TWI925660B - Motor unit for bicycle derailleur - Google Patents

Abstract

A motor unit 14 for a bicycle derailleur 10 includes an output shaft 24, a motor 26, a drive gear 28, an output gear 30, an intermediate gear structure 32, and an angle sensor 34. The motor 26 includes a motor shaft 36. The drive gear 28 is on the motor shaft 36 of the motor 26, and the output gear 30 is on the output shaft 24. The intermediate gear structure 32 is positioned in a load path between the drive gear 28 and the output gear 30, and the intermediate gear structure 32 includes at least one reduction gear 38 and one encoder 40. A rotational ratio between the encoder 40 and the output gear 30 is such that the encoder 40 rotates less than 360 degrees.

Description

Motor unit used in bicycle gearboxes

This invention relates generally to a motor unit for use in a bicycle gearbox.

Many bicycles have a chain-driven transmission system consisting of multiple front and rear sprockets. The rider can increase or decrease the gear ratio of the transmission system by shifting gears, which moves the chain from one sprocket to another via a derailleur. In an electronic derailleur system, the movement of the derailleur is controlled by a motor unit. To shift the chain from one sprocket to another, the motor unit determines which sprocket is currently engaged with the chain and the amount of movement required to reach the desired gear based on the position of the derailleur. In situations such as power outages, backlash, or skipped gears, the motor unit may lose the information needed to determine the position of the derailleur. There are challenges in designing a motor for an electric bicycle transmission that can determine the position of the gearbox in the event of power interruption, backlash, or gear skipping.

This document discloses a motor unit for a bicycle derailleur developed to solve the aforementioned problems. According to a first aspect of the invention, the motor unit for a bicycle derailleur includes an output shaft, a motor, a drive gear, an output gear, an intermediate gear structure, and an angle sensor. The motor includes a motor shaft. The drive gear is located on the motor shaft. The output gear is located on the output shaft. The intermediate gear structure is positioned in a load path between the drive gear and the output gear, and the intermediate gear structure includes at least one reduction gear and an encoder. The rotation ratio between the encoder and the output gear causes the encoder to rotate less than 360 degrees.

Regarding the motor unit for a bicycle gearbox according to the first state, a small motor unit can be provided, wherein the output gear rotates through its entire range, and the encoder rotates less than 360 degrees, thereby allowing the encoder's rotation to be determined after a power outage.

According to a second embodiment of the present invention, the motor unit for a bicycle derailleur according to the first embodiment is configured such that the rotational range of one of the output gears is limited by a rotation limiting structure of the bicycle derailleur. With respect to the motor unit for a bicycle derailleur according to the second embodiment, the rotational range of the output gear can be limited to prevent the encoder from rotating more than 360 degrees.

According to a third embodiment of the present invention, a motor unit for a bicycle derailleur according to the second embodiment is configured such that a bicycle derailleur body and the motor unit are connected to a connecting rod of the bicycle derailleur, and the limitation of the rotational range is mechanical. With respect to the motor unit for a bicycle derailleur according to the third embodiment, the connecting rod of the bicycle derailleur can be rotated and the rotational range limited in the event of a power outage.

According to a fourth embodiment of the present invention, a motor unit for a bicycle transmission according to a second embodiment is configured such that the output gear contacts a housing of the motor unit, and the limitation of the rotational range of the output gear is electrically induced. With respect to the motor unit for a bicycle transmission according to the fourth embodiment, the limitation of the rotational range of the output gear can be electrically adjusted.

According to a fifth embodiment of the present invention, a motor unit for a bicycle transmission according to any one of the first to fourth embodiments is configured such that the output gear is non-circular. For the motor unit for a bicycle transmission according to the fifth embodiment, the efficiency and battery life of the motor unit can be improved by using the output gear to transmit a variable rotation ratio.

According to a sixth embodiment of the present invention, a motor unit for a bicycle transmission according to any one of the first to fifth embodiments is configured such that the output gear is a sector gear. With respect to the motor unit for a bicycle transmission according to the sixth embodiment, the size and weight of the output gear can be reduced.

