooth following this drive tooth in the counter-clockwise direction; therefore, this drive tooth is thinner than the next tooth in the counter-clockwise direction.

[0037] The solution achieved by means of the sprocket of the present invention, in which the chain is shifted from a smaller sprocket to a larger sprocket and / or from a larger sprocket to a smaller sprocket in a defined manner in terms of its link sequence, ensures not only during the sprocket rotation during the engagement phase, but also during all engagement phases of the at least one sprocket with the bicycle chain, that the same tooth of at least one sprocket of the sprocket pair, preferably both sprockets, can engage with links of the same type.

[0038] In principle, all teeth of the larger and / or smaller sprockets in a sprocket pair can be fitted with the same axial thickness to simplify their production. Regarding the link sequence, to ensure the most precise positioning of the bicycle chain relative to the sprocket teeth on the sprocket pair, the larger and / or smaller sprockets can have at least one axial fine tooth and one axial coarse tooth alternating in the circumferential direction along a circumferential segment. The thickness of the coarse tooth is advantageously arranged such that it matches the meshing space of the outer link but not the meshing space of the inner link. The thickness of the fine tooth is advantageously arranged such that it matches the meshing space of the inner link. Thus, when the chain engages with the sprockets having alternating coarse and fine teeth, the chain can be guided on the sprockets with minimal axial clearance.

[0039] This application also relates to a bicycle rear wheel sprocket cassette freewheel having a plurality of sprockets with different numbers of teeth connected together to rotate together about a sprocket shaft in a non-slip manner, wherein the bicycle rear wheel sprocket cassette freewheel includes at least one bicycle rear wheel sprocket pair according to any one of the preceding claims. To apply the advantages of the aforementioned bicycle rear wheel sprocket pair as widely as possible to the sprocket cassette freewheel, the bicycle rear wheel sprocket cassette freewheel preferably has at least three sprockets with different numbers of teeth, the sprockets forming two bicycle rear wheel sprocket pairs constructed according to the foregoing description, wherein the sprocket with the intermediate number of teeth is the larger sprocket of one rear wheel sprocket pair and the smaller sprocket of the other rear wheel sprocket pair.

[0040] In this sense, particularly preferably, all sprockets of the rear wheel cassette with 22 or fewer teeth are constructed as bicycle rear wheel sprocket pairs as described above. Each sprocket on the non-axial end side of a sprocket set with 22 or fewer teeth is both the smaller sprocket of one sprocket pair and the larger sprocket of another sprocket set. By definition, the smallest sprocket in a sprocket set can be simply the smaller sprocket of a sprocket pair.

[0041] With a constant difference in the number of teeth, gear shift runout gradually decreases as the sprocket size increases (i.e., it moves further inward). Therefore, when the difference in the number of teeth between adjacent sprockets increases with the number of teeth, it is helpful to achieve relatively uniform gear shift runout across the entire sprocket cassette. However, there is an unavoidable numerical difference in gear shift runout between adjacent sprockets because sprockets only have integer numbers of teeth, and the difference in the number of teeth between adjacent teeth is also an integer.

[0042] Especially when the number of teeth on adjacent sprockets has at least one common divisor, the chain can be particularly advantageously shifted between two adjacent sprockets. Therefore, the rear sprocket cassette has a transition sprocket set, including a sprocket with 21 teeth referred to below as the "21T sprocket" and a smaller 18T sprocket with 18 teeth adjacent to it.

[0043] The rear sprocket cassette flywheel preferably has exactly one odd-numbered sprocket. Preferably, this odd-numbered sprocket is the aforementioned 21T sprocket.

[0044] A sprocket with z teeth is referred to as a "z T sprocket" in the following text.

[0045] The bicycle rear wheel sprocket freewheel with the aforementioned transition sprocket set is still an extremely advantageous bicycle rear wheel sprocket freewheel even without the aforementioned bicycle rear wheel sprocket pair. Therefore, this application also relates to a bicycle rear wheel sprocket freewheel having a plurality of sprockets with different numbers of teeth connected together in a non-slip manner about a sprocket shaft, wherein the sprocket shaft defines an axial direction along the sprocket shaft, a radial direction orthogonal to the sprocket shaft, and a circumferential direction around the sprocket shaft, and wherein the rear wheel sprocket freewheel has a transition sprocket set including a 21T sprocket and an 18T sprocket adjacent to the 21T sprocket. This sprocket freewheel can also be improved in the following manner.

[0046] The problem here is that, during engagement with the bicycle chain, the correspondence between the sprocket teeth and the corresponding links on the odd-numbered 21T sprockets alternates with each rotation. Thus, without additional measures, during chain engagement, the chain can be transferred longitudinally from the 21T sprocket to the 18T sprocket at each of two distinct relative positions in terms of the link sequence, depending on the number of rotations. Conversely, the chain can only be transferred to the 18T sprocket in an orientation defined in terms of the link type order, such that on the 18T sprocket, one set of teeth corresponds in a defined manner to the outer link links, and the remaining set corresponds in a defined manner to the inner link links. That is, in this case, if the 18T sprocket is the larger sprocket in a sprocket pair designed as described above, then the correct orientation of the chain on the 18T sprocket plays a decisive role in the correct orientation of the chain on the adjacent 16T sprocket. This also applies to the case of the smaller sprocket.

[0047] The chain can be transferred from the 21T sprocket to the 18T sprocket in a defined manner, with a predetermined and / or constructed desired correspondence between the teeth of the outer link and the 18T sprocket, solely for engagement with the outer link: the 21T sprocket has at least two upshift regions, each comprising an upshift recess, along a segment of its circumference on its end side facing the 18T sprocket. Each upshift region is further constructed and arranged to achieve the engagement transition of the bicycle roller chain from the 21T sprocket to the 18T sprocket on the transition sprocket set rotating clockwise (in the axial reference view of the transition sprocket set, in the reference state where the 18T sprocket is closer to the observer than the 21T sprocket). On the 21T sprocket, each of the at least two upshift recesses is assigned exactly one output tooth, which, due to its shape and orientation, is configured to be the last tooth engaged between the chain plates of the bicycle roller chain link during the upshifting process from the 21T sprocket to the 18T sprocket, in conjunction with the corresponding end-side upshift recess. An even number of teeth, preferably six, are provided between the output teeth of adjacent upshift recesses in the circumferential direction, where the output teeth of adjacent upshift recesses are not counted.

[0048] After a cyclist initiates a shifting process, for example by moving the chain guide rollers of the rear derailleur, the output tooth, in conjunction with the corresponding upshift recess, typically provides sufficient axial movement of the chain from the 21T sprocket to the 18T sprocket only when it engages with the outer chain link. This applies only to the same output tooth in each second cycle of the 21T sprocket.

[0049] By providing at least one second output tooth and an even number of intermediate teeth arranged circumferentially between the two output teeth, one of the two output teeth engages with the outer chain link during the same cycle of the sprocket, which helps to shorten the delay.

[0050] Furthermore, the same applies here: by constructing each upshift recess with only one output tooth (which means that the strength of the output tooth is structurally weakened compared to the other teeth, the weakening of the 21T sprocket can be minimized).

[0051] As a supplement or alternative, the 21T sprocket has at least two downshifting regions along its circumference on its end side facing the 18T sprocket, each including a downshifting recess. Each downshifting region is further configured to facilitate the engagement transition of the bicycle roller chain from the 18T sprocket to the 21T sprocket on the transition sprocket set, which rotates clockwise (in the axial view of the transition sprocket set, in the reference state). Advantageously, on the 21T sprocket, each downshifting recess is assigned exactly one receiving tooth, which, due to its shape and orientation, is configured to engage the first tooth between the chain plates of the bicycle roller chain link during the downshifting process from the 18T sprocket to the 21T sprocket, in conjunction with the corresponding end-side downshifting recess. In this way, the bicycle chain can shift from the 18T sprocket to the 21T sprocket, taking into account the defined correspondence. The bicycle chain meshes with the 18T sprocket when the teeth on the even number of 18T sprockets correspond in a defined manner to the different link types of the chain. To reduce delay, an even number of teeth are provided between the receiving teeth of adjacent downshift recesses in the circumferential direction, excluding the receiving teeth of adjacent downshift recesses.

[0052] The same applies here: the receiving tooth on the 21T sprocket can only engage with the bicycle chain, in conjunction with the corresponding downshift recess, if the receiving tooth can engage with the outer chain link, and the bicycle chain is axially close to the 21T sprocket to a sufficient degree for receiving. Based on the above arrangement, this always applies to one of the two receiving teeth.

[0053] As described above, similar to the output teeth, each downshift recess configuration is assigned only one receiving tooth. Therefore, the sprocket is only locally weakened to the necessary extent within the area of ​​the downshift recess configuration. Although the delay is somewhat aggravated by other receiving or output teeth arranged away from the first receiving or output tooth, the weakening of the sprocket is limited to a localized area and distributed at mutually spaced circumferential positions due to the construction of the receiving or output teeth. Therefore, the overall wear resistance of the sprocket is enhanced. Overall, the slight increase in shift delay is compensated by the enhanced wear resistance.

[0054] The shift delay can be further shortened in the following cases: the 21T sprocket

[0055] i) It has exactly three upshifting regions, each with an upshifting recess and exactly one output tooth, wherein an even number of teeth, preferably six, are provided between the output teeth of adjacent upshifting recesses in the circumferential direction, excluding the output teeth of adjacent upshifting recesses.

[0056] Or / and

[0057] ii) It has exactly three downshifting regions, each of which has a downshifting recess and exactly one receiving tooth, wherein an even number of teeth, preferably six teeth, are provided between the receiving teeth of adjacent downshifting recesses in the circumferential direction, wherein the receiving teeth of adjacent downshifting recesses are not counted.

[0058] Preferably, to enhance wear resistance, the receiving teeth are equidistantly distributed on the circumference of the 21T sprocket, or / and the output teeth are equidistantly distributed on the circumference of the 21T sprocket.

