MORE WEAR-RESISTANT BICYCLE SPROCKET PAIRING AND SPROCKET CASSETTE WITH SUCH

Description

[0001] The present invention relates to a bicycle rear wheel sprocket pair for meshing, force-transmitting, positive engagement with a bicycle roller chain. The rear wheel sprocket pair is rotatable about a sprocket axis, wherein the sprocket axis defines an axial direction running along the sprocket axis, a radial direction running orthogonal to the sprocket axis, and a circumferential direction encircling the sprocket axis. The rear wheel sprocket pair comprises a larger sprocket and a smaller sprocket connected to the larger sprocket for joint, slip-free rotation around the sprocket axis, coaxial and axially directly adjacent to the larger sprocket.

[0002] EP 1 188 658 B1 discloses a rear wheel sprocket cassette comprising seven sprockets. The tooth spacing of the sprockets, from the smallest, outermost sprocket to the largest, innermost sprocket, is 11, 13, 15, 17, 21, 25, 29, and 33. The known sprocket cassette thus has only sprockets with odd numbers of teeth. The outermost sprocket is the sprocket furthest from the longitudinal center plane of the bicycle carrying the sprocket cassette, which is orthogonal to the sprocket axis. The innermost sprocket is accordingly the sprocket closest to the longitudinal center plane of the bicycle.

[0003] Bicycle roller chains circulating in meshing engagement on the rear wheel pinion, comprising a plurality of chain rollers arranged at a predetermined pitch distance from one another in the longitudinal direction of the chain, and with chain plates connecting the chain rollers, are also known. The chain links of the known and conventional bicycle roller chains are formed by pairs of plates, with inner plate pairs and outer plate pairs alternating one after the other in the longitudinal direction of the chain, which, due to the closed, circumferential design of a bicycle roller chain, is also the direction of chain rotation. End regions of outer plate pairs overlap end regions of inner plate pairs in a conventional manner, so that the end regions of an inner plate pair are arranged between an end region of an outer plate pair and the chain roller held between this end region, with one inner plate end region on each of the two end faces of the chain roller.The clearance, measured in the chain width direction, i.e., parallel to the roller axes of the chain rollers, is therefore smaller between two inner plates of an inner plate pair than the clearance between two outer plates of an outer plate pair. The clearance of a plate pair defines the engagement space available for the engagement of a pinion tooth with the roller chain. Consequently, the roller chain alternates between narrow chain links defined by inner plate pairs and wide chain links defined by outer plate pairs. Due to the alternating inner and outer plate chain links in the chain's direction of rotation, a bicycle roller chain always has an even number of chain links. The bicycle roller chain is also referred to simply as a "bicycle chain" or "chain" below.

[0004] For the sake of simplicity, pinions with odd numbers of teeth are also referred to as "odd-numbered pinions" and pinions with even numbers of teeth are referred to as "even-numbered pinions".

[0005] The disadvantage of odd-numbered sprockets is that with each revolution of the bicycle chain, the engagement of a single tooth with a chain link type changes. Therefore, in successive revolutions of the bicycle chain, the same tooth alternately engages a narrow inner-link chain link and a wide outer-link chain link. Each tooth of an odd-numbered sprocket must therefore be designed to engage a narrow chain link.

[0006] A physical weakening of the sprocket can result from the shifting conditions that must be met to shift the bicycle chain from the sprocket to the next smaller sprocket. This shifting occurs, as is widely known, on the rear wheel cassette by a front derailleur. The derailleur's chain guide roller, which guides the bicycle chain, is positioned by the cyclist through appropriate power transmission mechanisms, such as a mechanical cable or an electric motor via a "shift-by-wire" system, coplanar with the sprocket that takes over the chain after the shifting process. The chain is thus shifted from the sprocket currently carrying the chain to the sprocket that will carry the chain in the future.

[0007] On the front side of the sprockets facing the next smaller sprocket, recesses are formed in the form of flat depressions on the front side into which link plates, usually outer link plates, of the bicycle chain can be inserted, at least partially, to guide the chain axially close to the larger sprocket and thus assist the shifting process. There are upshift recess formations that assist in shifting the chain from the larger sprocket to the next smaller sprocket during an upshift, and there are downshift recess formations that assist in shifting the chain from the adjacent smaller sprocket to the larger sprocket during a downshift.The shape and / or radially inner edge of the depression formations - when viewed axially from the outside of a sprocket pair consisting of a larger and an adjacent smaller sprocket, i.e., with the smaller sprocket closer to the observer - follow the course of the bicycle chain in the transition area between the smaller and larger sprockets during the associated shifting process. This means that the upshift depression formation and / or a radially inner edge thereof roughly approaches the smaller sprocket from a radially further outward location on the larger sprocket, progressing counterclockwise, and the downshift depression formation and / or a radially inner edge thereof roughly approaches the smaller sprocket from a radially further outward location on the larger sprocket, progressing clockwise.

[0008] Typically, pinions have teeth designed as output teeth. These are the last teeth to engage between the plate pairs of a chain link when shifting up to the next smaller pinion, before the chain leaves the larger pinion to the smaller pinion. In the usual drive directions of rotation of rear wheel pinions, i.e., when viewed along the pinion axis from the outside clockwise, an output tooth is generally adjacent to its associated upshift recess formation in a clockwise direction, so that the chain, when engaged with the output tooth, can move radially inward past the teeth following the output tooth in a counterclockwise direction, utilizing the upshift recess formation as a movement space.

[0009] Likewise, for downshifting, catch teeth are designed on the larger pinion. These are the first teeth to engage the bicycle chain that is to be shifted to the larger pinion. Here, the bicycle chain is axially brought closer to the larger pinion, utilizing the downshift groove formation as a space for movement. This allows the chain to initially move laterally past the teeth preceding the catch tooth in a clockwise direction, utilizing the upshift groove formation as a space for movement, and finally, the catch tooth, as the first tooth of the pinion, can engage the engagement space between two chain plates. A catch tooth is therefore adjacent to its associated downshift groove formation in a counterclockwise direction.

[0010] An output tooth and a catch tooth are physically designed differently from other teeth of the pinion in order to fulfill their respective engagement task during the associated shifting process. They can be designed with a tooth height measured in the radial direction and / or a different tooth width measured in the circumferential direction and / or a different tooth thickness measured in the axial direction and / or a different tooth tip shape and / or a different shape of at least one tooth flank and / or a different position of one or both tooth side surfaces relative to the pinion end face closest to them and / or a different tooth inclination about an inclination axis orthogonal to the radial projection direction of the tooth and / or a different tooth inclination about an inclination axis parallel to the radial projection direction of the tooth in order to act as the last engaging tooth during an upshift or as the first engaging tooth during a downshift.

[0011] A chain usually catches on the larger pinion in a pinion pair due to the larger engagement space on an outer plate pair. Furthermore, due to the system's design, outer plates, and thus outer plate pairs, can be axially closer to a pinion than inner plate pairs, since the outer plates of a chain rotating on a smaller pinion, facing a larger pinion, are always axially closer to the larger pinion than the inner plates facing the larger pinion.

[0012] Since, as described above, with odd-numbered sprockets, the assignment of a tooth to the type of chain link meshing with it alternates per sprocket revolution, with the familiar sprocket cassette, how the chain is transferred to the larger sprocket depends on the number of revolutions the smaller sprocket carrying the chain has completed before the gear shift. To securely catch the chain without unwanted latency—the time lag between the initiation of a gear shift by the rider and the actual execution of the gear shift on the sprocket—the larger sprocket is provided with two catch teeth directly behind one another in the circumferential direction, so that at least one of them engages with a pair of outer plates during downshifts, thereby catching the chain.

[0013] The same applies, mutatis mutandis, to the output teeth when upshifting.

[0014] To facilitate engagement with the chain, which is not yet or no longer fully rotating on the larger sprocket, the catch and output teeth are often thinner than other teeth that do not have to fulfill the functions of the catch and output teeth. This further structurally weakens the catch and output teeth, as well as the pinion as a whole.

[0015] Especially with modern electric-motor-assisted bicycle drives, higher torque values ​​can be transmitted permanently compared to the chain drive known from EP 1 188 658 B1. Furthermore, the electric-motor assistance of bicycle drives has increased the gear spread, i.e., the difference between the number of teeth of the largest and smallest sprocket of a cassette divided by the number of teeth of the smallest sprocket. Furthermore, the handling and shifting behavior of electric-motor-assisted bicycles has changed compared to bicycles powered solely by human power.

[0016] Due to the larger gear spread compared to the past, rear sprocket cassettes with a high number of sprockets must be developed to accommodate cyclists' desire for small gear steps between individual adjacent sprockets. Small gear steps, i.e. the difference in the number of teeth of a sprocket pair relative to the number of teeth of the smaller sprocket, are always required when the bicycle is propelled solely by muscle power without electric motor assistance. The trend toward larger tires and shorter chainstays often leads to the use of a relatively small chainring on the crank. As a result, the speed range in which electric motor assistance of the cyclist's propulsion is permitted according to the provisions of most road traffic regulations is increasingly shifting toward smaller rear sprockets.In Germany, for example, electric motor assistance is permitted up to a speed of 25 km / h, while in other countries it's permitted up to 20 km / h or 30 km / h. Therefore, the smaller sprockets in a sprocket cassette are particularly at risk of increased wear.

[0017] US 2019 / 359284 A1 discloses, according to the Examining Division of the European Patent Office, a bicycle rear wheel pinion pair for power-transmitting engagement with a bicycle roller chain, wherein the rear wheel pinion pair is rotatable about a pinion axis, wherein the pinion axis defines an axial direction running along the pinion axis, a radial direction running orthogonal to the pinion axis and a circumferential direction running around the pinion axis, wherein the rear wheel pinion pair comprises a larger pinion and a smaller pinion connected thereto for common slip-free rotation about the pinion axis, coaxial and axially immediately adjacent to the larger pinion, wherein the larger pinion 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 and the smaller pinion is exactly two teeth, wherein i) the larger pinion in its end face facing the smaller pinion,along a portion of its circumference, an upshift region with an upshift depression formation, wherein the upshift region is designed and arranged to allow a change in engagement of the bicycle roller chain from the larger to the smaller pinion on the rear wheel pinion pair rotating clockwise around the pinion axis - when viewing the rear wheel pinion pair axially in a reference state in which the smaller pinion is closer to the observer than the larger pinion - wherein only exactly one output tooth is assigned to the upshift depression formation on the larger pinion, which output tooth is designed by its shape and orientation to be the last tooth to engage between a pair of plates of a chain link of the bicycle roller chain during an upshift process from the larger pinion to the smaller pinion,and ii) the larger pinion, in its end face facing the smaller pinion, has a downshift region with a downshift depression formation along its circumference, wherein the downshift region is designed to allow a change in engagement of the bicycle roller chain from the smaller to the larger pinion on the rear wheel pinion pair rotating clockwise - when viewed axially of the rear wheel pinion pair in the reference state - about the pinion axis, wherein on the larger pinion, only exactly one catch tooth is assigned to the downshift depression formation, which, due to its shape and orientation, is designed to be the first tooth to engage between plates of a chain link of the bicycle roller chain during a downshift process from the smaller pinion to the larger pinion, in cooperation with the end-face downshift depression formation,Due to its design and orientation, the catch tooth only engages the bicycle roller chain to be shifted to the larger pinion if an outer link plate chain link is located at the circumferential position of the catch tooth, which provides a larger engagement space than an inner link plate chain link, and the bicycle roller chain is rejected if an inner link plate chain link is located at the circumferential position of the catch tooth.

[0018] It is therefore an object of the present invention to further develop a bicycle rear wheel pinion pairing mentioned at the outset in such a way that it can be made more stable without increasing the installation space requirements and can thus be used for operation with higher mechanical loads.

[0019] The present invention achieves this object in that the larger pinion of the aforementioned bicycle rear wheel pinion pairing has an even number of teeth equal to or less than 22, with the difference in the number of teeth between the larger and smaller pinions being exactly two teeth. Thus, both pinions of the pinion pairing are even-numbered pinions, so that the assignment of the individual pinion teeth to the type of chain link with which they mesh remains unchanged for the duration of the pinion's engagement with the bicycle chain. Therefore, if a tooth meshes with an outer link plate chain link during one revolution, this tooth meshes with an outer link plate chain link during each revolution of the pinion.

[0020] The larger sprocket has, on its end face facing the smaller sprocket, an upshift area with an upshift recess formation along a portion of its circumference. The upshift area is designed and arranged, as described above, to allow a change in engagement of the bicycle roller chain from the larger to the smaller sprocket on the rear wheel sprocket pair rotating clockwise around the sprocket axis.

[0021] Only the upshift range generally allows the chain to shift up to the next smaller sprocket. Likewise, only the downshift range generally allows the chain to shift down from the next smaller sprocket to the larger sprocket.

[0022] When clockwise and counterclockwise are used in this application as directions for the pinion pair, this always refers to a reference view of the pinion pair or a pinion cassette containing the pinion pair in the axial direction, with the smaller pinion of the pinion pair being closer to the observer than the larger pinion. Since the smaller pinion on the rear wheel of the bicycle carrying the pinion pair is located farther from the bicycle's longitudinal center plane orthogonal to the pinion axis and thus "further outward" than the larger pinion, the axial reference view is also referred to below as an axial view "from the outside."

