Bottom Bracket Transmission with a Planetary Design for a Bicycle or Pedelec

Abstract

A bottom bracket planetary gearbox for a bicycle or a pedelec includes a crank axle, a gearbox output shaft, four additional shafts, five shift elements, and three planetary gear sets. The planetary gear sets are coaxial with the crank axle. The shift elements are engageable to implement at least six gears.

Description

CROSS-REFERENCE TO RELATED APPLICATION

The present application is related and has right of priority to German Patent Application No. 10 2022 203 241.1 filed on Apr. 1, 2022 and is a nationalization of PCT/EP2023/058442 filed in the European Patent Office on Mar. 31, 2023, both of which are incorporated by reference in their entirety for all purposes.

FIELD OF THE INVENTION

The present invention relates generally to a bottom bracket planetary gearbox for a bicycle or a pedelec, the gearbox having a crank axle as the input and a gearbox output shaft as the output, at least four further shafts, at least three planetary gear sets, which are coaxial with the crank axle, and at least five shift elements for implementing at least six gears. The invention further relates generally to a bicycle or a pedelec having the bottom bracket gearbox.

BACKGROUND

For example, document DE 10 2016 225 169 A1 describes a planetary gearbox for a bicycle or a pedelec. The gearbox includes at least two planetary gear sets in order to implement only four gears. Of these planetary gear sets, at least one planetary gear set is necessarily a positive planetary gear set, which requires a large amount of installation space. Furthermore, at least four shift elements are necessary. In one further embodiment variant of the gearbox, four further gears are obtained by adding two further shift elements and one further planetary gear set. Due to the provided interconnection, or connection, of the various planetary gear sets, the known gearbox requires a large amount of installation space.

SUMMARY OF THE INVENTION

Consequently, the present invention provides a bottom bracket gearbox of the aforementioned type, which requires as little installation space as possible while having the fewest possible components.

The invention therefore relates to a bottom bracket planetary gearbox for a bicycle or a pedelec. The bottom bracket gearbox has a crank axle as the input and a gearbox output shaft as the output, and at least four further shafts, with the output preferably being implemented using a sprocket, a belt pulley, or the like. Furthermore, the bottom bracket gearbox has three planetary gear sets which are coaxial with the bottom bracket gearbox, and five shift elements for implementing at least six gears in the bottom bracket gearbox according to the invention. In order to provide a particularly effective and installation space-favorable embodiment of the bottom bracket gearbox, the crank axle Wan is connected to a second element of the second planetary gear set. Furthermore, the crank axle Wan is connectable to a first element of the first planetary gear set via a fourth shift element and a first shaft. The gearbox output shaft is connected to a first element of the second planetary gear set and to a first element of the third planetary gear set. A second element of the first planetary gear set is connected to a third element of the second planetary gear set via a second shaft. A third element of the first planetary gear set is connected to a second element of the third planetary gear set via a third shaft. In order to interlock the third planetary gear set, two elements of the third planetary gear set are connectable to each other via a fifth shift element.

In this way, the above-described connection of the only three provided planetary gear sets and the only five provided shift elements result in a particularly simple and compact configuration of the bottom bracket gearbox according to the invention. This also results in particularly low component loads and an advantageously high gearing efficiency due to the geometric transmission ratio range in the bottom bracket gearbox.

Preferably in addition to the input and the output, only four further shafts or shaft-like elements are used in order to mechanically connect elements of the planetary gear sets. The term “shaft” is not to be understood exclusively as a cylindrical, rotatably mounted machine element for transmitting torques, but is rather also to be understood as general connecting elements that connect the individual gear set elements to one another for torque transmission.

In order to achieve the installation space-favorable arrangement in the bottom bracket gearbox according to the invention, when the first shift element is engaged, the first shaft, which is connected to the first element of the first planetary gear set, is fixedly connected to a housing, when the second shift element is engaged, the third shaft, which is connected to the third element of the first planetary gear set and to the second element of the third planetary gear set, is fixedly connected to the housing, and, when the third shift element is engaged, a fourth shaft, which is connected to the third element of the third planetary gear shaft, is fixedly connected to the housing. Due to the above-described housing-side connection of the elements by the provided shift elements as brakes, the intended gears are implemented in combination with a highly compact design of the bottom bracket gearbox.

