Method for operating a gearing of an electric bicycle
By determining chain change points and adjusting motor torque based on predefined intervals, the method reduces mechanical stress and wear on electric bicycle gear systems, ensuring smooth and comfortable gear shifts.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- ROBERT BOSCH GMBH
- Filing Date
- 2025-11-25
- Publication Date
- 2026-06-18
AI Technical Summary
Bicycle gear systems, particularly on electric bicycles, experience high mechanical stress during gear changes due to combined rider and motor torque, leading to increased wear on the chain and sprockets.
A method for operating the gear system of an electric bicycle that involves capturing a switching signal, actuating a shifting device, determining the first and second chain change points, and adjusting motor torque accordingly based on predefined time intervals and mechanical properties to minimize wear and ensure smooth gear shifts.
This method reduces mechanical stress on the drivetrain components, extends their service life, and provides a smooth and comfortable shifting experience by precisely coordinating motor torque with the gear change process.
Smart Images
Figure EP2025084137_18062026_PF_FP_ABST
Abstract
Description
[0001] R.412420
[0002] - 1 -
[0003] Description
[0004] title
[0005] Method for operating the gear shift of an electric bicycle
[0006] State of the art
[0007] The present invention relates to a method for operating a gearshift of an electric bicycle, and to an electric bicycle.
[0008] Bicycle gear systems are commonly known as derailleur gears. In this system, the bicycle chain is moved between the sprockets by a shifting mechanism. Before a new gear is actually engaged, the chain typically has to complete a certain number of revolutions around the cassette. On e-bikes, in addition to the rider's pedaling torque, there may be motor torque from a drive unit applied to the drivetrain. This can lead to high mechanical stress on the drivetrain, particularly on the chain and sprockets, during gear changes.
[0009] Disclosure of the invention
[0010] The method according to the invention with the features of claim 1 is characterized, in contrast, by the fact that a particularly effective reduction of the torque acting on the bicycle chain during a shifting operation can be provided using simple and cost-effective means. In particular, this enables low wear and a long service life of the gear system. This is achieved according to the invention by a method for operating the gear system of an electric bicycle, wherein the gear system comprises a derailleur system with a shifting device. The shifting device is configured to move a bicycle chain onto different sprockets. The method comprises the steps: R.412420
[0011] - 2 -
[0012] Capturing a switching signal,
[0013] Actuating the switching device in response to the detected switching signal,
[0014] Determining the first chain replacement point at which the bicycle chain is moved by the shifting device at the earliest, and
[0015] Reducing the motor torque of an electric bicycle drive unit to a predetermined shifting motor torque at the first chain change time, wherein the determination of the first chain change time is based on a first time interval between the start of a movement of the shifting device and the earliest movement of the bicycle chain.
[0016] A switching device can preferably be considered an element that guides the bicycle chain, such as in particular a derailleur and / or a front derailleur.
[0017] The point at which a chain needs to be changed is considered to be the point in time when, during the shifting process, the bicycle chain is first moved directly against the sprockets.
[0018] The initial time interval between the start of the shifting mechanism's movement and the earliest movement of the bicycle chain can be based on predetermined mechanical and geometric properties of the derailleur system. This means that the initial time interval results, in particular, from a certain time delay between the actual movement of the bicycle chain immediately at the sprocket and the initial movement of the shifting mechanism.
[0019] Preferably, the first time interval and / or the point in time of the earliest movement of the bicycle chain can be estimated as a time interval or point in time which is known based on the mechanical properties of the derailleur system and / or has been determined, for example, by means of calibration. In particular, the exact first time interval or the exact earliest point in time of movement can vary due to tolerances, environmental influences, wear conditions, or the like. Therefore, an estimation of the earliest point in time of movement of the bicycle chain can be considered accordingly. R.412420
[0020] - 3 -
[0021] In other words, the process involves controlled actuation of the shifting device based on the detected shift signal. The first chain change point is then determined, at which point the bicycle chain is first moved by the shifting device after the shift signal. At this point, the motor torque of the e-bike's drive unit is reduced so that a predetermined shifting motor torque is present at the chain change point. The first chain change point is determined based on the initial time interval between the start of the shifting device's movement and the earliest actual movement of the bicycle chain.
