A bicycle bottom bracket assembly and a crank axle for a bicycle crank assembly

Abstract

A first radial outer ring distance is defined from the rotation center axis to the first radial outermost surface. A second radial outer ring distance is defined from the rotation center axis to the second radial outermost surface. A first radial inner ring distance is defined from the rotation center axis to the first radial innermost surface. A second radial inner ring distance is defined from the rotation center axis to the second radial innermost surface. At least one of the first radial outer ring distance and the first radial rolling element distance differs from a corresponding term of the second radial outer ring distance and the second radial rolling element distance. The first radial inner ring distance differs from the second radial inner ring distance.

Description

Technical Field

[0001] The present invention relates to a bicycle chassis assembly and a crankshaft for a bicycle crank assembly. Prior Technology

[0002] Cycling has become an increasingly popular form of recreation and a means of transportation. Furthermore, it has become a highly popular competitive sport for both amateurs and professional athletes.

[0003] Whether bicycles are used for leisure, transportation, or racing, the bicycle industry is constantly improving various systems of bicycles. One widely redesigned bicycle system is a bicycle chassis assembly and a crankshaft for a bicycle crank assembly. The bicycle chassis assembly and the crankshaft for the bicycle crank assembly are mounted to a bicycle frame.

[0004] For example, a bicycle chassis assembly is known in US7699532 and DE102008029088A1. Based on this prior art, the object of the present invention is to provide a bicycle chassis assembly that achieves a balance between drive efficiency and rigidity. The object of the present invention is also to provide a bicycle chassis assembly that improves the assemblability of the bicycle chassis assembly to the bicycle frame. Furthermore, for example, a crankshaft for a bicycle crank assembly is known in US20050011304A1 and US20060053962A1. Based on this prior art, the object of the present invention is to provide a crankshaft that achieves a balance between drive efficiency and rigidity. Summary of the Invention

[0005] According to a first embodiment of the present invention, a bicycle chassis assembly includes a first support member, a second support member, a first bearing unit, and a second bearing unit.

[0006] The first support member includes a first hanger mounting portion and a first bearing mounting portion. The first hanger mounting portion is configured to be mounted to a first axial end of a hanger component of a bicycle frame.

[0007] The second support member includes a second hanger mounting portion and a second bearing mounting portion. The second hanger mounting portion is configured to be mounted to a second axial end of the hanger component of the bicycle frame. The second axial end of the hanger component is opposite to the first axial end of the hanger component in an axial direction relative to a rotation center axis of the bicycle chassis assembly.

[0008] The first bearing unit includes a first outer ring, a first inner ring, and at least one first rolling element disposed between the first outer ring and the first inner ring in a radial direction relative to one of the rotational central axes. The first outer ring is configured to be fixed to the first bearing mounting portion of the first support member. The first outer ring has a first radially outermost surface facing the radial direction. The first inner ring has a first radially innermost surface facing the radial direction. The at least one first rolling element has a first center point.

[0009] The second bearing unit includes a second outer ring, a second inner ring, and at least one second rolling element disposed between the second outer ring and the second inner ring in the radial direction. The second outer ring is configured to be fixed to the second bearing mounting portion of the second support member. The second outer ring has a second radially outermost surface facing the radial direction. The second inner ring has a second radially innermost surface facing the radial direction. The at least one second rolling element has a second center point.

[0010] A first radial outer ring distance is defined in the radial direction from the rotation center axis to the first radial outermost surface. A second radial outer ring distance is defined in the radial direction from the rotation center axis to the second radial outermost surface. The first radial outer ring distance and the second radial outer ring distance are compared with each other as corresponding items.

[0011] A first radial rolling element distance is defined from the rotation center axis to the first center point. A second radial rolling element distance is defined from the rotation center axis to the second center point. The first radial rolling element distance and the second radial rolling element distance are compared with each other as corresponding items.

[0012] A first radial inner ring distance is defined in the radial direction from the rotation center axis to the first radial innermost surface. A second radial inner ring distance is defined in the radial direction from the rotation center axis to the second radial innermost surface. The first radial inner ring distance and the second radial inner ring distance are compared with each other as corresponding items.

[0013] At least one of the first radial outer ring distance and the first radial rolling element distance differs from one of the corresponding items of the second radial outer ring distance and the second radial rolling element distance. The first radial inner ring distance differs from the second radial inner ring distance.

[0014] Regarding the bicycle chassis assembly according to the first state, the first radial inner ring distance is different from the second radial inner ring distance.

[0015] Therefore, one of the crankshafts installed in the bicycle chassis assembly can include a large-diameter portion and a small-diameter portion. In other words, the bicycle chassis assembly can enhance rigidity through the large-diameter portion of the crankshaft and reduce weight through the small-diameter portion of the crankshaft.

[0016] Furthermore, the diameter of one of the first bearing unit and the second bearing unit is smaller than the diameter of the other of the first bearing unit and the second bearing unit. In other words, the rotational resistance of the smaller bearing unit is less than that of the larger bearing unit. Therefore, the bicycle chassis assembly can enhance drive efficiency by using the smaller of the first bearing unit and the second bearing unit, while simultaneously enhancing rigidity by using the larger of the first bearing unit and the second bearing unit.

[0017] According to a second embodiment of the present invention, the bicycle chassis assembly according to the first embodiment is configured such that the first support member and the second support member are formed as an integral single component.

[0018] Regarding the bicycle chassis assembly according to the second embodiment, the assemblability of the bicycle chassis assembly to the bicycle frame may be improved. Furthermore, the dimensional accuracy of the bicycle chassis assembly in one axial direction relative to one of the rotational central axes of the bicycle chassis assembly may be improved. Therefore, it is possible to install the first support member and the second support member of the bicycle chassis assembly to the bicycle frame without using spacers to eliminate unnecessary axial clearance.

[0019] According to a third embodiment of the present invention, the bicycle chassis assembly of the first embodiment is configured such that the first support member has a first axial inner end configured to be disposed within the hanger component of the bicycle frame in an installed state in which the bicycle chassis assembly is mounted to the hanger component of the bicycle frame. The second support member has a second axial inner end configured to be disposed within the hanger component of the bicycle frame in the installed state.

[0020] Regarding the bicycle chassis assembly according to the third state, the bicycle chassis assembly can reduce its weight and be installed on bicycle frames of various sizes.

[0021] According to a fourth embodiment of the present invention, the bicycle chassis assembly according to the third embodiment is configured such that the first axial inner end of the first support member and the second axial inner end of the second support member are separated from each other in the axial direction in the installed state.

[0022] Regarding the bicycle chassis assembly according to the fourth state, the bicycle chassis assembly can reduce its weight and be installed on bicycle frames of various sizes.

[0023] According to a fifth embodiment of the present invention, the bicycle chassis assembly according to any one of the first to fourth embodiments further includes a connecting tubular member. The connecting tubular member is configured to bridge an axial gap between the first axial inner end of the first support member and the second axial inner end of the second support member in the installed state.

[0024] Regarding the bicycle chassis assembly according to the fifth state, the bicycle chassis assembly is able to prevent foreign objects (for example, water and mud and the like) from entering the first bearing unit and the second bearing unit from a pipe.

[0025] According to a sixth embodiment of the present invention, the bicycle chassis assembly of the third embodiment is configured such that the first axial inner end of the first support member has a first threaded portion. The second axial inner end of the second support member has a second threaded portion configured to thread-engage with the first threaded portion of the first axial inner end in the installed state.

[0026] Regarding the bicycle chassis assembly according to the sixth state, the bicycle chassis assembly can be installed on bicycle frames of various sizes and prevent foreign objects (for example, water and mud and the like) from entering the first bearing unit and the second bearing unit from a pipe.