[0059] A particularly advantageous synergistic effect can be achieved by arranging the receiving teeth as adjacent teeth immediately next to the output teeth. Preferably, the receiving teeth and output teeth are adjacent in a clockwise direction. Since only one receiving tooth can receive the chain during each sprocket rotation, the body design is equivalent to treating each tooth that actually performs the receiving as a receiving tooth. As mentioned above, the receiving teeth are not only thinner than conventional teeth, but their tooth surfaces facing away from the smaller sprocket are also closer to the smaller sprocket than the conventional teeth of the 21T sprocket. Therefore, this receiving tooth, which is adjacent to the output teeth in a clockwise direction, can be used as the aforementioned upshifting drive tooth, which provides axial movement space for the chain, thereby facilitating the shift to the 18T sprocket.

[0060] Therefore, similarly, the output tooth adjacent to the receiving tooth in the counterclockwise direction can be used as the downshifting drive tooth of the receiving tooth. This output tooth is also finer than the conventional tooth of the 21T sprocket, and its tooth surface away from the smaller sprocket is closer to the smaller sprocket than the conventional tooth of the 21T sprocket. This downshifting drive tooth, on the one hand, makes the inner chain plate link that follows the outer chain plate link that is engaged by the receiving tooth in the counterclockwise direction spatially close to the smaller 18T sprocket. On the other hand, this downshifting drive tooth can engage into the smaller engagement space of the inner chain plate link.

[0061] This arrangement of a pair of output teeth and a receiving tooth adjacent to the output tooth in a clockwise direction ensures that shifting from the 18T sprocket to the 21T sprocket and in the opposite direction is performed in a specifically defined manner. Preferably, the 21T sprocket has more than one pair of such output teeth and receiving teeth adjacent to the output teeth in a clockwise direction. For example, the 21T sprocket may have two or three pairs of output teeth and receiving teeth.

[0062] Preferably, the output teeth, which are mutually driving teeth, and the receiving teeth, which are adjacent in the clockwise direction, are provided with a ramp on the side away from the 18T sprocket. The chain plates can be supported on this ramp by radial abutment engagement. This ramp has a radially outward slope, which is preferably formed by constructing the output teeth and receiving teeth in a stepped shape. Compared with the radially inward sections of the output teeth and receiving teeth, the radially outward sections of the output teeth and receiving teeth can be constructed to achieve the stepped construction scheme. The axial dimension of the ramp is preferably at least 50% of the thickness of the outer chain plate of the bicycle chain that interacts with the sprocket or sprocket cassette, so as to provide a ramp with sufficient support surface for the chain. The ramp can be inclined toward the next larger sprocket adjacent to the 21T sprocket, wherein the radial component of the normal vector of the ramp is greater than its axial component. The slope can theoretically be tilted in the opposite direction toward the 18T sprocket, but this is not the preferred option because in this case, the slope may form a V-shaped groove with the tooth surface away from the 18T sprocket, and dirt will accumulate in the groove.

[0063] The slope can be a flat surface. In order to provide the largest possible contact surface for the chain plates on the slope, and thus enable the chain to be supported as reliably as possible on the slope in the radial direction, the slope is at least partially constructed to complement the radially inward edges of the chain plates of the circular bicycle chain, especially the inner chain plates.

[0064] In order to provide a gear ratio that enables a larger torque on the rear wheel, that is, to convert the rotation of the chain links on the pedal crank into strength rather than speed, the transition sprocket set preferably also has a 24T sprocket, wherein a 21T sprocket is arranged axially between the 24T sprocket and the 18T sprocket.

[0065] In order to transfer the bicycle chain from sprocket 21T to sprocket 24T in a manner advantageously defined in terms of the link sequence, such that the predetermined teeth of sprocket 24T are reliably transferred to the outer link for engagement, sprocket 24T has at least two downshifting regions along its circumference on its end side facing sprocket 21T, each including a downshifting recess.

[0066] On the 24T sprocket, each downshift recess is equipped with exactly one receiving tooth. This receiving tooth, due to its shape and orientation, is configured to engage with the first tooth between the chain plates of the bicycle roller chain link during the downshifting process from the 21T sprocket to the 24T sprocket, in conjunction with the corresponding end-side downshift recess. The chain link engaging with the receiving tooth on the bicycle roller chain is typically an outer chain plate link, because compared to the inner chain plate links, this outer chain plate link can be further axially fed into the engagement area of ​​the receiving tooth in conjunction with the downshift recess.

[0067] An odd number of teeth are provided between the receiving teeth of adjacent downshift recesses in the circumferential direction, excluding the receiving teeth of adjacent downshift recesses. This ensures that within one cycle of the 24T sprocket, regardless of the relative orientation of the chain disengagement from the 21T sprocket, the receiving teeth reliably engage with the outer chain link. This results in a smaller structural weakening of the 24T sprocket while advantageously reducing shift delay.

[0068] As a supplement or alternative, the 24T sprocket has at least two upshift regions along a section of its circumference on the end side facing the 21T sprocket, each containing an upshift recess.

[0069] On the 24T sprocket, to enhance its wear resistance, each of the two upshift recesses is assigned exactly one output tooth, which is configured by its shape and orientation to be the last tooth between the chain plates of the bicycle roller chain link during the upshift process from the 24T sprocket to the 21T sprocket, in conjunction with the upshift recess on the corresponding end side.

[0070] To shorten shift delay during upshifting, the 24T sprocket preferably has an odd number of teeth between the output teeth of adjacent upshift recesses in the circumferential direction. The output teeth of adjacent upshift recesses are not included in the calculation.

[0071] The shift delay can be further shortened as follows: The 24T sprocket has exactly three upshift zones, each with an upshift recess and exactly one output tooth. An odd number of teeth are provided between the output teeth of adjacent upshift recesses in the circumferential direction. To ensure a uniform distribution of the delay along the sprocket circumference, seven teeth are preferred, excluding the output teeth of adjacent upshift recesses.

[0072] Alternatively / and, the 24T sprocket has exactly three downshifting zones, each having a downshifting recess and exactly one receiving tooth, wherein an odd number of teeth, preferably seven, are provided between the receiving teeth of adjacent downshifting recesses in the circumferential direction, wherein the receiving teeth of adjacent downshifting recesses are not counted.

[0073] To achieve a clear correspondence between sprocket teeth and the types of chain links they mesh with on as many sprockets as possible, bicycle rear wheel cassettes have as many even-numbered sprockets as possible. Therefore, the cassette preferably includes a first set of axially adjacent sprockets of different sizes, with a tooth difference of two teeth between them. These teeth are preferably provided with orientation configurations that allow the sprockets to mesh with the chain only in a predetermined orientation relative to the sprockets in a chain link sequence. Such orientation configurations may include at least one of the aforementioned coarse teeth, arranged circumferentially between two fine teeth and meshing only with the outer link links.

[0074] This first set of sprockets preferably connects to at least one sprocket, the difference in tooth count between this sprocket and the larger sprocket in the first set being 3 teeth. To ensure that the bicycle rear wheel cassette has only a few odd-numbered sprockets, the cassette preferably has a second set of sprockets of different sizes, wherein the difference in tooth count between axially adjacent sprockets is 3 teeth. This second set preferably contains an even number of sprockets, preferably two sprockets. The even-numbered sprockets in this second set are preferably equipped with the aforementioned orientation configuration, which ensures that the sprockets can only engage with the chain in a predetermined orientation relative to the sprockets in a chain link sequence.

[0075] The second group can connect to the third group of even-numbered sprockets of different sizes, wherein the smallest sprocket in the second group has a tooth difference of 4 teeth from its axially adjacent sprocket. Each sprocket in the third group preferably also has the aforementioned orientation member to achieve relative orientation of the chain with respect to the sprockets in terms of its link sequence.

[0076] A particularly preferred bicycle rear wheel sprocket cassette meeting the above criteria is a twelve-layer sprocket cassette cassette with the following tooth count levels: 10–12–14–16–18–21–24–28–32–38–44–52. For the reasons stated above, all sprocket pairs with fewer than 21 teeth are preferably constructed as the aforementioned rear wheel sprocket pairs.

[0077] The ramp described above in conjunction with the 21T sprocket can also be constructed on sprockets with more than 21 teeth on a cassette, for example, on a sprocket located between the chain line and the longitudinal center plane of the bicycle orthogonal to the sprocket axis. The description of the ramp above also applies to ramps preferably constructed on sprockets with more than 21 teeth. The ramp extends over at least two, preferably exactly two adjacent teeth, and forms radial and axial steps on the side of the sprocket opposite to the next smaller sprocket. The two adjacent teeth for the ramp extension are typically not a pair of teeth consisting of an output tooth and an adjacent receiving tooth on a sprocket with more than 21 teeth. The ramp is preferably constructed on at least one drive tooth. The receiving tooth or output tooth adjacent to the drive tooth with the ramp can also have a ramp. Compared to the ramp of the drive tooth adjacent to the receiving tooth or output tooth, the ramp of the receiving tooth and / or output tooth is preferably further outward in the radial direction. Larger sprockets may also have a ramp on the side opposite to the next smaller sprocket, or have multiple ramps distributed along their circumference.

[0078] As described above, the ramp allows the chain to be radially supported on the ramp via the abutting engagement of the chain plates in the larger sprockets. This prevents the bicycle chain from unintentionally shifting to the next smaller sprocket when pedaling backward using a conventional freewheel with a sprocket cassette. As the number of teeth increases, the sprockets move further away from the chain line, causing the chain to become increasingly skewed relative to the bicycle's longitudinal center plane, which is orthogonal to the sprocket axis, as it engages with the progressively larger sprockets. This chain skew during backward pedaling could lead to unintentional shifting of the chain to the next smaller sprocket on the larger, thus closer to the bicycle's longitudinal center plane, thus reducing the chain skew. The ramp suppresses this.

[0079] On smaller sprockets with 22 teeth or less, the shift ramp can be constructed on the side of the tooth surface facing the next smaller sprocket. These sprockets are typically located axially outside the chain line, so each link is stably held on the ramp facing outwards due to chain skewing or deflection.

[0080] The radially inner edge of the inner link of the chain plate, facing the sprocket shaft, is preferably supported on such a ramp. The ramp has a radially outward supporting surface. Specifically, when the chain shifts between the smaller sprocket and the larger sprocket with the ramp on the side facing the smaller sprocket, the two inner links of the same inner link can be radially supported internally, under the combined action of the tooth tips of the smaller sprocket at a certain axial distance from the ramp. The inner link plate further in the axial direction can be supported by the ramp, while the inner link plate further out in the axial direction can be supported by the tooth tips, particularly the radially outward surface of the tooth tips. Support is provided during both downshifting and upshifting.

