Method for operating a drive assembly of a bicycle

Abstract

The invention relates to a method for operating a drive assembly (10) of a bicycle, in particular an electric bicycle (100), the drive assembly (10) comprising a gear shift mechanism (5). The method has the steps of: detecting (51) a temporal pedal frequency curve (80), determining (52) a derivation function of the temporal pedal frequency curve, determining (53) a crank acceleration by means of the determined derivation function, and detecting (54) a shifting process if: the determined crank acceleration exceeds a specified acceleration threshold value, a maximum in the temporal curve of the determined crank acceleration is detected, and a riding state of the bicycle is detected.

Description

[0001] Description

[0002] title

[0003] Method for operating a drive system of a bicycle

[0004] State of the art

[0005] The present invention relates to a method for operating a drive arrangement of a bicycle, and to a bicycle.

[0006] Bicycles, including e-bikes, are known to have a drive unit that generates motor torque to assist the rider's manual pedaling. Typically, the motor torque is generated in response to the rider's pedaling force. This often involves directly detecting the rider's pedaling torque, for example, using sensors. This frequently requires a complex and costly drive system for the e-bike.

[0007] Disclosure of the invention

[0008] The method according to the invention with the features of claim 1 is characterized, in contrast, by the fact that a shift detection can be provided in a particularly simple and cost-effective manner on a drive assembly of a bicycle. In particular, this allows for the simple, reliable, and cost-effective provision of optimized motor operation in the case of an electric bicycle. According to the invention, this is achieved by a method for operating a drive assembly of a bicycle, preferably an electric bicycle, wherein the drive assembly comprises a gear shift and wherein the method comprises the following steps:

[0009] Recording a cadence profile over time,

[0010] Determining a derivative function of the time-dependent cadence curve, determining a crank acceleration using the determined derivative function, and

[0011] Detecting a switching operation when:

[0012] - the measured crank acceleration exceeds a predetermined acceleration threshold, and

[0013] - a maximum is detected in the temporal course of the determined crank acceleration, and

[0014] - a riding condition of the bicycle is detected.

[0015] Preferably, the cadence is recorded using a sensor. The recording can be done directly or alternatively indirectly, for example by conversion.

[0016] In particular, the cadence profile over time is essentially determined in the form of a mathematical function.

[0017] Preferably, the derivative function is determined by differentiating the determined cadence curve over time. For example, the derivative function can be used to determine the instantaneous gradient of the cadence curve over time at a specific point in time.

[0018] Crank acceleration is specifically determined as the angular acceleration of the crank movement.

[0019] A shifting process is understood to mean, in particular, a change of gear, preferably from one gear to the next.

[0020] Preferably, the acceleration threshold corresponds to a value of at least 700 rpm / s and, in particular, a maximum of 1200 rpm / s. Particularly preferably, the signal can be filtered beforehand using a low-pass filter, especially with a time constant of 0.2 s, wherein the acceleration threshold in this case is preferably at least 30 rpm / s, in particular a maximum of 50 rpm / s, and most preferably 40 rpm / s. The maximum is considered to be, in particular, a point in the time course of the determined crank acceleration at which the gradient of the determined crank acceleration is zero, in particular wherein the gradient before the maximum is positive and, in particular, after the maximum is negative.

[0021] The term "riding state" is specifically defined as the movement of the bicycle, without any restart from a standstill.

[0022] In other words, the method detects a gear shift based on the acceleration of the crank movement when predetermined criteria are met, namely when the crank acceleration exceeds a high acceleration threshold. This threshold can only occur during a gear change, for example, due to the chain jumping from one sprocket to the next. The reliable detection of a gear shift can be further improved by the additional criterion of identifying the maximum point in the crank acceleration curve.

[0023] This method offers the advantage of enabling the reliable and simple detection of gear changes. By determining and analyzing crank acceleration, a particularly cost-effective data acquisition method can be provided, as simple and inexpensive sensors can be used. Furthermore, the calculation can be performed very efficiently. A particular benefit is that, especially with an e-bike, particularly one without direct rider torque measurement, the riding experience can be improved by quickly adjusting the additionally determined instantaneous gear ratio to the actual global gear ratio used on the bike. This results in a significantly higher level of user comfort for the cyclist.