According to a seventh embodiment of the present invention, a motor unit for a bicycle derailleur, configured according to any one of the first to sixth embodiments, transmits a rotational force of the output shaft to a link of the bicycle derailleur. With respect to the motor unit for a bicycle derailleur according to the seventh embodiment, the link of the bicycle derailleur can be moved to move the chain to a desired sprocket.

According to an eighth embodiment of the present invention, a motor unit for a bicycle derailleur, configured according to any one of the first to seventh embodiments, is configured such that the bicycle derailleur comprises a base component, a linkage mechanism, and a chain guide for a front bicycle derailleur. With respect to the motor unit for a bicycle derailleur according to the eighth embodiment, the position of the front bicycle derailleur relative to a plurality of front sprockets can be determined after a power outage.

According to a ninth embodiment of the present invention, a motor unit for a bicycle derailleur, based on any one of the first to seventh embodiments, is configured such that the bicycle derailleur comprises a base component, a movable component, a linkage mechanism, and a chain guide, constituting a rear bicycle derailleur. With respect to the motor unit for a bicycle derailleur according to the ninth embodiment, the condition of the rear bicycle derailleur relative to a plurality of rear sprockets can be determined after a power outage.

According to a tenth embodiment of the present invention, a motor unit for a bicycle derailleur, based on any one of the first to ninth embodiments, is configured such that the motor unit is housed within a base component of the bicycle derailleur. With respect to the motor unit for a bicycle derailleur according to the tenth embodiment, the motor unit can be protected from damage, while simultaneously providing an aerodynamically and aesthetically pleasing bicycle derailleur.

According to an eleventh embodiment of the present invention, a motor unit for a bicycle derailleur, according to any one of the first to tenth embodiments, is configured such that the bicycle derailleur includes a power supply port configured to connect to a battery, and the power supply port is electrically connected to the motor. With respect to the motor unit for a bicycle derailleur according to the eleventh embodiment, the motor unit can be powered by a battery provided on the bicycle.

According to a twelfth embodiment of the present invention, a motor unit for a bicycle derailleur, according to any one of the first to eleventh embodiments, further includes a housing and a wireless communication unit. The motor, at least a portion of the output shaft, and the intermediate gear structure are housed within the housing of the motor unit. The wireless communication unit is configured to communicate with an additional wireless communication unit mounted on an additional bicycle assembly. With respect to the motor unit for a bicycle derailleur according to the twelfth embodiment, the motor unit is protected from damage and wireless communication between the motor unit and the additional bicycle assembly is facilitated.

According to a thirteenth embodiment of the present invention, a motor unit for a bicycle transmission according to any one of the first to twelfth embodiments further includes a controller configured to calculate the angle of either the output gear or the output shaft based on a detected value from the angle sensor. With respect to the motor unit for a bicycle transmission according to the thirteenth embodiment, the angle of the output gear or the output shaft can be determined from the value of the angle sensor.

According to the fourteenth embodiment of the present invention, the motor unit for a bicycle transmission according to any one of the first to thirteenth embodiments is configured such that the angle sensor is a magnetic sensor. With respect to the motor unit for a bicycle transmission according to the fourteenth embodiment, a value of the angle sensor can be determined under extreme environmental conditions such as high temperatures.

According to a fifteenth embodiment of the present invention, a motor unit for a bicycle transmission according to any one of the first to thirteenth embodiments is configured such that the angle sensor is an optical sensor. With respect to the motor unit for a bicycle transmission according to the fifteenth embodiment, a value of the angle sensor can be determined quickly and accurately, even under conditions of environmental magnetic interference.

According to a sixteenth embodiment of the present invention, a motor unit for a bicycle transmission, configured according to any one of the first to fifteenth embodiments, causes the encoder to rotate in response to a rotation of the motor shaft. With respect to the motor unit for a bicycle transmission according to the sixteenth embodiment, the position of the output gear can be controlled according to the rotation of the motor shaft.

According to a seventeenth embodiment of the present invention, a motor unit for a bicycle transmission according to any one of the first to sixteenth embodiments is configured such that the encoder is rotatably mounted on a first shaft of the intermediate gear structure, the output gear is rotatably mounted on a second shaft, and the second shaft is adjacent to the first shaft, with no other shaft between them. With respect to the motor unit for a bicycle transmission according to the seventeenth embodiment, the size of the motor unit can be minimized while maintaining the ability to accurately determine the position of the output shaft and/or the output gear.