[0081] However, during gear shifting, the inner chain plate, which is further inward in the axial direction, can also be supported on the ramp on the side of the sprocket (especially the tooth surface) facing the smaller sprocket.

[0082] The present invention also relates to a bicycle drive assembly, including the bicycle rear wheel sprocket pair and / or the bicycle rear wheel sprocket cassette freewheel as described above, the bicycle drive assembly having a bicycle roller chain adapted to engage with the sprockets of the bicycle rear wheel sprocket pair and / or the bicycle rear wheel sprocket cassette freewheel in a force-transmitting manner, wherein the bicycle roller chain has a plurality of chain rollers arranged successively at a certain interval, the chain rollers being connected by parallel chain plate pairs, wherein the bicycle roller chain has inner chain plate pairs with a small chain plate spacing and outer chain plates with a large chain plate spacing that alternately follow each other in the chain circumferential direction.

[0083] The bicycle drive assembly may have a single chain link in the area of ​​the pedal crank, such that any change in the gear ratio from the front chain link to the rear sprocket cassette can only be achieved by changing the chain engagement with one of the sprockets in the sprocket cassette.

[0084] To engage with the preferred twelve-layer sprocket cassette, a bicycle chain is preferably used, wherein the chain plate has a straight edge segment on its radially outer edge between two chain rollers connected by a chain plate, and the chain plate has a curved edge line on its radially inner edge. This results in the chain plate height, measured orthogonally to the chain rollers and orthogonally to the chain's circumferential direction, being smaller in the region between the chain rollers than in the region within the chain rollers themselves. This yields a narrower bicycle chain with sufficient tensile strength.

[0085] To achieve a fast and precise shifting process with minimal axial clearance in the shifting section between the sprocket of the current guiding chain and the sprocket of the next guiding chain, it is preferable, and particularly preferable, for at least one bicycle rear wheel sprocket pair, that during the shifting process of the bicycle roller chain moving from one sprocket to the sprocket axially adjacent to that sprocket, exactly one inner link is provided in the shifting section between the last link engaged with the sprocket still guiding the chain and the first link that is about to or has already engaged with the sprocket of the next guiding chain. Preferably, only exactly one inner link is provided in the shifting section. While this shifting configuration should not be excluded from applying equally to sprocket pairs where the tooth pitch between the larger and smaller sprockets exceeds two teeth, this shifting configuration is particularly suitable for sprockets with a tooth difference of two teeth. Attached Figure Description

[0086] The present invention will now be described in detail with reference to the accompanying drawings. Wherein:

[0087] Figure 1The bicycle rear wheel sprocket cassette freewheel of the present invention is shown in a reference view along the sprocket axis, wherein the larger the sprocket, the farther away it is from the observer.

[0088] Figure 1A for Figure 1 The sprocket-type flywheel in the middle is perpendicular to the sprocket shaft in terms of its viewing direction.

[0089] Figure 1B for Figure 1 The sprocket-type flywheel in the middle has a opposite viewpoint away from the longitudinal center plane.

[0090] Figure 2 A is the base view. Figures 1 to 1B The first bicycle rear wheel sprocket pair of the sprocket cassette freewheel of the present invention shown has a smaller sprocket with 10 teeth and a larger sprocket with 12 teeth.

[0091] Figure 2 B represents observing from the opposite direction. Figure 2 The bicycle rear wheel chainring shown in Figure A

[0092] Figure 3 A is the base view. Figures 1 to 1B The second bicycle rear wheel sprocket pair of the sprocket cassette freewheel of the present invention shown has a smaller sprocket with 12 teeth and a larger sprocket with 14 teeth.

[0093] Figure 3 B represents observing from the opposite direction. Figure 3 The bicycle rear wheel chainring shown in Figure A

[0094] Figure 4 A is the base view. Figures 1 to 1B The third bicycle rear wheel sprocket pair of the sprocket cassette freewheel of the present invention shown has a smaller sprocket with 14 teeth and a larger sprocket with 16 teeth.

[0095] Figure 4 B represents observing from the opposite direction. Figure 4 The bicycle rear wheel chainring shown in Figure A

[0096] Figure 4 In the baseline view (C), when the bicycle chain is downshifted from a 14T sprocket to a 16T sprocket... Figure 4 As shown in Figure A, the third bicycle rear wheel sprocket pair of the sprocket cassette freewheel of the present invention

[0097] Figure 4 D represents observing from the opposite direction. Figure 4 The bicycle rear wheel chainring shown in C

[0098] Figure 4 In the baseline view (E), when the bicycle chain shifts from a 16T sprocket to a 14T sprocket... Figure 4As shown in Figure A, the third bicycle rear wheel sprocket pair of the sprocket cassette freewheel of the present invention

[0099] Figure 4 F represents observing from the opposite direction. Figure 4 The bicycle rear wheel chainring shown in E

[0100] Figure 5 A is the base view. Figures 1 to 1B The fourth bicycle rear wheel sprocket pair of the sprocket cassette freewheel of the present invention shown has a smaller sprocket with 16 teeth and a larger sprocket with 18 teeth.

[0101] Figure 5 B represents observing from the opposite direction. Figure 5 The bicycle rear wheel chainring shown in Figure A

[0102] Figure 6 In the baseline view, Figures 1 to 1B The bicycle rear wheel sprocket pair shown has a smaller sprocket with 18 teeth and a larger sprocket with 21 teeth, and the rear wheel sprocket pair belongs to a transitional sprocket group with a total of three sprockets.

[0103] Figure 7 In the baseline view, Figures 1 to 1B The bicycle rear wheel sprocket pair shown has a smaller sprocket with 21 teeth and a larger sprocket with 24 teeth, and the rear wheel sprocket pair belongs to this transitional sprocket group which has a total of three sprockets.

[0104] Figure 8 for Figure 7 The bicycle shown depicts a rear wheel sprocket and a bicycle chain, which engages with a larger sprocket and downshifts to a smaller sprocket.

[0105] Figure 9 Figures 1 to 1B The bicycle rear wheel sprocket pair shown has a smaller sprocket with 24 teeth and a larger sprocket with 28 teeth.

[0106] Figure 10 In the baseline view, Figures 1 to 1B The larger sprocket of the sprocket-type flywheel shown is...

[0107] Figure 10A for Figure 10 The sprocket shown is viewed from a direction orthogonal to the sprocket axis.

[0108] Figure 10B When observing along the sprocket shaft with a line of sight away from the longitudinal center plane, Figure 10 The sprocket shown, and

[0109] Figure 11 For equipped with Figures 1 to 1BThe bicycle shown has a sprocket cassette and flywheel. Detailed Implementation

[0110] Figure 1 A preferred embodiment of the bicycle rear wheel sprocket cassette freewheel of the present invention has a non-slip connection for common winding with Figure 1 The twelve coaxial sprockets rotating on the sprocket shaft R, which is orthogonal to the drawing plane, together with the rear sprocket cassette flywheel, are represented by reference symbol 1.

[0111] Figure 1 The view of the sprocket cassette flywheel 1 is equivalent to the reference view described in the introduction to the instruction manual, that is, the view along the sprocket axis R, where the smallest sprocket and Figure 1 The observer is closest, and the largest sprocket is... Figure 1 The observer is the furthest away.

[0112] Figure 1 The number of teeth on the sprocket cassette 1 is: 10–12–14–16–18–21–24–28–32–38–44–52. That is, the sprocket cassette 1 includes a minimum sprocket 10 with ten teeth, a sprocket 12 with 12 teeth adjacent to it on its axial axis, a next larger sprocket 14 with 14 teeth, a next larger sprocket 16 with 16 teeth, and a sprocket 18 with 18 teeth adjacent to it on its axial axis.

[0113] The next larger sprocket 20 adjacent to sprocket 18 is a transition sprocket with 21 teeth. This transition sprocket is followed by sprocket 22 with 24 teeth, sprocket 24 with 28 teeth, sprocket 26 with 32 teeth, sprocket 28 with 38 teeth, sprocket 30 with 44 teeth, and finally, sprocket 32 ​​with 52 teeth as the largest sprocket.

[0114] The adjacent sprocket pairs of sprockets 10 to 18 among these sprockets 10 to 32 respectively form the bicycle rear wheel sprocket pairs of the present invention described above.

[0115] Among them, sprockets 12 to 16 are sprockets of two sprocket pairs, one as the smaller sprocket of the sprocket pair and the other as the larger sprocket of the sprocket pair. Sprockets 10 and 12 form bicycle rear wheel sprocket pair 11, sprockets 12 and 14 form bicycle rear wheel sprocket pair 13, sprockets 14 and 16 form bicycle rear wheel sprocket pair 15, and sprockets 16 and 18 form bicycle rear wheel sprocket pair 17.

[0116] In the sprocket cassette flywheel 1, the two sprockets 18 and 22 that are axially adjacent to the single transition sprocket 20 together with the transition sprocket 20 form a transition sprocket group 19.

[0117] To simplify the shifting process between axially adjacent sprockets, each sprocket (except the smallest sprocket 10) has at least one upshifting region 34 containing an upshifting recess 36 and an output tooth 38, and at least one downshifting region 40 containing a downshifting recess 42 and a receiving tooth 44.

[0118] For clarity, Figure 1 In the middle, only the largest sprocket 32 ​​with 52 teeth is provided with reference symbols for the upshifting region 34 with upshifting recess structure 36 and output tooth 38, and for the downshifting region 40 with downshifting recess structure 42 and receiving tooth 44.

[0119] These regions, namely upshifting region 34 and downshifting region 40, are always associated with the sprockets in which these regions are constructed. This means that upshifting region 34 is advantageous for the movement of the bicycle chain from the sprocket with upshifting region 34 to the next smaller axially adjacent sprocket, and downshifting region 40 is advantageous for the movement of the bicycle chain from that next smaller sprocket to the sprocket with downshifting region 40.

[0120] The recesses 36 and 42 allow the bicycle chain to axially approach the sprocket with the corresponding recess, because in particular the outer chain plate can be recessed into the recess designed as an axial end-side groove. If the recesses were not constructed at these locations, the outer chain plate of the bicycle chain might collide with the end side of the sprocket, thus limiting the axial approach of the bicycle chain to the end side with the recess.