[0024] The dependent claims describe preferred embodiments of the invention.

[0025] Preferably, the detection of the maximum in the temporal profile of crank acceleration is based on time-discrete, sequential values ​​of the measured crank acceleration. This means, for example, that instead of a completely continuous measurement of the cadence profile, a periodic measurement of time-discrete values ​​can be performed, perhaps using a high sampling rate. The detection of the maximum can then be achieved by comparing successive values ​​of the measured crank acceleration. This allows for a simple and cost-effective implementation of the method.

[0026] Preferably, the bicycle's riding state is detected when a detected cadence is at least equal to a predetermined riding cadence and when, simultaneously, a detected bicycle speed is at least equal to a predetermined riding speed. Preferably, the predetermined riding cadence is at least 2 rpm, more preferably at least 3 rpm. In particular, the predetermined riding speed is at least 2 km / h. This allows for a particularly simple determination that no restart from a standstill is currently taking place.

[0027] Preferably, determining the crank acceleration includes filtering the measured crank acceleration, in particular using a low-pass filter. This allows strong fluctuations in crank acceleration over short periods of time to be smoothed out, enabling simple and precise further processing of the measured data.

[0028] Particularly preferably, the method further includes the step of determining a gear ratio in response to the detection of a shifting operation. That is, each time a shifting operation is detected by the method, the instantaneous gear ratio of the bicycle's drivetrain is determined immediately in response. This allows, particularly in the case of an e-bike, a particularly effective way to ensure that the motor's operation is optimally matched to the rider's manual pedaling, thus enabling a particularly high level of riding comfort.

[0029] Furthermore, determining the translation ratio preferably includes the following steps:

[0030] - Continuous determination of an initial gear ratio based on a recorded cadence and bicycle speed,

[0031] - Providing a second gear ratio, particularly for use in functions of the drive system and / or the bicycle, and - updating the second gear ratio by the current first gear ratio when simultaneously:

[0032] - the recorded bicycle speed is greater than or equal to a predetermined threshold,

[0033] - an active driver intervention is detected,

[0034] - a predetermined trigger signal is detected, and

[0035] - no restart from a standstill is detected.

[0036] Continuous determination is defined in particular as the ongoing, uninterrupted determination of the first gear ratio. For example, this can be done discretely over time using a specific sampling rate. Preferably, various software functions or the like, which influence the operation of the bicycle, can be considered functions of the drive arrangement and / or the bicycle. For example, in the case of an electric bicycle, motor torque generation is considered a function. That is, the motor torque can be generated depending on the determined second gear ratio. In particular, updating the second gear ratio with the instantaneous value of the first gear ratio means that the instantaneous value of the second gear ratio is generated by an instantaneous value of the first gear ratio.Preferably, the predetermined speed threshold is at least 2 km / h, more preferably at least 4 km / h, and particularly preferably a maximum of 6 km / h. In particular, active rider intervention is defined as any interaction between the rider and the bicycle's drivetrain that generates a propulsive torque. That is, during active rider intervention, the rider's pedaling force at least partially generates a propulsive torque for the bicycle.

[0037] In other words, when the rider actively intervenes, the drivetrain is tensioned by the rider's pedaling force. In other words, the method uses two different gear ratios simultaneously at all times: a continuous first gear ratio and a global second gear ratio. The global second gear ratio is assumed to be the actual instantaneous gear ratio of the drive system and is used for all subsequent functions. In certain situations, when the aforementioned criteria are met, the second gear ratio is updated by the instantaneous first gear ratio. In all other situations and at all times, the currently valid second gear ratio is maintained. This allows the gear ratio of the drive system to be determined and provided in a particularly simple, cost-effective, and reliable manner.

[0038] Preferably, the trigger signal includes a gear change signal, which is generated in response to a detected gear change. For example, the gear change can be detected in response to an automatic actuation by a control unit, in particular by means of a gear change signal from a control unit. Alternatively or additionally preferably, the gear change can be detected in response to a shift command manually generated by the driver. Furthermore, alternatively or additionally preferably, the gear change can be determined automatically based on sensor signals. In particular, a recalculation of the gear ratio for the global second gear ratio is initiated with each detected gear change.