[0022] Preferably, the switching motor torque corresponds to a predetermined fraction of the previous motor torque, preferably a maximum of 30%, and more preferably a maximum of 20%. Alternatively, and more preferably, the switching motor torque is a predefined constant value. For example, the switching motor torque can be a maximum of 35 Nm, preferably a maximum of 25 Nm.
[0023] This method offers the advantage of enabling a particularly targeted and effective reduction of motor torque during the shifting process. By taking into account the initial time interval between the start of the shifting mechanism's movement and the earliest actual movement of the bicycle chain, the timing of the motor torque reduction can be precisely aligned with the actual duration of the chain's movement. This ensures, on the one hand, that the reduced shifting motor torque is applied during the chain's movement, allowing for shifting under low load and thus without wear. On the other hand, the motor torque reduction can be optimally timed to minimize its duration, ensuring effective propulsion and a high level of riding comfort for the e-bike user.
[0024] The dependent claims describe preferred embodiments of the invention.
[0025] Preferably, the method further comprises the steps of: determining a second chain change point at which the movement of the bicycle chain by the shifting device has ceased at the latest, and increasing the motor torque of the drive unit at the second chain change point. In particular, R.412420
[0026] - 4 - The second chain change point is considered to be the point in time at which the movement of the bicycle chain directly at the sprocket has ceased at the latest. Alternatively or additionally, preferably, the second chain change point is considered to be the point in time at which the bicycle chain is fully engaged with the new sprocket after the shifting process. The increase in the motor torque of the drive unit preferably occurs in such a way that a predetermined target motor torque is present precisely at the second chain change point. Preferably, the target motor torque can correspond to the motor torque before the shifting device is actuated, i.e., before the shifting process. This allows for a simple, effective, and time-efficient increase in motor torque after the shifting process. Thus, effective propulsion of the e-bike and a high level of riding comfort for the rider can be provided.
[0027] Preferably, the second chain change point is determined based on the first chain change point and a chain change time interval. The chain change time interval is defined as the time required to move the bicycle chain between the sprockets during the shifting process. In particular, the chain change time interval can be known in advance based on the mechanical and geometric properties of the derailleur system. For example, the chain change time interval can be known and stored individually for each gear change of the derailleur system. This allows for a particularly simple and efficient controlled gear shifting process.
[0028] Preferably, the second chain change time is determined based on the first chain change time and a second time interval. The second time interval is defined as the period between the start of the movement of the shifting device and the latest possible end of the bicycle chain's movement. That is, to determine the second chain change time, a second time interval is used, which is independent of the first time interval and, like the first time interval, begins with the start of the movement of the shifting device. For example, the second time interval can be known based on previously known mechanical and / or geometric properties of the derailleur system. Preferably, the second time interval can be individually defined and known for each possible gear change of the derailleur system. For example, the corresponding R.412420 can be defined for each gear change.
[0029] - 5 - the second time period is stored. This allows the procedure to be carried out in a particularly simple and efficient way.
[0030] Particularly preferably, determining the first chain replacement time includes determining the number of revolutions of the sprockets, preferably from the moment the shift signal is detected. Particularly preferably, or alternatively or additionally, determining the second chain replacement time includes determining the number of revolutions of the sprockets, particularly from the moment the shift signal is detected. In other words, a specific number of revolutions of the sprockets is determined, which occur from the detection of the shift signal until the first chain replacement time or until the second chain replacement time. This allows the chain replacement times to be determined in a particularly simple and reliable manner, for example, by detecting and tracking the rotational movement of the sprockets.
[0031] Preferably, the first chain change point is reached when the measured number of revolutions reaches a predefined number of shift revolutions. Alternatively, or preferably, the second chain change point is reached when the measured number of sprocket revolutions reaches a predefined number of shift revolutions. In other words, particularly from the moment the shift signal is detected, the sprocket revolutions are counted until the predefined number of shift revolutions is reached, in order to initiate the corresponding action planned for the first and / or second chain change point. This allows for particularly simple and precise monitoring of the shifting processes, especially since the sprocket rotation relevant for gear changes is also monitored.
