A TRANSMISSION SYSTEM FOR A BICYCLE

Abstract

A transmission system for a bicycle, wherein the system comprises a driver element configured and arranged to rotate about an axis. The transmission system comprises a cassette of sprockets mounted on the driver element to rotate together. The transmission system comprises a shifting unit arranged to move the cassette of sprockets in axial direction on the driver element. The shifting unit comprises an actuator element arranged to actuate the movement of the cassette of sprockets on the driver element. The actuator element is at least partially positioned between the driver element and the axis, and/or the actuator element is at least partially positioned in axial direction next to the driver element.

Claims

1. A transmission system for a bicycle comprising: one cassette of sprockets including at least a first and a second sprocket and configured to rotate about a rotational axis; and an actuator element configured to move the cassette in an axial direction of the rotational axis.

2. The system according to claim 1, wherein the cassette is mounted on a driver element.

3. The system according to claim 2, wherein the actuator element is at least partially positioned between the driver element and the rotational axis, and/or wherein the actuator element is at least partially positioned in the axial direction next to the driver element or on the driver element.

4. The system according to claim 2, wherein the system further comprises an axle coaxially arranged with respect to the driver element, and wherein the driver element is rotatable around the axle about the rotational axis.

5. The system according to claim 4, wherein the actuator element is positioned between the driver element and the axle.

6. The system according to claim 4, wherein the actuator element is mounted on the axle.

7. The system according to claim 4, wherein the actuator element is positioned inside the axle.

8. The system according to claim 4, wherein the actuator element is positioned on the driver element.

9. The system according to claim 4, wherein the actuator element comprises an electric actuator and/or electric motor, wherein the actuator element is powered by a power source, wherein the power source is mounted on or inside the axle.

10. (canceled)

11. The system according to claim 2, wherein the system further comprises a torque transfer element arranged to transfer torque from the cassette of sprockets to the driver element in a rotational direction about the rotational axis and to allow for a relative axial movement between the cassette of sprockets and the driver element.

12. The system according to claim 11, wherein the torque transfer element comprises a spring member arranged to flex in axial direction for allowing the relative axial movement between the cassette of sprockets and the driver element.

13. The system according to claim 2, wherein the system further comprises a position sensor arranged to sense a relative position of the cassette of sprockets and the driver element.

14. The system according to claim 2, wherein the system further comprises a force transfer element arranged for transferring a force in axial direction between the actuator element and the cassette of sprockets.

15. The system according to claim 14, wherein the force transfer element is rotationally coupled to the driver element.

16. The system according to claim 4, wherein a position sensor is positioned between a force transfer element and the axle.

17. The system according to claim 2, wherein a shifting unit is actuated using force generated by rotation of the driver element.

18. (canceled)

19. (canceled)

20. The system according to claim 1, wherein the sprockets are axially spaced from each other with a distance of less than 3.5 mm.

21.-33. (canceled)

34. The system according to claim 2, comprising a hub shell for coupling to a driven wheel of the bicycle, the hub shell being connected or connectable to the cassette of sprockets, wherein the system further comprises a hub transmission for imposing at least a first transmission ratio and a second transmission ratio between the driver element and a hub shell, and/or between the cassette of sprockets and the driver element.

35.-37. (canceled)

36. The system according to claim 34, wherein the system further comprises a hub shell, and wherein the hub transmission is contained by the hub shell.

37. The system according to claim 36, wherein the hub transmission is removably couplable to the hub shell.

38. The system according to claim 34, wherein the system further comprises a first freewheel arranged between the driver element and an input of the hub transmission to allow relative rotation between the driver element and the hub transmission input in one rotation direction and transmit torque in a second rotation direction opposite the first direction.

39. (canceled)

40. (canceled)

41. The system according to claim 34, wherein the first and second transmission ratios differ from each other by an amount that corresponds to approximately half of a sprocket ratio of a pair of consecutive sprockets of the cassette of sprockets.

42.-70.