[0023] According to the invention, only one output tooth is assigned to the upshift recess formation on the larger sprocket. Due to its shape and orientation, this output tooth, in cooperation with the front-end upshift recess formation, is designed to be the last tooth to engage between a pair of plates of a chain link of the bicycle roller chain during an upshift from the larger sprocket to the smaller sprocket. As a rule, only this specially designed output tooth, and no other tooth, engages the chain as the last tooth of the larger sprocket during an upshift.

[0024] Providing only one output tooth per upshift range has two advantages: firstly, the chain is transferred to the smaller sprocket with a defined alignment in terms of its chain link sequence, because, unlike in the prior art mentioned above, there are no longer two teeth following one another in the circumferential direction, each of which can act as the last engagement tooth due to its shape and orientation. The output tooth usually engages with an outer plate chain link, because the inner plate chain link following in a counterclockwise direction according to the reference view can slide radially inward past the tooth following the output tooth in a counterclockwise direction on the face of the larger sprocket facing the smaller sprocket due to its narrower dimensions considerably more easily. Secondly, it is sufficient to design only this one output tooth as such.As described above, a dropout tooth is typically axially thinner than a conventional non-dropout tooth to allow the bicycle chain axial movement toward the smaller sprocket. This allows for a reduction in the number of teeth on the larger sprocket that are structurally weakened by the reduction in thickness.

[0025] Additionally or alternatively, the larger sprocket has a downshift area with a downshift recess formation along its circumference on its end face facing the smaller sprocket. As described above, the downshift area is designed to allow a change in engagement of the bicycle roller chain from the smaller to the larger sprocket on the rear wheel sprocket pair rotating clockwise around the sprocket axis.

[0026] Additionally or alternatively, the downshift recess formation on the larger sprocket is assigned exactly one catch tooth, which, due to its shape and orientation, is designed, in cooperation with the front-end downshift recess formation, to be the first tooth to engage between the plates of a chain link of the bicycle roller chain during a downshift from the smaller sprocket to the larger sprocket. As a rule, only the catch tooth is designed to be the first tooth to engage a chain link when downshifting to the larger sprocket.

[0027] Due to the described design of the downshift recess formation with only exactly one assigned catch tooth, the chain is taken over by the larger pinion with a defined chain link sequence when downshifting from the smaller to the larger pinion. According to the invention, the catch tooth has a design and orientation such that it only engages with the chain being transferred to the larger pinion if there is an outer link plate chain link at the circumferential position of the catch tooth that provides a larger engagement space than an inner link plate chain link. If, for whatever reason, an inner link plate chain link is located at the location of the catch tooth, the chain is rejected. Furthermore, the design of only one catch tooth per downshift recess formation reduces the number of teeth that are structurally weakened to implement the catch function.

[0028] The larger pinion of the pinion pairing according to the invention can have only the feature of the upshift recess formation related to the upshift process with only exactly one associated output tooth, only the feature of the downshift recess formation related to the downshift process with only exactly one associated catch tooth or, particularly advantageously, both features in order to take over the bicycle chain in a clearly directed manner both from the smaller pinion of the pairing and to transfer it to it.

[0029] The fundamentally functional assignment of the output tooth to the upshift depression formation with which it interacts is generally a spatial assignment, because when upshifting, the bicycle chain generally angles towards the smaller pinion at the chain roller following the meshing output tooth in a counterclockwise direction, with at least one of the chain links following the chain link meshing with the output tooth in a counterclockwise direction axially engaging the upshift depression formation. The upshift depression formation is a recess on the end face facing the smaller pinion, which creates axial movement space for the chain. Therefore, the output tooth preferably follows the upshift depression formation directly in a clockwise direction. Therefore, there is preferably no further tooth in a clockwise direction between the upshift depression formation and the output tooth.

[0030] For the aforementioned pinions with a tooth count of no more than 22, it has proven sufficient for the larger pinion to have exactly one upshift zone along its entire circumference, with only one upshift groove formation, and consequently only one output tooth. When an upshift is initiated, it occurs within one pinion revolution. This is a latency that is readily accepted by cyclists. By creating only one upshift groove formation and only one output tooth, the weakening of the pinion caused by an upshift is minimized.

[0031] What was said above regarding the transfer tooth applies mutatis mutandis to the catch tooth. First, the chain is axially brought closer to the larger pinion receiving the chain by utilizing the downshift recess formed as an axial recess in the face. The chain is then caught by the catch tooth through positive engagement with a chain link and guided to the larger pinion. Therefore, the functional assignment of the catch tooth to its downshift recess formation is also a spatial assignment. The catch tooth preferably follows the downshift recess formation directly in a counterclockwise direction. Therefore, there is preferably no further tooth in a counterclockwise direction between the downshift recess formation and the catch tooth.

[0032] With a maximum shift latency of one pinion revolution, and minimal weakening of the larger pinion due to a downshift, the larger pinion can only have exactly one downshift range along its entire circumference and consequently only exactly one catch tooth.

[0033] Tests have shown that it has a positive influence on the wear pattern of the larger pinion and thus on its overall service life if the catch tooth, starting from the output tooth, is as far apart as possible in a clockwise direction from the output tooth. To achieve this greatest possible distance in a clockwise direction, it is also advantageous to have only one output tooth and one catch tooth. A large clockwise distance while simultaneously maintaining the boundary conditions necessary for shifting between the larger and smaller pinion can be achieved by placing a number of k teeth between the output tooth and the catch tooth, starting from the output tooth in a clockwise direction, where k = T - d, where T is the number of teeth on the larger pinion and where d is either 5 or 7. The output tooth and the catch tooth are not to be counted. Only the teeth located between the output tooth and the catch tooth in a clockwise direction count.In this case, d is preferably equal to 5 if the number of teeth T of the larger pinion is divisible by 6 without a remainder. If the number of teeth T of the larger pinion is not divisible by 6 without a remainder, d is preferably equal to 7. However, it should be noted that in principle d can also be equal to 7 if the number of teeth T of the larger pinion is divisible by six without a remainder.

[0034] With the same objective of achieving the greatest possible distance between the catching tooth in the clockwise direction and the output tooth of the larger pinion, the larger pinion can be designed in such a way that, starting from the catching tooth, there are 3 or 5 teeth in the clockwise direction between the catching tooth and the output tooth, not counting the catching tooth and the output tooth.

[0035] According to an advantageous, but not mandatory, further development, if the number of teeth of the larger pinion is divisible by 6 without a remainder, preferably 3 teeth, and if the number of teeth of the larger pinion is not divisible by 6 without a remainder, preferably 5 teeth are located clockwise between the catch tooth and the output tooth.

[0036] To give the bicycle chain sufficient axial movement even with a small axial distance between the smaller and larger sprockets, the tooth following the output tooth in a clockwise direction can be designed as an upshift mobilization tooth, whose tooth surface facing away from the smaller sprocket is closer to the smaller sprocket than the tooth surface of the tooth next but one following the mobilization tooth in a clockwise direction, facing away from the smaller sprocket. This mobilization tooth, whose tooth surface facing the smaller sprocket is generally not axially offset compared to the tooth next but one following it in a clockwise direction and is therefore thinner than the tooth next but one following it in a clockwise direction, is usually in mesh with an inner plate chain link and, when engaged, allows this link axial play towards the smaller sprocket.

[0037] Additionally or alternatively, to improve the axial mobility of the chain, the tooth following the catch tooth in a counterclockwise direction can be designed as a downshift mobilization tooth, the tooth surface of which faces away from the smaller pinion is closer to the smaller pinion than the tooth surface of the tooth next but one following the mobilization tooth in a counterclockwise direction, which faces away from the smaller pinion. This mobilization tooth, whose tooth surface facing the smaller pinion is generally not axially offset compared to the tooth next but one following it in a counterclockwise direction and is therefore thinner than the tooth next but one following it in a counterclockwise direction, is generally in mesh with an inner link of the chain plate and, when engaged, allows it axial play towards the smaller pinion.

[0038] The possibility obtained with the present pinion pairing of shifting the chain in a defined manner with regard to the sequence of its chain link types from the smaller pinion to the larger pinion and / or from the larger pinion to the smaller pinion ensures that one and the same tooth of at least one pinion, preferably of both pinions of the pinion pair, meshes with the bicycle chain with one and the same chain link type, not only during the pinion revolutions of an engagement phase, but during all engagement phases of the at least one pinion.

[0039] In principle, all teeth of the larger and / or smaller pinion of the pinion pair can be designed with the same axial thickness to simplify their production. To position the bicycle chain as precisely as possible on the pinion pair with regard to the chain link sequence relative to the pinion teeth, the larger pinion and / or the smaller pinion can each have an axially thinner and an axially thicker tooth, alternating at least along a circumferential section in the circumferential direction. The thickness of the thicker teeth is advantageously dimensioned such that the thicker teeth fit into the engagement space of an outer plate chain link, but not into the engagement space of an inner plate chain link. The thickness of the thinner teeth is advantageously dimensioned such that they fit into the engagement space of an inner plate chain link.As a result, if the chain is properly meshed with the pinion with alternating thicker and thinner teeth, the chain can be guided on the pinion with very little axial play.

[0040] The present application further relates to a bicycle rear sprocket cassette having a plurality of sprockets, each with a different number of teeth, connected for joint, slip-free rotation around the sprocket axis, wherein the bicycle rear sprocket cassette contains at least one bicycle rear sprocket pairing according to one of the preceding claims. In order to utilize the advantages of the bicycle rear sprocket pairing described above as extensively as possible on the sprocket cassette, the bicycle rear sprocket cassette preferably has at least three sprockets, each with a different number of teeth, which form two bicycle rear sprocket pairs designed according to the above description, wherein the sprocket with the middle number of teeth is the larger sprocket of one rear sprocket pairing and the smaller sprocket of the other rear sprocket pairing.

[0041] In this sense, it is particularly preferred that all sprockets of the rear wheel sprocket cassette with a tooth count of 22 or less be configured as bicycle rear wheel sprocket pairs as described above. Each sprocket that is not the axially end sprocket of the sprocket group with a tooth count of 22 or less, the smaller sprocket, is a sprocket pair and simultaneously the larger sprocket of another sprocket pair. By definition, the smallest sprocket of the sprocket group can only be the smaller sprocket of a sprocket pair.

[0042] Since, with a constant tooth count difference, the gear steps become smaller as the pinions become larger, i.e., further inward, it is helpful to achieve reasonably consistent gear steps across the entire sprocket cassette if the tooth count difference between adjacent pinions increases with the number of teeth. Inevitably, differences in the gear steps between adjacent pinions must be accepted, since pinions only have integer numbers of teeth, and tooth count differences between adjacent teeth are also integers.

[0043] Since shifting the chain between two adjacent sprockets can be carried out particularly advantageously when the number of teeth of the adjacent sprockets has at least one common divisor, the rear sprocket cassette can have a transition sprocket group comprising a sprocket with 21 teeth, hereinafter referred to as "21-T sprocket", and a smaller 18-T sprocket with 18 teeth immediately adjacent to it.

[0044] Preferably, the rear sprocket cassette has exactly one odd-numbered sprocket. This is preferably the aforementioned 21-tooth sprocket.

[0045] A pinion with a number z of teeth is referred to below as a "zT pinion".

[0046] Since the bicycle rear sprocket cassette explained below with the above-mentioned transition sprocket group is an extremely advantageous bicycle rear sprocket cassette even without the previously described bicycle rear sprocket pairing, the present application also relates to a bicycle rear sprocket cassette with a plurality of sprockets, each with a different number of teeth, connected for joint, slip-free rotation around the sprocket axis, wherein the sprocket axis defines an axial direction running along the sprocket axis, a radial direction running orthogonal to the sprocket axis, and a circumferential direction surrounding the sprocket axis, and wherein the rear sprocket cassette has a transition sprocket group comprising a 21-T sprocket and a smaller 18-T sprocket immediately adjacent to the 21-T sprocket. This sprocket cassette can also be further developed as explained below.

[0047] The problem here is that on the odd-numbered 21-T pinion, during engagement with the bicycle chain, the assignment of a pinion tooth to the chain link type it engages changes alternately from revolution to revolution. This means that, without further measures, the chain can be transferred from the 21-T pinion to the 18-T pinion in each of the two relative positions in the chain's longitudinal direction, which are distinguishable with regard to the sequence of chain link types, depending on the number of revolutions during the chain engagement. On the other hand, it can be advantageous to transfer the chain to the 18-T pinion only in a defined orientation with regard to the sequence of chain link types, so that on the 18-T pinion there is a defined assignment of one group of teeth to outer link plate chain links and of the other group of remaining teeth to inner link plate chain links.For example, if the 18-tooth sprocket is the larger sprocket in a sprocket pairing designed as described above, the correct chain orientation on the 18-tooth sprocket is crucial for the correct chain orientation on the immediately adjacent 16-tooth sprocket. This can continue for smaller sprockets.