[0121] The recesses 36 and 42 can have multiple different surface facets, which can have different positions and / or different angles relative to the sprocket shaft R. Thus, the bicycle chain can only be inserted into the recesses 36 and 42 at predetermined relative positions to the outer and inner chain plates, and is axially pushed away by the surface facets at a relative position offset by one chain pitch along the chain's circumferential direction. The surface facets can be constructed such that they extend into the intermediate cavity between two successive outer chain plates in the chain's circumferential direction toward the inner chain plate located between the outer chain plates, but the body of the outer chain plate located between the two inner chain plates is axially pushed away by the sprocket carrying that outer chain plate.

[0122] In the reference view of the rear wheel cassette 1, the receiving teeth 44 of each sprocket of the rear wheel cassette 1 are on a helix 45 that rotates radially outward in a counterclockwise direction.

[0123] exist Figure 1A In the diagram, the cassette freewheel 1 is shown in a view orthogonal to the sprocket axis R. The aforementioned longitudinal center plane LME of the bicycle carrying the cassette freewheel 1, orthogonal to the sprocket axis R, is shown as a dashed line for illustration. The actual distance between the longitudinal center plane LME and the cassette freewheel 1 is greater than... Figure 1A The shortened view shown.

[0124] Sprockets 10 to 30 are preferably formed from a solid, one-piece molded form, for example, by machining, into a so-called sprocket dome. Alternatively, two smaller sprockets 10 and 12 can be constructed as a single sprocket. In this case, the two smaller sprockets 10 and 12 can be connected to the sprocket dome of sprockets 14 to 30 via slotted nuts. The largest sprocket 32 ​​is constructed as a single sprocket. The sprocket dome can be connected to the support of sprocket 32 ​​in a known manner using pins or rivets or by material joining to transmit torque.

[0125] The axial distance between adjacent sprockets is typically less than the tooth height of a sprocket with a standard tooth shape. This small axial distance between sprockets requires an extremely narrow chain and very precise design of the toothed circumferential area of ​​each sprocket.

[0126] Figure 1B The sprocket cassette flywheel 1 is shown internally, that is, viewed along the sprocket axis R from the longitudinal center plane LME. The smaller sprocket, visible through the passageway constructed between the supports of the larger sprocket 32, is provided with reference numerals. Furthermore, refer to the following description... Figures 10 to 10B The following description will be used to further describe the larger sprocket.

[0127] Figure 2 A shows the smallest bicycle rear wheel sprocket pair 11 of the sprocket cassette 1 in a baseline view. Figure 2 B shows the same bicycle rear wheel sprocket pair 11 viewed axially but "from the inside," meaning the larger sprocket 12 is closer to the smaller sprocket 10. Figure 2 B's observer.

[0128] The smaller sprocket 10 is preferably constructed as a synchronous sprocket with coarser teeth 10a and finer teeth 10b. The axial thickness of the coarser teeth 10a is chosen such that it is only suitable for entering the engagement space of the outer link, but its thickness is greater than the distance between the two parallel inner links of the inner link. Therefore, in terms of the alternating link types along the chain loop direction, the bicycle chain can only engage with the sprocket 10 in exactly one relative orientation, that is, when the coarser tooth 10a corresponds to the outer link link. Since the number of links in the bicycle chain loop is even, and since the number of teeth on the sprocket 10 is even, once a correspondence is established between a tooth and a link type, this correspondence remains unchanged throughout the entire chain loop during the engagement of the sprocket 10 and the chain.

[0129] The teeth 10c of the smallest sprocket 10 have rounded tips that are shortened radially to facilitate the movement of the bicycle chain from the sprocket 10 to the next larger sprocket 12 that is axially adjacent, and to prevent the chain from colliding with the teeth 10c.

[0130] An upshift region 34 is constructed on the larger sprocket 12 of the sprocket pair 11, having an exact upshift recess 36 and an exact output tooth 38 clockwise adjacent to the upshift recess 36. The output tooth 38 is the first tooth clockwise, and its tooth surface facing the smaller sprocket 10 does not change due to the upshift recess 36. The output tooth 38 is the first tooth in the clockwise direction from which the upshift recess 36 no longer extends.

[0131] Furthermore, a downshifting region 40 is constructed on the larger sprocket 12, the counterclockwise distance of which from the upshifting region 34 is less than the clockwise distance. The single downshifting recess 42 no longer extends counterclockwise to the single receiving tooth 38; therefore, the receiving tooth is the first tooth whose shape is no longer altered by the downshifting recess 42, and this tooth follows the downshifting recess 42 counterclockwise.

[0132] Arrow D extending circumferentially indicates sprocket pair 11. Figure 11 The direction of drive rotation on the bicycle 70 in drive mode.

[0133] like Figure 2 As shown in the rear view of sprocket 12 in section B, sprocket 12 also has coarser teeth 12a and finer teeth 12b. The coarser teeth 12a, due to their thickness, can only engage with outer link plates. The distance between the two parallel inner links of an inner link plate is less than the thickness of the teeth 12a. Therefore, the bicycle chain can only loop in specific relative positions on the larger sprocket 12, that is, it can only loop when each tooth 12a corresponds to an outer link plate.

[0134] By applying only one output tooth 38 and only one receiving tooth 44, the bicycle chain can reliably directionally transfer between sprockets 10 and 12 at the relative position required to engage with the corresponding sprocket 10 or 12. In this process, only exactly one tooth needs to be weakened for each shift direction, thereby forming a larger, more wear-resistant sprocket 12.

[0135] The arrangement of the receiving tooth 44 and the output tooth 38 along the periphery of the larger sprocket 12, as shown, also reduces wear on the second smallest sprocket 12 of the cassette flywheel 1, because the upshifting area 34 and the downshifting area 40 transition into each other, meaning that very few teeth are weakened by the recessed structures 36 and 42. This allows for a large enough load-bearing surface to be provided for multiple teeth, thus giving it good load-bearing capacity. Compared to the lower load-bearing capacity of the sprocket 12, its wear tendency decreases as the load-bearing capacity of the sprocket 12 gradually increases. In the illustrated embodiment, three teeth of the larger sprocket 12 of the sprocket pair 11 are arranged clockwise between the receiving tooth 44 and the output tooth 38, starting from the receiving tooth 44.

[0136] Starting from the output tooth 38, seven teeth of a larger sprocket 12 are provided between the output tooth 38 and the receiving tooth 44, equivalent to five fewer teeth than the number of teeth on sprocket 12. In other words, practice shows that the largest possible distance between the receiving tooth 44 and the output tooth 38 in a clockwise direction, starting from the output tooth 38, will create favorable wear marks on the sprocket 12 during operation. Specifically, this favorable wear is particularly evident in bicycles equipped with a sprocket cassette 1 that are motor-assisted driven, thus transmitting a greater torque to the smaller sprocket of the sprocket cassette 1 more consistently compared to purely manual drive. In the example shown, these smaller sprockets are sprockets 10 to 18.

[0137] A push surface 12d is constructed on the middle tooth of the three teeth arranged clockwise between the receiving tooth 44 and the output tooth 38. This push surface is part of both the downshift recess 42 and the upshift recess 36. The push surface 12d, which is recessed relative to the end face of the sprocket 12 but higher and axially protrudes from the adjacent groove section in the circumferential direction, is suitable for engaging into the intermediate cavity between the two outer chain plates. If, during gear shifting, for some reason, no inner chain plate is provided at the position of the push surface 12d but an outer chain plate is provided, then the outer chain plate abutting against the push surface 12d will prevent the chain body from axially approaching the end face of the sprocket 12; the chain needs to move by this axial approach, therefore, the chain is pushed away.

[0138] When the chain downshifts from sprocket 10 to sprocket 12, the inner chain plate link 54 (see...) Figure 8 The radially inward inner edge 54c of the inner chain plate (see) Figure 8 The solid support of the chain roller 54c rests on the radially outward tooth tip surface 10cf of the tooth 10c. The inner edge 54c rests on the chain roller shaft 55 (see...). Figure 8 The tooth tip 10cf is concave between the two sides. Therefore, in order to provide the most planar and reliable support possible, the tooth tip 10cf is convex, wherein the front end of the tooth tip 10cf in the driving rotation direction D is further inward in the radial direction than the rear end of the tooth tip 10cf. Preferably, the convex shape of the tooth tip 10cf is complementary to the concave inner edge 54c of the chain 50.

[0139] The sprocket pair 11 has the following characteristics: In the reference view, the tooth of the sprocket 12 located behind the tooth 10c has a push-off surface 12h on its tooth surface facing the smaller sprocket 10. This push-off surface is part of the downshift recess 42 of the downshift region 40. The inner chain link can pass beside this push-off surface 12h on the side of the sprocket 12 facing the smaller sprocket 10 in the direction of the receiving tooth 44 of the sprocket 12, but the outer chain link cannot do so.

[0140] The push surface 12h terminates radially inward on a ramp 12c1, which has a support surface that is radially outward and preferably also convexly curved, which protrudes axially from the push surface 12h.

[0141] Therefore, when downshifting from sprocket 10 to sprocket 12, the inner chain link is supported on the sprocket pair by its two inner chain plates, that is, the inner chain plate that is more axially outward is supported on the tooth tip surface 10cf, and the inner chain plate that is more inward is supported on the ramp 12c1. This allows for good chain guidance in the shifting section. When engaging with sprockets 10 and 12 that are axially outside the chain line, chain misalignment helps the inner chain plates abut against the push surface 12h and the ramp 12c1, because this chain misalignment applies an axial force from the outer sprocket to the inner inward on the engaging sprocket.

[0142] Figure 3 A and Figure 3 B shows the bicycle rear wheel sprocket pair 13, which has been... Figure 2 A and Figure 2 B is known as sprocket 12, which here serves as the smaller sprocket of sprocket pair 13, and sprocket 14, which serves as the larger sprocket. Figure 3 A shows the bicycle rear wheel sprocket pair 13 as viewed from the outside in a baseline view. Figure 3 B shows the bicycle rear wheel sprocket pair 13 viewed axially in the opposite direction, that is, viewed from the inside.