This [Summary] is provided to introduce, in a simplified form, one of the concepts described further below in the [Implements]. This [Summary] is not intended to identify key or essential features of the claimed subject matter, nor is it intended to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to embodiments that address any or all of the shortcomings mentioned in any part of this invention. As used herein, the term "small and/or light-duty vehicle" refers to electric and non-electric vehicles (regardless of the number of wheels), but does not include four-wheeled vehicles with an internal combustion engine as one of the power sources to drive the wheels or four-wheeled electric vehicles that require a license to operate on public roads.

The selected embodiments will now be explained with reference to the accompanying drawings, in which the same element symbols in all the various drawings indicate corresponding or identical elements. Those skilled in the art will understand from the present invention that the following description of the embodiments is for illustrative purposes only and is not intended to limit the present invention as defined by the appended patent application and its equivalents.

Referring first to Figure 1, an exemplary bicycle 1 according to at least one disclosed embodiment of the present invention is shown, having a bicycle gearbox 10 including a motor unit 14. The bicycle 1 is, for example, a motocross bicycle or a mountain bike. Alternatively, the bicycle 1 may be a road bicycle. As shown in the schematic outline of Figure 2, the bicycle 1 may have an axial center plane P1 defining the left and right halves of the bicycle 1. The following directional terms "forward," "backward," "forward," "rearward," "left," "right," "lateral," "upward," and "downward," and any other similar directional terms, refer to the direction determined based on, for example, a rider sitting upright on the seat of the bicycle 1 with their hands facing the handlebars.

Continuing with Figure 1, the bicycle 1 includes a frame 2 attached to a rear wheel 3. A front fork 4 attaches a front wheel 5 to the frame 2. Pedals 6 on both sides of the bicycle 1 are attached to corresponding crank arms 7. The crank arms 7 are mounted 180 degrees to each other on both sides of the frame 2 and connected by a crankshaft 8 (indicated by a dotted line). The bicycle 1 of this embodiment is driven by a chain drive transmission system including a bicycle chain 9, a bicycle derailleur 10, and a bicycle sprocket 12. It should be understood that the bicycle derailleur 10 described herein can be configured as either or both of a rear bicycle derailleur 10A and/or a front bicycle derailleur 10B. Similarly, one of the bicycle sprockets 12 described herein may refer to one of a plurality of rear sprockets 12A and/or one of a plurality of front sprockets 12B.

In the engaged state, the bicycle chain 9 engages with one of the plurality of front sprockets 12B and one of the plurality of rear sprockets 12A, as described below with reference to Figures 4 and 5. A driving force applied to one of the pedals 6 causes the crankshaft 8 and the front sprocket 12B to rotate. As the front sprocket 12B rotates, the bicycle chain 9 drives around the rear sprocket 12A, transmitting power to the rear wheel 3 to propel the bicycle 1. Therefore, the front bicycle derailleur 10B shifts the bicycle chain 9 between the front sprockets 12B, and the rear bicycle derailleur 10A shifts the bicycle chain 9 between the rear sprockets 12A. As will be described in detail below, bicycle chain shifting via the rear derailleur 10A and/or the front derailleur 10B can be facilitated by an electric motor unit 14 included in either or both of the rear derailleur 10A and/or the front derailleur 10B. Shifting of the bicycle chain 9 alters the gear ratio of the chain drive transmission to increase or decrease the distance traveled by each rotation of the pedal 6. Other parts of the bicycle 1 are well-known and will not be described herein.

Figure 3A shows a side view of a rear bicycle derailleur 10A according to the present invention. The rear bicycle derailleur 10A includes a base component 16A, a movable component 18A, a linkage mechanism 20A, and a chain guide 22A. In the configuration described in detail below, the motor unit 14 is housed within the base component 16 of the bicycle derailleur 10, but the motor unit 14 can alternatively be configured to be housed within other components of the derailleur. The motor unit 14 can be housed in either the movable component 18A or the linkage mechanism 20A. Figure 3B shows a schematic illustration of a front bicycle derailleur 10B. The bicycle derailleur 10 may be a front bicycle derailleur 10B comprising a base component 16B, a linkage mechanism 20B and a chain guide 22B.