[0048] A defined transfer of the chain from the 21-T pinion to the 18-T pinion in a desired assignment of outer link chain links to teeth on the 18-T pinion, which are predetermined and / or designed for engagement only with outer link chain links, can be achieved in that the 21-T pinion has at least two upshift areas, each with an upshift depression formation, along a section of its circumference on its end face facing the 18-T pinion. Again, each upshift range is designed and arranged to allow a change in engagement of the bicycle roller chain from the 21-T pinion to the 18-T pinion on the transition pinion group rotating clockwise around the pinion axis - when the transition pinion group is viewed axially in a reference state in which the 18-T pinion is closer to the viewer than the 21-T pinion.On the 21-T pinion, each of the at least two upshift recess formations is assigned exactly one output tooth, which, due to its shape and orientation, is designed, in cooperation with the associated frontal upshift recess formation, to be the last tooth to engage between a pair of plates of a chain link of the bicycle roller chain during an upshift process from the 21-T pinion to the 18-T pinion. An even number of teeth, preferably six teeth, are located between the output teeth of circumferentially adjacent upshift recess formations, not counting the output teeth of the adjacent upshift recess formations.

[0049] The output tooth, in conjunction with its associated upshift groove formation, typically only allows sufficient axial chain movement for shifting the chain from the 21-tooth sprocket to the 18-tooth sprocket if the output tooth is engaged with an outer link plate after the cyclist initiates a shift, for example, by moving the chain guide pulley of a rear derailleur. With the 21-tooth sprocket, this is only the case for the same output tooth every other revolution of the sprocket.

[0050] By providing at least one second output tooth with an even number of intermediate teeth arranged between the two output teeth in the circumferential direction, one of the two output teeth is in engagement with an outer link plate chain link in one and the same revolution of the pinion, which leads to advantageously short latencies.

[0051] Furthermore, by forming only one output tooth per upshift depression formation, which usually represents a structural weakening of the strength of the output tooth compared to other teeth that are not output teeth, the weakening of the 21-T pinion can be limited to a minimum possible level.

[0052] Additionally or alternatively, the 21-tooth pinion can have at least two downshift areas, each with a downshift recess formation, along its circumference on its end face facing the 18-tooth pinion. Each downshift area is again designed to allow a change in engagement of the bicycle roller chain from the 18-tooth pinion to the 21-tooth pinion on the transition pinion group rotating clockwise around the pinion axis—when viewed axially of the transition pinion group in the reference state. Advantageously, on the 21-T pinion, each downshift recess formation is assigned only one catch tooth, which is designed by its shape and orientation, in cooperation with the frontal downshift recess formation assigned to it, to be the first tooth to engage between plates of a chain link of the bicycle roller chain during a downshift process from the 18-T pinion to the 21-T pinion.Thus, a bicycle chain that meshes with the 18-T pinion in a defined assignment of its different chain link types to the teeth on the even-numbered 18-T pinion can be shifted from the 18-T pinion to the 21-T pinion, taking the defined assignment into account. To achieve short latencies, an even number of teeth are located between the catch teeth of circumferentially adjacent downshift groove formations, not counting the catch teeth of the adjacent downshift groove formations.

[0053] Here, too, a catcher tooth on the 21-T sprocket, in conjunction with its associated downshift groove formation, can only engage a bicycle chain that is sufficiently axially close to the 21-T sprocket for engagement if the catcher tooth can engage an outer link of the chain plate. Due to the arrangement described above, this is always the case for one of the two catcher teeth.

[0054] Because, as with the output tooth, only one catch tooth is assigned to each downshift groove formation, the pinion is locally weakened in the area of ​​the downshift groove formation only to the extent necessary. While the additional catch tooth or output tooth positioned away from the first catch tooth or output tooth increases the latency, the weakening of the pinion is locally limited by the formation of the catch tooth or output tooth and distributed over spaced circumferential locations. This increases the wear resistance of the entire pinion. Overall, the slightly increased shift latency is more than compensated for by the increased wear resistance.

[0055] Even shorter shift latencies can be achieved if the 21-T pinion i) has exactly three upshift regions, each with an upshift depression formation and each with exactly one output tooth, wherein an even number of teeth, preferably six teeth, are located between the output teeth of circumferentially adjacent upshift depression formations, wherein the output teeth of the adjacent upshift depression formations are not to be counted, or / and ii) has exactly three downshift regions, each with a downshift depression formation and each with exactly one catch tooth, wherein an even number of teeth, preferably six teeth, are located between the catch teeth of circumferentially adjacent downshift depression formations, wherein the catch teeth of the adjacent downshift depression formations are not to be counted.

[0056] To increase wear resistance, the catch teeth are preferably distributed equidistantly around the circumference of the 21-T pinion and / or the output teeth are distributed equidistantly around the circumference of the 21-T pinion.

[0057] A particularly advantageous synergistic effect is achieved by arranging a catch tooth as the immediate adjacent tooth to a release tooth. The catch tooth is preferably adjacent to the release tooth in a clockwise direction. Since only one catch tooth can actually catch the chain during one sprocket revolution, each tooth that corresponds in its physical design to the tooth actually doing the catching is considered a catch tooth. As already described above, the catch tooth is not only thinner than a regular tooth, but its tooth surface facing away from the smaller sprocket is more closely aligned with the smaller sprocket than with regular teeth on the 21-T sprocket. Thus, such a catch tooth adjacent to the release tooth in a clockwise direction can serve as an upshift mobilization tooth as described above, which offers the chain axial movement space and thus facilitates switching to the 18-T sprocket.

[0058] Likewise, the output tooth, which is therefore adjacent to the catch tooth in the counterclockwise direction and which, due to its function, is also thinner than a regular tooth of the 21-T pinion and whose tooth surface facing away from the smaller pinion is closer to the smaller pinion compared to a regular tooth of a 21-T pinion, can serve the catch tooth as a downshift mobility tooth, which allows the inner plate chain link, which follows the outer plate chain link engaged by the catch tooth in the counterclockwise direction, on the one hand, spatial proximity to the smaller 18-T pinion and on the other hand can mesh in the smaller engagement space of the inner plate chain link.

[0059] Such an arrangement of a pair consisting of an output tooth and a catch tooth immediately adjacent to the output tooth in a clockwise direction ensures a particularly defined shifting behavior both from the 18-T pinion to the 21-T pinion and in the opposite shifting direction. Preferably, more than one pair consisting of such an output tooth and a catch tooth adjacent to the output tooth in a clockwise direction is arranged on the 21-T pinion. For example, two or three such pairs can be arranged on the 21-T pinion.

[0060] Preferably, both the output tooth and the immediately adjacent clockwise catching tooth, which are designed as mobilization teeth, are provided with a ramp on their side facing away from the 18-T pinion, on which ramp a chain plate can be supported by radial engagement. The ramp has a radially outward-facing ramp surface, which is preferably formed by a stepped design of the output tooth and the catching tooth. In order to achieve the stepped design, a radially further outward section of the output tooth and the catching tooth can be thinner than a radially further inward section of the output tooth or catching tooth. The ramp surface, the axial dimension of which is preferably at least 50% of the thickness of an outer plate of the chain link connected to the pinion orThe ramp surface, which interacts with the bicycle chain of the sprocket cassette to provide sufficient support for the chain, can be inclined toward the next largest sprocket adjacent to the 21-T sprocket, with the radial component of the normal vector of the ramp surface being greater in magnitude than its axial component. An opposite inclination of the ramp surface to the 18-T sprocket is possible in principle, but not preferred, since the ramp surface could then form a V-groove with the tooth surface facing away from the 18-T sprocket, in which dirt could accumulate.

[0061] The ramp surface can be a flat surface. To achieve the largest possible contact surface of a chain link plate on the ramp surface and thus the most secure support of the chain radially outward on the ramp, the ramp surface can be designed, at least in sections, to complement a radially inward-facing edge of the chain links, in particular the inner links, of the circulating bicycle chain.

[0062] In order to provide transmission ratios that enable high torque on the rear wheel, i.e. to transmit the chainring rotation on the crankset more strongly than quickly, the transition sprocket group preferably also has a 24-T sprocket, with the 21-T sprocket being arranged axially between the 24-T sprocket and the 18-T sprocket.

[0063] For an advantageous transfer of the bicycle chain from the 21-T pinion to the 24-T pinion with regard to the chain link sequence, so that predetermined teeth of the 24-T pinion are reliably transferred to outer link chain links for meshing engagement, the 24-T pinion can have at least two downshift areas, each with a downshift recess formation, along its circumference on its end face facing the 21-T pinion.

[0064] On the 24-T pinion, each downshift groove formation is assigned to exactly one catch tooth. Its shape and orientation, in conjunction with its associated frontal downshift groove formation, ensure that it is the first tooth to engage between the plates of a chain link of the bicycle roller chain during a downshift from the 21-T pinion to the 24-T pinion. The chain link of the bicycle roller chain that engages with the catch tooth is usually an outer link plate chain link, since, in conjunction with the downshift groove formation, it can be moved axially further into the engagement area of ​​the catch tooth than an inner link plate chain link.

[0065] An odd number of teeth are located between the catch teeth of circumferentially adjacent downshift groove formations, not counting the catch teeth of the adjacent downshift groove formations, so that within one revolution of the 24-T sprocket, regardless of the relative orientation of the chain when leaving the 21-T sprocket, a catch tooth reliably engages an outer link plate chain link. This results in advantageously short shift latencies while simultaneously minimizing structural weakening of the 24-T sprocket.

[0066] Additionally or alternatively, the 24-T pinion may have, in its end face facing the 21-T pinion, along a portion of its circumference, at least two upshift areas, each with an upshift recess formation.

[0067] To increase its wear resistance, only one output tooth is assigned to each of the two upshift recess formations on the 24-T pinion, which, due to its shape and orientation, is designed to be the last tooth to engage between a pair of plates of a chain link of the bicycle roller chain during an upshift process from the 24-T pinion to the 21-T pinion, in cooperation with the frontal upshift recess formation assigned to it.

[0068] To achieve short shift latencies during upshifts, the 24-T pinion preferably has an odd number of teeth between the output teeth of circumferentially adjacent upshift groove formations. The output teeth of the adjacent upshift groove formations are not included in this count.

[0069] Even shorter shift latencies can be achieved in that the 24-T pinion has exactly three upshift areas, each with an upshift depression formation and exactly one output tooth each, wherein an odd number of teeth are located between the output teeth of circumferentially adjacent upshift depression formations, preferably seven teeth for even distribution of the latencies along the pinion circumference, wherein the output teeth of the adjacent upshift depression formations are not counted, or / and that the 24-T pinion has exactly three downshift areas, each with a downshift depression formation and exactly one catch tooth each, wherein an odd number of teeth are located between the catch teeth of circumferentially adjacent downshift depression formations, preferably seven teeth, wherein the catch teeth of the adjacent downshift depression formations are not counted.

[0070] To achieve a clear assignment of pinion teeth to the types of chain links engaged by them on as many pinions as possible, the bicycle rear sprocket cassette has as many even-numbered pinions as possible. Therefore, the sprocket cassette preferably comprises a first set of directly axially adjacent, differently sized pinions, between which the difference in the number of teeth is 2 teeth each. These teeth are preferably formed with orientation formations which only allow engagement of the pinions with the chain in a predetermined orientation of the chain link sequence relative to the pinions. Such orientation formations can comprise at least one thicker tooth described above, which is arranged circumferentially between two thinner teeth and only allows engagement with an outer link chain link.

[0071] This first set is preferably followed by at least one pinion, which has a tooth count difference of 3 teeth from the largest pinion of the first set. So that the bicycle rear sprocket cassette has only a small number of odd-numbered pinions, the cassette preferably comprises a second set of differently sized pinions, of which axially adjacent pinions each have a tooth count difference of 3 teeth. This second set preferably contains an even number of pinions, preferably two pinions. Even-numbered pinions of this second set are preferably again designed with the above-mentioned orientation formations, which allow engagement of the pinions with the chain only in a predetermined orientation of the chain link sequence relative to the pinions.

[0072] The second set can be followed by a third set of even-numbered pinions of different sizes, the smallest pinion of which in the second set and the axially adjacent pinions each having a tooth count difference of 4 teeth. Preferably, each pinion of the third set again has the aforementioned orientation means for aligning the chain relative to the pinions with respect to their chain link sequence.

[0073] A particularly preferred bicycle rear sprocket cassette corresponding to the above criteria is a twelve-speed sprocket cassette with the following tooth number gradation: 10 - 12 - 14 - 16 - 18 - 21 - 24 - 28 - 32 - 38 - 44 - 52. For the reasons stated above, all sprocket pairs with a tooth number of less than 21 are preferably designed as the rear sprocket pairs described above.

[0074] The ramp surface described above in connection with the 21-T sprocket can also be formed on the sprockets of the sprocket cassette with a greater number of teeth than 21, for example on the sprockets located between the chain line and the longitudinal center plane of the bicycle that is orthogonal to the sprocket axis. The above description of the ramp surface also applies to the ramp surfaces preferably formed on sprockets with a greater number of teeth than 21. The ramp surface extends over at least, preferably exactly two adjacent teeth, and forms a radial and axial step on the side of a sprocket facing away from the next smallest sprocket. The two adjacent teeth over which the ramp surface extends are generally not a pair of a release tooth and a catch tooth immediately adjacent to it on sprockets with a greater number of teeth than 21. The formation preferably takes place on at least one mobilization tooth. The catch tooth or catch tooth adjacent to a mobilization tooth provided with a rampThe output tooth can also have a ramp. The ramp of a fang tooth and / or a output tooth is preferably located radially further outward than the ramp of a mobilization tooth immediately adjacent to the fang tooth or output tooth. The largest pinion can also have a ramp surface on its side facing away from the next smallest pinion, or have multiple ramp surfaces distributed along its circumference.