[0143] On the larger sprocket 14 of sprocket pair 13, the same lowercase letters indicate the same tooth type or tooth surface as on sprocket 12. To enhance wear resistance, sprocket pair 13 also has only one upshift region 34, which has exactly one upshift recess 36 and exactly one output tooth 38. The upshift recess 36 of sprocket 14 has surface facets, all of which are recessed axially relative to the end face of sprocket 14, but the degree of recess may vary and / or they may be inclined relative to each other, for example, so that the chain can be tilted about its chain longitudinal direction, thereby allowing the guide hole located radially inside the chain to enter the engagement space of the outer link so that the chain is tilted longitudinally toward the tooth tip of receiving tooth 44, or so that the chain still engaged with output tooth 38 is tilted about the chain longitudinal direction toward the smaller sprocket 12 on the output tooth.

[0144] Starting from the receiving tooth 44, five teeth are provided clockwise between the receiving tooth 44 and the output tooth 38 of the sprocket 14, wherein the middle tooth has a push surface 14d on its tooth surface facing the smaller sprocket 12. This push surface has the same function as the push surface 12d of the smaller sprocket 12 described above.

[0145] Starting from the output tooth 38, seven teeth are provided between the output tooth 38 and the receiving tooth 44 of the sprocket 14. These teeth can be constructed as conventional teeth 14a and 14b, wherein the thickness of tooth 14a can be greater than that of tooth 14b. Specifically, it is advantageous to have a thickness greater than the inner width of the meshing space between the two parallel inner chain plates of the inner chain plate link. The number of teeth provided clockwise between the output tooth 38 and the receiving tooth 44 of the sprocket 14 is equivalent to the number of teeth of the sprocket 14 minus 7.

[0146] like Figure 3 The rear view of sprocket 14, viewed from the inside, is shown in section B. Figure 3 In A, the fine tooth 14b following the output tooth 38 in the clockwise direction has a grooved surface 14e on its tooth surface opposite to the smaller sprocket 12. This grooved surface constructs this special fine tooth 14b as the driving tooth 14b' for the upshifting process. Compared with the conventional fine tooth 14b, this driving tooth provides greater axial movement clearance for the inner chain plate links of the bicycle chain that mesh with the driving tooth.

[0147] Similarly, Figure 3 As shown in B, Figure 3 In A, the fine tooth 14b adjacent to the receiving tooth 44 in the counterclockwise direction has a grooved surface 14f on its tooth surface opposite to the smaller sprocket 12. This grooved surface constructs this special fine tooth 14b as the driving tooth 14b" for the downshifting process. Compared with the conventional fine tooth 14b, this driving tooth provides a larger axial movement clearance for the inner chain plate links that mesh through the driving tooth.

[0148] Therefore, the upshifting drive gear 14b' assists the upshifting process by providing movement clearance to the bicycle chain. The downshifting drive gear 14b" assists the downshifting process.

[0149] Starting from the output tooth 38, there are five teeth between the output tooth 38 and the receiving tooth 44 of the sprocket 14.

[0150] The tooth adjacent to the receiving tooth 44 of the sprocket 14 in the clockwise direction has a push surface 14h, which is radially inwardly restricted by a ramp 14c1 having a support surface facing radially outward. The support surface body is used to support the inner chain plate of the inner chain plate link during downshifting.

[0151] The tooth adjacent to the output tooth 38 of sprocket 14 in the counterclockwise direction has a push surface 14i, which is radially inwardly restricted by a ramp 14c2 having a radially outward supporting surface. This supporting surface body is used to support the inner chain plate of the inner chain plate link when shifting from sprocket 12 to sprocket 14. Just as the push surface 14h in the downshifting region 40, the push surface 14i in the upshifting region 34 allows the inner chain plate link to pass by when shifting to sprocket 14, but does not allow the outer chain plate link of the bicycle chain to pass by. The ramp 14c2 having a radially outward supporting surface is preferably convex, corresponding to the concave shape of the inner chain plate 54c, so that the inner chain plate can abut as planarly as possible.

[0152] Figure 4 A and Figure 4 B shows a bicycle rear wheel sprocket pair 15 with sprockets 16 and 14, to be precise, Figure 4 A is the baseline view, and in Figure 4 Viewed from the opposite direction in section B, i.e., from the inside. The sprocket 14 of the bicycle rear wheel sprocket pair 15 is the same as the sprocket 14 of the aforementioned rear wheel sprocket pair 13.

[0153] The same lowercase letter following the reference symbol 16 of sprocket 16 indicates a functional component or component segment of sprocket 14 or sprocket 12, represented by the same lowercase letter.

[0154] As with the aforementioned two rear sprocket pairs 11 and 13, the larger sprocket 16 of rear sprocket pair 15 also has exactly one upshift region 34, which has exactly one upshift recess 36 and exactly one output tooth 38. Furthermore, the larger sprocket 16 has exactly one downshift region 40, which has exactly one downshift recess 42 and exactly one receiving tooth 44.

[0155] Starting from the receiving tooth 44, five teeth are provided clockwise between the receiving tooth 44 and the output tooth 38. Among these five teeth, the middle tooth has a push surface 16d, which has been described in conjunction with the aforementioned sprockets 12 and 14.

[0156] Starting from the output tooth 38, nine teeth are arranged clockwise between the output tooth 38 and the receiving tooth 44. These teeth are alternately constructed as coarse teeth 16a and fine teeth 16b to ensure a clear orientation of the bicycle chain relative to the sprocket 16 in the circumferential direction. The fine tooth 16b' adjacent to the output tooth 38 in the clockwise direction is the driving tooth for the upshifting process of shifting to the smaller sprocket 14. The fine tooth 16b" adjacent to the receiving tooth 44 in the counterclockwise direction is the driving tooth for the downshifting process of shifting from the smaller sprocket 14 to the larger sprocket 16. Figure 4 B shows the corresponding groove surface 16e of the drive tooth 16b' and the groove surface 16f of the drive tooth 16b".

[0157] The number of teeth located clockwise between the output tooth 38 and the receiving tooth 44 is equivalent to the number of teeth of the sprocket 16 minus 7.

[0158] It is worth noting that the teeth with the push surface 16h and the supporting ramp 16c1 adjacent to the push surface 16h are axially adjacent to the sprocket drive teeth 14b" with the convex tooth top surface 14cf in the sprocket 14. This is such that when the chain is downshifted from the sprocket 14 to the sprocket 16, the inner chain plate link 52 that passes axially outward from the push surface 16h can also be supported on its radial inner edge 52c by its two inner chain plate bodies. The inner chain plate on the outer axis is on the tooth top surface 14cf, and the inner chain plate on the inner axis is on the ramp 16c1.

[0159] Figure 4 Figure C shows, from a reference view, the downshifting process of the bicycle chain 50 from sprocket 14 to the larger sprocket 16. The receiving tooth 44 of sprocket 16 has received the chain 50, specifically, the outer chain plate link 54. The next outer chain plate link 54 in the drive rotation direction remains engaged with sprocket 14. In the shifting path between sprockets 14 and 16, only one inner chain plate link 52 is present, which does not engage with either sprocket 14 or 16 during the shifting process.

[0160] Figure 4 D is shown from the opposite perspective, that is, from the axial interior. Figure 4 The shifting process of C.

[0161] Figure 4 E shows, from a reference view, the shifting process of the bicycle chain 50 from sprocket 16 to the smaller sprocket 14. The output tooth 38 of sprocket 16 remains engaged with the chain 50, specifically with the outer chain plate link 54. The next outer chain plate link 54, in the opposite direction of the drive rotation, has already engaged with a tooth of sprocket 14. In the shifting path between sprockets 16 and 14, only one inner chain plate link 52 is present, which does not engage with either sprocket 14 or 16 during the shifting process.

[0162] Figure 4 F is shown from the opposite perspective, that is, from the axial interior. Figure 4 The shifting process of E.

[0163] Corresponding to the previous Figure 3 A and Figure 3 B or Figure 4 A and Figure 4 B, Figure 5 A and Figure 5 B shows the last and largest bicycle rear wheel sprocket pair 17 of the invention, specifically... Figure 5 A is the baseline view, and in Figure 5Viewed from the inside along opposite axes in B.

[0164] The same lowercase letter following the reference symbol 18 of sprocket 18 indicates a functional component or component segment of sprocket 12, 14, or 16, which is represented by the same lowercase letter.

[0165] As with the aforementioned rear sprocket pairs 11, 13, and 15, rear sprocket pair 17 also has exactly one upshift region 34 on the larger sprocket 18, which has exactly one upshift recess 36 and exactly one output tooth 38. Furthermore, the larger sprocket 18 has only one downshift region 40, which has exactly one downshift recess 42 and exactly one receiving tooth 44.

[0166] On the larger sprocket 18, which is particularly advantageous for the wear resistance of the sprocket 18, only three teeth are provided clockwise between the receiving tooth 44 and the output tooth 38. Starting from the output tooth 38, 13 teeth are provided clockwise between the output tooth 38 and the receiving tooth 44, which is equivalent to the number of teeth of the sprocket 18 minus 5.

[0167] Of the 13 teeth arranged clockwise between the output tooth 38 and the receiving tooth 44, the tooth immediately adjacent to the output tooth 38 or the receiving tooth 44 is constructed as driving teeth 18b' or 18b" as described above. The remaining teeth are constructed as coarse teeth 18a and fine teeth 18b as described above, so as to reliably guide the chain on the sprocket 18 during engagement.

[0168] When downshifting from sprocket 16 to sprocket 18, the inner chain link is also supported by two inner chain plates on the tooth top surface 16cf and the ramp 18c1. In a clockwise direction in front of the receiving tooth 44 of sprocket 18, the tooth clearance 43 increases radially inward to provide space for the chain roller directly in front of the receiving tooth 44 to move radially inward when downshifting to sprocket 18.

[0169] The aforementioned sprocket pairs 11, 13, 15, and 17 can only shift gears from the larger sprocket to the next smaller sprocket axially adjacent within the shifting region 36. This means that on each of the larger sprockets in the aforementioned sprocket pairs 11, 13, 15, and 17, the chain shifts from the larger sprocket to the next smaller sprocket at exactly one position; specifically, the corresponding output tooth 38 is the last tooth of the larger sprocket still engaged with the chain. Based on the indicated drive rotation direction D, the chain link following the output tooth 38 slides laterally counterclockwise past the tooth adjacent to the output tooth 38 in the counterclockwise direction, making full use of the corresponding shifting recess structure 36 as a movement space during this process.