[0027] According to a seventh embodiment of the present invention, the bicycle chassis assembly of the third embodiment is configured such that the first axial inner end of the first support member and the second axial inner end of the second support member overlap each other in a press-fit manner in the installed state.

[0028] Regarding the bicycle chassis assembly according to the seventh state, the bicycle chassis assembly can be installed on a bicycle frame of various sizes and prevents foreign objects (for example, water and mud and the like) from entering the first bearing unit and the second bearing unit from a pipe.

[0029] According to an eighth embodiment of the present invention, the bicycle chassis assembly of the third embodiment is configured such that the first axial inner end of the first support member and the second axial inner end of the second support member overlap each other in the installed state. An elastic sealing member is disposed radially between the first axial inner end of the first support member and the second axial inner end of the second support member in the installed state.

[0030] Regarding the bicycle chassis assembly according to the eighth state, the bicycle chassis assembly can be installed on bicycle frames of various sizes and prevent foreign objects (for example, water and mud and the like) from entering the first bearing unit and the second bearing unit from a pipe.

[0031] According to a ninth embodiment of the present invention, the bicycle chassis assembly according to any one of the first to eighth embodiments further includes a tubular sealing member. The tubular sealing member is configured to bridge an axial gap between the first inner ring of the first bearing unit and the second inner ring of the second bearing unit in an installed state where the bicycle chassis assembly is mounted to one of the hanger components of the bicycle frame.

[0032] Regarding the bicycle chassis assembly according to the ninth state, the bicycle chassis assembly is able to prevent foreign objects (for example, water and mud and the like) from entering the first bearing unit and the second bearing unit from a pipe.

[0033] According to a tenth embodiment of the present invention, the bicycle chassis assembly according to any one of the first to ninth embodiments is configured such that the first radial inner ring distance is greater than the second radial inner ring distance. The first radial innermost surface defines a first opening. The second radial innermost surface defines a second opening.

[0034] The first opening and the second opening are configured such that a crankshaft can be inserted into the bicycle chassis assembly by moving it in the axial direction from the first opening toward the second opening, and can be removed from the bicycle chassis assembly by moving it in the axial direction from the second opening toward the first opening.

[0035] Regarding the bicycle chassis assembly according to the tenth embodiment, the bicycle chassis assembly can enhance rigidity by the large-diameter portion of the crankshaft and reduce weight by the small-diameter portion of the crankshaft. The bicycle chassis assembly can enhance drive efficiency by the smaller of the first bearing unit and the second bearing unit, while enhancing rigidity by the larger of the first bearing unit and the second bearing unit.

[0036] According to an eleventh embodiment of the present invention, a bicycle chassis assembly includes a first bearing unit and a second bearing unit.

[0037] The first bearing unit includes a first outer ring, a first inner ring, and at least one first rolling element disposed between the first outer ring and the first inner ring in a radial direction relative to a rotational axis of the bicycle frame assembly. The first outer ring is configured to be fixed to a first axial end of a hanger component of a bicycle frame. The first inner ring has a first radially innermost surface facing the radial direction.

[0038] The second bearing unit includes a second outer ring, a second inner ring, and at least one second rolling element disposed between the second outer ring and the second inner ring in the radial direction. The second outer ring is configured to be fixed to a second axial end of a hanger component of the bicycle frame. The second axial end of the hanger component is opposite to the first axial end of the hanger component in an axial direction relative to a rotational center axis of the bicycle chassis assembly. The second inner ring has a second radially innermost surface facing the radial direction.

[0039] A first radial inner ring distance is defined in the axial direction from the rotation center axis to the first radial innermost surface. A second radial inner ring distance is defined in the axial direction from the rotation center axis to the second radial innermost surface. The first radial inner ring distance is different from the second radial inner ring distance.

[0040] Regarding the bicycle chassis assembly according to the eleventh embodiment, the bicycle chassis assembly can enhance rigidity through the large-diameter portion of the crankshaft and reduce weight through the small-diameter portion of the crankshaft. The bicycle chassis assembly can enhance drive efficiency through the smaller of the first bearing unit and the second bearing unit, while enhancing rigidity through the larger of the first bearing unit and the second bearing unit. The bicycle chassis assembly can reduce its weight because it can be assembled without the first support member and the second support member.

[0041] According to a twelfth embodiment of the present invention, the bicycle chassis assembly according to the eleventh embodiment is configured such that the first radial inner ring distance is greater than the second radial inner ring distance. The first radial innermost surface defines a first opening. The second radial innermost surface defines a second opening.

[0042] The first opening and the second opening are configured such that a crankshaft can be inserted into the bicycle chassis assembly by moving it in the axial direction from the first opening toward the second opening, and can be removed from the bicycle chassis assembly by moving it in the axial direction from the second opening toward the first opening.

[0043] Regarding the bicycle chassis assembly according to the twelfth embodiment, the bicycle chassis assembly can enhance rigidity by the large-diameter portion of the crankshaft and reduce weight by the small-diameter portion of the crankshaft. The bicycle chassis assembly can enhance drive efficiency by the smaller of the first bearing unit and the second bearing unit, while enhancing rigidity by the larger of the first bearing unit and the second bearing unit.

[0044] According to a thirteenth embodiment of the present invention, the bicycle chassis assembly of the eleventh or twelfth embodiment is configured such that the first outer ring is fixed to the first axial end of the hanger component of the bicycle frame in a press-fit manner. The second outer ring is fixed to the second axial end of the hanger component of the bicycle frame in a press-fit manner.

[0045] Regarding the bicycle chassis assembly according to the thirteenth version, the bicycle chassis assembly can reduce its weight because it is assembled without the first support member and the second support member.

[0046] According to one fourteenth embodiment of the present invention, a bicycle chassis assembly includes a first support member, a second support member, a first bearing unit, and a second bearing unit.

[0047] The first support member includes a first hanger mounting portion and a first bearing mounting portion. The first hanger mounting portion is configured to be mounted to a first axial end of a hanger component of a bicycle frame.

[0048] The second support member includes a second hanger mounting portion and a second bearing mounting portion. The second hanger mounting portion is configured to be mounted to a second axial end of the hanger component of the bicycle frame. The second axial end of the hanger component is opposite to the first axial end of the hanger component in an axial direction relative to a rotation center axis of the bicycle chassis assembly.

[0049] The first bearing unit includes a first outer ring, a first inner ring, and at least one first rolling element disposed between the first outer ring and the first inner ring in a radial direction relative to one of the rotational central axes of the bicycle chassis assembly. The first outer ring is configured to be fixed to the first bearing mounting portion of the first support member. The first inner ring has a first radially innermost surface facing the radial direction, the first radially innermost surface defining a first opening.

[0050] The second bearing unit includes a second outer ring, a second inner ring, and at least one second rolling element disposed between the second outer ring and the second inner ring in the radial direction. The second outer ring is configured to be fixed to the second bearing mounting portion of the second support member. The second inner ring has a second radially innermost surface facing the radial direction. The second radially innermost surface defines a second opening.

[0051] The first opening and the second opening are configured such that a crankshaft can be inserted into the bicycle chassis assembly from one of the first opening and the second opening toward the other of the first opening and the second opening in the axial direction, and the crankshaft can be removed from the bicycle chassis assembly by moving the crankshaft from the other of the first opening and the second opening toward the first opening and the second opening in the axial direction. The first support member and the second support member are formed as a single integral component.