[0075] As described above, the ramp surfaces can support the chain on larger sprockets by engaging the chain plates radially on the outside of the ramp surface, thus preventing the bicycle chain from accidentally shifting to the next smaller sprocket when pedaling backwards and utilizing the normal freewheel function of the sprocket cassette. As the number of teeth increases, the sprockets move increasingly further away from the chain line, so that when the bicycle chain engages with larger sprockets, the bicycle chain becomes increasingly inclined relative to the bicycle's longitudinal center plane, which is orthogonal to the sprocket axis. This chain skew can lead to an unwanted shifting movement of the chain to the next smaller sprocket when pedaling backwards on larger sprockets, which are therefore closer to the bicycle's longitudinal center plane, and thus to a smaller amount of skew. The ramp surface can counteract this.

[0076] On smaller sprockets, with 22 teeth or fewer, shift-assisting ramps can be formed on the tooth surfaces on the side facing the next smallest sprocket. Since these sprockets are usually located axially outside the chain line, individual chain links can be held in place by the chain's skewed running or chain pull on the ramps on the outward-facing tooth surface.

[0077] Preferably, radially inner edges of inner-link chain links facing the pinion axis are supported on such ramps. The ramps have a radially outward-facing support surface. In this case, in interaction with a tooth tip of an axially adjacent smaller pinion that is axially adjacent to a ramp at a distance, both inner plates of one and the same inner-link chain link can be physically supported radially inward when the chain is shifted between the smaller pinion and the larger pinion that carries a ramp on the side facing the smaller pinion. The axially further inward inner plate can be supported by the ramp and the axially further outward inner plate can be supported by the tooth tip, in particular by a radially outward-facing surface of the tooth tip. The support can occur both during downshifting and upshifting.

[0078] However, it is also conceivable that only the inner plate located further axially inwards is supported on a ramp on the side of a pinion facing the smaller pinion, in particular a tooth surface, during a gear shift.

[0079] The present application also relates to a bicycle drive assembly, comprising a bicycle rear wheel pinion pair as described above and / or a bicycle rear wheel pinion cassette as described above, with a bicycle roller chain designed for meshing, power-transmitting engagement with the pinions of the bicycle rear wheel pinion pair or the bicycle rear wheel pinion cassette, wherein the bicycle roller chain has a plurality of chain rollers arranged one after the other at a pitch distance and connected to one another by pairs of parallel plates, wherein the bicycle roller chain has, in the chain circumferential direction, alternating inner plate pairs with a smaller plate spacing and outer plate pairs with a larger plate spacing.

[0080] The bicycle drivetrain assembly may have a single chainring in the crank area, so that any change in transmission ratio from the front chainring to the rear sprocket cassette is achieved only by changing the chain engagement with one of the sprockets of the sprocket cassette.

[0081] For engagement with the above-preferred twelve-speed sprocket cassette, a bicycle chain is preferred whose chain plates have a straight edge section on the radially outer edge between the two chain roller axes connected by a chain plate, and whose chain plates have a curved edge line on the radially inner edge such that the plate height, measured orthogonally to the chain roller axis and orthogonally to the chain rotation direction, is lower in an area between the chain roller axes than in the area of ​​the chain roller axes. This results in a narrow yet sufficiently tensile bicycle chain.

[0082] To achieve a fast, precise shifting process with minimal axial play of the bicycle chain in a shifting section between the currently chain-guiding pinion and the future chain-guiding pinion, it is preferred for at least one bicycle rear wheel pinion pairing, more preferably for several bicycle rear wheel pinion pairings, that during a shifting process in which the bicycle roller chain is shifted from one pinion to a pinion axially adjacent to it, exactly one inner plate chain link is located in the shifting section between the last chain link that is in engagement with the still chain-guiding pinion and the first chain link that is or is in engagement with the future chain-guiding pinion. Preferably, only exactly one inner plate chain link is located in the shifting section.Although it should not be excluded that this reversal condition can also apply to pinion pairs with a tooth spacing of more than two teeth between the larger and smaller pinion, the reversal condition applies particularly to pinions with a tooth number difference of two teeth.

[0083] The present invention is explained in more detail below with reference to the accompanying drawings. It shows: Fig. 1a bicycle rear wheel sprocket cassette according to the invention when viewed along the sprocket axis, with increasingly larger sprockets being arranged with increasing distance from the viewer, Fig. 1Athe sprocket cassette of Figure 1 with view orthogonal to the pinion axis, Fig. 1B the pinion cassette of Figure 1 with opposite viewing direction away from the longitudinal center plane, Fig. 2A a first bicycle rear wheel pinion pairing according to the invention of the pinion cassette of the Figures 1 to 1Bwith a smaller pinion with 10 teeth and a larger pinion with 12 teeth when viewed as a reference, Fig. 2B the bicycle rear wheel pinion pairing of Figure 2A viewed in the opposite direction, Fig. 3A a second bicycle rear wheel pinion pairing according to the invention of the pinion cassette of the Figures 1 to 1B with a smaller pinion with 12 teeth and a larger pinion with 14 teeth when viewed as a reference, Fig. 3B the bicycle rear wheel pinion pairing of Figure 3A viewed in the opposite direction, Fig. 4A shows a third bicycle rear wheel pinion pairing according to the invention of the pinion cassette of the Figures 1 to 1B with a smaller pinion with 14 teeth and a larger pinion with 16 teeth when viewed as a reference, Fig. 4B the bicycle rear wheel pinion pairing of Figure 4A viewed in the opposite direction, Fig. 4C the third bicycle rear wheel sprocket pairing according to the invention of the sprocket cassette of Fig. 4Awhen shifting a bicycle chain from the 14-T pinion to the 16-T pinion, when viewed as a reference, Fig. 4D the bicycle rear wheel pinion pairing of Figure 4C viewed in the opposite direction, Fig. 4E the third bicycle rear wheel sprocket pairing according to the invention of the sprocket cassette of Fig. 4A when shifting a bicycle chain from the 16-T pinion to the 14-T pinion, when viewed as a reference, Fig. 4F the bicycle rear wheel pinion pairing of Figure 4E viewed in the opposite direction, Fig. 5A a fourth bicycle rear wheel pinion pairing according to the invention of the pinion cassette of the Figures 1 to 1B with a smaller pinion with 16 teeth and a larger pinion with 18 teeth when viewed as a reference, Fig. 5B the bicycle rear wheel pinion pairing of Figure 5A viewed in the opposite direction, Fig. 6 a bicycle rear wheel sprocket pairing of the sprocket cassette of the Figures 1 to 1Bwith a smaller pinion with 18 teeth and with a larger pinion with 21 teeth when viewed as a reference, whereby the rear wheel pinion pairing belongs to a transitional pinion group with a total of three pinions, Fig. 7 a bicycle rear wheel pinion pairing of the pinion cassette of the Figures 1 to 1B with a smaller pinion with 21 teeth and with a larger pinion with 24 teeth when viewed as a reference, whereby the rear wheel pinion pairing belongs to the transitional pinion group with a total of three pinions, Fig. 8 the bicycle rear wheel pinion pairing of Figure 7 with a bicycle chain, which is engaged with the larger pinion and shifted down to the smaller pinion, Fig. 9 a bicycle rear wheel pinion pairing of the pinion cassette of the Figures 1 to 1B with a smaller pinion with 24 teeth and a larger pinion with 28 teeth, Fig. 10the largest pinion of the pinion cassette of the Figures 1 to 1B when viewed in reference, Fig. 10Athe pinion of Figure 10with a viewing direction orthogonal to the pinion axis, Fig. 10B the pinion of Figure 10 when viewed along the pinion axis looking away from the longitudinal center plane, and Fig. 11a with the pinion cassette of the Figures 1 to 1B equipped bicycle.

[0084] In Figure 1 is a preferred embodiment of the invention of a bicycle rear wheel sprocket cassette with twelve coaxial, slip-free for common rotation about the axis perpendicular to the plane of the drawing of Figure 1 orthogonal pinion axis R interconnected pinions generally designated 1.

[0085] The consideration of the sprocket cassette 1 in Figure 1 corresponds to the reference view described in the introduction to the description, ie looking along the pinion axis R, with the smallest pinion facing the observer from Figure 1 is closest and the largest pinion in the viewer of Figure 1 is the furthest away.

[0086] The number of teeth of the sprocket cassette 1 from Figure 1 is: 10 - 12 - 14 - 16 - 18 - 21 - 24 - 28 - 32 - 38 - 44 - 52. The pinion cassette 1 therefore comprises a smallest pinion 10 with ten teeth, a pinion 12 with 12 teeth axially adjacent to this, a next larger pinion 14 with 14 teeth, a next larger pinion 16 with 16 teeth, and a pinion 18 with 18 teeth axially adjacent to this.

[0087] The next largest pinion, 20, adjacent to pinion 18, is a transition pinion with 21 teeth. This is followed by a pinion 22 with 24 teeth, a pinion 24 with 28 teeth, a pinion 26 with 32 teeth, a pinion 28 with 38 teeth, a pinion 30 with 44 teeth, and finally, the largest pinion, a pinion 32 with 52 teeth.

[0088] Of these pinions 10 to 32, the immediately adjacent pinion pairs of pinions 10 to 18 each form a bicycle rear wheel pinion pairing according to the invention as described above.

[0089] Pinions 12 to 16 each represent two pinions in a pair of pinions: one as the smaller pinion of the pair of pinions and one as the larger pinion of the pair of pinions. Pinions 10 and 12 form a bicycle rear wheel pinion pair 11, pinions 12 and 14 form a bicycle rear wheel pinion pair 13, pinions 14 and 16 form a bicycle rear wheel pinion pair 15, and pinions 16 and 18 form a bicycle rear wheel pinion pair 17.

[0090] The two pinions 18 and 22 axially adjacent to the only odd-numbered transition pinion 20 in the pinion cassette 1 form, together with the transition pinion 20, a transition pinion group 19.

[0091] To facilitate shifting operations between axially adjacent pinions, the pinions, with the exception of the smallest pinion 10, each have at least one upshift region 34 with an upshift recess formation 36 and an output tooth 38 and each have at least one downshift region 40 with a downshift recess formation 42 and a catch tooth 44.

[0092] For better clarity, Figure 1 only the largest pinion 32 with 52 teeth is provided with reference numerals for the upshift range 34 with the upshift recess formation 36 and the output tooth 38 and for the downshift range 40 with the downshift recess formation 42 and the catch tooth 44.

[0093] The ranges: upshift range 34 and downshift range 40, always refer to the pinion on which the ranges are formed. This means that the upshift range 34 facilitates shifting a bicycle chain from the pinion carrying the upshift range 34 to the axially adjacent, next smaller pinion, and the downshift range 40 facilitates shifting the bicycle chain from the next smaller pinion to the pinion carrying the downshift range 40.

[0094] The recess formations 36 and 42 allow the bicycle chain to move axially closer to the pinion bearing the respective recess formations, since outer link plates, in particular, can engage the recess formations designed as axial front-end recesses. Without the formation of recess formations at these locations, the outer link plates of the bicycle chain would collide with the front face of the pinion, which would limit the bicycle chain's axial approach to the front face bearing the recess formations.

[0095] The recess formations 36 and 42 can have a plurality of different surface facets, which can have a different position relative to the pinion axis R and / or a different inclination relative to one another. This makes it possible to ensure that the bicycle chain can only penetrate into the recess formations 36 or 42 with a predetermined relative position with respect to its outer plates and inner plates, and is axially repelled by a surface facet when the relative position is offset by one chain pitch in the chain's circumferential direction. The surface facet can be designed such that it can penetrate into the space between two outer plates that follow one another in the chain's circumferential direction toward an inner plate located between the outer plates, but physically axially repel an outer plate located between two inner plates from the pinion that carries it.

[0096] When viewed in reference to the rear wheel cassette 1, the catching teeth 44 of the individual pinions of the rear wheel cassette 1 are located on a spiral 45 rotating counterclockwise radially outwards.

[0097] In Figure 1A The pinion cassette 1 is shown viewed orthogonally to the pinion axis R. For clarification, the previously mentioned longitudinal center plane LME of the bicycle carrying the pinion cassette 1, which is orthogonal to the pinion axis R, is shown in dashed lines. The actual distance between the longitudinal center plane LME and the pinion cassette 1 is greater than in the abbreviated representation of Figure 1A .

[0098] The pinions 10 to 30 are preferably formed in one piece as a so-called pinion dome, for example, by machining from solid material. Alternatively, the two smallest pinions 10 and 12 can be formed as individual pinions. The two smallest pinions 10 and 12 can then be connected to the pinion dome of the pinions 14 to 30 via a grooved nut. The largest pinion 32 is formed as a single pinion. The pinion dome can be connected in a conventional manner with pins or rivets or by a material bond to the struts of the pinion 32 for torque transmission.

[0099] The axial distance between the directly adjacent pinions is generally smaller than the tooth height of a regular-shaped pinion tooth. The small axial distance between the individual pinions requires a very narrow chain and an extremely precise design of the toothed circumferential areas of the individual pinions.