71. A rear hub assembly comprising a transmission system according to claim 2.

72. (canceled)

73. (canceled)

74. A bicycle comprising a bicycle frame with a fork, and a rear wheel, having a rear hub assembly according to claim 2, arranged in the fork, wherein the cassette of sprockets is axially movable on the driver element between two extreme positions, and wherein in at least one of the two extreme positions an axial spacing between a sprocket of the cassette and the bicycle frame is at most 2 mm.

75. (canceled)

76. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0084] Embodiments of the present invention will now be described in detail with reference to the accompanying drawings in which:

[0085] FIG. 1A shows an example of a transmission system for a bicycle with the cassette of sprockets distal to a bicycle frame;

[0086] FIG. 1B shows an example of a transmission system for a bicycle with the cassette of sprockets proximal to a bicycle frame;

[0087] FIGS. 2A and 2B show a schematic example of a tensioner;

[0088] FIGS. 3A and 3B show schematic representations of respective examples of a transmission system comprising a hub transmission;

[0089] FIG. 4 shows a schematic representation of an example of a transmission system for selectively engaging two transmission modes;

[0090] FIG. 5 shows a schematic representation of a flow chart of a control unit;

[0091] FIG. 6A shows an example of a transmission system for a bicycle mounted to a bicycle frame, wherein the cassette of sprockets is positioned distal to the bicycle frame;

[0092] FIG. 6B shows an example of a transmission system for a bicycle mounted to a bicycle frame, wherein the cassette of sprockets is positioned proximal to the bicycle frame;

[0093] FIG. 7 shows a schematic representation of a flow chart of a method for operating a bicycle transmission system;

[0094] FIG. 8 shows a bicycle.

DETAILED DESCRIPTION

[0095] FIGS. 1A and 1B show examples of a transmission system 1 for a bicycle. The transmission system 1 comprises a driver element 2. The driver element 2 is configured and arranged to rotate about an axis 4. The transmission system 1 comprises a cassette of sprockets 6. Here, the cassette has six sprockets, but it will be appreciated the cassette may have any other number of sprockets, such as one, two three, four, five, seven, eight or nine sprockets.

[0096] The sprockets are arranged to selectively engage an endless drive member 16. The endless drive member 16 is here embodied as a chain, but it will be appreciated that other options are also possible, such as a belt. The sprockets of the cassette are, here, fixed to each other. The sprockets of the cassette 6 are, in this example, arranged in geometrical order. The sprockets particularly extend in parallel sprocket planes, which sprocket planes are parallel to a drive plane in which the endless drive member 16 extends.

[0097] The cassette of sprockets 6 is mounted on the driver element 2 to rotate together. The cassette of sprockets can be driven via the endless drive member 16. The endless drive member may for example also engage a front chain wheel of the bicycle attached to a crank.

[0098] Torque can be transmitted between the cassette of sprockets 6 and the driver element 2 about the axis 4. The cassette 6 and the driver element 2 are movable relative to one another in axial direction. The cassette of sprockets 6 is in this example particularly movable in axial direction relative to the driver element 2 from a first position as shown in FIG. 1A, and a second position as shown in FIG. 1B.

[0099] The transmission system 1 comprises a shifting unit. The shifting unit is arranged to move the cassette of sprockets 6 in axial direction on the driver element 2, so as to select an appropriate sprocket. In particular, the shifting unit is arranged to axially move the cassette 6, so as to align any one of the sprockets with the endless drive member 16. FIG. 1A shows a first outermost, here the largest, sprocket of the cassette 6 being aligned with the endless drive member 16, and FIG. 1B shows a second outermost, here the smallest sprocket of the cassette 6 being aligned with the endless drive member 16. Hence, the cassette 6 can be moved in axial direction between two axially extreme positions, here an axially outward most position as shown in FIG. 1A, and an axially inward most position as shown in FIG. 1B. It will be appreciated that the cassette may assume any position in between the inward and outward most positions, to align any sprocket in between the two outermost sprockets with the endless drive member 16. The shifting unit may be arranged to axially move the cassette between indexed axial positions. The shifting unit may for example move the cassette between a finite set of preprogrammed axial positions relative to the drive element 2. The indexing may be adapted to the cassette 6, e.g. to the number of sprockets, and the axial spacing between the sprockets. In this example, the shift unit is arranged to move the cassette 6 between six preprogrammed axial positions, each position corresponding to a sprocket of the cassette 6 being aligned with the endless drive member 16.