[0032] A particularly advantageous feature is the individually defined number of shift revolutions for each gear change. This means that for each shift from one sprocket to an adjacent sprocket, a correspondingly individually adjusted number of shift revolutions is defined separately. This takes into account the different diameters and mechanical properties during the respective gear changes between the various sprockets, allowing the reduction of engine torque to be precisely timed for each gear change. R.412420
[0033] - 6 -
[0034] Preferably, the number of revolutions of the sprockets is determined based on a detected sprocket speed and / or based on a detected motor speed and an instantaneous gear ratio. That is, the sprocket speed can be detected directly, for example by means of a speed sensor, or alternatively or additionally preferably based on the motor speed of the drive unit and the instantaneous gear ratio, in which case the rotation of the sprockets is determined based on the mechanical relationship between motor speed and the gear ratio of the drivetrain. Furthermore, alternatively or additionally preferably, the number of revolutions can be determined based on a detected cadence and an instantaneous gear ratio. This allows the rotational movement of the sprockets to be reliably monitored in a simple and cost-effective manner.
[0035] Preferably, the determination of the first chain replacement time is based on predefined time intervals for the movement of the shifting device and / or for the movement of the bicycle chain. In particular, the predefined time intervals are fixed based on the mechanical and / or geometric properties of the derailleur system. For example, the predefined time intervals can be initially calculated and / or calibrated. Furthermore, preferably, the predefined time intervals for the movements of the shifting device and / or bicycle chain are stored by a control unit. This enables a particularly simple and efficient implementation of the method.
[0036] Preferably, the method further comprises the steps of: detecting a fully completed gear change, particularly before reaching the second chain change point. The method also includes the step of: increasing the engine torque in response to the detection of the fully completed gear change, or alternatively, the step of: preventing the reduction of the engine torque. In particular, the engine torque is increased to the previous engine torque of the drive unit before the reduction. That is, if a gear change is detected prematurely, the engine torque is increased back to its original value before the shifting process. Alternatively, preferably, especially if the engine torque has not yet been reduced, the reduction of the engine torque is actively prevented if the gear change to be achieved has already been detected as completed. This allows for particularly effective and convenient rapid engine assistance. R.412420
[0037] - 7 -
[0038] Preferably, the detection of a completed gear change can be based on one or more sensor signals. For example, an instantaneous gear ratio can be determined and monitored using a cadence and a rear wheel speed, whereby, in particular, the completed gear change can be determined based on the determined gear ratio.
[0039] More preferably, the method further comprises the steps of: determining a time-dependent pedaling torque profile, estimating a future time-dependent pedaling torque profile based on the recorded time-dependent pedaling torque profile, and generating the shift signal such that a minimum of the estimated time-dependent pedaling torque profile occurs during the movement of the bicycle chain through the shifting device. That is, the generation of the shift signal is controlled in a targeted manner such that the subsequent time interval of the chain movement is precisely such that the minimum of the pedaling torque of the estimated time-dependent pedaling torque profile occurs during this time interval. Preferably, the estimation of the future time-dependent pedaling torque profile is based on the assumption that the pedaling torque generated by the rider is periodic, in particular essentially corresponding to a sinusoidal oscillation.This allows not only the synchronization of the motor torque with the shift point, but also the optimal adaptation of this shift point to the temporal pedaling torque curve. This keeps the overall torque on the bicycle chain particularly low during the shifting process, resulting in exceptionally low-wear shifting.
[0040] Preferably, the shift signal is detected based on a manually and / or automatically generated shift signal. A manually generated shift signal can preferably be considered to be one generated manually by a bicycle rider, in particular by means of a shift lever. The shift lever can preferably be configured for mechanical actuation, for example by means of a cable, or for electronic actuation of the shifting device, wherein, in particular, in each case, an electrical signal is generated by the shift lever when it is actuated. An automatically generated shift signal can, in particular, be considered to be one generated by means of a control unit, which is preferably generated automatically based on one or more parameters. R.412420
[0041] - 8 -
[0042] Furthermore, the invention leads to an electric bicycle comprising a gear system, which has a derailleur system with a shifting device configured to move a bicycle chain between different sprockets. Preferably, the sprockets of the gear system are part of a cassette arranged on a rear wheel hub of the electric bicycle. The electric bicycle also includes a control unit configured to carry out the described method. The control unit is preferably also configured to control the actuation of a drive unit of the electric bicycle.
[0043] Brief description of the drawings
[0044] Exemplary embodiments of the invention are described in detail below with reference to the accompanying drawings. The drawing shows:
[0045] Figure 1 shows a simplified schematic view of an electric bicycle in which a method for operating a gearshift according to a first embodiment of the invention is carried out.