[0039] Preferably, the shifting process is detected based on the recorded cadence. Particularly preferably, this involves recording a cadence profile over time, determining a derivative function of the cadence profile over time, determining the crank acceleration using the determined derivative function, and detecting the shifting process when the determined crank acceleration exceeds a predetermined acceleration threshold, a maximum in the time-dependent crank acceleration is detected, and the bicycle's riding state is simultaneously recognized. This allows for software-based shift detection, making the detection of the shifting process particularly simple and cost-effective.

[0040] Preferably, the trigger signal includes a monitoring signal, which is generated by a monitoring unit. The monitoring unit can preferably be a software function of a control unit. In particular, the monitoring unit can alternatively be referred to as a "watchdog." This allows for particularly flexible initiation of the recalculation of the global second rate ratio. Thus, a highly adaptable execution of the method is possible, enabling simple and efficient operation. Furthermore, the trigger signal can be generated with precise accuracy to obtain highly reliable information about the current rate ratio. Most preferably, the monitoring signal is generated by the monitoring unit based on a comparison of the first and second rates.This means that to update the second translation ratio, the current relationship between the first and second translation ratios is considered relative to each other. This allows for a particularly targeted update of the second translation ratio, ensuring a high degree of accuracy.

[0041] Preferably, the monitoring unit integrates the difference between the first and second gear ratios over time and generates the monitoring signal when the result of the integration reaches or exceeds a predetermined trigger threshold. In other words, the trigger signal is generated when the cumulative difference between the first and second gear ratios exceeds a threshold over time. This provides a particularly simple and efficient way to obtain precise information about the actual instantaneous gear ratio.

[0042] Active driver intervention is particularly likely to be detected using the following steps:

[0043] Recording cadence,

[0044] Detecting an initial rear wheel speed,

[0045] Determining a second rear wheel speed using the recorded cadence,

[0046] Determining a speed threshold by multiplying the determined first rear wheel speed by a predetermined factor, and detecting active driver intervention when the determined second rear wheel speed is at least equal to the determined speed threshold.

[0047] In particular, the first rear wheel speed is directly detected, for example, using a speed sensor. Alternatively, the first rear wheel speed can be calculated from a detected bicycle speed. Preferably, the second rear wheel speed is determined using a known rear wheel circumference. More preferably, the first rear wheel speed is determined using the instantaneous second gear ratio. Preferably, the predetermined factor has a value less than 1, preferably greater than 0.5. This allows active rider input to be reliably detected using simple and cost-effective means.

[0048] Preferably, the continuous determination of the first gear ratio includes filtering the recorded cadence, preferably using a first-order low-pass filter. This smooths out fluctuations in the recorded cadence, making the further determination of the gear ratios particularly simple and precise.

[0049] Preferably, the continuous determination of the first gear ratio comprises determining the rear wheel rotational speed using the recorded bicycle speed and a known rear wheel circumference, and determining the ratio of the determined rear wheel rotational speed to the determined cadence. That is, the first gear ratio can be calculated directly using the rear wheel rotational speed, the known rear wheel circumference, and the cadence. This allows the first gear ratio to be calculated precisely and reliably at any time using simple and cost-effective means.

[0050] Preferably, the drive arrangement comprises a motor configured to generate motor torque to assist the rider's pedaling force. The method preferably further includes the step of generating motor torque only during detected active rider input. That is, the generation of motor torque, preferably controlled, only occurs when the method positively detects active rider input. In particular, the generation of motor torque, preferably actively controlled, is prevented when no active rider input is detected. This allows the motor torque to be provided simply and precisely only while the rider is actively pedaling, i.e., actively generating at least a portion of the propulsive torque to move the bicycle forward using muscle power.Precise detection of active rider input and corresponding adjustment of the motor operation enables particularly reliable and comfortable bicycle operation. Preferably, the generation of motor torque depends on a ratio between the first and second rear wheel speeds. Alternatively or additionally, preferably, motor torque generation is prevented when free pedaling is detected. In particular, the motor torque can be generated gradually depending on the ratio between the first and second rear wheel speeds, provided this ratio is greater than or equal to a predetermined threshold.