[0100] Figure 1B shows the pinion cassette 1 from the inside, i.e. viewed from the longitudinal center plane LME along the pinion axis R. Where the smaller pinions can be seen through the passages formed between the struts of the largest pinion 32, they are designated by reference numerals. Otherwise, for a further description of the largest pinion, please refer to the explanation below of the Figures 10 to 10B referred to.

[0101] Figure 2A shows the smallest bicycle rear wheel pinion pair 11 of the pinion cassette 1 in reference view. Figure 2B shows the same bicycle rear wheel pinion pair 11 viewed axially, but "from the inside", i.e. in such a way that the larger pinion 12 is visible to the viewer from Figure 2B is closer than the smaller pinion 10.

[0102] The smaller pinion 10 is preferably designed as a synchronization pinion with thicker teeth 10a and thinner teeth 10b. The axial thickness of the thicker teeth 10a is selected such that they only fit into the engagement space of an outer plate chain link, but are thicker than the distance between two parallel inner plates of an inner plate chain link. Therefore, with respect to its sequence of chain link types alternating along the chain's rotational direction, a bicycle chain can only mesh with the pinion 10 in exactly one relative orientation, namely when outer plate chain links are assigned to the thicker teeth 10a. Due to the even number of chain links in one bicycle chain revolution and the even number of teeth on the pinion 10, once a tooth has been assigned to a chain link type, this assignment remains unchanged for the entire engagement period of the pinion 10 with the chain, across all pinion revolutions.A tooth 10c of the smallest pinion 10 has a rounded and thus radially shortened tooth head in order to facilitate the transfer of the bicycle chain from the pinion 10 to the axially adjacent next larger pinion 12 and to avoid a collision of the chain with the tooth 10c.

[0103] On the larger pinion 12 of the pinion pair 11, exactly one upshift range 34 is formed with exactly one upshift depression formation 36 and exactly one output tooth 38 directly adjacent to the upshift depression formation 36 in a clockwise direction. The output tooth 38 is the first tooth in a clockwise direction whose tooth surface facing the smaller pinion 10 is not altered by the upshift depression formation 36. The output tooth 38 is therefore the first tooth in a clockwise direction to which the upshift depression formation 36 no longer extends. Furthermore, exactly one downshift range 40 is formed on the larger pinion 12, which has a greater distance from the upshift range 34 in a counterclockwise direction than in a clockwise direction.The single downshift recess 42 no longer extends counterclockwise to the single catching tooth 38, which is consequently the first tooth that no longer changes in shape from the downshift recess 42 and follows the downshift recess 42 in the counterclockwise direction.

[0104] The arrow D running in the circumferential direction shows the drive rotation direction of the pinion pair 11 in drive operation at the Figure 11 shown bicycle 70.

[0105] As you can see on the back view of the pinion 12 of Figure 2BAs can be seen, the pinion 12 also has thicker teeth 12a and thinner teeth 12b, of which the thicker teeth 12a, due to their thickness, can only mesh with outer link plate chain links. The distance between two parallel inner links of an inner link plate chain link is smaller than the thickness of the teeth 12a. Consequently, the bicycle chain can only rotate on the larger pinion 12 in a specific relative position, namely when each of the teeth 12a is assigned an outer link plate chain link.

[0106] By using only one output tooth 38 and only one catch tooth 44, a directed transfer of the bicycle chain can be ensured with the relative position between the pinions 10 and 12 required for meshing engagement with the respective pinion 10 or 12. Only one tooth needs to be weakened for each shifting direction, resulting in a larger, wear-resistant pinion 12.

[0107] The arrangement of the catch tooth 44 and the output tooth 38 along the circumference of the larger pinion 12 in the form shown has a further wear-reducing effect on the second-smallest pinion 12 of the cassette 1, because the upshift range 34 and the downshift range 40 merge into one another, which means a weakening of a very small number of teeth due to the recessed formations 36 and 42. Thus, many teeth can be designed with the largest possible load flanks, which gives them good load-bearing capacity. With increasing load-bearing capacity of the pinion 12, its tendency to wear decreases compared to a lower load-bearing capacity of the pinion 12. Starting from the catch tooth 44, three teeth of the larger pinion 12 of the pinion pair 11 lie clockwise between the catch tooth 44 and the output tooth 38 in the illustrated embodiment.

[0108] Starting from the output tooth 38, there are seven teeth of the larger pinion 12 between the output tooth 38 and the catch tooth 44; this corresponds to the number of teeth on pinion 12 minus 5. It has been shown that, starting from the output tooth 38, the greatest possible distance between the catch tooth 44 in a clockwise direction and the output tooth 38 leads to a favorable wear pattern on the pinion 12 during operation, particularly when the bicycle equipped with the pinion cassette 1 is powered by an electric motor and thus, compared to a drive by pure muscle power, a higher torque is permanently transmitted to the smaller pinions of the pinion cassette 1. In the example shown, these smaller pinions are pinions 10 to 18.

[0109] On the middle tooth of the three teeth located clockwise between the catch tooth 44 and the output tooth 38, a deflection surface 12d is formed, which is part of both the downshift recess formation 42 and the upshift recess formation 36. The deflection surface 12d, which is recessed relative to the end face of the pinion 12, but raised and axially protruding relative to its circumferentially adjacent recessed section, is designed to engage in the space between two outer plates. If, for whatever reason, an outer plate is located at the location of the deflection surface 12d during the shifting process, the chain is physically prevented from axially approaching the end face of the pinion 12, which is necessary for shifting the chain, by the outer plate contacting the deflection surface 12d, and the chain is thus deflected.

[0110] When shifting the chain down from pinion 10 to pinion 12, a radially inward-pointing inner edge 54c (see Fig. 8 ) of an inner plate of an inner plate chain link 54 (see Fig. 8 ) physically supported on a radially outwardly facing head surface 10cf of the tooth 10c. The inner edge 54c is between the chain roller axes 55 (see Fig. 8 ) is concavely shaped. For the most flat and secure support possible, the head surface 10cf is therefore convexly shaped, with the leading end of the head surface 10cf in the drive direction of rotation D being located radially further inward than the trailing end of the head surface 10cf. Preferably, the convex shape of the head surface 10cf is complementary to the concave inner edge 54c of the chain 50.

[0111] The pinion pair 11 has a special feature here: the tooth of the pinion 12 located behind the tooth 10c when viewed in reference has a deflection surface 12h on its tooth surface facing the smaller pinion 10, which is part of the downshift recess 42 of the downshift area 40. An inner link plate chain link can pass this deflection surface 12h on the side of the pinion 12 facing the smaller pinion 10 toward the catch tooth 44 of the pinion 12, but an outer link plate chain link cannot.

[0112] The deflection surface 12h ends radially inward at a ramp 12c1, which has a radially outward-pointing, preferably also convexly curved support surface, which projects axially relative to the deflection surface 12h.

[0113] When shifting down from pinion 10 to pinion 12, an inner-link chain link can therefore be supported by its two inner plates on the pinion pair, namely with the axially outer inner plate on the head surface 10cf and with the inner inner plate on the ramp 12c1. This allows the chain to be well guided in the shifting section. The chain skew when the chain engages with pinions 10 and 12 located axially outside the chain line supports the contact of the inner plate on the deflection surface 12h and on the ramp 12c1, because on pinions located outside the chain line, the chain skew causes a force on the engaging pinion axially inward.

[0114] The Figures 3A and 3B show the bicycle rear wheel pinion pairing 13 with the already from the Figures 2A and 2B known pinion 12, this time as a smaller pinion of pairing 13, and with pinion 14 as a larger pinion. Figure 3Ashows the bicycle rear wheel pinion pair 13 when viewed from the outside, Figure 3B shows the bicycle rear wheel pinion pair 13 viewed axially in the opposite direction, i.e. from the inside.

[0115] On the larger pinion 14 of the pinion pair 13, the same types of teeth or tooth surfaces are designated with the same lower case letters as on the pinion 12. To increase its wear resistance, the pinion pair 13 also has only exactly one upshift area 34 with exactly one upshift recess formation 36 and exactly one output tooth 38.The upshift recess formation 36 of the pinion 14 in turn has surface facets, which are all arranged axially recessed relative to the end face of the pinion 14, but can be recessed to different degrees and / or can be inclined relative to one another, for example to allow an inclination of the chain about its chain longitudinal direction and thus to incline an insertion opening located radially on the inside of the chain into an engagement space of an outer plate chain link about the chain longitudinal direction towards the tooth head of the catch tooth 44 or to be able to incline the chain, which is still engaged on the output tooth 38, about the chain longitudinal direction on the output tooth towards the smaller pinion 12.

[0116] Starting from the catch tooth 44, there are five teeth in a clockwise direction between the catch tooth 44 and the output tooth 38 of the pinion 14, of which the middle tooth has a deflection surface 14d on its tooth surface facing the smaller pinion 12. This has the same function as previously described for the deflection surface 12d on the smaller pinion 12.

[0117] Starting from the output tooth 38, there are seven teeth between the output tooth 38 and the catch tooth 44 of the pinion 14. These teeth can be designed as conventional teeth 14a and 14b. The teeth 14a can again be thicker than the teeth 14b, advantageously with a thickness that exceeds the clear width of the engagement space between two parallel inner plates of an inner-link chain link. The number of teeth located clockwise between the output tooth 38 and the catch tooth 44 of the pinion 14 corresponds to the number of teeth on the pinion 14 minus 7.

[0118] In the rear view from inside the pinion 14 in Figure 3B you can see that the Figure 3A the thin tooth 14b following the output tooth 38 in a clockwise direction has a recessed surface 14e on its tooth surface facing away from the smaller pinion 12, which recessed surface forms this special thin tooth 14b as a mobilization tooth 14b' of an upshift process, which allows an inner plate chain link of a bicycle chain engaged by it more axial movement play than an ordinary thin tooth 14b.

[0119] Likewise, one can see in Figure 3B that the Figure 3Athe thin tooth 14b adjacent to the catch tooth 44 in the counterclockwise direction has a recessed surface 14f on its tooth surface facing away from the smaller pinion 12, which recessed surface forms this special thin tooth 14b as a mobilization tooth 14b" of a downshift process, which allows an inner plate chain link engaged by it more axial movement play than an ordinary thin tooth 14b.

[0120] The upshift mobilization tooth 14b' thus supports the upshift process by allowing the bicycle chain some movement. The downshift mobilization tooth 14b" supports the downshift process.

[0121] Starting from the output tooth 38, there are five teeth between the output tooth 38 and the catch tooth 44 of the pinion 14.

[0122] The tooth adjacent to the catching tooth 44 of the pinion 14 in a clockwise direction in turn has a deflection surface 14h which is delimited radially inwardly by a ramp 14c1 with a radially outwardly facing support surface for the physical support of an inner plate of an inner plate chain link during downshifting.

[0123] The tooth adjacent to the output tooth 38 of the pinion 14 in the counterclockwise direction has a deflection surface 14i, which is delimited radially inward by a ramp 14c2 with a radially outward-facing support surface for physically supporting an inner plate of an inner-plate chain link when upshifting from the pinion 12 to the pinion 14. Like the deflection surface 14h in the downshift range 40, the deflection surface 14i in the upshift range 34 allows an inner-plate chain link to pass when upshifting to the pinion 14, but not an outer-plate chain link of the bicycle chain. The ramp 14c2 with its radially outward-facing support surface is preferably convexly shaped, corresponding to the concave shape of an inner plate 54c, in order to enable the inner plate to bear as flatly as possible.

[0124] In the Figures 4A and 4B the bicycle rear wheel pinion pair 15 with the pinions 16 and 14 is shown, namely in Figure 4Ain reference and in Figure 4B viewed in the opposite direction, i.e., from the inside. The pinion 14 of the bicycle rear wheel pinion pair 15 is the pinion 14 of the previously discussed rear wheel pinion pair 13. The same lowercase letters following the reference number 16 of the pinion 16 designate functionally equivalent components or component sections of the pinion 14 or the pinion 12, which are designated there with the same lowercase letters.

[0125] Like the two rear wheel pinion pairs 11 and 13 above, the larger pinion 16 of the rear wheel pinion pair 15 also has exactly one upshift range 34 with exactly one upshift recess formation 36 and exactly one output tooth 38. Furthermore, the larger pinion 16 has exactly one downshift range 40 with exactly one downshift recess formation 42 and exactly one catch tooth 44.

[0126] Starting from the catching tooth 44, there are five teeth between the catching tooth 44 and the output tooth 38 in a clockwise direction, the middle of the five teeth having a deflection surface 16d, which has already been explained in connection with the previously described pinions 12 and 14.

[0127] Starting from the output tooth 38, there are nine teeth between the output tooth 38 and the catch tooth 44 in a clockwise direction, which are designed alternately as thick teeth 16a and thin teeth 16b for the clear orientation of the bicycle chain relative to the pinion 16 in the circumferential direction. The thin tooth 16b' adjacent to the output tooth 38 in a clockwise direction is a mobilization tooth for an upshift to the smaller pinion 14. The thin tooth 16b" adjacent to the catch tooth 44 in a counterclockwise direction is a mobilization tooth for a downshift from the smaller pinion 14 to the larger pinion 16. Figure 4Bthe corresponding recess surfaces 16e of the mobilization tooth 16b' and 16f of the mobilization tooth 16b" are shown.