[0046] Figure 2 shows a highly simplified schematic view of the method according to the invention.
[0047] Figure 3 shows a simplified schematic view of a diagram with time-dependent signal profiles during the execution of the procedure of Figure 1, and
[0048] Figure 4 shows a simplified diagram with time profiles of signals during the execution of a method according to a second embodiment of the invention.
[0049] Embodiments of the invention
[0050] Preferably, all identical components, elements, and / or units in all figures are designated with the same reference numerals. R.412420
[0051] - 9 -
[0052] Figure 1 shows a simplified schematic view of an electric bicycle 100, in which a method 10 for operating a gear shift 1 of the electric bicycle 100 is carried out according to a first embodiment of the invention.
[0053] Figure 2 shows a highly simplified schematic view of the method of the first embodiment, and Figure 3 shows a simplified schematic view of a diagram 20 during the execution of the method 10.
[0054] The electric bicycle 100 comprises a drive unit 110 with a motor, which is in particular an electric motor. The motor can be supplied with electrical energy by means of an electrical energy storage device 109 of the electric bicycle 100. The drive unit 110 is arranged in the area of a bottom bracket of the electric bicycle 100.
[0055] The motor torque generated by the motor provides motor assistance to the pedaling force generated by the rider of the electric bicycle 100. The rider's muscle power can be applied via a crank mechanism with cranks 104.
[0056] The drive unit 110 further comprises a control unit 50, which is configured to actuate the motor in a controlled manner. For example, the control unit 50 can control an electrical actuation current to actuate the motor. Preferably, the control unit 50 is additionally configured to carry out the method 10 according to the invention.
[0057] The electric bicycle 100 comprises a gear system 1, which is designed as a derailleur system 2. The derailleur system 2 includes a cassette 101 on a rear wheel hub of the electric bicycle 100. The cassette 101 comprises a number of sprockets 5, by means of which different gear ratios can be provided in the drivetrain of the electric bicycle 100.
[0058] The electric bicycle 100 is driven by a chainring 107, which can be driven by the motor torque of the drive unit 110 as well as by the pedaling torque applied via the cranks 104. The resulting total torque is transmitted from the chainring via the bicycle chain 4 to the cassette 101. R.412420
[0059] - 10 -
[0060] Furthermore, the derailleur system includes a shifting device 3, which can move the bicycle chain 4 between the different sprockets of the cassette 101 in order to change the gear ratio. In particular, the shifting device 3 can be designed as a front derailleur or a rear derailleur.
[0061] The switching device 3 can be actuated by means of a switching signal 15. The switching signal 15 can either be generated automatically by the control unit 50, for example depending on various driving parameters such as bicycle speed and / or cadence. Alternatively, and preferably, the switching signal 15 can be generated by means of a manual switching device 8, which includes, for example, a shift lever.
[0062] Method 10 allows for precise coordination of the motor torque provision of the drive unit 110 with the switching operations in order to enable efficient and low-wear operation of the electric bicycle 100, as described below with reference to Figures 2 and 3.
[0063] In method 10, the switching signal 15 is first generated. Upon response to the generation of the switching signal 15, the switching device 3 is immediately actuated. In particular, an actuator of the switching device 3 is actuated in a controlled manner, such that the switching device moves the bicycle chain 4 to change it to a different sprocket 5.
[0064] Immediately afterwards, a first chain change time 21 is determined. The first chain change time 21 represents a time at which the bicycle chain 4 is moved by the shifting device 3 at the earliest.
[0065] Figure 3 schematically illustrates the movement of the bicycle chain 4 by the temporal progression of the chain position 40. The movement of the bicycle chain 4, i.e., the changing of the sprockets 5, takes place within a chain change time interval 33, which lies between the first chain change time 21 and a second chain change time 22. At the second chain change time 22, the movement of the bicycle chain 4 is terminated by the shifting device 3 at the latest. R.412420
[0066] - 11 -
[0067] Determining the second chain change time 22 can be done simultaneously with determining the first chain change time 21 (see Figure 2).
[0068] When determining 12 the first chain replacement time 21, a first time interval 31 between the start 23 of a movement of the shifting device 3 and the earliest movement of the bicycle chain 4 is taken into account.