[0052] Regarding the bicycle chassis assembly according to the fourteenth embodiment, the assemblability of the bicycle chassis assembly to the bicycle frame may be improved. Furthermore, the dimensional accuracy of the bicycle chassis assembly in one axial direction relative to one of the rotational central axes of the bicycle chassis assembly may be improved. Therefore, it is possible to install the first support member and the second support member of the bicycle chassis assembly to the bicycle frame without using spacers to eliminate unnecessary axial clearance.

[0053] According to a fifteenth embodiment of the present invention, the bicycle chassis assembly according to the fourteenth embodiment is configured such that a first radial inner ring distance is defined in the axial direction from the rotation center axis to the first radial innermost surface. A second radial inner ring distance is defined in the axial direction from the rotation center axis to the second radial innermost surface. The first radial inner ring distance is equal to the second radial inner ring distance.

[0054] Regarding the bicycle chassis assembly according to the fifteenth embodiment, the assemblability of the bicycle chassis assembly to the bicycle frame may be improved. Furthermore, the dimensional accuracy of the bicycle chassis assembly in one axial direction relative to one of the rotational central axes of the bicycle chassis assembly may be improved. Therefore, it is possible to mount the first support member and the second support member of the bicycle chassis assembly to the bicycle frame without having spacers to eliminate unnecessary axial clearance.

[0055] According to a sixteenth embodiment of the present invention, the bicycle chassis assembly according to the fourteenth embodiment is configured such that a first radial inner ring distance is defined in the radial direction from the rotation center axis to the first radial innermost surface. A second radial inner ring distance is defined in the radial direction from the rotation center axis to the second radial innermost surface. The first radial inner ring distance is different from the second radial inner ring distance.

[0056] Regarding the bicycle chassis assembly according to the sixteenth embodiment, the bicycle chassis assembly can enhance rigidity by the large-diameter portion of the crankshaft and reduce weight by the small-diameter portion of the crankshaft. The bicycle chassis assembly can enhance drive efficiency by the smaller of the first bearing unit and the second bearing unit, while enhancing rigidity by the larger of the first bearing unit and the second bearing unit.

[0057] According to a seventeenth embodiment of the present invention, the bicycle chassis assembly according to the sixteenth embodiment is configured such that the first radial inner ring distance is greater than the second radial inner ring distance. The first opening and the second opening are configured such that a crankshaft can be inserted into the bicycle chassis assembly by moving it axially from the first opening toward the second opening, and can be removed from the bicycle chassis assembly by moving it axially from the second opening toward the first opening.

[0058] Regarding the bicycle chassis assembly according to the seventeenth embodiment, the bicycle chassis assembly can enhance rigidity by the large-diameter portion of the crankshaft and reduce weight by the small-diameter portion of the crankshaft. The bicycle chassis assembly can enhance drive efficiency by the smaller of the first bearing unit and the second bearing unit, while enhancing rigidity by the larger of the first bearing unit and the second bearing unit.

[0059] According to an eighteenth embodiment of the present invention, a crankshaft for a bicycle crank assembly includes a large-diameter portion, a small-diameter portion, and a transition step.

[0060] The large-diameter portion includes a first bearing mounting section having a first bearing mounting diameter. The small-diameter portion includes a second bearing mounting section having a second bearing mounting diameter smaller than the first bearing mounting diameter. The transition step is positioned between the large-diameter portion and the small-diameter portion in an axial direction relative to one of the rotational center axes of the crankshaft. The second bearing mounting section is spaced apart from the transition step in this axial direction.

[0061] Regarding the crankshaft for the bicycle crank assembly according to the eighteenth embodiment, the crankshaft can enhance rigidity through its large-diameter portion and reduce its weight through its small-diameter portion. The crankshaft can enhance drive efficiency through its small-diameter portion while enhancing rigidity through its large-diameter portion.

[0062] According to a nineteenth embodiment of the present invention, the crankshaft of the bicycle crank assembly according to the eighteenth embodiment is configured such that an axial distance defining the second bearing mounting section and the transition step in the axial direction is in the range of 0.1 mm to 70 mm.

[0063] Regarding the crankshaft for the bicycle crank assembly according to the nineteenth embodiment, the crankshaft can enhance rigidity through its large-diameter portion and reduce its weight through its small-diameter portion. The crankshaft can enhance drive efficiency through its small-diameter portion while enhancing rigidity through its large-diameter portion.

[0064] According to a twentieth aspect of the present invention, a crankshaft for a bicycle crank assembly includes a large-diameter portion, a small-diameter portion, and a transition step.

[0065] The large-diameter section includes a first bearing mounting section. The first bearing mounting section has a first bearing mounting diameter.

[0066] The smaller diameter section includes a second bearing mounting section. This second bearing mounting section has a second bearing mounting diameter that is smaller than that of the first bearing mounting diameter.

[0067] The transition step is positioned between the large-diameter portion and the small-diameter portion in the axial direction relative to one of the rotational center axes of the crankshaft.

[0068] The diameter difference between the first bearing mounting diameter and the second bearing mounting diameter is equal to or greater than 2 mm.

[0069] Regarding the crankshaft for the bicycle crank assembly according to the twentieth embodiment, the crankshaft can enhance its rigidity through the large-diameter portion and reduce its weight through the small-diameter portion. The crankshaft can enhance drive efficiency through the small-diameter portion while enhancing rigidity through the large-diameter portion.

[0070] According to a twenty-first embodiment of the present invention, the crankshaft of the bicycle crank assembly is configured such that the diameter difference is equal to or less than 60 mm.

[0071] Regarding the crankshaft used in the bicycle crank assembly according to the twenty-first specification, the crankshaft can reduce its weight by using the small-diameter portion. The crankshaft can reduce its rotational resistance. Simple Explanation of the Diagram

[0072] Now refer to the accompanying diagrams that form part of this original disclosure:

[0073] Figure 1 is a side view of a bicycle according to one embodiment of the present invention;

[0074] Figure 2A is a cross-sectional view of a bicycle chassis assembly according to a first embodiment of the present invention;

[0075] Figure 2B is a cross-sectional view of a bicycle chassis assembly according to a first embodiment of the present invention;

[0076] Figure 2C is a cross-section of a bicycle chassis assembly according to a variation of a first embodiment of the present invention;

[0077] Figure 2D is a cross-section of a bicycle chassis assembly according to a variation of a first embodiment of the present invention;

[0078] Figure 3A is a cross-sectional view of a bicycle chassis assembly according to a second embodiment of the present invention;

[0079] Figure 3B is a cross-sectional view of a bicycle chassis assembly according to a variation of the second embodiment of the present invention;

[0080] Figure 4A is a cross-sectional view of a bicycle chassis assembly according to a third embodiment of the present invention;

[0081] Figure 4B is a cross-sectional view of a bicycle chassis assembly according to a variation of the third embodiment of the present invention;

[0082] Figure 4C is a cross-sectional view of a bicycle chassis assembly according to a variation of the third embodiment of the present invention;

[0083] Figure 5 is a cross-sectional view of a bicycle chassis assembly according to a fourth embodiment of the present invention;

[0084] Figure 6 is a cross-sectional view of a bicycle chassis assembly according to a fifth embodiment of the present invention; and

[0085] Figure 7 is a cross-section of a bicycle chassis assembly and a crankshaft according to a sixth embodiment of the present invention. Implementation

[0086] Selected embodiments of the invention will now be illustrated with reference to the accompanying drawings. Those skilled in the art will appreciate that the following description of embodiments of the invention is provided for illustrative purposes only and not for limiting the scope of the invention, which is defined by the appended claims and their equivalents.