[0100] The drive plane in which the endless drive member extends, is preferably fixed relative to the driver element 2, and is for example positioned approximately halfway between opposite axial ends of the driver element 2. In this example, an axial dimension of the cassette 6, here a axial distance between the largest sprocket and the smallest sprocket, is approximately half of the distance between opposite axial ends of the driver element 2.

[0101] The system 1 can further comprise a tensioner 60 for tensioning the endless drive member 16. An schematic example of a tensioner is shown in FIGS. 2A and 2B. The tensioner 60 can comprise two pulley wheels 61, 62 and a spring. The tensioner can further comprise a friction element arranged to generate friction in at least one direction of motion of the endless drive member 16.

[0102] The shifting unit comprises an actuator element 8. The actuator element 8 is arranged to actuate the movement of the cassette of sprockets 6 on the driver element 2. The actuator element 8 is in this example at least partially positioned between the driver element 2 and the axis 4. The actuator element 8 is may additionally or alternatively be positioned at least partially in axial direction next to the driver element 2. In FIG. 1A the cassette of sprockets 6 is shown in an outward axial position. In FIG. 1B the cassette of sprockets 6 is shown in an inward axial position.

[0103] The transmission system 1 can comprise an axle 10, e.g. a hollow axle, coaxially arranged with respect to the driver element 2, and the driver element 2 can be rotatable around the axle 10 about the axis 4. The axle 10 can be at least partially formed by a wheel axle, e.g. a rear wheel axle of a bicycle. The axle 10 may be fixed to a frame of the bicycle, for example between dropouts of the frame. The actuator element 8 is, here, positioned between the driver element 2 and the axle 10. The actuator element 8 is in this example mounted on the axle 10. The actuator element 8 can alternatively be positioned inside the axle 10, e.g. in a cavity of the axle 10. The actuator element 8 can comprise an electric motor. The actuator element 8 can be powered by a power source, e.g. an electric power source such as a battery, wherein the power source can be mounted on or inside the axle 10.

[0104] The transmission system 1 can further comprises a torque transfer element 12. The torque transfer element 12 can be arranged to transfer torque from the cassette of sprockets 6 to the driver element 2 in a rotational direction about the axis 4 and to allow for a relative movement between the cassette of sprockets 6 and the driver element 2 in an axial direction. The torque transfer element 12 can comprise a spring member arranged to flex in axial direction for allowing the relative axial movement between the cassette of sprockets 6 and the driver element 2. The transmission system 1 can further comprise a position sensor arranged to sense a relative position of the cassette of sprockets 6 and the driver element 2.

[0105] The transmission system 1 can further comprise a force transfer element 14 arranged for transferring a force in axial direction between the actuator element 8 and the cassette of sprockets 6. The force transfer element 14 can be rotationally coupled to the driver element 2. The force transfer element 14 can be rotatable, e.g. together with the driver element 2, relative to the actuator element 8. Alternatively, the force transfer element can be rotationally coupled to the actuator element, and can be rotatable relative to the driver element 2. The position sensor can be positioned between the force transfer element 14 and the axle 10. Switching the endless drive member from one sprocket to the next can be induced by rotation of the driver element 2. The sprockets can be spaced equidistantly from each other in axial direction. The sprockets can be axially spaced from each other with a distance of less than 3.5 mm, preferably less than 3.3 mm, more preferably less than 3.0 mm. The cassette of sprockets 6 comprises at most 9 sprockets, such as at most 8, 7, 6 or 5 sprockets.