[0069] The start 23 is considered to be simultaneous with the switching signal 15. This means that during the first time interval 31, the switching device 3 is already moving, but the bicycle chain 4 is not yet moving due to the mechanical and geometric properties of the derailleur system 2.
[0070] Preferably, the first time interval 31, and in particular the chain change interval 33, are known in advance for each separate gear change, i.e., for all different sprockets 5, from the mechanical and geometric properties of the derailleur system 2. For example, the first time interval 31 and the chain change interval 33 can be stored in a lookup table.
[0071] In method 10, the motor torque 25 of the drive unit 110 is reduced 13 to a predetermined switching motor torque 26 at the first chain change time 21. During the chain change time interval 33, the motor torque 25 is kept constant at the switching motor torque 26. In particular, the motor torque 25 is reduced such that it corresponds to the predetermined switching motor torque 26 at the latest at the first chain change time 21.
[0072] Preferably, the switching motor torque 26 corresponds to a low torque value, for example a maximum of 10 Nm. Alternatively, preferably, the switching motor torque 26 can also correspond to a torque of 0 Nm.
[0073] Subsequently, preferably starting at the earliest from the second chain change point 22, a controlled increase 19 of the motor torque 25 of the drive unit 110 takes place. The motor torque 25 can then be increased back to its original value before the shifting process. R.412420
[0074] - 12 -
[0075] In method 10, the second chain change time 22 can be determined based on the sum of the first time interval 31 and the chain change time interval 33. Alternatively, and preferably, the second chain change time 22 can also be determined directly based on a second time interval 32 between the start 23 of the movement of the shifting device 3 and a latest end of the movement of the bicycle chain 4 (see Figure 3). The second time interval 32 can preferably also be known beforehand based on the mechanical and geometric properties of the derailleur 2.
[0076] In this method, the chain change times 21 and 22 are determined based on a calculation 12a of the number of revolutions of the sprockets 5 from the moment the shift signal 15 is detected. This means that the number of revolutions of the sprockets 5 required between the detection of the shift signal 15 and the first or second chain change time 21 or 22 can be determined. The reduction 13 and increase 19 of the motor torque 25 can be carried out such that it reaches the respective value when the corresponding number of revolutions of the sprockets 5 is reached.
[0077] Determining the number of revolutions of the pinions 5 is preferably done on the basis of a direct detection of the pinion speed or on the basis of a detected motor speed, in particular by means of a motor speed sensor, as well as a known instantaneous gear ratio of the derailleur system 2. This allows the instantaneous state of the derailleur system 2 to be monitored particularly precisely.
[0078] Additionally, the method 10 can include the detection 16 of a fully completed gear change before the second chain change point 22. For example, this can be done based on speed and / or torque monitoring of the electric bicycle's drivetrain 100.
[0079] If the completed gear change is detected before the reduction of engine torque 25 begins, the reduction of engine torque 25 can be specifically prevented. Alternatively or additionally, if the reduction of engine torque 25 has already begun, the engine torque 25 can be directly increased again upon detection of the fully completed gear change. R.412420
[0080] - 13 -
[0081] Method 10 thus offers the advantage that the timing of shifting operations and the provision of motor torque 25 can be optimally and precisely coordinated. By reducing the motor torque 25 precisely during the actual movement of the bicycle chain 4 between the sprockets 5, i.e., during the chain change interval 33, a particularly low load on the bicycle chain 4 during gear changes can be achieved. This enables smooth and time-efficient shifting operations and, above all, reduces wear on the derailleur 2. Furthermore, the reduction of the motor torque 25 can be precisely and efficiently coordinated with the gear change, thereby also providing a high level of riding comfort for the rider of the electric bicycle 100.
[0082] Figure 4 shows a simplified schematic view of a diagram 20 of signal waveforms during the execution of a method 10 according to a second embodiment of the invention. The second embodiment essentially corresponds to the first embodiment of Figures 1 to 3, with the difference being the additional synchronization of the gear changes to a pedaling torque profile of the rider. In detail, the method 10 of the second embodiment additionally comprises determining a time-dependent pedaling torque profile 45 of the pedaling torque generated by the rider while pedaling. In particular, the pedaling torque profile 45 is tracked over time. Furthermore, a future time-dependent pedaling torque profile 45 is estimated based on the recorded time-dependent pedaling torque profile.
[0083] Preferably, the estimation of the future pedaling torque profile is based on the assumption that the rider, especially when pedaling smoothly, generates a pedaling torque which has a substantially sinusoidal profile over time.