[0087] In the following embodiments, if the plurality of components and parts correspond to each other, the corresponding components and parts are indicated by the same symbol. [First Embodiment] []

[0088] [The general structure of a bicycle]

[0089] As shown in Figure 1, a bicycle 1 includes a bicycle chain 9, a bicycle frame 11, a handlebar 13, a front wheel 17 and a rear wheel 19, a gear shifter 24, a drivetrain 25 and a front fork 20. The bicycle 1 includes a crankshaft 51 for a bicycle crank assembly 27 and a bicycle chassis assembly 53.

[0090] The bicycle frame 11 includes a hanger component 11a. The hanger component 11a is disposed on the lower and central portion of the bicycle frame 11. The hanger component 11a is substantially formed in a tubular shape.

[0091] As shown in Figure 2A, the hanger component 11a includes a first axial end 12a and a second axial end 12b. The hanger component 11a further includes a main body component 12c.

[0092] The first axial end 12a is disposed on one end side of the main body component 12c. The second axial end 12b is disposed on the other end side of the main body component 12c.

[0093] The main body component 12c extends axially relative to the rotation center axis C1 of one of the bicycle chassis assembly 53. The main body component 12c is substantially formed in a tubular shape. The rotation center axis of one of the crankshafts 51 is coaxial with the rotation center axis C1 of the bicycle chassis assembly 53.

[0094] The main body component 12c is disposed between the first axial end 12a and the second axial end 12b. The main body component 12c is integrally formed with the first axial end 12a and the second axial end 12b. The main body component 12c, the first axial end 12a, and the second axial end 12b are formed as a single integral component.

[0095] As shown in Figure 1, the front fork 20 is rotatably attached to the bicycle frame 11. The handlebars 13 are fixed to the front fork 20. The front wheel 17 is rotatably attached to the front fork 20. The rear wheel 19 is rotatably attached to a rear portion of the bicycle frame 11 via a bicycle rear wheel hub assembly 29. A front tire 17a is attached to the front wheel 17. A rear tire 19a is attached to the rear wheel 19.

[0096] A shift mechanism 24 is attached to the handlebars 13. The shift mechanism 24 operates a bicycle rear derailleur 26 via a control cable. For example, the bicycle rear derailleur 26 is attached to a rear portion of the bicycle frame 11.

[0097] The bicycle rear derailleur 26 moves the bicycle chain 9 from one rear sprocket of a bicycle rear sprocket assembly 28 to another rear sprocket of the same assembly via a shifting device 24. These rear sprockets are illustrated in Figure 1 with a simplified description.

[0098] The drivetrain 25 mainly comprises the bicycle crank assembly 27 and the bicycle rear sprocket assembly 28. Specifically, the drivetrain 25 mainly comprises the bicycle crank assembly 27, the bicycle rear wheel hub assembly 29, and the bicycle rear sprocket assembly 28. The bicycle chain 9 can also be considered part of the drivetrain 25.

[0099] The bicycle crank assembly 27 is rotatably supported on a lower portion of the bicycle frame 11 (for example, the hanger component 11a of the bicycle frame 11). The bicycle crank assembly 27 includes at least one bicycle front sprocket 35. In this embodiment, the bicycle crank assembly 27 includes a single bicycle front sprocket 35 that engages with the bicycle chain 9. The bicycle crank assembly 27 may include a plurality of bicycle front sprockets, and the bicycle chain 9 can be shifted among the plurality of bicycle front sprockets by a bicycle front derailleur.

[0100] The bicycle crank assembly 27 is mounted on the crankshaft 51. For example, the bicycle crank assembly 27 is attached to the crankshaft 51 in a non-rotatable manner. Specifically, the bicycle crank assembly 27 is attached to the crankshaft 51 in a non-rotatable manner so that pedaling torque can be transmitted from the bicycle crank assembly 27 to the crankshaft 51.

[0101] The crankshaft 51 is rotatably supported on a lower portion of the bicycle frame 11 (for example, a hanger component 11a of the bicycle frame 11). For example, the crankshaft 51 is rotatably supported on the hanger component 11a of the bicycle frame 11 via a bicycle chassis assembly 53. Details of the bicycle chassis assembly 53 will be described later.

[0102] The bicycle rear wheel hub assembly 29 is mounted on the rear portion of the bicycle frame 11. The bicycle rear wheel hub assembly 29 rotatably supports the bicycle rear sprocket assembly 28. The bicycle rear sprocket assembly 28 is mounted to the bicycle rear wheel hub assembly 29.

[0103] [Bicycle chassis assembly configuration]

[0104] As shown in Figure 1, the bicycle base bracket assembly 53 is mounted to the hanger component 11a. As shown in Figure 2A, the bicycle base bracket assembly 53 includes a first support member 55, a second support member 57, a first bearing unit 61, and a second bearing unit 62.

[0105] The first support member 55 and the second support member 57 are formed as a single integral component. Specifically, the first support member 55 and the second support member 57 are connected to each other by a connecting portion 59.

[0106] The connecting portion 59 is housed within the hanger component 11a of the bicycle frame 11. The connecting portion 59 is integrally formed with the first support member 55 and the second support member 57. In other words, the connecting portion 59, the first support member 55, and the second support member 57 are formed as a single integral component. For example, the connecting portion 59 is formed in a tubular shape.

[0107] The first support member 55 includes a first hanger mounting portion 55a and a first bearing mounting portion 55b.

[0108] The first hanger mounting portion 55a is configured to be mounted to a first axial end 12a of the hanger component 11a of the bicycle frame 11. The first hanger mounting portion 55a is positioned radially inside the first axial end 12a of the hanger component 11a in a radial direction relative to a rotation center axis C1 of the bicycle chassis assembly 53. For example, the first hanger mounting portion 55a is formed in a tubular shape.

[0109] The first bearing mounting portion 55b is configured to mount the first bearing unit 61. In this embodiment, the first bearing mounting portion 55b is positioned axially outward of the first axial end 12a of the hanger component 11a in an axial direction relative to the rotation center axis C1 of the bicycle chassis assembly 53. For example, the first bearing mounting portion 55b is formed in a tubular shape. For example, the first bearing unit 61 is mounted to the first bearing mounting portion 55b by a press-fit method.

[0110] The second support member 57 includes a second hanger mounting portion 57a ​​and a second bearing mounting portion 57b.

[0111] The second hanger mounting portion 57a ​​is configured to be mounted to the second axial end 12b of one of the hanger components 11a of the bicycle frame 11. The second axial end 12b of the hanger component 11a is opposite to the first axial end 12a of the hanger component 11a in the axial direction relative to the rotation center axis C1 of one of the bicycle chassis assembly 53.

[0112] The second hanger mounting portion 57a ​​is positioned radially inside the second axial end 12b of the hanger component 11a in the radial direction relative to the rotation center axis C1 of the bicycle chassis assembly 53. For example, the second hanger mounting portion 57a ​​is formed in a tubular shape.

[0113] The second bearing mounting portion 57b is configured to mount the second bearing unit 62. In this embodiment, the second bearing mounting portion 57b is positioned radially inward of the second axial end 12b of the hanger component 11a in the radial direction relative to the rotation center axis C1 of the bicycle chassis assembly 53. For example, the second bearing unit 62 is mounted to the second bearing mounting portion 57b by a press-fit method.

[0114] The first bearing unit 61 rotatably supports the crankshaft 51. The first bearing unit 61 includes a first outer ring 61a, a first inner ring 61b, and at least one first rolling element 61c. The at least one first rolling element 61c is disposed between the first outer ring 61a and the first inner ring 61b in a radial direction relative to one of the rotational central axes C1.