[0128] The number of teeth in a clockwise direction between the output tooth 38 and the catch tooth 44 corresponds to the number of teeth on the pinion 16 minus 7.

[0129] It is noteworthy that the mobilization tooth 14b" of the pinion 14 with a convex head surface 14cf is axially adjacent to the tooth with the deflection surface 16h and with the support ramp 16c1 delimiting this deflection surface 16h, so that even when the chain is shifted down from the pinion 14 to the pinion 16, an inner plate chain link 52 passing axially outwards past the deflection surface 16h can be physically supported with its two inner plates on its radially inner edge 52c, the axially outer inner plate on the head surface 14cf and the axially inner inner plate on the ramp 16c1.

[0130] In Figure 4CIn reference view, a downshifting process of a bicycle chain 50 from pinion 14 to the larger pinion 16 is shown. The catch tooth 44 of pinion 16 has already caught the chain 50, or more precisely, an outer link plate link 54 of the same. The next outer link plate link 54 in the drive direction is still engaged with pinion 14. In the shifting path between pinions 14 and 16, there is only one inner link plate link 52, which is not engaged with either pinion 14 or 16 during the shifting process.

[0131] Figure 4D shows the switching process of Figure 4C in the opposite direction, i.e. from the axial inside.

[0132] In Figure 4EIn reference view, an upshift of a bicycle chain 50 from pinion 16 to the larger pinion 14 is shown. The output tooth 38 of pinion 16 is still engaged with the chain 50, more precisely with an outer link plate link 54 thereof. The next outer link plate link 54 opposite the drive direction of rotation is already engaged by a tooth of pinion 14. In the shifting path between pinions 16 and 14, there is only exactly one inner link plate link 52, which is not engaged with either pinion 14 or 16 during the shifting process.

[0133] Figure 4F shows the switching process of Figure 4E in the opposite direction, i.e. from the axial inside.

[0134] In the Figures 5A and 5B is in accordance with the previous Figures 3A and 3B 4A and 4B respectively, the largest and last bicycle rear wheel pinion pair 17 according to the invention is shown, namely in Figure 5A in reference and in Figure 5Bviewed from the inside in the opposite axial direction.

[0135] The same lower case letters after the reference number 18 of the pinion 18 designate functionally identical components or component sections of the pinions 12, 14 or 16, which are designated there with the same lower case letters.

[0136] Like the previously discussed rear sprocket pairs 11, 13, and 15, the rear sprocket pair 17 on the larger sprocket 18 also has only one upshift range 34 with exactly one upshift recess formation 36 and with exactly one output tooth 38. The larger sprocket 18 also has only one downshift range 40 with exactly one downshift recess formation 42 and with exactly one catch tooth 44.

[0137] On the larger pinion 18, which is particularly advantageous for the wear resistance of the pinion 18, there are only three teeth, starting from the catch tooth 44 in a clockwise direction between the catch tooth 44 and the output tooth 38. Starting from the output tooth 38, there are 13 teeth in a clockwise direction between the output tooth 38 and the catch tooth 44, which corresponds to the number of teeth on pinion 18 minus 5.

[0138] Of the 13 teeth located clockwise between the output tooth 38 and the catch tooth 44, the teeth immediately adjacent to the output tooth 38 and the catch tooth 44 are designed as mobilization teeth 18b' and 18b" respectively, as described above. The remaining teeth are designed as thick teeth 18a and thin teeth 18b for secure guidance of the chain on the pinion 18 during meshing engagement, as described above.

[0139] Even when downshifting from pinion 16 to pinion 18, an inner-link chain link can be supported with its two inner plates once on the head surface 16cf and once on the ramp 18c1. Clockwise in front of the catch tooth 44 of pinion 18, the tooth gap 43 is enlarged radially inward to provide radial inward movement space for the chain roller immediately preceding the catch tooth 44 when downshifting to pinion 18.

[0140] The previously described sprocket pairs 11, 13, 15 and 17 can each only upshift from the larger sprocket to the axially adjacent next smaller sprocket in the upshift range 36. This means that on each larger sprocket of the aforementioned sprocket pairs 11, 13, 15 and 17, the chain is only shifted from the larger sprocket to the next smaller one at exactly one point, and in such a way that the respective output tooth 38 is the last tooth of the larger sprocket that is still in mesh with the chain. Due to the drive rotation direction D shown, chain links following the output tooth 38 slide laterally past the teeth adjacent to the output tooth 38 in a counterclockwise direction, thereby utilizing the respective upshift recess formation 36 as a movement space.

[0141] Likewise, on the aforementioned sprocket pairs 11, 13, 15, and 17, the chain can only be shifted from the smaller to the larger sprocket at one point each, and always only in such a way that the catch tooth 44 of the larger sprocket is the first tooth of the larger sprocket that engages between two plates, usually outer plates, of a chain link. The chain links adjacent to the catch tooth 44 in a clockwise direction approach the larger sprocket by utilizing the downshift recess formation 42, so that the outer plate chain link assigned to the catch tooth 44 can axially move into its engagement area.

[0142] If the cyclist issues the shift command in such a way that the relevant shift tooth on the larger, clockwise-rotating sprocket—output tooth 38 or catch tooth 44—has just passed the shifting range on the rear wheel, the initiated shifting process takes place in the next sprocket revolution when the output tooth 38 or catch tooth 44 returns to the angular range or shifting range relevant for executing a shift relative to the front derailleur. The shifting latency for both downshifting and upshifting on sprocket pairs 11, 13, 15, and 17 is a maximum of one sprocket revolution, which is usually tolerated by cyclists. Experience has shown that higher shifting latencies are no longer tolerated and are perceived as a malfunction.

[0143] The pinion 18 is the smallest of three pinions 18, 20 and 22 of a transition pinion group 19, which, with pinion 20, has the only odd-numbered pinion of the rear wheel cassette 1.

[0144] In Figure 6 The smaller pinion pairing of pinions 20 and 18 of the transition pinion group 19 is shown in reference view.

[0145] The same lower case letters after the reference number 20 of the pinion 20 designate functionally identical components or component sections of the pinions 12, 14, 16 or 18, which are designated there with the same lower case letters.

[0146] One problem is that each tooth of the even-numbered pinion 18 is assigned the same type of chain link for engagement between the respective plates of the respective chain link for the entire duration of the meshing engagement of the pinion 18 with the bicycle chain.

[0147] However, on the odd-numbered pinion 20 with 21 teeth, the type of chain link assigned to a tooth for positive engagement changes with each revolution. Nevertheless, the chain should be transferred from the odd-numbered pinion 20 in a defined manner, with regard to the relative position of the chain link sequence, both during upshifts to pinion 18 and during downshifts to pinion 22. On the even-numbered pinions 20 and 22, it should not be randomly determined whether a tooth engages an outer link plate chain link or an inner link plate chain link; rather, a defined chain transfer should be ensured by the appropriate design of the transition pinion group 19.

[0148] For this purpose, the transition pinion 20 has three identical circumferential sections, each with seven teeth, which successively form the entire circumference of the transition pinion 20. In turn, each of the three circumferential sections has exactly one output tooth 38 and exactly one catch tooth 44. Likewise, each of the three circumferential sections has exactly one upshift area 34 with exactly one upshift recess formation 36 and exactly one downshift area 40 with exactly one downshift recess formation 36. By arranging the three circumferential sections next to each other, the shift latency of the transition pinion 20 is very short. Between the catch tooth 44 and the output tooth 38, there are five teeth on the pinion 20 in a clockwise direction. Between two output teeth 38, or between two catch teeth 44, there are six teeth in the circumferential direction of the pinion 20.Thus, when an inner link plate is undesirably brought closer to a catch tooth 44 of the pinion 20 during a downshift from the pinion 18, for whatever reason, and therefore there is no positive engagement of the catch tooth 44 with the bicycle chain, an outer link plate and thus an outer link plate chain link is brought closer to the catch tooth 44 of the pinion 20 which is next in the counterclockwise direction, utilizing the movement space provided by the downshift recess formation 42, which the catch tooth 44 can catch.

[0149] The same applies mutatis mutandis to the upshift process and the output tooth 38 of pinion 20. If, immediately after the cyclist initiates the upshift process, an inner link plate chain link is in positive engagement with the output tooth 38, the bicycle chain remains on pinion 20 until the next output tooth 38 engages an outer link plate chain link in a counterclockwise direction, and the bicycle chain can then be shifted to the smaller pinion 18, utilizing the movement space provided by the upshift recess formation 36.

[0150] The catching tooth 44 and the output tooth 38 are extremely advantageously arranged such that, when the three identical circumferential sections are arranged side by side, the output tooth 38 and the catching tooth 44 are immediate neighbors. Since the teeth 38 and 44 are specially designed as output teeth and catching teeth, respectively, and generally have a smaller thickness and a close axial proximity to the adjacent smaller pinion 18, the teeth 38 and 44 not only function as output teeth 38 and catching tooth 44, but the output tooth 38 forms a mobilization tooth 20b" for the catching tooth 44, and the catching tooth 44 forms a mobilization tooth 20b' for the output tooth 38.

[0151] Due to this dual function of the delivery tooth 38 and the catching tooth 44, each also as a mobilization tooth 20b" or 20b', no additional structural tooth weakening by forming separate mobilization teeth is required despite the juxtaposition of three circumferential sections, each with at least two modified and thus weakened teeth 38 and 44, which overall leads to a stable and wear-resistant transition pinion 20.

[0152] In Figure 7 For reference purposes, the larger pinion pairing of the transition pinion group 19 with the 24-T pinion 22 and the 21-T pinion 20 is shown.

[0153] Here, too, it is important to shift the bicycle chain from the odd-numbered pinion 20 with a clear relative arrangement of the chain link sequence to the larger pinion 22.

[0154] The same lower case letters after the reference number 22 of the pinion 22 designate functionally identical components or component sections of the pinions 12, 14, 16, 18 or 20, which are designated there with the same lower case letters.

[0155] The 24-T pinion 22 also has three identical circumferential sections, which successively form the complete circumference of the pinion 22. Each circumferential section therefore has eight teeth. Figure 7 For the sake of simplicity, only exactly one circumferential section of the pinion 22 is provided with reference numerals.

[0156] Clockwise at the outermost end of the circumferential section is the mobilization tooth 22b' for the counterclockwise adjacent output tooth 38. Further counterclockwise, the output tooth 38 is followed by three teeth on which the upshift recess formation 36 and the downshift recess formation 42 are formed, wherein a deflection surface 22d is formed on the middle tooth of the three teeth.

[0157] The three teeth are followed in a counterclockwise direction by the catch tooth 44, which in turn is adjacent to its mobilization tooth 22b" in a counterclockwise direction. In a counterclockwise direction at the outermost end of the circumferential section there is a regular tooth of the pinion 22, which is designed, for example, as a thick tooth 22a in such a way that it can only engage with an outer link plate chain link.

[0158] Although mobilization teeth 22b' and 22b" are formed here in addition to a release tooth 38 and a catch tooth 44, both recess formations 36 and 42 for downshifting and upshifting are formed in a space of only three teeth, so that overall a moderate structural weakening is realized by material removal on the pinion 22 and the pinion 22 as a whole has a high stability and wear resistance. The larger a pinion is, the less significant the formation of recess formations and the like are as a structural weakening of the strength of the pinion.

[0159] Although the unknown rotational speed of pinion 20 means that the relative position of the bicycle chain in relation to the chain link sequence is unknown, the catch tooth 44 that an outer link plate chain link approaches will catch the chain through positive engagement with the chain link, thus ensuring a downshift. This is at the latest the second catch tooth 44, which reaches a relevant shifting range relative to the front derailleur that initiates the shifting process.

[0160] Likewise, the chain is transferred to the smaller pinion 20 by only one tooth per circumferential section of the pinion 22, namely the output tooth 38 as the last engaging tooth. Since the output tooth 38 on the pinion 22 is always assigned an outer link plate chain link, an upshift takes place from the pinion 22 to the pinion 20 closest to the output tooth 38 passing the shifting area of ​​the front derailleur. This results in a very short shifting latency of only one-third of a revolution and, due to the design of only one tooth as the output tooth 38 per circumferential section, the smallest possible weakening of the pinion 22.

[0161] The radially inner base of the tooth gap 43, which is immediately adjacent to the catch tooth 44 in a clockwise direction, is located radially closer to the pinion axis R than the tooth bases of the other tooth gaps. Due to the radially inward movement path thus provided for a chain roller, the shifting path taken by the bicycle chain when shifting from the smaller pinion 20 to the larger pinion 22 can be adjusted so that its length is an integer multiple of the chain pitch. This is a prerequisite for a shifting process between two pinions.

[0162] At the pinion pair 19, it is also possible to support both inner plates of an inner-plate chain link when shifting up from pinion 22 to pinion 20, namely for the axially further outward inner plate on the head surface 20ci and for the axially further inward inner plate on the ramp 22c2, which radially delimits the deflection surface 22i. The head surface 20ci is convex to provide the most extensive possible support for a concave inner edge 54c of an inner plate, although the end of the head surface 20ci leading in the drive direction of rotation is arranged radially further outward than the trailing end of the head surface 20ci.