[0084] In method 10 of the second embodiment, the switching signal 15 is generated such that a minimum of the estimated time-dependent pedaling torque profile occurs during the movement of the bicycle chain 4 by the switching device 3. In other words, the switching process is executed in such a time-controlled manner that the chain movement occurs during minimum pedaling torque values. In detail, the switching signal 15 is controlled in such a way as R.412420
[0085] - 14 - shows that the minimum 46 of the time-dependent pedaling torque curve 45, particularly in the middle, lies within the chain change time interval 33. This allows for a particularly low overall torque on the bicycle chain 4 during the shifting process, thus providing particularly low-wear shifting operations and therefore a long service life of the derailleur system 2.
Claims
R.412420 - 15 - Claims 1. Method for operating a gearshift (1) of an electric bicycle (100), wherein the gearshift (1) comprises a derailleur gear (2) with a shifting device (3) which is configured to move a bicycle chain (4) between different sprockets (5), comprising the steps: Detection of a switching signal (15), Actuating (11) the switching device (3) in response to the detected switching signal (15), Determining (12) a first chain change time (21) at which the bicycle chain (4) is moved by the shifting device (3) at the earliest, and reducing (13) a motor torque (25) of a drive unit (110) of the electric bicycle (100) at the first chain change time (21) to a predetermined shifting motor torque (26), wherein the determination (12) of the first chain change time (21) is based on a first time interval (31) between a start (23) of a movement of the shifting device (3) and an earliest movement of the bicycle chain (4).
2. The method of claim 1, further comprising the steps of: Determining (14) a second chain change time (22) at which the movement of the bicycle chain (4) by the shifting device (3) is at the latest terminated, and Increasing (19) the motor torque (25) of the drive unit (110) from the second chain replacement time (22).
3. Method according to claim 2, wherein the second chain change time (22) is determined based on the first chain change time (21) and a chain change time interval (33) required to move the bicycle chain (4) between the sprockets (5). R.412420 - 16 - 4. Method according to claim 2 or 3, wherein the second chain change time (22) is determined based on a second time interval (32) between the start (23) of the movement of the switching device (3) and a latest end of the movement of the bicycle chain (4).
5. Method according to one of the preceding claims, wherein determining (12) the first chain change time (21), in particular and / or the second chain change time (22), comprises determining (12a) a number of revolutions of the pinions (5), in particular from the detection of the switching signal (15).
6. Method according to claim 5, wherein the first chain change time (21), in particular and / or the second chain change time (22), is reached when the determined number of revolutions reaches a predefined number of switching revolutions.
7. Method according to claim 6, wherein the number of shift revolutions is individually defined for each gear change.
8. Method according to one of claims 5 to 7, wherein the determination (12a) of a number of revolutions of the pinion (5) is based on a pinion speed and / or based on a motor speed and an instantaneous gear ratio.
9. Method according to one of the preceding claims, wherein the determination (12) of the first chain change time (21), in particular and / or the second chain change time (22), is based on predefined time intervals for the movement of the switching device (3) and / or for the movement of the bicycle chain (4).
10. Method according to any one of claims 2 to 9, further comprising the steps: detecting (16) a fully completed gear change, in particular before the second chain change time (22) and: Increasing the engine torque (25) in response to the detection (16) of the fully completed gear change, or Preventing the reduction (13) of the motor torque (25). R.412420 - 17 - 11. Method according to any of the preceding claims, further comprising: determining a time-dependent pedaling torque profile (45), Estimating a future temporal pedaling torque profile (45) based on the recorded temporal pedaling torque profile (45), and Generating the switching signal (15) such that a minimum (46) of the estimated time-dependent pedaling torque profile (45) is present during the movement of the bicycle chain (4) by the switching device (3).
12. Method according to one of the preceding claims, wherein the detection of the switching signal (15) is based on a manually and / or automatically generated switching signal (15).
13. Electric bicycle, comprising: a gear shift (1) comprising a derailleur gear shift (2) with a shifting device (3) which is configured to move a bicycle chain (4) between different sprockets (5), in particular wherein the sprockets (5) are part of a cassette (101) on a rear wheel hub (102) of the bicycle (100), and a control unit (50) which is configured to carry out the method (10) according to one of the preceding claims.