[0115] The first outer ring 61a is configured to be fixed to the first bearing mounting portion 55b of the first support member 55. The first outer ring 61a has a first radial outermost surface 61d facing the radial direction.

[0116] The first inner ring 61b faces the crankshaft 51 in the radial direction. The first inner ring 61b rotates integrally with the crankshaft 51. The first inner ring 61b has a first radial innermost surface 61e facing the radial direction. When viewed from the axial direction relative to the rotation center axis C1, the first radial innermost surface 61e is formed in a circular shape.

[0117] At least one first rolling element 61c has a first center point P1. The first center point P1 is defined on a circular line extending in a circumferential direction relative to a rotational central axis C1. Preferably, at least one first rolling element 61c includes a plurality of first rolling elements 61c in this circumferential direction.

[0118] The second bearing unit 62 rotatably supports the crankshaft 51. The second bearing unit 62 includes a second outer ring 62a, a second inner ring 62b, and at least one second rolling element 62c. The at least one second rolling element 62c is radially disposed between the second outer ring 62a and the second inner ring 62b.

[0119] The second outer ring 62a is configured to be fixed to the second bearing mounting portion 57b of the second support member 57. The second outer ring 62a has a second radial outermost surface 62d facing the radial direction.

[0120] The second inner ring 62b faces the crankshaft 51 in the radial direction. The second inner ring 62b rotates integrally with the crankshaft 51.

[0121] A sealing shield 67 may be radially positioned between the first inner ring 61b and the crankshaft 51. The sealing shield 67 rotates integrally with the first inner ring 61b and the crankshaft 51. The sealing shield 67 may be omitted if necessary.

[0122] A sealing shield 68 may be radially positioned between the second inner ring 62b and the crankshaft 51. The sealing shield 68, the second inner ring 62b, and the crankshaft 51 rotate integrally. The sealing shield 68 may be omitted if necessary.

[0123] The second inner ring 62b has a second radial innermost surface 62e facing the radial direction. When viewed from the axial direction relative to the rotation center axis C1, the second radial innermost surface 62e is formed in a circular shape.

[0124] The first radial innermost surface 61e defines a first opening S1. The second radial innermost surface 62e defines a second opening S2. The crankshaft 51 passes through the first opening S1 and the second opening S2.

[0125] The first opening S1 and the second opening S2 are configured such that the crankshaft 51 can be inserted into the bicycle chassis assembly 53 by moving the crankshaft 51 axially from the first opening S1 toward the second opening S2.

[0126] The first opening S1 and the second opening S2 are configured such that the crankshaft 51 can be removed from the bicycle chassis assembly 53 by moving the crankshaft 51 axially from the second opening S2 toward the first opening S1.

[0127] For example, the diameter DS1 of one of the first openings S1 is larger than the diameter DS2 of one of the second openings S2. The inner diameter of one of the innermost radial surfaces of the sealing shield 67 is larger than the inner diameter of one of the innermost radial surfaces of the sealing shield 68. The inner diameter of one of the innermost radial surfaces 61e of the first inner ring 61b is larger than the inner diameter of one of the innermost radial surfaces 62e of the second inner ring 62b.

[0128] At least one second rolling element 62c has a second center point P2. The second center point P2 is defined on a circular line extending in a circumferential direction relative to the rotation center axis C1. Preferably, at least one second rolling element 62c includes a plurality of second rolling elements 62c in the circumferential direction.

[0129] As shown in Figure 2B, a first radial outer ring distance D11 is defined in the radial direction from the rotation center axis C1 to the first radial outermost surface 61d. A second radial outer ring distance D12 is defined in the radial direction from the rotation center axis C1 to the second radial outermost surface 62d. The first radial outer ring distance D11 and the second radial outer ring distance D12 are compared with each other as corresponding items.

[0130] A first radial rolling element distance D21 is defined from the rotation center axis C1 to the first center point P1. A second radial rolling element distance D22 is defined from the rotation center axis C1 to the second center point P2. The first radial rolling element distance D21 and the second radial rolling element distance D22 are compared with each other as corresponding items.

[0131] A first radial inner ring distance D31 is defined in the radial direction from the rotation center axis C1 to the first radial innermost surface 61e. A second radial inner ring distance D32 is defined in the radial direction from the rotation center axis C1 to the second radial innermost surface 62e. The first radial inner ring distance D31 and the second radial inner ring distance D32 are compared with each other as corresponding items.

[0132] At least one of the first radial outer ring distance D11 and the first radial rolling element distance D21 is different from one of the corresponding items of the second radial outer ring distance D12 and the second radial rolling element distance D22.

[0133] For example, the first radial outer ring distance D11 is different from the second radial outer ring distance D12. The first radial rolling element distance D21 is different from the second radial rolling element distance D22. The first radial outer ring distance D11 may be equal to the second radial outer ring distance D12. The first radial rolling element distance D21 may be equal to the second radial rolling element distance D22.

[0134] Specifically, the first radial outer ring distance D11 is greater than the second radial outer ring distance D12. The first radial rolling element distance D21 is greater than the second radial rolling element distance D22.

[0135] The first radial inner ring distance D31 is different from the second radial inner ring distance D32. For example, the first radial inner ring distance D31 is greater than the second radial inner ring distance D32. The first radial inner ring distance D31 can be equal to the second radial inner ring distance D32.

[0136] In the above bicycle base bracket assembly 53, the first hanger mounting portion 55a is threadedly engaged with the first axial end 12a of the hanger component 11a of the bicycle frame 11. The second hanger mounting portion 57a ​​is threadedly engaged with the second axial end 12b of the hanger component 11a of the bicycle frame 11.

[0137] The engagement portion of the first hanger mounting portion 55a with one of the first axial ends 12a is indicated by a thick line in Figures 2A and 2B. The engagement portion of the second hanger mounting portion 57a ​​with one of the second axial ends 12b is indicated by a thick line in Figures 2A and 2B.

[0138] [Variations of the First Embodiment]

[0139] (A1) As a variation of the first embodiment, the bicycle base bracket assembly 53 can be configured as follows.

[0140] The first hanger mounting portion 55a can be fixed to the first axial end 12a of the hanger component 11a of the bicycle frame 11 by a press-fit method. In other words, the engaging portion of the first hanger mounting portion 55a and the first axial end 12a (indicated by thick lines in Figures 2A and 2B) is press-fitted.

[0141] For example, one of the outer peripheral surfaces of the first hanger mounting portion 55a is press-fitted into the inner peripheral surface of the first axial end 12a without having a thread engagement.

[0142] Preferably, the inner diameter of one of the inner peripheral surfaces of the first axial end 12a is larger than the minor diameter of one of the female threaded components of the second axial end 12b.

[0143] Preferably, the outer diameter of the first hanger mounting portion 55a of the first support member 55 is larger than the minor diameter of one of the male threaded components of the second hanger mounting portion 57a ​​of the second support member 57.

[0144] In this configuration, the second hanger mounting portion 57a ​​is threadedly engaged with the second axial end 12b of the hanger component 11a of the bicycle frame 11. Therefore, the second hanger mounting portion 57a ​​is screwed into the second axial end 12b of the hanger component 11a of the bicycle frame 11.

[0145] (A2) As a variation of the first embodiment, the bicycle base bracket assembly 53 can be configured as follows.

[0146] The second hanger mounting portion 57a ​​can be fixed to the second axial end 12b of the hanger component 11a of the bicycle frame 11 by a press-fit. In other words, the engaging portion of the second hanger mounting portion 57a ​​and the second axial end 12b (indicated by thick lines in Figures 2A and 2B) is press-fitted.