[0106] The transmission system 1 can further comprise a hub transmission 18. The hub transmission 18 can impose at least a first transmission ratio and a second transmission ratio between the driver element 2 and a hub shell. The hub transmission 18 is in this example, at least partially, positioned in axial direction next to the driver element 2. The system 1 can further comprise a hub shell 20. The hub shell here contains the hub transmission, e.g. the hub shell can be positioned diametrically adjacent to the hub transmission 18. The hub shell 20 can be removably couplable to the hub transmission 18, to allow a wheel change without having to change the hub transmission 18. The system 1 can further comprise a first freewheel 22 arranged between the driver element and an input of the hub transmission 18, to allow relative rotation between the driver element 2 and the hub transmission 18 input in one direction, e.g. a non-driving direction, and transmit torque in the opposite direction, e.g. a driving direction.

[0107] FIGS. 2A and 2B show a schematic example of a tensioner 60. The tensioner 60 comprises an upper pully wheel 61 and a lower pully wheel 61. The tensioner 60 also comprises a cage member 64. The upper and lower pully wheels 61, 62 are rotatably mounted to the cage member 64. The tensioner 60 also comprises a base member 65. The base member 65 can be, e.g. pivotably, mounted to the bicycle frame. The cage member 64 is here pivotable about a first pivot axis 66. Hence, here, the upper and lower pully wheels 61, 62 are pivotable, along with the cage member 64, about the first pivot axis 66. The upper and lower pullies 61, 62 extend in the same plane, which plane particularly corresponds to drive plane in which the endless drive member 16 extends.

[0108] Here, the upper and lower pully wheels 61, 62 are jointly pivotable about the first pivot axis 66, but it will be appreciated that the first and second pully wheels 61, 62 may be independently pivotable about the first pivot axis 66. For example, the cage member 64 may include a first pivot arm associated with the first pully wheel 61 and a second pivot arm associated with the second pully wheel 62, wherein the first and second pivot arms are independently pivotable about the first pivot axis 66.

[0109] The base member 65 is here pivotable about a second pivot axis 67. The base member 65 and the cage member 64 are, here, coupled to each other at the first pivot axis 66. The base member 65 may be mounted to the frame at the second pivot axis 67. Here, the second pivot axis 67 is concentric with the cassette 6. The second pivot axis 67 and the rotational axis 4 of the cassette 6 hence coincide in this example. The second pivot axis 67 may alternatively be eccentric with respect to the cassette 6, such that the second pivot axis 67 is offset from the rotational axis 4.

[0110] Here, the first pivot axis 66 is offset from the respective rotation axis of the upper and lower pully wheels 61, 62. The first pivot axis 66 may alternatively coincide with the rotation axis of the upper pully wheel 61.

[0111] FIG. 2A shows the tensioner 60 in a first state, associated with the endless drive member 16 engaging a relatively large-radius sprocket of the cassette 6. FIG. 2B shows the tensioner 60 in a second state associated with the endless drive member 16 engaging a relatively small-radius sprocket of the cassette 6. To account for the radius difference between the sprockets, in relation to the fixed length of the endless drive member 16, the tensioner 60 is movable between the first state and the second state, in accordance with the endless drive member 16 being shifted between the sprockets of the cassette. It will be appreciated that the cassette 6 may include more than two sprockets, for example sized between the sprockets shown in FIGS. 2A, 2B, and that the tensioner can accordingly assume a state between the first and second state. The first and second states as shown in FIGS. 2A and 2B may correspond to respective extreme states of the tensioner 60. The tensioner 60 may be spring biased towards the second state, as shown in FIG. 2B. A resistance mechanism may be provided to provide a friction resistance to the movement of the tensioner 60 between the first and second state, to prevent bouncing of the endless drive member 16 and facilitate shifting of the endless drive member 16 while riding. As the cassette 6 can be moved laterally along the rotation axis 4, the tensioner 60 need not be moved in axial direction, along the axis 4, to effect a gear shift. The tensioner 60 may hence be maintained in an axially fixed position relative to the driver element in use.