Referring to Figures 4 and 8, the bicycle derailleur 10 includes a wireless communication unit 62 configured to communicate with an additional wireless communication unit 64 mounted on an additional bicycle assembly 66. The motor unit 14 includes the wireless communication unit 62, but the wireless communication unit 62 may alternatively be mounted in other components of the bicycle derailleur 10. In the embodiments described herein, it should be understood that the wireless communication unit 62 may be included in either the rear derailleur 10A or the front derailleur 10B.

Figure 4 is an exploded view of a motor unit 14 for a bicycle transmission 10 according to the present invention. The motor unit 14 includes an output shaft 24, a motor 26, a drive gear 28, an output gear 30, an intermediate gear structure 32, and an angle sensor 34. The motor 26 includes a motor shaft 36 on which the drive gear 28 is mounted. The output gear 30 is mounted on the output shaft 24. The intermediate gear structure 32 is positioned in a load path between the drive gear 28 and the output gear 30. The intermediate gear structure 32 includes at least one reduction gear 38 and an encoder 40. In the embodiments described herein, the intermediate gear structure 32 includes two reduction gears, namely a first reduction gear 38A and a second reduction gear 38B, and an encoder 40. However, it should be understood that the intermediate gear structure 32 can be configured to include one reduction gear, three reduction gears, or any other suitable number of reduction gears. In the illustrated embodiment, the angle sensor 34 is configured as a magnetic sensor. It should be understood that the angle sensor can alternatively be configured as an optical sensor or any other suitable type of sensor.

Each gear in the intermediate gear structure 32 is rotatably mounted on its own shaft. The encoder 40 is rotatably mounted on a first shaft 42 of the intermediate gear structure 32, and the output gear is rotatably mounted on a second shaft 44. As shown in the motor unit 14 illustrated in Figures 4 to 6, the second shaft 44 is configured to be adjacent to the first shaft 42, with no other shaft between them. However, it should be understood that the first shaft 42 and the second shaft 44 can alternatively be configured to be separated from one or more gears and shafts of the intermediate gear structure. The shaft is supported by an upper gear shaft support member 46 and a lower gear shaft support member 48. As shown in the exploded view of Figure 4, and referring to Figure 8, the motor unit 14 further includes a housing 50 in which at least a portion of the motor 26, the output shaft 24, and the intermediate gear structure 32 are housed. The housing 50 includes a substrate. In an assembled state, the wireless communication unit 62 is disposed in the substrate. The intermediate gear structure 32 is disposed on a first side of the housing 50 opposite to the substrate, and the wireless communication unit 62 is disposed on a second side of the housing 50 opposite to the substrate, the second side being opposite to the first side.

In the configuration of motor unit 14 described herein, the rotational range of one of the output gears 30 is limited by a rotation limiting structure 52 of the bicycle transmission 10. An angle sensor 34 is configured to detect the rotation of encoder 40, and a rotation ratio between encoder 40 and output gear 30 causes encoder 40 to rotate less than 360 degrees. Equation 1 below shows a general formula for this configuration, where G represents the gear, n represents the number of gears, R represents the rotation ratio between the nth gear and the n'th gear, and _θn represents the rotation angle of the nth gear. Equation 1: _θn × R( _Gn :Gn _' ) = θn _' < 360°

The following will show exemplary equations for different positions of encoder 40 relative to output gear 30. In the exemplary formulas shown herein, output gear 30 is denoted as _G0 and _θ0 is the rotation angle of output gear 30. In a preferred embodiment, the rotation ratio between output gear 30 and encoder 40 is in the range of 4.5 to 7. When encoder 40 is on or mounted on one of the gears ( _G1 ) adjacent to output gear 30, the equation is shown as Equation 2 below. Equation 2: _θ0 × R( _G0 : _G1 ) = _θ1 < 360°

When encoder 40 is mounted on one of two gears ( _G2 ) that is separated from output gear 30, the equation is shown as Equation 3 below. Equation 3: _θ0 × [R( _G0 : _G1 ) × R( _G1 : _G2 )] = _θ2 < 360°

When encoder 40 is mounted on one of three gears ( _G3 ) that is separated from output gear 30, the equation is expressed as Equation 4 below. Equation 4: _θ0 × [R( _G0 : _G1 ) × R( _G1 : _G2 ) × R( _G2 : _G3 )] = _θ3 < 360°

When a part of the main body of the bicycle derailleur 10 (such as base component 16 or movable component 18A) and the motor unit are connected to a linkage of the bicycle derailleur 10, the limitation of the rotational range can be mechanical. Alternatively, when the output gear 30 contacts the housing 50 of the motor unit 14, the limitation of the rotational range of the output gear 30 can be electrical.