[0147] For example, the outer peripheral surface of the second hanger mounting portion 57a ​​is press-fitted into the inner peripheral surface of the second axial end 12b without having a thread engagement.

[0148] Preferably, the minor diameter of one of the first female threaded components of the first axial end 12a is larger than the inner diameter of one of the inner peripheral surfaces of the second axial end 12b. Preferably, the outer peripheral surface of one of the second hanger mounting portions 57a of the second support member 57 is smaller than the major diameter of one of the male threaded components of one of the first hanger mounting portions 55a of the first support member 55. Preferably, the outer peripheral surface of the second hanger mounting portion 57a ​​of the second support member 57 is smaller than the minor diameter of the first female threaded component of the first axial end 12a.

[0149] In this configuration, the first hanger mounting portion 55a engages with the first axial end 12a of the hanger component 11a of the bicycle frame 11 via a thread. Therefore, the first hanger mounting portion 55a is screwed into the first axial end 12a of the hanger component 11a of the bicycle frame 11.

[0150] (A3) As a variation of the first embodiment, the bicycle base bracket assembly 53 can be configured as follows. The first hanger mounting portion 55a and the second hanger mounting portion 57a ​​can be fixed to the first axial end 12a and the second axial end 12b of the hanger component 11a respectively by a press-fit method.

[0151] (A4) As a variation of the first embodiment, the bicycle base bracket assembly 53 can be configured as follows.

[0152] As shown in Figure 2C, the bicycle chassis assembly 53 may further include a tubular sealing member 69. The tubular sealing member 69 is configured to bridge an axial gap between the first inner ring 61b of the first bearing unit 61 and the second inner ring 62b of the second bearing unit 62 in the mounted state of the bicycle chassis assembly 53 to the hanger component 11a of the bicycle frame 11.

[0153] In this embodiment, the tubular sealing member 69 covers the first bearing unit 61. The tubular sealing member 69 covers the second inner ring 62b of the second bearing unit 62. The tubular sealing member 69 engages with the sealing shield 68 in a concave-convex manner.

[0154] The tubular sealing member 169 can be configured as shown in Figure 2D. The tubular sealing member 169 covers the first bearing unit 61. The tubular sealing member 169 engages with the second inner ring 62b of the second bearing unit 62 in a concave-convex manner. The second bearing unit 62 is covered by a sealing shield 68.

[0155] The tubular sealing members 69 and 169 are arranged radially inward from the first support member 55 and the second support member 57 relative to the rotation center axis C1 of the bicycle base assembly 53. For example, the tubular sealing members 69 and 169 are arranged radially inward from the first support member 55, the second support member 57 and the first connecting portion 59 relative to the rotation center axis C1.

[0156] Preferably, the tubular sealing members 69, 169 are arranged to prevent any contaminants (such as mud and water) from entering the first bearing unit 61 (for example, the first rolling element 61c). The tubular sealing members 69, 169 are arranged to prevent any contaminants (such as mud and water) from entering the second bearing unit 62 (for example, the second rolling element 62c). [Second Embodiment] []

[0157] The bicycle 1 in the second embodiment has a configuration that is substantially the same as that in the first embodiment. In the second embodiment, the explanation of the identical configuration is omitted. The same symbols as in the above embodiments are added to the components with the identical configuration.

[0158] The bicycle chassis assembly 53 can be configured as follows. As shown in Figure 3A, the bicycle chassis assembly 53 further includes a locking member 70. The locking member 70 is configured to hold the first support member 55 and the second support member 57. Specifically, the locking member 70 is configured to hold the first support member 55, the second support member 57, and the first connecting portion 59.

[0159] The locking member 70 includes an abutting member 70a and a protruding member 70b. The abutting member 70a abuts the second axial end 12b of the hanger member 11a of the bicycle frame 11 in the axial direction relative to the rotation center axis C1 of the bicycle chassis assembly 53. For example, the abutting member 70a is formed in a tubular shape.

[0160] The protruding member 70b protrudes from the adjacent member 70a. For example, the protruding member 70b is formed in a tubular shape. One outer diameter of the protruding member 70b is smaller than one outer diameter of the adjacent member 70a.

[0161] The protruding member 70b is positioned in a radial direction relative to one of the rotation center axes C1 between the second axial end 12b of the hanger member 11a and the second hanger mounting portion 57a. In this embodiment, the second hanger mounting portion 57a ​​can be fixed to the locking member 70 by a press-fit mechanism.

[0162] The protruding part 70b engages threadedly with the second axial end 12b of the hanger part 11a. A male threaded part on the radially outer side of the protruding part 70b is screwed into a female threaded part on the radially inner side of the second axial end 12b. The threaded engagement portion of the protruding part 70b and the second axial end 12b is indicated by a thick line in Figure 3A.

[0163] The protruding member 70b is press-fitted into the second hanger mounting portion 57a. For example, the inner peripheral surface of one of the adjacent members 70a and the inner surface of one of the protruding members 70b are press-fitted into the second hanger mounting portion 57a. The press-fitting portion of the protruding member 70b and one of the second hanger mounting portions 57a is indicated by a thick line in Figure 3A.

[0164] In this case, the first hanger mounting portion 55a may have the same configuration as in the first embodiment described above. For example, the first hanger mounting portion 55a may be screwed into the first axial end 12a of the hanger component 11a. The first hanger mounting portion 55a may be press-fitted into the first axial end 12a of the hanger component 11a.

[0165] [Variations of the Second Embodiment]

[0166] (B1) As a variation of the second embodiment, the bicycle base bracket assembly 53 can be configured as follows.

[0167] Instead of the press-fit between the second hanger mounting portion 57a ​​and the locking member 70 in the second embodiment shown in Figure 3A, the locking member 70 can be threadedly engaged with the second hanger mounting portion 57a. In this case, the female threaded part on the radially inner side of one of the adjacent parts 70a and the protruding parts 70b is screwed into the male threaded part on the radially outer side of one of the second hanger mounting portions 57a.

[0168] The first hanger mounting portion 55a can be screwed into the first axial end 12a of the hanger component 11a. In place of the threaded engagement between the first hanger mounting portion 55a and the first axial end 12a of the hanger component 11a, the first hanger mounting portion 55a can also be press-fitted into the first axial end 12a of the hanger component 11a.

[0169] (B2) As a variation of the second embodiment, the bicycle base bracket assembly 53 can be configured as follows.

[0170] The locking member 70 can be press-fitted into the second axial end 12b of the hanger member 11a in place of the threaded engagement and can be threaded into the second hanger mounting portion 57a ​​(see Figure 3A).

[0171] In this configuration, the outer peripheral surface of the protruding member 70b is press-fitted into the inner peripheral surface of the second axial end 12b. The female threaded parts of the adjacent member 70a and the protruding member 70b are screwed into the male threaded parts of the second hanger mounting portion 57a.

[0172] The first hanger mounting portion 55a can be screwed into the first axial end 12a of the hanger component 11a. The first hanger mounting portion 55a can be press-fitted into the first axial end 12a of the hanger component 11a.

[0173] (B3) As a variation of the second embodiment, the bicycle base bracket assembly 53 can be configured as follows.

[0174] As shown in Figure 3B, the locking member 70 can be threadedly engaged with the second hanger mounting portion 57a. For example, the locking member 70 is threadedly engaged with the second hanger mounting portion 57a ​​when the second axial end 12b of the hanger component 11a is threadedly engaged with the second hanger mounting portion 57a.