[0051] Furthermore, the invention leads to an electric bicycle drive system comprising a drive assembly and a control unit. The control unit is configured to carry out the described method. The invention also relates to a bicycle, in particular an electric bicycle with an electric bicycle drive system.

[0052] Preferably, the drive arrangement includes a motor. Preferably, the control unit is additionally configured for controlled actuation of the motor. The motor is preferably arranged on a hub of the bicycle, preferably a rear wheel hub. In other words, the bicycle is an electric bicycle with a hub drive. Alternatively, and preferably, the motor can also be arranged in the area of ​​a bottom bracket of the bicycle, so that it is, in particular, a bicycle with a mid-drive motor.

[0053] The electric bicycle drive system, drive arrangement, or bicycle / electric bicycle is particularly preferably designed to be completely free of torque sensors and / or bearing force sensors. This means that, in particular, no torque sensor and / or bearing force sensor is present for detecting pedal actuation. This allows for a particularly simple and cost-effective bicycle design. The drive arrangement is operated without torque sensors and / or bearing force sensors using the method according to the invention. The method according to the invention is used to operate the drive arrangement without torque sensors and / or bearing force sensors. This means that no sensor data from a torque sensor and / or a bearing force sensor is used to detect pedal actuation.

[0054] Brief description of the drawings: The invention is described below with reference to an exemplary embodiment in conjunction with the figures. In the figures, functionally identical components are each identified by the same reference numerals. The figures show:

[0055] Figure 1 shows a simplified schematic view of a bicycle in which a method according to a preferred embodiment of the invention is carried out.

[0056] Figure 2 shows a highly simplified schematic view of the method according to the invention.

[0057] Figure 3 shows a highly simplified schematic detail of the method according to the invention.

[0058] Figure 4 shows a further highly simplified schematic detail of the method according to the invention.

[0059] Figure 5 shows a further highly simplified schematic detail of the method according to the invention, and

[0060] Figure 6 shows an exemplary cadence curve over time, which occurs during the

[0061] The procedure can be used to carry it out.

[0062] Embodiments of the invention

[0063] Figure 1 shows a simplified schematic view of a bicycle 100 with a drive arrangement 10, in which a method 1 according to a preferred embodiment of the invention is carried out.

[0064] The bicycle 100 is an electric bicycle 100, which features a hub drive. Specifically, the electric bicycle 100 comprises a motor that is located on the hub of one of the rear wheels 110 of the electric bicycle 100.

[0065] In an alternative (not shown) preferred embodiment, the electric bicycle 100 can also be a mid-drive motor in which the motor is arranged in the area of ​​a bottom bracket. In particular, the motor is designed as an electric motor and can be supplied with electrical energy by means of an electrical energy storage device 109 of the electric bicycle 100.

[0066] A motor torque generated by the motor of the drive arrangement 10 can provide motor support to the pedaling force generated by muscle power of a rider of the electric bicycle 100.

[0067] The rider's muscle power can be applied via a crank mechanism comprising cranks 104. The crank mechanism is connected to the hub of the rear wheel 110 via a chain drive.

[0068] The drive arrangement 10 also includes a gearshift 5, which has several different gears. The gearshift 5 is preferably designed as a derailleur gearshift, with several different sprockets.

[0069] Preferably, the gear shift 5 can be operated manually by the rider of the electric bicycle 100, and / or automatically controlled by a control unit 50 of the electric bicycle 100.

[0070] The control unit 50 of the electric bicycle 100 can, for example, be integrated into the drive arrangement 10. The control unit 50 is configured for the controlled actuation of the motor and for carrying out the method 1 of the preferred embodiment.

[0071] When the electric bicycle 100 is in operation, the motor torque is provided depending on the pedaling force generated by the rider.

[0072] The method 1 according to the invention offers the advantage that the operation of the electric bicycle 100 can be enabled in a particularly simple and cost-effective manner. Specifically, it allows for the operation of the motor that is dependent on pedal actuation, thereby eliminating the need for torque sensors and bearing force sensors. The electric bicycle 100 is preferably designed without torque sensors and bearing force sensors.