As will be described below with reference to Figure 8, motor unit 14 further includes a controller 60 configured to calculate the angle of either the output gear 30 or the output shaft 24 based on a detection value from angle sensor 34. Because the encoder is limited to rotation of less than 360 degrees, even if data regarding the position of the bicycle gearbox 10 is lost (e.g., power interruption, backlash, or gear skipping), controller 60 can determine the condition of the bicycle gearbox 10 (e.g., the relative position of the base component and the movable component) from the rotation ratio between encoder 40 and output gear 30, and thus determine the gear ratio of the transmission system.

Figures 5 and 6 show a side view and a top view of the gear structure of motor unit 14, respectively. Motor 26, including motor shaft 36, drives drive gear 28. Drive gear 28 drives at least one reduction gear 38, which in turn drives encoder 40. Therefore, encoder 40 is configured to rotate in response to rotation of motor shaft 36 of motor 26. Encoder 40 drives output gear 30, which in turn drives output shaft, and the rotational force of output shaft is transmitted to a linkage of bicycle gearbox 10 to move gearbox 10. The encoder 40 may have a reduction gear function, which enables the encoder 40 to reduce the rotational speed transmitted by the self-reducing gear 38.

Turning to Figure 7A, a schematic illustration of one of the gear structures in the motor unit 14 of a bicycle transmission 10 according to the present invention is shown. As described above, a motor 26, including a motor shaft 36, drives a drive gear 28. In the gear structure shown in Figure 7A, the drive gear 28 is a worm gear. Alternatively or concurrently, the drive gear may be a round gear, a non-round gear, a sector gear, or any other suitable gear type. An angle sensor 34 is configured to detect the rotation of an encoder 40, which drives the output gear 30 and the output shaft. In the illustrated embodiment of Figure 7A, the output gear 30 is circular; however, it should be understood that the output gear may alternatively be configured as one of the non-circular output gears 130 shown in Figure 7B, one of the sector gears 230 shown in Figure 7C, or any other suitable gear type.

Turning to Figure 8, a schematic diagram of a motor unit 14 for a bicycle derailleur 10 according to the present invention is shown. To power the motor 26, the bicycle derailleur 10 includes a power supply port 56 configured to connect to a battery 58, and the power supply port 56 is electrically connected to the motor 26. As described above and schematically shown in Figure 8, the motor unit 14 also includes a controller 60 mounted on an encoder 40 for calculating the angle of the output gear 30 or the output shaft 24 based on the detected value of an angle sensor 34. As described above with reference to Figure 3B, a wireless communication unit 62 is configured to communicate with an additional wireless communication unit 64 mounted on an additional bicycle assembly 66. The additional bicycle assembly 66 may be, for example, an additional controller and may communicate with one or more switches 68. Although Figure 8 depicts the additional bicycle assembly 66 as being powered by the same battery 58 that powers the motor unit 14, it should be understood that in another configuration, the additional bicycle assembly 66 may be powered by a single battery. One or more switches 68 are configured to receive a shift command from the rider to initiate a shifting operation. Thus, one or more switches 68 may be configured as a gearshift mounted on the handlebars of the bicycle 1. Although the additional bicycle assembly 66 described above may be an additional controller, it should be understood that an additional wireless communication unit 64 may be mounted on any suitable additional bicycle assembly.