Within the framework of the present invention, in the bottom bracket gearbox according to the invention, the first shift element, the second shift element, and the third shift element are each an interlocking brake and/or the fourth shift element and the fifth shift element are each a freewheel unit.

The shift elements as brakes are preferably interlocking shift elements, for example, low-cost shifting dogs or the like, for example, having a toothed brake ring and a corresponding shift pawl. Brakes as shift elements have the advantage that these are readily accessible from the outside for actuation. Since the provided freewheel units are used as clutches, it is advantageous when the brakes are in the form, for example, of single-sided brakes in order to prevent the gearbox from interlocking when the direction of rotation reverses at the input or at the output.

Preferably, permanently engaged freewheel units are used as freewheel units. This has the advantage that no engagement is necessary with the passive shift elements. The permanently engaged freewheel unit transmits a torque when this freewheel unit is interlocked. No torque is transmitted in the opposite direction of rotation. It is conceivable, however, that engageable and disengageable freewheel units or even engageable and disengageable freewheel brakes are used.

In the bottom bracket gearbox according to the invention, in order to interlock the third planetary gear set, within the framework of a first interlock variant, the first element of the third planetary gear set is connectable to the third element of the third planetary gear set via the fifth shift element. Furthermore, within the framework of a second interlock variant, the first element of the third planetary gear set is connectable to the second element of the third planetary gear set via the fifth shift element. In addition, within the framework of a third interlock variant, the second element of the third planetary gear set is connectable to the third element of the third planetary gear set via the fifth shift element.

A preferred embodiment of the invention provides that at least one of the provided planetary gear sets is a negative planetary gear set, whereby a particularly installation space-favorable arrangement results. It is also conceivable that one of the planetary gear sets is a positive planetary gear set.

A negative planetary gear set is preferably convertible into a positive planetary gear set when the planet carrier connection and the ring gear connection to this gear set are interchanged with one another and the value of the stationary transmission ratio is increased by 1. A negative planetary gear set has planet gears, which are rotatably mounted on its planet carrier and mesh with the sun gear and the ring gear of this planetary gear set, such that, when the planet carrier is held and the sun gear rotates, the ring gear rotates in the direction that is opposite the direction of rotation of the sun gear. A positive planetary gear set has inner and outer planet gears, which are rotatably mounted on its planet carrier and are in tooth engagement with one another, wherein the sun gear of this planetary gear set meshes with the inner planet gears, and the ring gear of this planetary gear set meshes with the outer planet gears, such that, when the planet carrier is held and the sun gear rotates, the ring gear rotates in the same direction of rotation as the sun gear.

For a person skilled in the art, this means that, in the single gear sets as a negative planetary gear set, a first element is a sun gear, a second element is a planet carrier, or a planet spider, and a third element is a ring gear. Furthermore, this means that, in the case of a single gear set as a positive planetary gear set, the first element is a sun gear, the second element is a ring gear, and the third element is a planet carrier, or a planet spider.

In order to further optimize the control of the bottom bracket gearbox according to the invention, at least one torque sensor or the like is provided at the input and/or at the output.

In order to electrically support the input in the bottom bracket gearbox according to the invention, at least one electric machine or the like is connected or connectable, or fixedly or detachably coupled, to the input, or to the crank axle and/or to the output, or to the gearbox output shaft. Preferably, the electric machine is arranged axially parallel to the crank axle.

One further aspect of the present invention claims a bicycle or a pedelec having the above-described bottom bracket gearbox. This yields the above-described advantages and further advantages.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is explained in greater detail in the following with reference to the drawings, wherein:

FIG. 1 shows a schematic basic view of one possible embodiment variant of a bottom bracket planetary gearbox for a bicycle or a pedelec;

FIG. 2 shows a schematic basic view of the bottom bracket gearbox with a first interlock variant in a third planetary gear set;

FIG. 3 shows a schematic basic view of the bottom bracket gearbox with a second interlock variant in the third planetary gear set;

FIG. 4 shows a schematic basic view of the bottom bracket gearbox shown in FIG. 1 with a positive planetary gear set as a first planetary gear set by way of example;

FIG. 5 shows a schematic basic view of the bottom bracket gearbox shown in FIG. 1 with a positive planetary gear set as a second planetary gear set by way of example;