[0112] FIGS. 3A and 3B show a schematic representation of respective examples of a transmission system 1 comprising an exemplary hub transmission 18. The hub transmission 18 is, here, operable according to two transmission ratios, e.g. a first transmission ratio and a second transmission ratio. The first transmission ratio may be a 1:1 ratio. The second transmission ratio may be a speed reducing or increasing transmission ratio, wherein the driver element 2 is coupled to the hub shell 20 via, e.g. a reduction step or increase step imposed by a planetary gear system 21. It will be appreciated that the hub transmission 18 can also be operable according to more than two transmission ratios, such as three or four transmission ratios. In this example, the hub transmission 18 comprises a planetary gear system. In the example of FIG. 3A, the planetary gear system is in particular a sunless planetary gear system, including a ring gear, here two differently sized ring gears 32, 36, a planet gear, here two differently sized planet gears 42, 46, and a planet carrier 44. In the example of FIG. 3B, the planetary gear system is in particular a ringless planetary gear system, including a sun gear, here two sun gears 28, 29, a planet gear, here two differently sized planet gears 42, 46, and a planet carrier 44.

[0113] The hub transmission 18 is here provided between the hub shell 20 and the axle 10. The hub transmission 18 includes an intermediate shell 19 which forms an output of the hub transmission 18. The intermediate shell 19 is detachably couplable to the hub shell 20, such that the hub transmission 18, and the driver element 2 and cassette 6, can be separated from the wheel. This way, a wheel of the bicycle can be changed, without having to change the hub transmission 18, driver element 2 and cassette 6.

[0114] The driver element 2 is here integrated with an input of the hub transmission 18, here comprising by a first gear wheel 32 and a second gear wheel 36. The first gear wheel 32 and the second gear wheel 36 are in this example rigidly connected to each other.

[0115] The first gear wheel 32 is couplable to the intermediate shell 19, here via a freewheel 34 and clutch 35, for operating the hub transmission according to a first transmission ratio, here a 1:1 transmission ratio. The driver element 2 is also connected, here integrated, to the second gear wheel 36. which in turn is couplable to a first ring gear 40 via a second clutch freewheel 38, for operating the hub transmission according to a second transmission ratio. The first ring gear 40 is arranged to engage a first planet gear 42. The first planet gear 42 is mounted on a carrier 44 to rotate together about the axle 10, here facilitated by one-way bearing 45. The second planet gear 46, here rigidly coupled to the first planet gear 44, is arranged to engage a second ring gear 48. The second ring gear 48 is connected to, here integrated with, the intermediate shell 19. The second planet gear 46, in this example has a smaller outer diameter than the first planet gear 42. Also, the second ring gear 46 has a smaller diameter than the first ring gear 40.

[0116] It will be appreciated that the hub transmission 18 as described herein need not only be combined with an axially movable cassette of sprockets 6, but may also be used in combination with an axially stationary cassette 6, e.g. conventional derailleur systems. The hub transmission can for example also be used with an axially stationary cassette of sprockets 6 that contains only one sprocket.

[0117] FIG. 4 shows a schematic representation of an example of a transmission system, e.g. as shown in the examples of FIGS. 3A, 3B. A crank 50 is provided which may be connected to front chain wheel. The front chain wheel may be selectively coupled to one of the sprockets of the cassette 6, via an endless drive member 16, e.g. a chain or belt. The cassette 6 is couplable to the hub shell 20, e.g. via the intermediate shell 19, through the freewheel 34 and the clutch 35. In a closed state of the clutch 35, a first transmission path is formed from the crank 50 to the hub shell 20, via the cassette 6, and via a 1:1 transmission ratio of the hub transmission 18. Here, the first transmission path bypasses the planetary gear system 21. In an open state of the clutch 35, a transmission path is formed from the crank 50 to the hub shell 20, via the cassette 6 and via the planetary gear system 21 of the hub transmission 18 to the hub shell 20. The second freewheel 38 is arranged between the input of the crank 50 and the output to the hub shell 20. The hub shell 20 may be connected to a rear wheel of a bicycle.