[0073] The method 1 according to the invention is described in detail below with reference to Figures 2 to 6. Method 1 essentially comprises three main functions: an engagement detection 11, a transmission ratio determination 12, and a switching detection 13 (see Figure 2). It should be noted that these three main functions can at least partially overlap, interact with each other, and be interdependent. Based on the aforementioned functions of method 1, the generation 30 of the motor torque takes place.

[0074] Figure 3 shows a highly simplified schematic detail of method 1 of the preferred embodiment. Figure 3 shows the intervention detection 11 in more detail. This preferably includes simultaneously detecting 21 the speed of the electric bicycle 100, detecting 23 a first rear wheel rotation speed, and detecting 22 a pedaling cadence.

[0075] The bicycle speed can be calculated based on the recorded first rear wheel rotation speed and an instantaneous gear ratio, or alternatively, preferably, it can be recorded directly using a speed sensor.

[0076] The first rear wheel rotation speed is preferably detected directly by means of a speed sensor.

[0077] The cadence is preferably recorded using a cadence sensor.

[0078] Furthermore, a second rear wheel speed is determined using the detected cadence and an instantaneous gear ratio of the drive train of the electric bicycle 100. The instantaneous gear ratio can preferably be provided using function 12 of method 1, as described later.

[0079] Subsequently, a speed threshold value is determined by multiplying the determined first rear wheel speed by a predetermined factor. The factor is preferably less than 1 and in particular has the value 0.7. Based on the determined values, a detection step 20 is then carried out in which the presence of various operating states of the electric bicycle 100 can be detected.

[0080] Active rider intervention is detected when the measured second rear wheel speed is at least equal to the measured speed threshold. This means that in this case, it is recognized that the rider is actively interacting with the drivetrain and contributing to the propulsive torque of the e-bike by means of their pedaling force.

[0081] In method 1, the generation of engine torque occurs only when active driver intervention is detected. In other operating states, where no active driver intervention is detected, no engine torque is provided and / or the provision of engine torque is actively prevented.

[0082] Alternatively or additionally, preferably, the generation of motor torque 30 can be achieved depending on the ratio of the first rear wheel speed and the second rear wheel speed. In particular, the assistance is gradually released depending on the speed ratio when the ratio of the two rear wheel speeds exceeds a certain value.

[0083] Detection step 20 further includes the detection of free-pedaling (27) when, after the end of a detected rider intervention, the determined rear wheel rotational speed is less than or equal to the determined rotational speed threshold. This means that in this case, the electric bicycle 100 can move at a certain positive speed and a certain cadence may also be present, but there is no rider intervention. Therefore, pedaling does not contribute to the propulsive torque of the electric bicycle 100.

[0084] Furthermore, detection step 20 includes the detection 28 of a standstill of the electric bicycle 100 if the detected bicycle speed and, additionally, the detected cadence are less than or equal to a respective predefined standstill threshold. That is, at low bicycle speed and low cadence, the standstill of the electric bicycle 100 is detected. Furthermore, detection step 20 includes the detection 29 of a movement initiation of the electric bicycle 100 if the detected bicycle speed is greater than or equal to a predefined initialization speed and if, at the same time, the detected cadence is less than or equal to a predefined initialization cadence.This means that in this case, in particular after switching on the drive arrangement 10 of the electric bicycle 100, a positive speed can be present, or, for example, the electric bicycle 100 can start rolling from a standstill, for example due to a slope, without a pedaling frequency.

[0085] Figure 4 shows a further highly simplified schematic detail of method 1 of the preferred embodiment of the invention. Figure 4 illustrates the determination of the translation ratio 12 in more detail.

[0086] In method 1, two different translation ratios are used simultaneously at all times: a continuous first translation ratio and a global second translation ratio.

[0087] The global second transmission ratio is determined in step 42 and assumed to be the actual instantaneous transmission ratio of the drive arrangement 10.

[0088] The second gear ratio provided in step 42 is used for further functions of the drive arrangement 10 and / or the electric bicycle 100. In detail, the second gear ratio determined in step 42 is used to generate the motor torque, which is generated during active rider intervention depending on the determined gear ratio.