FIG. 6 shows a schematic basic view of the bottom bracket gearbox shown in FIG. 1 with a positive planetary gear set as a third planetary gear set by way of example;

FIG. 7 shows a schematic view of the bottom bracket gearbox shown in FIG. 1 with a torque sensor at the input, which is indicated by way of example;

FIG. 8 shows a schematic view of the bottom bracket gearbox shown in FIG. 1 with an electric machine arranged at the input, which is indicated by way of example;

FIG. 9 shows a schematic view of the bottom bracket gearbox shown in FIG. 1 with an electric machine arranged at the output by way of example; and

FIG. 10 shows a gear shift matrix with the engageable and disengageable gears in the bottom bracket gearbox according to the invention, according to FIGS. 1-9.

DETAILED DESCRIPTION

Reference will now be made to embodiments of the invention, one or more examples of which are shown in the drawings. Each embodiment is provided by way of explanation of the invention, and not as a limitation of the invention. For example, features illustrated or described as part of one embodiment can be combined with another embodiment to yield still another embodiment. It is intended that the present invention include these and other modifications and variations to the embodiments described herein.

FIGS. 1-9 show various embodiments with reference to schematic basic views of a bottom bracket planetary gearbox according to the invention for a bicycle or a pedelec 1 merely by way of example. FIG. 1 shows the schematically indicated bicycle or pedelec 1 with the bottom bracket gearbox.

Regardless of the embodiments, the bottom bracket gearbox includes, in a housing, or bottom bracket housing 2, a crank axle Wan, or pedal crank, as the input with the pedals, and a gearbox output shaft Wab as the output with a sprocket, or belt pulley (not shown in greater detail). Furthermore, four further shafts including a first shaft W1, a second shaft W2, a third shaft W3, and a fourth shaft W4 are provided, which are coupled, or connected, to the elements of three planetary gear sets, including first planetary gear set RS1, second planetary gear set RS2, and third planetary gear set RS3. The elements of the first planetary gear set RS1, the second planetary gear set RS2, and the third planetary gear set RS3 are coaxial with the crank axle Wan. In addition, five shift elements, including a first shift element B1, a second shift element B2, a third shift element B3, a fourth shift element F1, and a fifth shift element F2, F2′, F2″ are provided for implementing six gears, such as a first gear ratio V1, a second gear ratio V2, a third gear ratio V3, a fourth gear ratio V4, a fifth gear ratio V5, and a sixth gear ratio V6. The first shift element B1, the second shift element B2, and the third shift element B3 are each a switchable brake, while the fourth shift element F1 and the fifth shift element F2 are each a permanently engaged freewheel unit.

Furthermore, regardless of the embodiments, in the bottom bracket gearbox according to the invention, the crank axle Wan is connected to a second element of the second planetary gear set RS2, and the crank axle Wan is connectable to a first element of the first planetary gear set RS1 via the fourth shift element F1 and the first shaft W1. Consequently, when the fourth shift element F1 is interlocked, the crank axle Wan is connected to the first shaft W1. Furthermore, the gearbox output shaft Wab is connected to a first element of the second planetary gear set RS2 and to a first element of the third planetary gear set RS3, a second element of the first planetary gear set RS1 is connected to a third element of the second planetary gear set RS2 via the second shaft W2, a third element of the first planetary gear set RS1 is connected to a second element of the third planetary gear set RS3 via the third shaft W3, and two elements of the third planetary gear set RS3 are connectable to each other via the fifth shift element F2, F2′, F2″ to interlock the third planetary gear set RS3.

The above-described connection of the elements of the planetary gear sets RS1, RS2, RS3, of the shafts Wab, Wab, W1, W2, W3, W4, and of the shift elements B1, B2, B3, F1, F2, F2′, F2″ results in a particularly installation space-favorable embodiment of the bottom bracket gearbox.

In FIGS. 1-3 and 7-9, the three provided planetary gear sets RS1, RS2, RS3 are each an installation space-favorable negative planetary gear set. As such, a sun gear SR1, SR2, SR3 is provided as the first element, a planet carrier PT1, PT2, PT3 is provided as the second element, and a ring gear HR1, HR2, HR3 is provided as the third element in the planetary gear sets RS1, RS2, RS3, respectively.