[0170] On the aforementioned sprocket pairs 11, 13, 15, and 17, the chain can only move from the smaller sprocket to the larger sprocket in one position, specifically, always such that the receiving tooth 44 of the larger sprocket is the first tooth between the two chain plates (usually the outer chain plate) of the larger sprocket's meshing link. The chain link adjacent to the receiving tooth 44 in the clockwise direction approaches the larger sprocket by fully utilizing the downshift recess structure 42, allowing the outer chain plate link corresponding to the receiving tooth 44 to reach its meshing area axially.

[0171] If the rider gives a shift command such that the relevant shift tooth, output tooth 38 or receiving tooth 44, on the clockwise rotating larger sprocket has just passed the shift area on the rear wheel, then the shift process begins on the next revolution of the sprocket when output tooth 38 or receiving tooth 44 re-enters the angular range or shift area relative to the derailleur that is relevant to the shift process. For downshifts and upshifts, the rider's generally acceptable shift delay on sprocket pairs 11, 13, 15, and 17 is a maximum of one revolution of the sprocket. According to the invention, longer shift delays are not permitted and are considered a fault.

[0172] Sprocket 18 is the smallest of the three sprockets 18, 20 and 22 in the three-sprocket transition sprocket set 19, and sprocket 20 in the transition sprocket set is the only odd-numbered sprocket in the rear wheel cassette flywheel 1.

[0173] Figure 6 The smaller sprocket pair of sprockets 20 and 18 of the transition sprocket set 19 is shown in a baseline view.

[0174] The same lowercase letter following the reference symbol 20 of sprocket 20 indicates that the same lowercase letter indicates the functional part or part section of sprocket 12, 14, 16 or 18.

[0175] The problem is that during the engagement of the sprocket 18 with the bicycle chain, each tooth of the even-numbered sprocket 18 corresponds to the same type of chain link so that it can engage with the corresponding chain plate of the corresponding chain link.

[0176] However, on the odd-numbered sprocket 20 with 21 teeth, the type of link corresponding to a particular tooth changes with each rotation to achieve form-fit engagement. But in terms of the relative position of the link sequence, the chain should still move in a defined manner from the odd-numbered sprocket 20 to sprocket 18 during upshifting and to sprocket 22 during downshifting. On the even-numbered sprockets 20 and 22, whether a tooth engages with an outer or inner link should not be a random event, but rather should be shifted in a defined manner by constructing a corresponding transition sprocket set 19.

[0177] For this purpose, the transition sprocket 20 has three identical circumferential sections, each with seven teeth, which successively form the entire circumference of the transition sprocket 20. Each of the three circumferential sections has exactly one output tooth 38 and exactly one receiving tooth 44. Each of the three circumferential sections also has exactly one upshift region 34 containing exactly one upshift recess 36, and exactly one downshift region 40 containing exactly one downshift recess 36. Because the three circumferential sections are arranged consecutively, the shifting delay of the transition sprocket 20 is extremely short. Between the receiving tooth 44 and the output tooth 38, five teeth are provided on the sprocket 20 clockwise. Between two output teeth 38 or between two receiving teeth 44, six teeth are provided circumferentially on the sprocket 20. Therefore, if, during the downshifting process of sprocket 18, the inner chain plate unintentionally approaches the receiving tooth 44 of sprocket 20 for any reason, resulting in the receiving tooth 44 not engaging with the shape of the bicycle chain, then the outer chain plate and an outer chain plate link will approach the next receiving tooth 44 of sprocket 20 in the counterclockwise direction while making full use of the movement space provided by the downshifting recess structure 42. The receiving tooth 44 can receive the outer chain plate link.

[0178] This also applies similarly to the upshifting process and the output tooth 38 of sprocket 20. If the inner chain link immediately engages with the output tooth 38 after the rider begins the upshifting process, the bicycle chain remains on sprocket 20 until the next output tooth 38 in the counterclockwise direction engages with the outer chain link. In this way, the bicycle chain can move to the smaller sprocket 18 while making full use of the movement space created by the upshift recess structure 36.

[0179] The receiving tooth 44 and the output tooth 38 are particularly advantageously arranged such that, in the case of three identical circumferential sections arranged in succession, the output tooth 38 and the receiving tooth 44 are close to each other. The teeth 38 and 44 are always specifically constructed as output teeth and receiving teeth, and generally have a small thickness and are easy to approach the adjacent smaller sprocket 18 in the axial direction. Therefore, the teeth 38 and 44 not only serve as output teeth 38 and receiving teeth 44, but the output tooth 38 forms the driving tooth 20b" of the receiving tooth 44, and the receiving tooth 44 forms the driving tooth 20b' of the output tooth 38.

[0180] Since the output tooth 38 and the receiving tooth 44 have the dual function of simultaneously serving as driving teeth 20b" or 20b', although each of the three circumferential sections has at least two modified teeth 38 and 44 whose strength is weakened, and the three circumferential sections are arranged in succession, it is not necessary to implement additional structural tooth weakening by forming separate driving teeth, thus making the transition sprocket 20 stable and wear-resistant overall.

[0181] Figure 7The larger sprocket pair of the transition sprocket set 19, which has 24T sprocket 22 and 21T sprocket 20, is shown in a baseline view.

[0182] Here, it is equally important to shift the bicycle chain from the odd-numbered sprocket 20 to the larger sprocket 22, given a clear relative arrangement of the chain links.

[0183] The same lowercase letter following the reference symbol 22 of sprocket 22 indicates the same functional part or part segment of sprockets 12, 14, 16, 18 or 20, indicated by the same lowercase letter.

[0184] The 24T sprocket 22 also has three identical circumferential sections, which successively form the entire circumference of the sprocket 22. Therefore, each circumferential section has eight teeth. For simplicity, Figure 7 Reference symbols are provided for exactly one circumferential section of the sprocket 22.

[0185] A drive tooth 22b' is provided at the outermost end of the circumferential section in the clockwise direction, which serves as the drive tooth 38 adjacent to it in the counterclockwise direction. There are also three teeth that follow the output tooth 38 in the counterclockwise direction, and upshifting recess structure 36 and downshifting recess structure 42 are constructed on these teeth, wherein the middle tooth of the three teeth forms a push surface 22d.

[0186] The receiving tooth 44 follows these three teeth in a counterclockwise direction, and the receiving tooth is adjacent to its driving tooth 22b" in a counterclockwise direction. A conventional tooth of the sprocket 22 is provided at the outermost end of the circumferential section in the counterclockwise direction. This tooth is exemplarily constructed as a coarse tooth 22a, so that it can only mesh with the outer chain plate link.

[0187] Although drive teeth 22b' and 22b" are constructed in addition to output tooth 38 and receiving tooth 44, the two recessed structures 36 and 42 used for downshifting and upshifting are constructed in a space with only three teeth. This achieves moderate structural weakening of the sprocket 22 as a whole by removing material from the sprocket 22, and makes the sprocket 22 have high overall stability and wear resistance. The larger the sprocket, the less obvious the structural weakening of the sprocket strength caused by the construction of recessed structures, etc.

[0188] Since the number of rotations of sprocket 20 is unknown, the relative positions of the chain links when the bicycle downshifts from sprocket 20 to sprocket 22 are also unknown. Nevertheless, the corresponding receiving tooth 44 near the outer link receives the chain by meshing with the shape of the link, thereby realizing the downshifting process. This process occurs no later than the second receiving tooth 44, which reaches the relevant shift area relative to the derailleur that caused the shift.

[0189] Similarly, in each circumferential segment of sprocket 22, the chain is transferred to the smaller sprocket 20 by exactly a single tooth, namely the output tooth 38, which is the last tooth to engage. The output tooth 38 on sprocket 22 always corresponds to an outer chain link; therefore, the upshift from sprocket 22 to sprocket 20 occurs on the next output tooth 38 passing through the shift area of ​​the derailleur. This means an extremely short shift delay of only one-third of a revolution, and because only one tooth in each circumferential segment is configured as the output tooth 38, the weakening of sprocket 22 is minimal.

[0190] The radially inner root of the tooth gap 43, immediately adjacent to the receiving tooth 44 in a clockwise direction, is closer to the sprocket shaft R in the radial direction than the roots of the other tooth gaps. By providing movement space for the chain rollers radially inward in the manner described above, the shifting path of the bicycle chain when shifting from the smaller sprocket 20 to the larger sprocket 22 can be adjusted so that its length is an integer multiple of the chain pitch. This is the boundary condition for the shifting process between the two sprockets.

[0191] The two inner chain plates of the inner chain plate link can also be supported on the sprocket pair 19 when shifting from sprocket 22 to sprocket 20. That is, the inner chain plate that is more axially outward is supported on the tooth tip surface 20ci, and the inner chain plate that is more axially inward is supported on the ramp 22c2, which radially restricts the push surface 22i. In order to support the concave inner edge 54c of the inner chain plate as planarly as possible, the tooth tip surface 20ci is convex, but the front end of the tooth tip surface 20ci in the driving rotation direction is radially more outward than the rear end of the tooth tip surface 20ci.

[0192] Figure 8 This illustration shows how a bicycle chain 50, formed by a series of outer chain plate links 52 and inner chain plate links 54, disengages from the sprocket 22 and shifts up to a smaller sprocket 20. As shown, the output tooth 38 is the last tooth of the sprocket 22 that engages with the bicycle chain 50.

[0193] Figure 9 The sprocket pair consisting of the 28T sprocket 24 and the aforementioned 24T sprocket 22 is shown only as an example. Sprocket 22 has been discussed above. Sprocket 24 has, in principle, two upshifting regions 34 and two downshifting regions 40 along its circumference, wherein the regions 34 and 40 that shift in the same direction are arranged radially opposite to each other on sprocket 24.

[0194] The same lowercase letter following the reference symbol 24 of sprocket 24 indicates that the same lowercase letter indicates the functional part or part section of sprockets 12, 14, 16, 18, 20 or 22.

[0195] Sprocket 24 also has a tooth clearance 43, with the tooth roots radially inward biased toward the sprocket shaft R. However, this tooth clearance 43 is insignificant to the displacement of the chain between adjacent sprockets 24 and 22, but plays an important role in the displacement of the bicycle chain between sprocket 24 and the next larger sprocket 26.