[0089] Furthermore, the process continuously determines the first gear ratio 41, which is calculated based on the recorded cadence and bicycle speed. The recorded cadence is also filtered using a first-order low-pass filter. The first gear ratio is then calculated as the ratio of a determined rear wheel rotational speed to the filtered cadence. The rear wheel rotational speed is calculated using the recorded bicycle speed and the known rear wheel circumference. Under certain conditions, the second gear ratio 43 is updated by the current first gear ratio.This means that when update 43 is executed, the currently valid value of the global second translation ratio is replaced by the current value of the first translation ratio. In particular, the current global second translation ratio is maintained as long as no update 43 is requested.

[0090] Update 43 is performed when the following criteria are met simultaneously:

[0091] - the recorded bicycle speed is greater than or equal to a predetermined threshold,

[0092] - active driver intervention is detected by means of intervention detection 11 ,

[0093] - a predetermined trigger signal is detected, and

[0094] - a driving condition 15 of the electric bicycle 100 is detected.

[0095] Driving condition 15 is specifically defined as a state of the electric bicycle 100 in which there is no restart from a standstill. This means that the electric bicycle 100 moves at a predetermined minimum speed.

[0096] The detection of the trigger signal is indicated by step 16 in Figure 4.

[0097] The trigger signal includes a gear change signal, which is generated in response to a detected gear change. Gear change detection is performed using function 13 of method 1, as described later.

[0098] Alternatively or additionally, preferably, the trigger signal includes a monitoring signal, which is generated by a monitoring unit. For example, such a monitoring unit can also be referred to as a "watchdog." The monitoring signal is generated by the monitoring unit based on a comparison of the first and second gear ratios. Here, the difference between the first and second gear ratios is integrated over time, and the monitoring signal is generated when the result of the integration reaches or exceeds a predetermined trigger threshold.

[0099] Alternatively or additionally, preferably, the monitoring unit can generate the monitoring signal after a predetermined period of time.

[0100] The gear ratio determination 12 thus allows for a particularly simple and cost-effective way to precisely determine and provide the current estimated actual gear ratio. The determination of the continuous first gear ratio can be carried out in a particularly simple manner and without complex and expensive sensor technology. Because the second gear ratio actually used is only updated by the first gear ratio according to certain criteria, a high degree of precision in the gear ratio used can be provided in a simple way, especially since large fluctuations in the first gear ratio, which can occur, for example, due to operational reasons in certain operating situations of the electric bicycle 100, are not taken into account.

[0101] Figure 5 shows a further highly simplified schematic detail of method 1 of the preferred embodiment of the invention. In Figure 5, the switching indicator 13 is shown in a highly simplified schematic representation.

[0102] The shift detection 13 is based on the detection of jumps 81 in the temporal course of the cadence 80, as shown in simplified form in Figure 6.

[0103] In the switching detection 13, the temporal cadence profile 80 is first recorded 51 during the operation of the electric bicycle 100. Based on the temporal cadence profile 80, a derivative function of the temporal cadence profile 80 is then determined 52.

[0104] Furthermore, a crank acceleration 53 is determined using the determined derivative function. In particular, in step 53, a time course of the crank acceleration is generated based on the derivative function. Preferably, the determination 53 of the crank acceleration also includes filtering the determined crank acceleration using a low-pass filter. The detection 54 of a switching operation then occurs when the following criteria are met simultaneously:

[0105] - The measured crank acceleration exceeds a predetermined acceleration threshold,

[0106] - a maximum is detected in the temporal progression of the determined crank acceleration, and

[0107] - a driving condition 15 of the electric bicycle 100 is detected.

[0108] Preferably, the driving state 15 of the electric bicycle 100 can be recognized, in particular analogous to the function 12 described above, if the detected cadence is at least equal to a predetermined driving cadence and if, at the same time, a detected bicycle speed is at least equal to a predetermined driving speed.

[0109] Preferably, the crank acceleration is determined and provided in discrete sequential values. The maximum in the temporal progression of the crank acceleration is identified based on these discrete sequential values, particularly when an increasing value is detected in a previous epoch and a decreasing value is detected in the current epoch.

[0110] The shift detection 13 is therefore based on the detection of high, sudden changes in cadence that occur during shifting operations when the power transmission to the sprockets of the cassette is interrupted for a brief moment during the shifting process.

[0111] The specific criteria of the inventive method 1 allow for a particularly simple execution of the detection process while simultaneously enabling particularly precise detection of the switching operations. In particular, false detections can be reliably avoided as a result.