In detail, as a result, the crank axle Wan is connected to the planet carrier PT1 of the second planetary gear set RS2. Furthermore, the crank axle Wan is connectable to the sun gear SR1 of the first planetary gear set RS1 via the fourth shift element F1, which is a freewheel unit. The gearbox output shaft Wab is connected to the sun gear SR2 of the second planetary gear set RS2 and to the sun gear SR3 of the third planetary gear set RS3. The planet carrier PT1 is connected to the ring gear HR2 of the second planetary gear set RS2 via the second shaft W2. The ring gear HR1 of the first planetary gear set RS1 is connected to the planet carrier PT3 of the third planetary gear set RS3 via the third shaft W3. In order to interlock the third planetary gear set RS3, as a first interlock variant, as shown in FIG. 1, the sun gear SR3 is connectable to the ring gear HR3 of the third planetary gear set RS3 via the fifth shift element F2, which is a freewheel unit, or, as a second interlock variant, as shown in FIG. 2, the sun gear SR3 is connectable to the planet carrier PT3 via the fifth shift element F2′, which is a freewheel unit, or, as a third interlock variant, as shown in FIG. 3, the ring gear HR3 is connectable to the planet carrier PT3 via the fifth shift element F2″, which is a freewheel unit. Furthermore, when the first shift element B1 as a brake is engaged, the sun gear SR1 of the first planetary gear set RS1 is fixedly connected to the housing 2 via the first shaft W1. When the second shift element B2 as a brake is engaged, the ring gear HR1 of the first planetary gear set RS1 and the planet carrier PT3 of the third planetary gear set RS3 are fixedly connected to the housing 2 via the third shaft W3. When the third shift element B3 as a brake is engaged, the ring gear HR3 of the third planetary gear set RS3 is fixedly connected to the housing 2 via the fourth shaft W4. When the fourth shift element F1 as a freewheel unit is interlocked, the crank axle Wan is connected to the first shaft W1. When the fifth shift element F2 as a freewheel unit is interlocked, as shown in FIG. 1, the gearbox output shaft Wab is connected to the fourth shaft W4 and the third planetary gear set RS3 is interlocked.

In FIGS. 4-6, a positive planetary gear set is always provided in the three provided planetary gear sets RS1, RS2, RS3. In the positive planetary gear set, the ring gear connection and the planet carrier connection are interchanged.

In FIG. 4, for example, the first planetary gear set RS1 is a positive planetary gear set, while the second planetary gear set RS2 and the third planetary gear set RS3 are each a negative planetary gear set. In FIG. 5, for example, the second planetary gear set RS2 is a positive planetary gear set, while the first planetary gear set RS1 and the third planetary gear set RS3 are each a negative planetary gear set. In FIG. 6, for example, the third planetary gear set RS3 is a positive planetary gear set, while the first planetary gear set RS1 and the second planetary gear set RS2 are each a negative planetary gear set. The use of a positive planetary gear set results in greater flexibility in the selection of the transmission ratios.

FIG. 7 shows an embodiment of the bottom bracket gearbox according to the invention, in which a torque sensor 3 is connected, or connectable, to the crank axle Wan. For example, a disk-shaped torque sensor 3 is arranged at the gearbox input. The torque sensor 3 can also have a different embodiment, however.

FIGS. 8 and 9 each show an embodiment of the bottom bracket gearbox according to the invention with an additional electric machine EM. The electric machine EM is connected to the crank axle Wan, as indicated in FIG. 8. It is also conceivable that the electric machine EM is connected to the gearbox output shaft Wab, as indicated in FIG. 9. The electric machine EM is preferably arranged axially parallel to the crank axle Wan. A coaxial arrangement of the electric machine EM with the crank axle Wan would also be possible, however. Regardless thereof, it is advantageous to connect the electric machine EM via a freewheel unit or the like, so that, during operation without the electric machine EM, no losses are caused by the rotating electric machine EM.

FIG. 10 shows, by way of example, a gear shift matrix for the embodiments of the bottom bracket gearbox according to the invention, which are shown in FIGS. 1-9. In the gear shift matrix, shift elements B1, B2, B3, F1, F2, F2′, F2″ are indicated for the respective gear V1, V2, V3, V4, V5, V6. An “X” for a freewheel unit F1, F2, F2′, F2″ as a shift element in the gear shift matrix means that the freewheel unit is interlocked. This functions automatically without external actuation. Furthermore, an “X” for a brake B1, B2, B3 as a shift element in the gear shift matrix means that the brake B1, B2, B3 is engaged. This functions via a suitable actuator system.