[0163] In Figure 8An example is shown of how a bicycle chain 50 consisting of a sequence of outer link plate chain links 52 and inner link plate chain links 54 is shifted up from the meshing engagement with the pinion 22 to the smaller pinion 20. It can be seen that the output tooth 38 is the last tooth of the pinion 22 that engages with the bicycle chain 50.

[0164] Merely as an example, Figure 9 A pinion pairing consisting of the 28-T pinion 24 and the previously discussed 24-T pinion 22 is shown. The pinion 22 has already been discussed above. The pinion 24 essentially has two upshift ranges 34 and two downshift ranges 40 along its circumference, with the same-direction shifting ranges 34 and 40 located diametrically opposite each other on the pinion 24.

[0165] The same lower case letters after the reference number 24 of the pinion 24 designate functionally identical components or component sections of the pinions 12, 14, 16, 18, 20 or 22, which are designated there with the same lower case letters.

[0166] The pinion 24 also has tooth spaces 43 with the tooth base offset radially inward toward the pinion axis R. However, these tooth spaces 43 do not play a role in shifting the chain between the adjacent pinions 24 and 22, but rather in shifting the bicycle chain between the pinion 24 and the next larger pinion 26.

[0167] In Figure 10The largest pinion 32 is shown detached from the other pinions 10 to 30 for reference purposes. The pinion 32 comprises a gear ring 60, an intermediate ring 62, and a radially inner spline 64 for transmitting torque to a driver (not shown but readily known to those skilled in the art) or to an adapter arranged between the spline 64 and the driver. The spline profile of the adapter or driver, which interacts with the radially inner profile of the spline 64, is complementary to the radially inner spline profile of the spline 64. Radially outer struts 66a and 66b connect the gear ring 60 to the intermediate ring 62 in a torque-transmitting manner. Radially inner struts 68 connect the intermediate ring to the spline 64.

[0168] To avoid undesired bending deformation of the struts 66b and 68, these are arranged such that their radially inner strut ends precede the radially outer ones in the drive direction of rotation D. The struts 66a are wider in the circumferential direction than the struts 66b.

[0169] Fastening openings 70 indicate where the pinion dome, consisting of the pinions 14 to 30 connected to one another in one piece and the smaller pinions 12 and 10 screwed onto the pinion dome, is connected to the largest pinion 32 in a torque-transmitting manner using connecting means such as pins, rivets, screws and the like.

[0170] The fastening holes 70 are arranged, on the one hand, as radially outward as possible, but without interfering with the engagement of the pinion teeth with the bicycle chain, and, on the other hand, are formed in the most stable areas of the pinion 32. Therefore, the fastening holes 70 are formed primarily in the wider radially outer struts 66a and near the connection points of the intermediate ring 62 with the radially inner struts 68.

[0171] In Figure 10Ais a view of the largest pinion 32 viewed orthogonally to the pinion axis R. There, it can be seen that the pinion 32 is offset outwards, i.e. away from the longitudinal center plane LME, in the areas radially closer to the pinion axis R. As a result, the driver located radially inside the splined ring 64 requires as little axial space as possible to accommodate the twelve-speed pinion cassette 1. In addition, the larger pinion 32 is stiffened against bending moments that act on the largest pinion 32 due to the chain skew. The pinion 32 and the pinion dome connected to it stiffen each other.

[0172] The sprocket cassette 1 is designed such that all smaller sprockets 10 to 30 transmit their torque directly to the sprocket 32, which transmits the torque transmitted by the rider or the electric motor via the bicycle chain 50 to the sprocket cassette 1 to the rear wheel hub via the aforementioned driver.

[0173] As on the side of the pinion 32 pointing towards the longitudinal center plane LME, to which the observer of the Figure 10B As can be seen, thick teeth 32a and thin teeth 32b are also formed on the largest pinion 32, alternating in the circumferential direction. The recesses on the axially facing tooth surfaces for forming thin teeth 32b are formed exclusively on the side of the larger pinion 32 facing away from the next smaller pinion 30.

[0174] The same lower case letters after the reference number 32 of the pinion 32 designate functionally identical components or component sections of the pinions 12, 14, 16, 18, 20, 22 or 24, which are designated there with the same lower case letters.

[0175] In Figure 10B Furthermore, the formation of ramps is shown on some of the output teeth 38, on some of the fangs 44, and on the mobilization teeth 32b' and 32b" adjacent to the ramp-forming output teeth 38 and fangs 44. The ramps are marked with the reference symbol of the respective tooth and the lowercase letter g. On the mobilization teeth, the ramps are marked with the same apostrophes as the corresponding mobilization teeth.

[0176] The ramps 38g, 32g', 44g and 32g" form a radial and axial step of the tooth surface of the associated teeth 38, 32b', 44 and 32b" facing away from the next smaller pinion 30. The ramps 38g, 32g', 44g and 32g" form a ramp surface facing radially outwards, i.e. away from the pinion axis R, on which radially inward-facing edge surfaces of the bicycle chain 50 can be supported.

[0177] These ramps 38g, 32g', 44g and 32g" stabilize the chain 50 in a special way when meshing with the largest pinion 32.

[0178] When pedaling backward using the freewheel normally present on the rear wheel hub, under certain circumstances the skew of the chain can have a stabilizing effect on the meshing engagement of the pinion 32 with the bicycle chain 50. Since the output teeth 38 and the adjacent mobilization teeth 32b', in particular, support the shifting of the chain to the next smaller pinion 30, to which the skew applies, a ramp is formed primarily there. Ramps are also formed on the shift-relevant teeth of a downshift range, i.e., on the catch tooth 44 and its mobilization tooth 32b', to stabilize the chain 50.

[0179] The ramps mentioned not only hold the chain itself in the event of a very unfavorable effect of the chain skew towards the front chainring on pinion 32, but also support the shifting of the chain 50 down to the larger pinion 32 or up from the larger pinion 32 to the next smaller pinion 30. The ramps make it possible for the chain to be held stably and with physical guidance even in a radially further outward position on pinion 32 in the shift-relevant areas: upshift area 34 and downshift area 40, than would be the case with a conventional tooth engagement, in which the catch tooth 44, the output tooth 38 or the adjacent mobilization teeth 32b" or 32b' radially engage completely in the spaces between the chain links.

[0180] Thus, the ramps stabilize the chain 50 against the chain skew to the front chainring when the chain guide roller of the front derailleur is aligned coplanar with the pinion 32 to hold the chain on the larger pinion 32, and the chain skew acts against holding the chain 50 on the pinion 32. Furthermore, the ramps support the shifting of the chain 50 when the chain guide roller of the front derailleur is aligned coplanar with the future chain-guiding pinion while the chain 50 is still engaged on the current chain-guiding pinion.

[0181] The ramps shown can also be formed on pinions 30, 28, 26, etc., preferably on the side of the respective pinion facing away from the next smallest pinion. However, since the chain skew decreases in magnitude toward the medium-sized pinions of the sprocket cassette 1, the ramps are particularly important on the larger pinions 32, 30, and also 28.

[0182] In Figure 11A bicycle provided with a pinion cassette 1 according to the invention is shown schematically and generally designated 70. A front wheel 72 and a rear wheel 74 are mounted on a bicycle frame 76 by respective Figure 11 The front wheel 72 can be connected to the bicycle frame 76 via a sprung fork 78. The rear wheel 74 can also be connected to the bicycle frame 76 via a sprung suspension 80.

[0183] The rear wheel 74 is connected to a drive assembly 82 comprising a single front chainring 24 and the only Figure 1A bicycle rear wheel sprocket cassette 1, shown schematically, can be driven. The drive torque can be transmitted via pedal cranks 88 and a pedal crankshaft 88a connected to them to the front chainring 84 and from there via the bicycle chain 50 via the sprocket cassette 126 to the rear wheel 74. To assist a cyclist who drives the pedal cranks 88 with muscle power, a supporting electric motor 90 can be arranged on the bicycle frame 76 in such a way that this also transmits its supporting drive torque via the pedal crankshaft 88a to the front chainring 84. A gear, in particular a planetary gear, can be provided between the pedal crankshaft 88a and the chainring 84. The transmission ratio of the gear must be taken into account when calculating the effective number of teeth of the chainring 84.The actual number of teeth on the 84-tooth chainring must be multiplied by the factor with which the transmission transmits the torque introduced into it to its output side. An increase in the torque through the transmission thus leads to a higher effective number of teeth on the 84-tooth chainring than the actual number of teeth, and vice versa.

[0184] A battery 92 as an energy storage device for the supporting electric motor 90 can be provided in or on the frame 76.

[0185] The bicycle chain 50 can be brought into meshing engagement in a conventional manner by a rear derailleur or front derailleur 94 with a pinion selected by the rider from the plurality of pinions 10 to 32 of the pinion cassette 1 for torque transmission to the rear wheel 74. The front derailleur 94 has a chain guide roller 96 closest to the pinion cassette 1 and a tension roller 98.

[0186] Both the cyclist's muscle torque and the assisting torque of the electric motor 90 are transmitted to the rear wheel 74 on the example bicycle 70 via the rear wheel sprocket cassette 1. The electric motor 90 thus has the effect as if the cyclist could access a pedaling power increased by the assisting power of the electric motor 90.

[0187] Since the bicycle 70 shown as an example has exactly one front chainring 84, the entire gear range of the bicycle 70 is realized by the sprocket cassette 1.

Claims

1. Bicycle rear-wheel sprocket pairing (11, 13, 15, 17) for engaging in a force-transmitting manner with a bicycle roller chain (50), wherein the rear-wheel sprocket pairing (11, 13, 15, 17) is rotatable about a sprocket axis (R), wherein the sprocket axis (R) defines an axial direction running along the sprocket axis (R), a radial direction running so as to be orthogonal to the sprocket axis (R), and a circumferential direction encircling the sprocket axis (R), wherein the rear-wheel sprocket pairing (11, 13, 15, 17) comprises a larger sprocket (12, 14, 16, 18) and a coaxial smaller sprocket (10, 12, 14, 16) which for rotating conjointly in a slip-free manner about the sprocket axis (R) is connected to said larger sprocket (12, 14, 16, 18) so as to be axially directly adjacent to the latter, wherein the larger sprocket (12, 14, 16, 18) has an even tooth count of equal to or less than 22 teeth, and wherein the difference in the tooth count between the larger and the smaller sprocket (10, 12, 14, 16) is exactly two teeth, wherein i) the larger sprocket (12, 14, 16, 18) in the end side thereof that points towards the smaller sprocket (10, 12, 14, 16), along a portion of the circumference thereof has an upshift region (34) having an upshift depression formation (36), wherein the upshift region (34), when axially viewing the rear-wheel sprocket pairing (11, 13, 15, 17) in a reference state in which the smaller sprocket (10, 12, 14, 16) lies closer to the observer than the larger sprocket (12, 14, 16, 18), is configured and disposed so as to permit on the rear-wheel sprocket pairing (11, 13, 15, 17) rotating in the clockwise direction about the sprocket axis (R) a change of engagement of the bicycle roller chain (50) from the larger to the smaller sprocket (10, 12, 14, 16), wherein on the larger sprocket (12, 14, 16, 18) the upshift depression formation (36) is assigned only exactly one release tooth (38) which by way of the design and orientation thereof, when interacting with the end-side upshift depression formation (36) during an upshift procedure from the larger sprocket (12, 14, 16, 18) to the smaller sprocket (10, 12, 14, 16), is configured to be the last tooth that engages between a link plate pair of a chain link (52) of the bicycle roller chain (50); and ii) the larger sprocket (12, 14, 16, 18) in the end side thereof that points towards the smaller sprocket (10, 12, 14, 16), along the circumference thereof has a downshift region (40) having a downshift depression formation (42), wherein the downshift region (40), when axially viewing the rear-wheel sprocket pairing (11, 13, 15, 17) in the reference state, is configured so as to permit on the rear-wheel sprocket pairing (11, 13, 15, 17) rotating in the clockwise direction about the sprocket axis (R) a change of engagement of the bicycle roller chain (50) from the smaller to the larger sprocket (12, 14, 16, 18), wherein on the larger sprocket (12, 14, 16, 18) the downshift depression formation (42) is assigned only exactly one catch tooth (44) which by way of the design and orientation thereof, when interacting with the end-side downshift depression formation (42) during a downshift procedure from the smaller sprocket (10, 12, 14, 16) to the larger sprocket (12, 14, 16, 18), is configured to be the first tooth that engages between link plates of a chain link of the bicycle roller chain (50), wherein the catch tooth (44) has such a configuration and orientation that it only engages in the bicycle roller chain (50) which is intended to be placed around the larger pinion (12, 14, 16, 18) when an outer link plate chain link (54) is located at the circumferential position of the catch tooth (44) which provides a greater engagement space than an inner link plate chain link (52), and the bicycle roller chain (50) is deflected when an inner link plate chain link (52) is located at the circumferential position of the catch tooth (44).

2. Bicycle rear-wheel sprocket pairing (11, 13, 15, 17) according to Claim 1, characterized in that the release tooth (38) in the clockwise direction is directly contiguous to the upshift depression formation (36).

3. Bicycle rear-wheel sprocket pairing (11, 13, 15, 17) according to Claim 1 or 2, characterized in that the larger sprocket (12, 14, 16, 18) along the entire circumference thereof has exactly one upshift region (34) having an upshift depression formation (36) and exactly one release tooth (38).