[0112] A switching operation detected in step 54 can then be used to initiate a recalculation of the transmission ratio in the transmission ratio determination 12, as described above.

Claims

Claims 1. Method for operating a drive arrangement (10) of a bicycle, in particular an electric bicycle (100), wherein the drive arrangement (10) comprises a gear shift (5), comprising the steps: Recording (51) a cadence profile over time (80), determining (52) a derivative function of the cadence profile over time, determining (53) a crank acceleration using the determined derivative function, and Detect (54) a switching operation when: - the measured crank acceleration exceeds a predetermined acceleration threshold, and - a maximum is detected in the temporal course of the determined crank acceleration, and - a riding condition of the bicycle is detected.

2. Method according to claim 1, wherein the detection of the maximum in the temporal course of the crank acceleration is based on temporally discrete sequential values ​​of the determined crank acceleration.

3. Method according to one of the preceding claims, wherein the riding state of the bicycle is recognized when a detected cadence is at least equal to a predetermined riding cadence and when a detected bicycle speed is at least equal to a predetermined riding speed.

4. Method according to one of the preceding claims, wherein determining (53) the crank acceleration comprises: filtering the determined crank acceleration, in particular by means of a low-pass filter.

5. A method according to any of the preceding claims, further comprising the step of: Determining a translation ratio in response to the detection (54) of a switching operation.

6. The method of claim 5, wherein determining the gear ratio comprises: continuously determining (41) a first gear ratio based on a detected cadence and a detected bicycle speed, Providing (42) a second transmission ratio, in particular for use in functions of the drive assembly (10) and / or the bicycle, and Updating (43) the second translation ratio by the current first translation ratio when simultaneously: - the recorded bicycle speed is greater than or equal to a predetermined threshold, - an active driver intervention is detected, - a predetermined trigger signal is detected, and - no restart from a standstill is detected.

7. Method according to claim 6, wherein the trigger signal comprises a gear change signal which is generated in response to a detected gear change.

8. Method according to one of claims 6 or 7, wherein the trigger signal comprises a monitoring signal which is generated in a controlled manner by means of a monitoring unit, in particular wherein the monitoring signal is generated by the monitoring unit based on a comparison of the first translation ratio with the second translation ratio, preferably wherein the monitoring unit integrates a difference between the first translation ratio and the second translation ratio over time and generates the monitoring signal when a predetermined trigger threshold is reached or exceeded.

9. Method according to any one of claims 6 to 8, wherein the active driver intervention is detected by means of the following steps: Recording (22) the cadence, Detecting (23) a first rear wheel rotation speed, in particular directly by means of a speed sensor, Determining (24) a second rear wheel speed using the detected cadence, Determining (25) a speed threshold by multiplying the determined first rear wheel speed by a predetermined factor, and detecting (26) the active rider intervention when the determined second rear wheel speed is at least equal to the determined speed threshold.

10. Method according to any one of claims 6 to 9, wherein the continuous determination (41) of the first translation ratio comprises: filtering the detected cadence, in particular by means of a first-order low-pass filter, and / or Determining the rear wheel speed using the recorded bicycle speed and a previously known rear wheel circumference, and determining the ratio of the determined rear wheel speed to the determined pedaling frequency.

11. Method according to any one of claims 6 to 10, further comprising the step: Generating (30) a motor torque depending on the second transmission ratio, in particular wherein the motor torque is generated exclusively during the detected active driver intervention.

12. Method according to any of the preceding claims, further comprising the step of: Generating (30) the engine torque as a function of a ratio of first rear wheel speed and second rear wheel speed 13. Electric bicycle drive system comprising: a drive arrangement (10), and a control unit (50) which is configured to carry out the method according to one of the preceding claims.

14. Electric bicycle drive system according to claim 13, wherein the drive arrangement (10) comprises a motor (1) which can be arranged on a hub of the electric bicycle (100).

15. Electric bicycle drive system according to claim 13 or 14, wherein the bicycle or the drive arrangement (10) is designed without a torque sensor and / or bearing force sensor.

16. Bicycle, in particular an electric bicycle (100), comprising an electric bicycle drive system according to any one of claims 13 to 15.

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