Specifically, the gear shift matrix according to FIG. 10 indicates that, in order to implement a first gear V1, the fourth shift element F1 as a freewheel unit and the fifth shift element F2, F2′, F2″ as a freewheel unit are interlocked. In order to implement a second gear V2, the first shift element B1 as a brake is engaged and the fifth shift element F2 as a freewheel unit is interlocked. In order to implement a third gear V3, the third shift element B3 as a brake is engaged and the fourth shift element F1 as a freewheel unit is interlocked. In order to implement a fourth gear V4, the first shift element B1 as a brake and the third shift element B3 as a brake are engaged. In order to implement a fifth gear V5, the second shift element B2 as a brake is engaged and the fourth shift element F1 as a freewheel unit is interlocked. In order to implement a sixth gear V6, the first shift element B1 as a brake and the second shift element B2 as a brake are engaged. As a result, only two shift elements need to be used at the same time to shift a gear.

Modifications and variations can be made to the embodiments illustrated or described herein without departing from the scope and spirit of the invention as set forth in the appended claims. In the claims, reference characters corresponding to elements recited in the detailed description and the drawings may be recited. Such reference characters are enclosed within parentheses and are provided as an aid for reference to example embodiments described in the detailed description and the drawings. Such reference characters are provided for convenience only and have no effect on the scope of the claims. In particular, such reference characters are not intended to limit the claims to the particular example embodiments described in the detailed description and the drawings.

REFERENCE CHARACTERS

• • 1 bicycle or a pedelec
  • 2 housing or bottom bracket housing
  • 3 torque sensor
  • SR1 sun gear of the first planetary gear set
  • PT1 planet carrier of the first planetary gear set
  • HR1 ring gear of the first planetary gear set
  • SR2 sun gear of the second planetary gear set
  • PT2 planet carrier of the second planetary gear set
  • HR2 ring gear of the second planetary gear set
  • SR3 sun gear of the third planetary gear set
  • PT3 planet carrier of the third planetary gear set
  • HR3 ring gear of the third planetary gear set
  • Wan crank axle
  • Wab gearbox output shaft
  • EM electric machine
  • W1 first shaft
  • W2 second shaft
  • W3 third shaft
  • W4 fourth shaft
  • RS1 first planetary gear set
  • RS2 second planetary gear set
  • RS3 third planetary gear set
  • B1 first shift element as brake
  • B2 second shift element as brake
  • B3 third shift element as brake
  • F1 fourth shift element as freewheel unit
  • F2,F2′,F2″ fifth shift element as freewheel unit
  • V1 first gear
  • V2 second gear
  • V3 third gear
  • V4 fourth gear
  • V5 fifth gear
  • V6 sixth gear

Claims

1-15. (canceled)

16. A bottom bracket planetary gearbox for a bicycle or a pedelec (1), comprising: a crank axle (Wan) as an input;a gearbox output shaft (Wab) as an output;at least four further shafts including a first shaft (W1), a second shaft (W2), a third shaft (W3), and a fourth shaft (W4);five shift elements including a first shift element (B1), a second shift element (B2), a third shift element (B3), a fourth shift element (F1), and a fifth shift element (F2, F2′, F2″);a first planetary gear set (RS1) coaxial with the crank axle (Wan), the crank axle (Wan) being connectable to a first element of the first planetary gear set (RS1) via the fourth shift element (F1) and the first shaft (W1);a second planetary gear set (RS2) coaxial with the crank axle (Wan), the crank axle (Wan) being connected to a second element of the second planetary gear set (RS2), a second element of the first planetary gear set (RS1) being connected to a third element of the second planetary gear set (RS2) via the second shaft (W2); anda third planetary gear set (RS3) coaxial with the crank axle (Wan), the gearbox output shaft (Wab) being connected to a first element of the second planetary gear set (RS2) and to a first element of the third planetary gear set (RS3), a third element of the first planetary gear set (RS1) being connected to a second element of the third planetary gear set (RS3) via the third shaft (W3), two of the first element, the second element, and a third element of the third planetary gear set (RS3) being connectable to one another via the fifth shift element (F2, F2′, F2″) to interlock the third planetary gear set (RS3),wherein at least six gears (V1, V2, V3, V4, V5, V6) are implementable.