4. Bicycle rear-wheel sprocket pairing (11, 13, 15, 17) according to one of the preceding claims, characterized in that the catch tooth (44) in the counterclockwise direction is directly contiguous to the downshift depression formation (42).

5. Bicycle rear-wheel sprocket pairing (11, 13, 15, 17) according to one of the preceding claims, characterized in that the larger sprocket (12, 14, 16, 18) along the entire circumference thereof has exactly one downshift region (40) and exactly one catch tooth (44).

6. Bicycle rear-wheel sprocket pairing (11, 13, 15, 17) according to one of the preceding claims, characterized in that in the clockwise direction, when axially viewing the rear-wheel sprocket pairing (11, 13, 15, 17) in the reference state, k teeth lie between the release tooth (38) and the catch tooth (44), wherein the release tooth (38) and the catch tooth (44) are not to be included in the count, and wherein k = T - d, where T is the tooth count of the larger sprocket (12, 14, 16, 18) and where d equals 5 or equals 7.

7. Bicycle rear-wheel sprocket pairing (11, 13, 15, 17) according to Claim 6, characterized in that, when T is divisible by 6 into integer numbers without a remainder, d equals 5, and when T is not divisible by 6 into integer numbers without a remainder, d equals 7.

8. Bicycle rear-wheel sprocket pairing (11, 13, 15, 17) according to one of the preceding claims, characterized in that in the clockwise direction, when axially viewing the rear-wheel sprocket pairing (11, 13, 15, 17) in the reference state, n teeth lie between the catch tooth (44) and the release tooth (38), wherein the catch tooth (44) and the release tooth (38) are not to be included in the count, wherein n equals 3 or equals 5.

9. Bicycle rear-wheel sprocket pairing (11, 13, 15, 17) according to Claim 8, characterized in that, when the tooth count of the larger sprocket (12, 14, 16, 18) is divisible by 6 into integer numbers without a remainder, n equals 3, and when the tooth count of the larger sprocket (12, 14, 16, 18) is not divisible by 6 into integer numbers without a remainder, n equals 5.

10. Bicycle rear-wheel sprocket pairing (11, 13, 15, 17) according to one of the preceding claims, characterized in that that a tooth face of the tooth (12b', 14b', 16b', 18b') contiguous to the release tooth (38) in the clockwise direction that points away from the smaller sprocket (10, 12, 14, 16) in an axial direction lies closer to the smaller sprocket (10, 12, 14, 16) than the tooth face of the next but one tooth that follows this tooth (12b', 14b', 16b', 18b') in the clockwise direction that points away from the smaller sprocket (10, 12, 14, 16) in an axial direction, or / and in that the tooth face of the tooth (12b", 14b", 16b", 18b") following the catch tooth (44) in the counterclockwise direction that points away from the smaller sprocket (10, 12, 14, 16) in an axial direction lies closer to the smaller sprocket (10, 12, 14, 16) than the tooth face of the next but one tooth that follows this tooth (12b", 14b", 16b", 18b") in the counterclockwise direction that points away from the smaller sprocket (10, 12, 14, 16) in an axial direction.

11. Bicycle rear-wheel sprocket pairing (11, 13, 15, 17) according to one of the preceding claims, characterized in that the larger sprocket (12, 14, 16, 18) or / and the smaller sprocket (10, 12, 14, 16), alternating sequentially in the circumferential direction along at least one circumferential portion, have / has in each case one thinner tooth (10b, 12b, 14b, 16b, 18b) and one thicker tooth (10a, 12a, 14a, 16a, 18a).

12. Bicycle rear-wheel sprocket cassette (1) having a plurality of sprockets (10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32) which are connected for conjointly rotating in a slip-free manner about the sprocket axis (R) and have in each case a different tooth count, wherein the bicycle rear-wheel sprocket cassette (1) contains at least one bicycle rear-wheel sprocket pairing (11, 13, 15, 17) according to one of the preceding claims.

13. Bicycle rear-wheel sprocket cassette (1) according to Claim 12, characterized in that the bicycle rear-wheel sprocket cassette (1) has at least three sprockets (12, 14, 16) which have in each case a different tooth count and are associated with two bicycle rear-wheel sprocket pairings (11, 13, 15, 17) according to one of Claims 1 to 11, wherein the sprocket (12, 14, 16) having the medium tooth count is the larger sprocket (12, 14, 16) of the one rear-wheel sprocket pairing (11, 13, 15) and the smaller sprocket (12, 14, 16) of the other rear-wheel sprocket pairing (13, 15, 17).

14. Bicycle rear-wheel sprocket cassette (1) according to Claim 12 or 13, characterized in that all the sprockets of the rear-wheel sprocket cassette (1) having tooth counts of 20 or less form bicycle rear-wheel sprocket pairings (11, 13, 15, 17) according to one of Claims 1 to 11.

15. Bicycle rear-wheel sprocket cassette (1) according to one of Claims 12 to 14, characterized in that the rear-wheel sprocket cassette (1) has a transition sprocket group (19) comprising a 21-T sprocket (20) having 21 teeth, a smaller 18-T sprocket (18) having 18 teeth being directly adjacent thereto.

16. Bicycle rear-wheel sprocket cassette (1) according to Claim 15, characterized in that i) the 21-T sprocket (20) in the end side thereof that points towards the 18-T sprocket (18), along a portion of the circumference thereof has at least two upshift regions (34) having in each case one upshift depression formation (36), wherein each upshift region (34), when axially viewing the transition sprocket group (19) in a reference state in which the 18-T sprocket (18) lies closer to the observer than the 21-T sprocket (20) (21), is configured and disposed so as to permit on the transition sprocket group (19) rotating in the clockwise direction about the sprocket axis (R) a change of engagement of the bicycle roller chain (50) from the 21-T sprocket (20) to the 18-T sprocket (18), wherein on the 21-T sprocket (20) each upshift depression formation (36) is in each case assigned only exactly one release tooth (38) which by way of the design and orientation thereof, when interacting with the end-side upshift depression formation (36) assigned thereto during an upshift procedure from the 21-T sprocket (20) to the 18-T sprocket (18), is configured to be the last tooth that engages between a link plate pair of a chain link (52) of the bicycle roller chain (50) wherein an even number of teeth lie between the release teeth (38) of upshift depression formations (36) that are adjacent in the circumferential direction, wherein the release teeth (38) of the adjacent upshift depression formations (36) are not to be included in the count; or / and ii) the 21-T sprocket (20) in the end side thereof that points towards the 18-T sprocket (18), along the circumference thereof has at least two downshift regions (40) having in each case one downshift depression formation (42), wherein each downshift region (40), when axially viewing the transition sprocket group (19) in the reference state, is configured so as to permit on the transition sprocket group (19) rotating in the clockwise direction about the sprocket axis (R) a change of engagement of the bicycle roller chain (50) from the 18-T sprocket (18) to the 21-T sprocket (20), wherein on the 21-T sprocket (20) each downshift depression formation (42) is in each case assigned exactly only one catch tooth (44) which by way of the design and orientation thereof, when interacting with the end-side downshift depression formation (42) assigned thereto during a downshift procedure from the 18-T sprocket (18) to the 21-T sprocket (20) is configured to be the first tooth that engages between link plates of a chain link (52) of the bicycle roller chain (50), wherein an even number of teeth lie between the catch teeth (44) of downshift depression formations (42) that are adjacent in the circumferential direction, wherein the catch teeth (44) of the adjacent downshift depression formations (42) are not to be included in the count.

17. Bicycle rear-wheel sprocket cassette (1) according to Claim 16, characterized in that the 21-T sprocket (20) i) has exactly three upshift regions (34) having in each case one upshift depression formation (36) and in each case exactly one release tooth (38), wherein six teeth lie in each case between the release teeth (38) of upshift depression formations (36) that are adjacent in the circumferential direction, wherein the release teeth (38) of the adjacent upshift depression formations (36) are not to be included in the count, or / and ii) has exactly three downshift regions (40) having in each case one downshift depression formation (42) and in each case exactly one catch tooth (44), wherein six teeth lie in each case between the catch teeth (44) of downshift depression formations (42) that are adjacent in the circumferential direction, wherein the catch teeth (44) of the adjacent downshift depression formations (42) are not to be included in the count.

18. Bicycle rear-wheel sprocket cassette (1) according to Claim 16 or 17, characterized in that the transition sprocket group (19) additionally has a 24-T sprocket (22) having 24 teeth, wherein the 21-T sprocket (20) is axially disposed between the 24-T sprocket and the 18-T sprocket (18).

19. Bicycle rear-wheel sprocket cassette (1) according to Claim 15, characterized in that i) the 24-T sprocket (22) in the end side thereof that points towards the 21-T sprocket (20), along a portion of the circumference thereof, has at least two upshift regions (34) having in each case one upshift depression formation (36), wherein each upshift region (34), when axially viewing the transition sprocket group (19) in a reference state in which the 21-T sprocket (20) lies closer to the observer than the 24-T sprocket (22), is configured and disposed so as to permit on the transition sprocket group (19) rotating in the clockwise direction about the sprocket axis (R) a change of engagement of the bicycle roller chain (50) from the 24-T sprocket (22) to the 21-T sprocket (20), wherein on the 24-T sprocket (22) each upshift depression formation (36) is assigned only exactly one release tooth (38) which by way of the design and orientation thereof, when interacting with the end-side upshift depression formation (36) assigned thereto during an upshift procedure from the 24-T sprocket (22) to the 21-T sprocket (20), is configured to be the last tooth that engages between a link plate pair of a chain link (52) of the bicycle roller chain (50), wherein an uneven number of teeth lie between the release teeth (38) of upshift depression formations (36) that are adjacent in the circumferential direction, wherein the release teeth (38) of the adjacent upshift depression formations (36) are not to be included in the count, or / and ii) the 24-T sprocket (24) in the end side thereof that points towards the 21-T sprocket (20), along the circumference thereof has at least two downshift regions (40) having in each case one downshift depression formation (42), wherein each downshift region (40), when axially viewing the transition sprocket group (19) in the reference state, is configured so as to permit on the transition sprocket group (19) rotating in the clockwise direction about the sprocket axis (R) a change of engagement of the bicycle roller chain (50) from the 21-T sprocket (20) to the 24-T sprocket (24), wherein the 24-T sprocket (24) of each downshift depression formation (42) is in each case assigned only exactly one catch tooth (44) which by way of the design and the orientation thereof, when interacting with the end-side downshift depression formation (42) assigned thereto during a downshift procedure from the 21-T sprocket (20) to the 24-T sprocket (22) is configured to be the first tooth that engages between link plates of a chain link (52) of the bicycle roller chain (50), wherein an uneven number of teeth lie between the catch teeth (44) of downshift depression formations (42) that are adjacent in the circumferential direction, wherein the catch teeth (44) of the adjacent downshift depression formations (42) are not to be included in the count.

20. Bicycle rear-wheel sprocket cassette (1) according to Claim 19, characterized in that the 24-T sprocket (22) i) has exactly three upshift regions (34) having in each case one upshift depression formation (36) and in each case exactly one release tooth (38), wherein seven teeth lie in each case between the release teeth (38) of upshift depression formations (36) that are adjacent in the circumferential direction, wherein the release teeth (38) of the adjacent upshift depression formations (36) are not to be included in the count, or / and ii) has exactly three downshift regions (40) having in each case one downshift depression formation (42) and exactly one catch tooth (44), wherein seven teeth lie in each case between the catch teeth (44) of downshift depression formations (42) that are adjacent in the circumferential direction, wherein the catch teeth (44) of the adjacent downshift depression formations (42) are not to be included in the count.

21. Bicycle rear-wheel sprocket cassette (1) according to one of Claims 12 to 20, characterized in that the bicycle rear-wheel sprocket cassette (1) is a twelve-fold sprocket cassette (1) having the following tooth count increments: 10 - 12 - 14 - 16 - 18 - 21 - 24 - 28 - 32 - 38 - 44 - 52.

22. Bicycle drive assembly, comprising a bicycle rear-wheel sprocket pairing (11, 13, 15, 17) according to one of Claims 1 to 11 or a bicycle rear-wheel sprocket cassette (1) according to one of Claims 12 to 21, having a bicycle roller chain (50) which is configured for engaging in a meshing, force-transmitting manner with the sprockets (10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32) of the bicycle rear-wheel sprocket pairing (11, 13, 15, 17) or the bicycle rear-wheel sprocket cassette (1), respectively, wherein the bicycle roller chain (50) has a plurality of chain rollers which are mutually successive at a pitch spacing and which are connected to one another by pairs of parallel link plates, wherein the bicycle roller chain (50) in the chain revolving direction has inner link plate pairs having a smaller link plate spacing alternating sequentially with outer link plate pairs having a larger link plate spacing.

23. Bicycle drive assembly according to Claim 22, characterized in that it applies to at least one bicycle rear-wheel sprocket pairing (11, 13, 15, 17) that in a shift procedure in which the bicycle roller chain (50) is repositioned from one sprocket (10, 12, 14, 16, 18) to a sprocket (10, 12, 14, 16, 18) axially adjacent thereto, exactly one inner link-plate chain link is situated between the last chain link (52) which engages with the still chain-guiding sprocket (10, 12, 14, 16, 18) and the first chain link (52) which comes to engage, or engages, with the future chain-guiding sprocket (10, 12, 14, 16, 18).