[0196] Figure 10 The largest sprocket 32, detached from the remaining sprockets 10 to 30, is shown in a baseline view. Sprocket 32 ​​includes a toothed ring 60, an intermediate ring 62, and a radially inner wedge ring 64 for transmitting torque to a drive mechanism (not shown but well known to those skilled in the art), or to an adapter arranged between the wedge ring 64 and the drive mechanism. The wedge profile of the adapter or drive mechanism, interacting with the radially inner profile of the wedge ring 64, is complementary to the radially inner wedge profile of the wedge ring 64. Radially outer supports 66a and 66b connect the toothed ring 60 to the intermediate ring 62 in a torque-transmitting manner. A radially inner support 68 connects the intermediate ring to the wedge ring 64.

[0197] To prevent undesirable bending deformation of supports 66b and 68, these supports are arranged such that the radially inner support end leads the radially outer support end in the direction of drive rotation. Support 66a is wider than support 66b in the circumferential direction.

[0198] The fastening hole 70 shows how the sprocket dome, which consists of integrally connected sprockets 14 to 30 and smaller sprockets 12 and 10 screwed into the sprocket dome, is connected to the largest sprocket 32 ​​by means of pins, rivets, screws, etc., in order to transmit torque.

[0199] The fastening hole 70 is arranged as far outward as possible in the radial direction without interfering with the meshing of the sprocket teeth and the bicycle chain, and is also constructed within the most stable area of ​​the sprocket 32. Therefore, the fastening hole 70 is specifically constructed in the wider radial outer bracket 66a and close to the connection point between the intermediate ring 62 and the radial inner bracket 68.

[0200] exist Figure 10A In the diagram, the largest sprocket 32 ​​is shown in a view orthogonal to the sprocket axis R. As shown, the sprocket 32 ​​is constructed to be concave outwards in the radial region near the sprocket axis R, that is, concave away from the longitudinal center plane LME. Therefore, the transmission device located radially inside the wedge ring 64 requires as little axial structural space as possible to accommodate the twelve-layer sprocket cassette flywheel 1. Furthermore, the larger sprocket 32 ​​is thus reinforced to resist the bending moment acting on the largest sprocket 32 ​​due to chain misalignment. The sprocket 32 ​​and the sprocket dome connected to it are mutually reinforced.

[0201] The sprocket cassette 1 is configured such that all the smaller sprockets 10 to 30 transmit their torque directly to the sprocket 32, which transmits the torque from the rider or electric motor to the sprocket cassette 1 via the bicycle chain 50 to the rear wheel hub through the aforementioned transmission mechanism.

[0202] For example, the side of sprocket 32 ​​facing the longitudinal center plane LME, i.e. Figure 10B As shown from the side the observer is looking at, coarse teeth 32a and fine teeth 32b are also alternately constructed circumferentially on the largest sprocket 32. The grooves on the tooth surfaces facing axially for forming fine teeth 32b are only constructed on the side of the larger sprocket 32 ​​facing away from the next sprocket 30.

[0203] The same lowercase letter following the reference symbol 32 of sprocket 32 ​​indicates that the same lowercase letter indicates the functionally identical part or part segment of sprockets 12, 14, 16, 18, 20, 22 or 24.

[0204] Figure 10B It is also shown that ramps are constructed on some output teeth 38 and some receiving teeth 44, as well as on the mobilizing teeth 32b' and 32b" adjacent to the output teeth 38 and receiving teeth 44 that form the ramps. The ramps are marked with the reference symbol and lowercase letter g of the corresponding teeth. The ramps on the mobilizing teeth are marked with the same apostrophe as the corresponding mobilizing teeth.

[0205] Ramps 38g, 32g', 44g, and 32g" form radial and axial steps opposite to the tooth surfaces of the next smaller sprocket 30, corresponding to teeth 38, 32b', 44, and 32b". Ramps 38g, 32g', 44g, and 32g" form a radially outward slope, that is, away from the sprocket shaft R, on which the radially inward edge surface of the bicycle chain 50 can be supported.

[0206] These ramps 38g, 32g', 44g and 32g" stabilize the chain 50 in a special way when it engages with the largest sprocket 32.

[0207] When pedaling backward using the freewheel, typically located on the rear hub, chain misalignment can, under certain circumstances, affect the engagement of the sprocket 32 ​​with the bicycle chain 50 to stabilize it. Specifically, the output tooth 38 and its adjacent driving tooth 32b', based on their technical design, assist in the chain's movement toward the next smaller sprocket 30 affected by the misalignment; therefore, a ramp is initially constructed there. Ramps are also constructed on the shift-related teeth in the downshifting area, namely on the receiving tooth 44 and its driving tooth 32b', to stabilize the chain 50.

[0208] The aforementioned ramp not only holds the chain in place even when chain misalignment has a very adverse effect on the front sprocket on sprocket 32, but also assists the chain 50 when downshifting to a larger sprocket 32 ​​or upshifting from a larger sprocket 32 ​​to the next smaller sprocket 30. In other words, the ramp allows the chain to be held stably and also provides physical guidance to the chain even when the chain is located radially outward on sprocket 32 ​​in the shift-related areas (i.e., upshifting area 34 and downshifting area 40), compared to conventional toothed meshing examples where the receiving tooth 44, output tooth 38, or its adjacent driving tooth 32b" or 32b' engages radially into the middle gap of the link.

[0209] Therefore, when the chain guide rollers of the transmission are aligned with the sprocket 32 ​​to hold the chain on the larger sprocket 32, and when chain skew contributes to the holding of chain 50 on sprocket 32, the ramp stabilizes chain 50 to counteract chain skew towards the front sprocket. Furthermore, while chain 50 is still engaged on the sprocket of the current guide chain, and when the chain guide rollers of the transmission are aligned with the sprocket of the chain to be guided, the ramp assists in the displacement of chain 50.

[0210] The ramp shown can also be constructed on sprockets 30, 28, 26, etc., and more specifically, it is preferably constructed on the side of the corresponding sprocket away from the next smaller sprocket. However, since the chain skew is reduced towards the sprocket of the middle size of the sprocket cassette 1, the ramp is particularly important on the larger sprockets 32, 30, and 28.

[0211] Figure 11 A bicycle equipped with the chainring cassette 1 of the present invention is roughly shown, both denoted by reference numeral 70. The front wheel 72 and rear wheel 74 are designed to be wound around... Figure 11 The corresponding axle is fixed to the bicycle frame 76 in a rotational manner orthogonal to the drawing plane. The front wheel 72 can be connected to the bicycle frame 76 via a spring fork 78. The rear wheel 74 can be connected to the bicycle frame 76 via a spring suspension 80.

[0212] The rear wheel 74 can be driven by a drive assembly 82, which includes a single front sprocket 24 and only... Figure 1The bicycle rear wheel cassette 1 is roughly illustrated. Drive torque is transmitted to the front chainring 84 via the pedal crank 88 and the pedal crank shaft 88a connected to it, and then to the rear wheel 74 via the chain 50 and the cassette 1. To assist the cyclist manually driving the pedal crank 88, an auxiliary electric motor 90 can be mounted on the bicycle frame 76, which also transmits its auxiliary drive torque to the front chainring 84 via the pedal crank shaft 88a. A gearbox, particularly a planetary gearbox, can be provided between the pedal crank shaft 88a and the chainring 84. The gearbox's gear ratio needs to be considered when calculating the effective number of teeth on the chainring 84. The actual number of teeth on the chainring 84 needs to be multiplied by a coefficient used by the gearbox to transmit the introduced torque to its output side. The torque increases due to the gearbox; therefore, the effective number of teeth on the chainring 84 is increased relative to the actual number of teeth, and vice versa.

[0213] A battery 92 may be provided in or on the frame 76 as an energy storage device for the auxiliary motor 90.

[0214] The bicycle chain 50 can be engaged with a sprocket selected by the rider from among the multiple sprockets 10 to 32 of the sprocket cassette 1 using a known method via a shifting mechanism or derailleur 94 to transmit torque to the rear wheel 74. The derailleur 94 has a chain guide roller 96 and a tension roller 98 that are closest to the sprocket cassette 1.

[0215] In the example bicycle 70, both the rider's manual torque and the auxiliary torque of the electric motor 90 are transmitted to the rear wheel 74 via the rear wheel sprocket cassette 1. Therefore, the electric motor 90 has the same effect as if the rider could utilize the increased pedaling power provided by the auxiliary power of the electric motor 90.

[0216] The exemplary bicycle 70 has exactly one front chainring 84, so the entire gear range of the bicycle 70 is achieved by the chainring cassette 1.

Claims

1. A bicycle rear wheel sprocket pair for engaging with a bicycle roller chain in a force-transmitting manner, wherein the rear wheel sprocket pair is rotatable about a sprocket shaft, wherein the sprocket shaft defines an axial direction along the sprocket shaft, a radial direction orthogonal to the sprocket shaft, and a circumferential direction around the sprocket shaft, wherein the rear wheel sprocket pair includes a larger sprocket and a smaller sprocket coaxially adjacent to the larger sprocket in the axial direction, the smaller sprocket being connected to the larger sprocket to rotate together about the sprocket shaft in a slip-free manner, wherein the larger sprocket has an even number of teeth equal to or less than 22 teeth, and wherein the difference in the number of teeth between the larger sprocket and the smaller sprocket is exactly two teeth, wherein i) The larger sprocket has a shifting region comprising a shifting recess along a segment of its circumference on its end side facing the smaller sprocket, wherein, in an axial view of the rear wheel sprocket pair, with the smaller sprocket closer to the observer than the larger sprocket, the shifting region is constructed and arranged to facilitate the engagement transition of the bicycle roller chain from the larger sprocket to the smaller sprocket on the rear wheel sprocket pair rotating clockwise about the sprocket axis, wherein on the larger sprocket, the shifting recess is provided with exactly one output tooth, the output tooth being configured, due to its shape and orientation, to engage, during the shifting process from the larger sprocket to the smaller sprocket, the last tooth between the chainplate pairs of the bicycle roller chain links in conjunction with the shifting recess on the end side. as well as ii) The larger sprocket has a downshift region along its circumference on its end side facing the smaller sprocket, including a downshift recess, wherein in the reference state in the axial view of the rear wheel sprocket pair, the downshift region is configured to realize the engagement transition of the bicycle roller chain from the smaller sprocket to the larger sprocket on the rear wheel sprocket pair rotating clockwise about the sprocket axis, wherein on the larger sprocket, the downshift recess is provided with exactly one receiving tooth, the receiving tooth being configured by its shape and orientation to engage the first tooth between the chain plates of the bicycle roller chain link during the downshift process from the smaller sprocket to the larger sprocket, in conjunction with the downshift recess on the end side.