[0175] In this configuration, the locking member 70 includes an adjacent member 70a but does not have a protruding member 70b. A male threaded member on the radially outer side of the second hanger mounting portion 57a ​​is screwed into a female threaded member on the radially inner side of the second axial end 12b of the hanger member 11a. A female threaded member on the radially inner side of the adjacent member 70a is screwed into a male threaded member on the radially outer side of the second hanger mounting portion 57a.

[0176] The first hanger mounting portion 55a can be screwed into the first axial end 12a of the hanger component 11a. The first hanger mounting portion 55a can be press-fitted into the first axial end 12a of the hanger component 11a.

[0177] (B4) As a variation of the second embodiment, it can be the bicycle base bracket assembly 53 of (B3) shown in the following configuration diagram 3B.

[0178] The locking member 70 can be threadedly engaged with the second hanger mounting portion 57a. For example, the locking member 70 includes an adjacent part 70a but does not have a protruding part 70b. The adjacent part 70a of the locking member 70 is threadedly engaged with the second hanger mounting portion 57a ​​in a state where it is press-fitted into one of the second axial ends 12b of the hanger member 11a.

[0179] The first hanger mounting portion 55a can be screwed into the first axial end 12a of the hanger component 11a. The first hanger mounting portion 55a can be press-fitted into the first axial end 12a of the hanger component 11a.

[0180] (B5) As a variation of the second embodiment, it can be the bicycle base bracket assembly 53 of (B3) shown in the following configuration diagram 3B.

[0181] The adjacent part 70a of the locking member 70 can be press-fitted into the second hanger mounting part 57a in a state where the second hanger mounting part 57a is press-fitted into one of the second axial ends 12b of the hanger member 11a.

[0182] The first hanger mounting portion 55a can be screwed into the first axial end 12a of the hanger component 11a. The first hanger mounting portion 55a can be press-fitted into the first axial end 12a of the hanger component 11a. [Third Embodiment] []

[0183] The bicycle 1 in the third embodiment has a configuration similar to that in the above embodiments. In the third embodiment, the explanation of the same configuration is omitted. The same symbols as in the above embodiments are added to the components with the same configuration.

[0184] As shown in Figure 4A, the first support member 55 has a first axial inner end 55c. The first axial inner end 55c is configured to be positioned within the hanger member 11a of the bicycle frame 11 in one of the installation states of the bicycle base bracket assembly 53 being mounted to the hanger member 11a of the bicycle frame 11.

[0185] The first axial inner end 55c is provided as part of the first hanger mounting portion 55a. The first axial inner end 55c is formed in a tubular shape.

[0186] The first support member 55 further has a first abutting surface 55d. The first abutting surface 55d abuts the first axial end 12a of the hanger member 11a of the bicycle frame 11.

[0187] The second support member 57 has a second axial inner end 57c. The second axial inner end 57c is configured to be positioned within the hanger member 11a of the bicycle frame 11 in the mounted state where the bicycle base bracket assembly 53 is mounted to the hanger member 11a of the bicycle frame 11.

[0188] The second axial inner end 57c is provided as part of the second hanger mounting portion 57a. The second axial inner end 57c is formed in a tubular shape.

[0189] The second support member 57 further has a second abutment surface 57d. The second abutment surface 57d abuts the second axial end 12b of the hanger member 11a of the bicycle frame 11.

[0190] In the installed state where the bicycle frame 11 hanger component 11a is mounted to the bicycle frame 11, the hanger component 11a is positioned between the first adjacent surface 55d and the second adjacent surface 57d. For example, the first hanger mounting portion 55a and the second hanger mounting portion 57a ​​are mounted to the bicycle frame 11 hanger component 11a in a state where the first adjacent surface 55d and the second adjacent surface 57d are adjacent to the first axial end 12a and the second axial end 12b of the bicycle frame 11 hanger component 11a, respectively.

[0191] The first hanger mounting portion 55a of the first support member 55 can be mounted to the first axial end 12a of the hanger component 11a of the bicycle frame 11 in the same manner as in the above embodiment. The second hanger mounting portion 57a ​​of the second support member 57 can be mounted to the second axial end 12b of the hanger component 11a of the bicycle frame 11 in the same manner as in the above embodiment.

[0192] The first axial inner end 55c of the first support member 55 and the second axial inner end 57c of the second support member 57 are separated from each other in the axial direction when the bicycle base bracket assembly 53 is installed on the hanger component 11a of the bicycle frame 11.

[0193] For example, the first axial inner end 55c of the first support member 55 and the second axial inner end 57c of the second support member 57 are arranged at a predetermined interval in the axial direction.

[0194] The bicycle chassis assembly 53 further includes a second connecting tubular member 60. The second connecting tubular member 60 is configured to bridge an axial gap between a first axial inner end 55c of the first support member 55 and a second axial inner end 57c of the second support member 57 in the installed state.

[0195] The connecting tubular member 60 is housed within the hanger component 11a of the bicycle frame 11. The connecting tubular member 60 is installed to the first axial inner end 55c of the first support member 55 and the second axial inner end 57c of the second support member 57.

[0196] At least one resilient sealing member, such as an O-ring, may be disposed in a radial direction relative to one of the rotational central axes C1 between the first axial inner end 55c of the first support member 55 and the connecting tubular member 60. Preferably, a plurality of resilient sealing members, such as an O-ring, may be disposed in a radial direction between the first axial inner end 55c of the first support member 55 and the connecting tubular member 60.

[0197] At least one resilient sealing member, such as an O-ring, may be radially disposed between the second axial inner end 57c of the second support member 57 and the connecting tubular member 60. Preferably, a plurality of resilient sealing members, such as an O-ring, may be radially disposed between the second axial inner end 57c of the second support member 57 and the connecting tubular member 60.

[0198] Preferably, the connecting tubular member 60 is installed to the first axial inner end 55c and the second axial inner end 57c by a press-fit method. The connecting tubular member 60 can be fixed to the first axial inner end 55c and the second axial inner end 57c by adhesive.

[0199] The connecting tubular member 60 is formed in a tubular shape. Preferably, the connecting tubular member 60 is formed of a resin. The connecting tubular member 60 may also be formed of a metallic material.

[0200] The engagement portion of the first axial end 12a of the hanger component 11a and one of the first hanger mounting portions 55a is indicated by a thick line in FIG4A. The first axial end 12a of the hanger component 11a and the first hanger mounting portion 55a engage with each other at the engagement portion in the same manner as in the above embodiment.

[0201] The engagement portion between the second axial end 12b of the hanger component 11a and one of the second hanger mounting portions 57a is indicated by a thick line in FIG4A. The second axial end 12b of the hanger component 11a and the second hanger mounting portion 57a ​​engage with each other at the engagement portion in the same manner as in the above embodiment.

[0202] [Variations of the Third Embodiment]

[0203] (C1) As a variation of the second embodiment, the bicycle base bracket assembly 53 can be configured as follows.

[0204] As shown in Figure 4B, the first axial inner end 55c of the first support member 55 has a first threaded portion 55e. The first threaded portion 55e is disposed on one of the inner peripheral surfaces of the first axial inner end 55c. The first threaded portion 55e is a female threaded component.

[0205] The second axial inner end 57c of the second support member 57 has a second threaded portion 57e. The second threaded portion 57e is configured to engage with the first threaded portion 55e of the first axial inner end 55c in the mounted state of the bicycle chassis assembly 53 mounted to the hanger component 11a of the bicycle frame 11.

[0206] The second threaded portion 57e is disposed on the outer peripheral surface of one of the second axial inner ends 57c. The second threaded portion 57e is a male threaded component. The engagement portion of the first threaded portion 55e and the second threaded portion 57e is indicated by a thick line in FIG4B.