[0118] Table 1 shows an example of system transmission ratios that can be obtained with a transmission system as described herein, particularly as shown in FIG. 4.

TABLE-US-00001 TABLE 1 Cassette Hub System transmis- transmis- transmis- Sprocket Front chain sion sion sion teeth wheel teeth ratio ratio ratio step 1 12 32 2.67 1 2.67 2 12 32 2.67 1.12 2.38 1.12 3 15 32 2.13 1 2.13 1.12 4 15 32 2.13 1.12 1.90 1.12 5 19 32 1.68 1 1.68 1.13 6 19 32 1.68 1.12 1.50 1.12 7 24 32 1.33 1 1.33 1.13 8 24 32 1.33 1.12 1.19 1.12 9 30 32 1.07 1 1.07 1.12 10 30 32 1.07 1.12 0.95 1.12 11 38 32 0.84 1 0.84 1.13 12 38 32 0.84 1.12 0.75 1.12 13 48 32 0.67 1 0.67 1.13 14 48 32 0.67 1.12 0.60 1.12

[0119] Table 1 particularly shows an example in which the cassette includes seven different sprockets, having 12, 15, 19, 24, 30, 38 and 48 teeth respectively. With this cassette, and a front chain wheel having 32 teeth in this example, seven different transmission ratios are obtained. The hub transmission is operable in this example according to two different transmission ratios, here of 1 and 1.12. Accordingly, the transmission system can selectively impose 14 different system transmission ratios between an input and output, e.g. between the crank 50 and the hub shell 20. In this example, each system transmission ratio differs approximately 12%.

[0120] The hub transmission 18 is operable according to at least a first transmission ratio and a second transmission ratio. The first transmission ratio of the hub transmission is in this example 1:1 ratio. The first and second hub transmission ratios can differ from each other by at least 18%. The first and second hub transmission ratios can differ from each other by an amount that corresponds to approximately half of a sprocket ratio of a pair of consecutive sprockets of the cassette of sprockets 6. The second hub transmission ratio can be a reduction ratio, lowering the hub transmission output speed with respect to the hub transmission input speed. The second hub transmission ratio can be an increase ratio, increasing the hub transmission output speed with respect to the transmission input speed. At least one of the hub transmission ratios can be adjustable.

[0121] A control unit can be provided for controlling a transmission ratio change of the transmission system 1, e.g. using the actuator element 8 and/or a further actuator element of the hub transmission 18. The further actuator may for example be arranged for operating the clutch 35, e.g. for switching the clutch 35 from a closed state to an open state and vice versa. The control unit can be integrated with the actuator element 8. The control unit can be attached to the axle 10. The control unit can be positioned inside the intermediate shell 19 and/or the hub shell 20. The actuator element 8 can comprise a receiver arranged for receiving a wireless shift signal from a shifter of the bicycle.

[0122] FIG. 5 shows a schematic representation of a flow chart of a control unit 26. A shift signal 28 can be transmitted to the control unit 26. The shift signal can be an upshift signal or a downshift signal, generated by a shifter attached to a bicycle handlebar. The control unit 26 can be configured to selectively control the actuator element 8 and/or the further actuator of the hub transmission 18 for selecting the next higher transmission ratio in response to receiving an upshift signal, and for selecting the next lower transmission ratio in response to receiving a downshift signal. The control unit 26 can be arranged to delay a shifting of the hub transmission 18 by a predefined time period after initiating a movement of the cassette of sprockets 6.

[0123] The transmission system 1 can further comprise an electric propulsion motor arranged for propelling the bicycle and/or an electric generator arranged for generating power. The electric motor can be coupled to the hub shell 20. The electric motor can alternatively or additionally be coupled to the crank 50 of the bicycle. The sprocket ratio steps between each pair of consecutive sprockets can be at least 12%. The sprocket ratio steps between each pair of consecutive sprockets can be at least 15%.