2. The bicycle rear wheel sprocket set according to claim 1, Its features are, The output tooth follows the upshift recess in a clockwise direction.

3. The bicycle rear wheel sprocket set according to claim 1 or 2, Its features are, The larger sprocket has exactly one upshift area along its entire circumference, the upshift area having an upshift recess and exactly one output tooth.

4. The bicycle rear wheel sprocket set according to claim 1 or 2, Its features are, The receiving tooth follows the downshift recess structure in a counterclockwise direction.

5. The bicycle rear wheel sprocket set according to claim 1 or 2, Its features are, The larger sprocket has exactly one downshifting zone and exactly one receiving tooth along its entire circumference.

6. The bicycle rear wheel sprocket set according to claim 1 or 2, Its features are, In the reference state in the axial view of the rear sprocket pair, k teeth are provided between the output tooth and the receiving tooth in a clockwise direction, wherein the output tooth and the receiving tooth are not included in the calculation, and wherein k = T – d, where T is the number of teeth of the larger sprocket, and wherein d is equal to 5 or equal to 7.

7. The bicycle rear wheel sprocket set according to claim 6, Its features are, If T is divisible by 6, then d equals 5; if T is not divisible by 6, then d equals 7.

8. The bicycle rear wheel sprocket set according to claim 1 or 2, Its features are, In the reference state in the axial view of the rear sprocket pair, n teeth are provided between the receiving tooth and the output tooth in a clockwise direction, wherein the receiving tooth and the output tooth are not counted, and n is equal to 3 or equal to 5.

9. The bicycle rear wheel sprocket set according to claim 8, Its features are, If the number of teeth on the larger sprocket is divisible by 6, then n equals 3; if the number of teeth on the larger sprocket is not divisible by 6, then n equals 5.

10. The bicycle rear wheel sprocket set according to claim 1 or 2, Its features are, The tooth following the output tooth in the clockwise direction that is away from the tooth surface of the smaller sprocket is closer to the smaller sprocket than the tooth surface of the next tooth following the output tooth in the clockwise direction that is away from the tooth surface of the smaller sprocket. Or / and The tooth that follows the receiving tooth in the counterclockwise direction is closer to the smaller sprocket than the tooth surface of the next tooth that follows the receiving tooth in the counterclockwise direction.

11. The bicycle rear wheel sprocket set according to claim 1 or 2, Its features are, The larger sprocket and / or the smaller sprocket each have: at least one fine tooth and one coarse tooth alternating in the circumferential direction along a circumferential segment.

12. A bicycle rear wheel sprocket freewheel having a plurality of sprockets of different numbers of teeth connected together to rotate together about a sprocket shaft in a non-slip manner, wherein the bicycle rear wheel sprocket freewheel comprises at least one bicycle rear wheel sprocket pair according to any one of claims 1 to 11.

13. The bicycle rear wheel sprocket cassette freewheel according to claim 12, Its features are, The bicycle rear wheel sprocket cassette has at least three sprockets with different numbers of teeth, the sprockets belonging to two pairs of the bicycle rear wheel sprockets, wherein the sprocket with the middle number of teeth is the larger sprocket of one rear wheel sprocket pair and the smaller sprocket of the other rear wheel sprocket pair.

14. The bicycle rear wheel sprocket cassette freewheel according to claim 12 or 13, Its features are, All sprockets of the rear wheel sprocket cassette with 20 or fewer teeth form several pairs of the bicycle rear wheel sprockets.

15. The bicycle rear wheel sprocket cassette freewheel according to claim 12 or 13, Its features are, The rear sprocket cassette flywheel has a transition sprocket assembly, including a 21T sprocket with 21 teeth, adjacent to a smaller 18T sprocket with 18 teeth.

16. The bicycle rear wheel sprocket cassette freewheel according to claim 15, Its features are, i) The 21T sprocket has at least two upshift regions, each comprising an upshift recess, along a segment of its circumference on its end side facing the 18T sprocket. In an axial view of the transition sprocket assembly, with the 18T sprocket closer to the observer than the 21T sprocket, each upshift region is constructed and arranged to facilitate the engagement transition of the bicycle roller chain from the 21T sprocket to the 18T sprocket on the transition sprocket assembly rotating clockwise about the sprocket axis. On the T-sprocket, each of the two upshift recesses is assigned exactly one output tooth. This output tooth, due to its shape and orientation, is configured to engage with the last tooth between the chain plates of the bicycle roller chain link during the upshifting process from the 21T sprocket to the 18T sprocket, in conjunction with the corresponding end-side upshift recess. An even number of teeth are provided between the output teeth of adjacent upshift recesses in the circumferential direction, excluding the output teeth of adjacent upshift recesses. Or / and ii) The 21T sprocket has at least two downshift regions along its circumference on its end side facing the 18T sprocket, each including a downshift recess construction, wherein in the reference state in the axial view of the transition sprocket assembly, each downshift region is configured to realize the engagement transition of the bicycle roller chain from the 18T sprocket to the 21T sprocket on the transition sprocket assembly rotating clockwise about the sprocket axis, wherein on the 21T sprocket, each downshift recess construction is assigned exactly one receiving tooth, the receiving tooth being configured by its shape and orientation to engage the first tooth between the chain plates of the bicycle roller chain link during the downshift process from the 18T sprocket to the 21T sprocket, in conjunction with the corresponding downshift recess construction on the end side, wherein an even number of teeth are provided between the receiving teeth of adjacent downshift recess constructions in the circumferential direction, wherein the receiving teeth of adjacent downshift recess constructions are not counted.

17. The bicycle rear wheel sprocket cassette freewheel according to claim 16, Its features are, The 21T sprocket i) It has exactly three upshift regions, each with an upshift recess and exactly one output tooth, wherein six teeth are provided between the output teeth of adjacent upshift recesses in the circumferential direction, excluding the output teeth of adjacent upshift recesses. Or / and ii) Having exactly three downshifting regions, each downshifting region having a downshifting recess and exactly one receiving tooth, wherein six teeth are provided between the receiving teeth of adjacent downshifting recesses in the circumferential direction, wherein the receiving teeth of adjacent downshifting recesses are not counted.

18. The bicycle rear wheel sprocket cassette freewheel according to claim 16, Its features are, The transition sprocket assembly also has a 24T sprocket with 24 teeth, wherein the 21T sprocket is axially arranged between the 24T sprocket and the 18T sprocket.

19. The bicycle rear wheel sprocket cassette freewheel according to claim 15, Its features are, i) The 24T sprocket has at least two upshift regions, each comprising an upshift recess, along a segment of its circumference on its end side facing the 21T sprocket. In an axial view of the transition sprocket assembly, with the 21T sprocket closer to the observer than the 24T sprocket, each upshift region is constructed and arranged to facilitate the engagement transition of the bicycle roller chain from the 24T sprocket to the 21T sprocket on the transition sprocket assembly rotating clockwise about the sprocket axis. On the sprocket, each of the two upshift recesses is provided with exactly one output tooth. This output tooth, due to its shape and orientation, is configured to engage with the last tooth between the chain plates of the bicycle roller chain link during the upshift process from the 24T sprocket to the 21T sprocket, in conjunction with the corresponding end-side upshift recess. An odd number of teeth are provided between the output teeth of adjacent upshift recesses in the circumferential direction, excluding the output teeth of adjacent upshift recesses. Or / and ii) The 24T sprocket has at least two downshift regions along its circumference on its end side facing the 21T sprocket, each including a downshift recess construction, wherein in the reference state in the axial view of the transition sprocket assembly, each downshift region is configured to realize the engagement transition of the bicycle roller chain from the 21T sprocket to the 24T sprocket on the transition sprocket assembly rotating clockwise about the sprocket axis, wherein on the 24T sprocket, each downshift recess construction is assigned exactly one receiving tooth, the receiving tooth being configured by its shape and orientation to engage the first tooth between the chain plates of the bicycle roller chain link during the downshift process from the 21T sprocket to the 24T sprocket, in conjunction with the corresponding downshift recess construction on the end side, wherein an odd number of teeth are provided between the receiving teeth of adjacent downshift recess constructions in the circumferential direction, wherein the receiving teeth of adjacent downshift recess constructions are not counted.

20. The bicycle rear wheel sprocket cassette freewheel according to claim 19, Its features are, The 24T sprocket i) It has exactly three upshift regions, each with an upshift recess and exactly one output tooth, wherein seven teeth are provided between the output teeth of adjacent upshift recesses in the circumferential direction, excluding the output teeth of adjacent upshift recesses. Or / and ii) Having exactly three downshifting regions, each downshifting region having a downshifting recess and exactly one receiving tooth, wherein seven teeth are provided between the receiving teeth of adjacent downshifting recesses in the circumferential direction, wherein the receiving teeth of adjacent downshifting recesses are not counted.

21. The bicycle rear wheel sprocket cassette freewheel according to claim 12 or 13, Its features are, The bicycle rear wheel sprocket is a twelve-layer sprocket cassette cassette with the following tooth counts: 10 – 12 – 14 – 16 – 18 – 21 – 24 – 28 – 32 – 38 – 44 – 52.

22. A bicycle drive assembly comprising a bicycle rear wheel sprocket pair according to any one of claims 1 to 11 or a bicycle rear wheel sprocket cassette freewheel according to any one of claims 12 to 21, the bicycle drive assembly having a bicycle roller chain adapted to engage with the sprockets of the bicycle rear wheel sprocket pair or the bicycle rear wheel sprocket cassette freewheel in a force-transmitting manner, wherein the bicycle roller chain has a plurality of chain rollers arranged sequentially at a certain interval, the chain rollers being connected by parallel chain plate pairs, wherein the bicycle roller chain has inner chain plate pairs with a smaller chain plate spacing and outer chain plates with a larger chain plate spacing that alternate sequentially in the chain circumferential direction.

23. The bicycle drive assembly according to claim 22, Its features are, For at least one bicycle rear wheel sprocket pair, during the shifting process of the bicycle roller chain moving from one sprocket to a sprocket axially adjacent to the sprocket, there is exactly one inner sprocket link between the last link engaged with the sprocket that is still guiding the chain and the first link that is about to or has already engaged with the sprocket that is about to guide the chain.

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