Although only selected embodiments have been chosen to illustrate the invention, those skilled in the art will understand from the invention that various changes and modifications can be made to this document without departing from the scope of the invention as defined in the appended claims. For example, the size, shape, position, or orientation of various components can be changed as needed and/or desired. Components shown as directly connected or in contact with each other may have an intermediate structure disposed between them. The function of one element can be performed by two elements, and vice versa. The structure and function of one embodiment can be used in another embodiment. Not all advantages may be present simultaneously in a particular embodiment. Each feature that differs from prior art (alone or in combination with other features) should also be considered a separate description of the applicant's further invention, including the structural and/or functional concepts embodied by such feature(s). Therefore, the above description of embodiments of the present invention is for illustrative purposes only and is not intended to limit the present invention as defined by the appended patent application and its equivalents.

1: Bicycle 2: Frame 3: Rear wheel 4: Front fork 5: Front wheel 6: Pedals 7: Crankarm 8: Crankshaft 9: Bicycle chain 10: Bicycle derailleur 10A: Rear bicycle derailleur 10B: Front bicycle derailleur 12: Bicycle sprocket 12A: Rear sprocket 12B: Front sprocket 14: Electric motor unit 16: Base component 16A: Base component 16B: Base component 18A: Movable component 20A: Linkage mechanism 20B: Linkage mechanism 22A: Chain guide 22B: Chain guide 24: Output shaft 26: Motor 28: Drive gear 30: Output gear 32: Intermediate gear structure 34: Angle sensor 36: Motor shaft 38: Reduction gear 38A: First reduction gear 38B: Second reduction gear 40: Encoder 42: First shaft 44: Second shaft 46: Upper gear shaft support component 48: Lower gear shaft support component 50: Housing 52: Rotation limiting structure 56: Power supply port 58: Battery 60: Controller 62: Wireless communication unit 64: Additional wireless communication unit 66: Additional bicycle assembly 68: Switch 130: Non-circular output gear 230: Sector gear P1: Axial center plane

A more comprehensive and better understanding of the invention and its many accompanying advantages will be easily obtained through the following detailed description, taken in conjunction with the accompanying figures, in which:

Figure 1 is a right side view of an example bicycle according to the present invention, which is used in a motor unit of a bicycle transmission.

Figure 2 shows the outline of one of the bicycles;

Figure 3A is a side view of a rear bicycle gearbox of a chain coupled to a rear sprocket of a bicycle according to the present invention;

Figure 3B is a schematic diagram of a bicycle gearbox according to the present invention;

Figure 4 is an exploded view of a motor unit for a bicycle transmission according to the present invention;

Figure 5 is a side view of a gear structure in a motor unit of a bicycle transmission according to the present invention;

Figure 6 is a top view of a gear structure in a motor unit of a bicycle transmission according to the present invention;

Figures 7A to 7C are schematic diagrams of a gear structure in a motor unit of a bicycle transmission according to the present invention; and

Figure 8 is a schematic diagram of a motor unit for a bicycle transmission according to the present invention.

14: Electric Motor Unit

24: Output Shaft

26: Motor

28: Drive Gear

30: Output Gear

32: Intermediate Gear Structure

34: Angle Sensor

38A: First reduction gear

38B: Second reduction gear

40: Encoder

42: First Axis

44: Second Axis

46: Upper gear shaft support component

48: Lower gear shaft support component

50: Shell

52: Rotational confinement structure

62: Wireless Communication Unit

Claims (22)