17. The bottom bracket planetary gearbox of claim 16, wherein: the first shaft (W1) is connected to the first element of the first planetary gear set (RS1), the first shaft (W1) being fixedly connected to a housing (2) when the first shift element (B1) is engaged,the third shaft (W3) is connected to the third element of the first planetary gear set (RS1) and to the second element of the third planetary gear set (RS3), the third shaft (W3) being fixedly connected to the housing (G) when the second shift element (B2) is engaged, andthe fourth shaft (W4) is connected to the third element of the third planetary gear set (RS3), the fourth shaft (W4) being fixedly connected to the housing (2) when the third shift element (B3) is engaged.

18. The bottom bracket planetary gearbox of claim 16, wherein each of the first shift element (B1), the second shift element (B2), and the third shift element (B3) is an interlocking brake, and each of the fourth shift element (F1) and the fifth shift element (F2, F2′, F2″) is a freewheel unit.

19. The bottom bracket planetary gearbox of claim 16, further comprising a torque sensor (3) connected to the crank axle (Wan).

20. The bottom bracket planetary gearbox of claim 16, further comprising at least one electric machine (EM) connected or connectable to the crank axle (Wan) or to the gearbox output shaft (Wab).

21. The bottom bracket planetary gearbox of claim 20, wherein the electric machine (EM) is axially parallel to the crank axle (Wan).

22. The bottom bracket planetary gearbox of claim 16, wherein the first element of the third planetary gear set (RS3) is connectable to the third element of the third planetary gear set (RS3) via the fifth shift element (F2) to interlock the third planetary gear set (RS3).

23. The bottom bracket planetary gearbox of claim 16, wherein the first element of the third planetary gear set (RS3) is connectable to the second element of the third planetary gear set (RS3) via the fifth shift element (F2′) to interlock the third planetary gear set (RS3).

24. The bottom bracket planetary gearbox of claim 16, wherein the second element of the third planetary gear set (RS3) is connectable to the third element of the third planetary gear set (RS3) via the fifth shift element (F2″) to interlock the third planetary gear set (RS3).

25. The bottom bracket planetary gearbox of claim 16, wherein at least one of the first planetary gear set (RS1), the second planetary gear set (RS2), or the third planetary gear set (RS3) is a negative planetary gear set.

26. The bottom bracket planetary gearbox of claim 25, wherein, for each of the at least one of the first planetary gear set (RS1), the second planetary gear set (RS2), or the third planetary gear set (RS3), the first element is a sun gear (SR1, SR2, SR3), the second element is a planet carrier (PT1, PT2, PT3), and the third element is a ring gear (HR1, HR2, HR3).

27. The bottom bracket planetary gearbox of claim 16, wherein at least one of the first planetary gear set (RS1), the second planetary gear set (RS2), or the third planetary gear set (RS3) is a positive planetary gear set.

28. The bottom bracket planetary gearbox of claim 27, wherein, for each of the at least one of the first planetary gear set (RS1), the second planetary gear set (RS2), or the third planetary gear set (RS3), the first element is a sun gear (SR1, SR2, SR3), the second element is a ring gear (HR1, HR2, HR3), and the third element is a planet carrier (PT1, PT2, PT3).

29. The bottom bracket planetary gearbox of claim 16, wherein: each of the first shift element (B1), the second shift element (B2), and the third shift element (B3) is a brake, and each of the fourth shift element (F1) and the fifth shift element (F2, F2′, F2″) is a freewheel unit,for implementing a first gear (V1), the fourth shift element (F1) is interlocked, and the fifth shift element (F2, F2′, F2″) is interlocked;for implementing a second gear (V2), the first shift element (B1) is engaged, and the fifth shift element (F2) is interlocked;for implementing a third gear (V3), the third shift element (B3) is engaged, and the fourth shift element (F1) is interlocked;for implementing a fourth gear (V4), the first shift element (B1) is engaged, and the third shift element (B3) is engaged;for implementing a fifth gear (V5), the second shift element (B2) is engaged, and the fourth shift element (F1) is interlocked; andfor engaging a sixth gear (V6), the first shift element (B1) is engaged, and the second shift element (B2) is engaged.

30. A bicycle or pedelec (1), comprising the bottom bracket planetary gearbox of claim 16.