[0124] The hub transmission 18 can be a continuously variable transmission, e.g. a ratchet type of continuously variable transmission. A transmission ratio-spread of the continuously variable transmission can be smaller than the sprocket ratio step between a pair of consecutive sprockets. A transmission ratio-spread of the continuously variable transmission can be smaller than the sprocket ratio step between three consecutive sprockets. The continuously variable transmission can have at least a transmission ratio of 1:1, and an increase ratio increasing the hub transmission output speed with respect to the transmission input speed. An input of the continuously variable transmission can be coupled to the driver element 2 and an output of the continuously variable transmission can be coupled to the intermediate shell 19. An input of the continuously variable transmission can be coupled to the cassette of sprockets 6 and an output of the continuously variable transmission can be connected to the driver element 2. An input of the continuously variable transmission can be coupled to a crank of the bicycle and an output of the continuously variable transmission can be connected to a front chainring of the bicycle.

[0125] FIGS. 6A and 6B show examples of a transmission system 1 mounted to a bicycle frame 24. FIGS. 6A, 6B particular show a top view of a chain stay 1007 of the bicycle frame 24, wherein a transmission system 1 is mounted between a pair of dropouts. FIG. 6A shows the cassette of sprockets 6 at an outward most position, corresponding to the position as shown in FIG. 1A. FIG. 6B shows the cassette of sprockets 6 at an inward most position, corresponding to a position as shown in FIG. 1B. In the outward most position, as shown in FIG. 6B, the cassette of sprockets 6 is positioned close to the bicycle frame 24, wherein an outermost sprocket, here the smallest sprocket, may be axially spaced from the frame 24 by a distance of 2 mm or less. This can be achieved because the endless drive member 16 does not engage the outermost sprocket at the outermost position.

[0126] FIG. 7 shows a schematic representation of a flow chart of a method 100 for operating a bicycle transmission system 1. Thereto, a rotatable driver element 2 and a cassette of sprockets 6 mounted on the driver element 2 are provided. In a first step 102 the movement of the cassette of sprockets 6 on the driver element 2 is actuated. The cassette of sprockets 6 is moved in axial direction on the driver element 2 in step 104. The cassette of sprockets 6 is moved by the shifting unit. The step 104 can be performed after step 102 or in parallel with step 104.

[0127] FIG. 8 shows a bicycle 1000, comprising a transmission system as described herein. The bicycle 1000 comprises a frame 24 with a front fork 1005 and a rear fork having a chain stay 1007, as well as a front wheel and a rear wheel 1011, 1013 located in the front and rear fork respectively. The bicycle 1000 further comprises a crank 50, coupled to a front chain wheel 1019, wherein an endless drive element, here a chain 1023 threads, over the front chain wheel 1019 and one of the sprockets of the cassette 6. The bicycle 1000 also comprises a control unit 500, here connected to handlebars 1031.

[0128] Herein, the invention is described with reference to specific examples of embodiments of the invention. It will, however, be evident that various modifications and changes may be made therein, without departing from the essence of the invention. For the purpose of clarity and a concise description features are described herein as part of the same or separate embodiments, however, alternative embodiments having combinations of all or some of the features described in these separate embodiments are also envisaged.

[0129] However, other modifications, variations, and alternatives are also possible. The specifications, drawings and examples are, accordingly, to be regarded in an illustrative sense rather than in a restrictive sense.

[0130] For the purpose of clarity and a concise description features are described herein as part of the same or separate embodiments, however, it will be appreciated that the scope of the invention may include embodiments having combinations of all or some of the features described.

[0131] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word comprising does not exclude the presence of other features or steps than those listed in a claim. Furthermore, the words a and an shall not be construed as limited to only one, but instead are used to mean at least one, and do not exclude a plurality. The mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to an advantage.