A motor unit (14) for a bicycle transmission (10) includes: an output shaft (24); a motor (26) including a motor shaft (36); a drive gear (28) located on the motor shaft (36) of the motor (26); an output gear (30) located on the output shaft (24); an intermediate gear structure (32) positioned in a load path between the drive gear (28) and the output gear (30), the intermediate gear structure (32) including at least one reduction gear (38) and an encoder (40); and An angle sensor (34) is configured to detect the rotation of the encoder (40), which is located between the output gear (30) and the at least one reduction gear (38). For example, the motor unit (14) for a bicycle gearbox (10) in claim 1, wherein the at least one reduction gear (38) includes a first reduction gear, and the encoder (40) is adjacent to the first reduction gear, with no other gear between them. A motor unit (14) for a bicycle transmission (10) includes: an output shaft (24); a motor (26) including a motor shaft (36); a drive gear (28) located on the motor shaft (36) of the motor (26); an output gear (30) located on the output shaft (24); an intermediate gear structure (32) positioned in a load path between the drive gear (28) and the output gear (30), the intermediate gear structure (32) including at least one reduction gear (38) and an encoder (40); and An angle sensor (34) is configured to detect the rotation of the encoder (40). The at least one reduction gear (38) includes a first reduction gear, and the encoder (40) is adjacent to the first reduction gear, with no other gear between them. For example, the motor unit (14) for a bicycle gearbox (10) in claim 2 or 3, wherein the at least one reduction gear (38) includes a second reduction gear, and the first reduction gear is located between the encoder (40) and the second reduction gear. As in claim 1 or 3, a motor unit (14) for a bicycle gearbox (10), wherein at least one reduction gear (38) is disposed between the encoder (40) and the drive gear (28). For example, the motor unit (14) for a bicycle gearbox (10) in request item 1 or 3, wherein a rotation ratio between the encoder (40) and the output gear (30) causes the encoder (40) to rotate less than 360 degrees. As in claim 1 or 3, a motor unit (14) for a bicycle gearbox (10) wherein the rotatable range of one of the output gears (30) is limited by a rotation limiting structure (52) of the bicycle gearbox (10). As in claim 7, a motor unit (14) for a bicycle derailleur (10), wherein in a configuration in which a body of the bicycle derailleur (10) and the motor unit (14) are connected to a link of the bicycle derailleur (10), the limitation of the range of rotation is mechanical. As in claim 7, a motor unit (14) for a bicycle transmission (10), wherein in a configuration in which the output gear (30) contacts a housing (50) of the motor unit (14), the rotational range of the output gear (30) is limited electrically. For example, the motor unit (14) for a bicycle gearbox (10) in request item 1 or 3, wherein the output gear (30) is non-circular. For example, the motor unit (14) for a bicycle transmission (10) in request item 1 or 3, wherein the output gear (30) is a sector gear. As in request item 1 or 3, a motor unit (14) for a bicycle gearbox (10) wherein the rotational force of one of the output shafts (24) is transmitted to one of the links of the bicycle gearbox (10). The motor unit (14) for a bicycle derailleur (10) as described in claim 1 or 3, wherein the bicycle derailleur (10) is a front bicycle derailleur (10B) comprising a base component (16B), a linkage mechanism (20) and a chain guide (22B). As in claim 1 or 3, a motor unit (14) for a bicycle derailleur (10), wherein the bicycle derailleur (10) is a rear bicycle derailleur (10A) comprising a base component (16A), a movable component (18A), a linkage mechanism (20A) and a chain guide (22A). The motor unit (14) for a bicycle gearbox (10) as requested in item 1 or 3, wherein the motor unit (14) is housed within a base component (16A, 16B) of the bicycle gearbox (10). As in claim 1 or 3, a motor unit (14) for a bicycle gearbox (10), wherein the bicycle gearbox (10) includes a power supply port (56) configured to connect to a battery (58), and the power supply port (56) is electrically connected to the motor (26). The motor unit (14) for a bicycle transmission (10) as claimed in claim 1 or 3 further includes: a housing (50) in which at least a portion of the motor (26), the output shaft (24) and the intermediate gear structure (32) are housed; and a wireless communication unit (62) configured to communicate with an additional wireless communication unit (64) mounted on an additional bicycle assembly (66). The motor unit (14) for a bicycle gearbox (10) as described in claim 1 or 3 further includes: a controller (60) configured to calculate an angle of one of the output gears (30) and the output shaft (24) based on a detection value of the angle sensor (34). For example, the motor unit (14) for a bicycle gearbox (10) in request item 1 or 3, wherein the angle sensor (34) is a magnetic sensor. For example, the motor unit (14) for a bicycle gearbox (10) in request item 1 or 3, wherein the angle sensor (34) is an optical sensor. As in request 1 or 3, a motor unit (14) for a bicycle gearbox (10) wherein the encoder (40) is configured to rotate in response to a rotation of one of the motor shafts (36) of the motor (26). For example, the motor unit (14) for a bicycle transmission (10) of claim 1 or 3, wherein the encoder (40) is rotatably mounted on a first shaft (42) of the intermediate gear structure (32); the output gear (30) is rotatably mounted on a second shaft (44); and the second shaft (44) is adjacent to the first shaft (42), with no other shaft between them.