[0207] (C2) As a variation of the second embodiment, it can be the bicycle base bracket assembly 53 of (C2) shown in the following configuration diagram 4B.

[0208] The first axial inner end 55c of the first support member 55 and the second axial inner end 57c of the second support member 57 can overlap each other in a press-fit manner when the bicycle base bracket assembly 53 is installed on the hanger component 11a of the bicycle frame 11.

[0209] Specifically, the first axial inner end 55c and the second axial inner end 57c are positioned so that they face each other in the radial direction relative to the rotation center axis C1 of the bicycle chassis assembly 53. The first axial inner end 55c and the second axial inner end 57c overlap each other in a press-fit manner in the installed state without having the first threaded portion 55e and the second threaded portion 57e.

[0210] The meshing portion of the first threaded portion 55e and the second threaded portion 57e (indicated by thick lines in Figure 4B) is a portion in which the first axial inner end 55c and the second axial inner end 57c can overlap each other.

[0211] (C3) As a variation of the second embodiment, the bicycle base bracket assembly 53 can be configured as follows.

[0212] As shown in Figure 4C, the first axial inner end 55c of the first support member 55 and the second axial inner end 57c of the second support member 57 overlap each other in a press-fit manner when the bicycle base bracket assembly 53 is installed on the hanger component 11a of the bicycle frame 11.

[0213] An elastic sealing member 63 is positioned in the radial direction between the first axial inner end 55c of the first support member 55 and the second axial inner end 57c of the second support member 57 in the installation state where the bicycle base bracket assembly 53 is installed to the hanger component 11a of the bicycle frame 11.

[0214] Specifically, the first axial inner end 55c and the second axial inner end 57c are positioned so that they face each other in the radial direction relative to the rotational center axis C1 of the bicycle chassis assembly 53. A resilient sealing member 63 is disposed in a recess of the first axial inner end 55c and a recess of the second axial inner end 57c. For example, the resilient sealing member 63 includes an O-ring. [Fourth Embodiment] []

[0215] The bicycle 1 in the fourth embodiment has a configuration similar to that in the above embodiments. In the fourth embodiment, explanations of the same configuration are omitted. The same symbols as in the above embodiments are added to the components with the same configuration.

[0216] As shown in Figure 5, the hanger component 11a includes a first axial end 12a and a second axial end 12b. The hanger component 11a further includes a main body component 12c. The hanger component 11a includes a third bearing mounting portion 12d and a fourth bearing mounting portion 12e.

[0217] The third bearing mounting portion 12d is configured to mount a first bearing unit 161. The third bearing mounting portion 12d is disposed on the first axial end 12a of the hanger component 11a of the bicycle frame 11. The third bearing mounting portion 12d is integrally formed with the first axial end 12a of the hanger component 11a. For example, the third bearing mounting portion 12d is formed in a tubular shape.

[0218] The fourth bearing mounting portion 12e is configured to mount a second bearing unit 162. The fourth bearing mounting portion 12e is disposed on the second axial end 12b of the hanger component 11a of the bicycle frame 11. The fourth bearing mounting portion 12e and the second axial end 12b of the hanger component 11a are integrally formed. For example, the fourth bearing mounting portion 12e is formed in a tubular shape.

[0219] The main body component 12c is integrally formed with the first axial end 12a and the second axial end 12b. Specifically, the main body component 12c is integrally formed with the first axial end 12a, the second axial end 12b, the third bearing mounting portion 12d, and the fourth bearing mounting portion 12e.

[0220] A bicycle chassis assembly 153 includes a first bearing unit 161 and a second bearing unit 162. The configuration of the first bearing unit 161 and the second bearing unit 162 may be the same as those in the above embodiments.

[0221] The first bearing unit 161 is mounted to the third bearing mounting portion 12d of the hanger component 11a of the bicycle frame 11. The first bearing unit 161 includes a first outer ring 161a, a first inner ring 161b, and at least one first rolling element 161c. The at least one first rolling element 161c is arranged between the first outer ring 161a and the first inner ring 161b in a radial direction relative to the rotation center axis C1 of the bicycle chassis assembly 153.

[0222] The first outer ring 161a is configured to be fixed to the first axial end 12a of a hanger component 11a of the bicycle frame 11. For example, the first outer ring 161a is configured to be fixed to the first axial end 12a of the hanger component 11a of the bicycle frame 11 by a press-fit. Specifically, the first outer ring 161a is configured to be fixed to the third bearing mounting portion 12d by a press-fit. The first inner ring 61b has a first radially innermost surface 161e facing the radial direction.

[0223] The second bearing unit 162 is mounted to the fourth bearing mounting portion 12e of the hanger component 11a of the bicycle frame 11. The second bearing unit 162 includes a second outer ring 162a, a second inner ring 162b, and at least one second rolling element 162c disposed in the radial direction between the second outer ring 162a and the second inner ring 162b.

[0224] The second outer ring 162a is configured to be fixed to the second axial end 12b of the hanger component 11a of the bicycle frame 11. For example, the second outer ring 162a is configured to be fixed to the second axial end 12b of the hanger component 11a of the bicycle frame 11 by a press-fit. Specifically, the second outer ring 162a is configured to be fixed to the fourth bearing mounting portion 12e by a press-fit. The second inner ring 162b has a second radially innermost surface 162e facing the radial direction.

[0225] The second axial end 12b of the hanger component 11a is opposite to the first axial end 12a of the hanger component 11a in the axial direction relative to the rotation center axis C1 of the bicycle chassis assembly 153. The second inner ring 62b has a second radial innermost surface 62e facing the radial direction relative to the rotation center axis C1 of the bicycle chassis assembly 153.

[0226] The first radial inner ring distance D131 is defined in the radial direction from the rotation center axis C1 to the first radial innermost surface 161e. The second radial inner ring distance D132 is defined in the radial direction from the rotation center axis C1 to the second radial innermost surface 162e. The first radial inner ring distance D131 and the second radial inner ring distance D132 are compared with each other as corresponding items.

[0227] The first radial inner ring distance D131 is different from the second radial inner ring distance D132. For example, the first radial inner ring distance D131 is greater than the second radial inner ring distance D132. The first radial innermost surface 161e defines the first opening S1. The second radial innermost surface 62e defines the second opening S2.

[0228] The first opening S1 and the second opening S2 are configured such that the crankshaft 51 can be inserted into the bicycle chassis assembly 153 by moving it axially from the first opening S1 toward the second opening S2, and can be removed from the bicycle chassis assembly 153 by moving it axially from the second opening S2 toward the first opening S1. [Fifth Embodiment] []

[0229] The bicycle 1 in the fourth embodiment has a configuration similar to that in the above embodiments. In the fifth embodiment, the explanation of the same configuration is omitted. The same symbols as in the above embodiments are added to the components with the same configuration.

[0230] As described in the above embodiments, the first opening S1 is defined by the first radial innermost surfaces 61e and 161e. The second opening S2 is defined by the second radial innermost surfaces 62e and 162e.

[0231] As shown in Figure 6, the first opening S1 and the second opening S2 are configured such that the crankshaft 51 can be inserted into the bicycle chassis assembly 253 by moving it axially from one of the first opening S1 and the second opening S2 toward the other of the first opening S1 and the second opening S2. The insertion direction of one of the crankshafts 51 is indicated by a shaded arrow in Figure 6.

[0232] The first opening S1 and the second opening S2 are configured such that the crankshaft 51 can be removed from the bicycle chassis assembly 253 by moving it axially from one of the first opening S1 and the second opening S2 toward the other of the first opening S1 and the second opening S2. One of the removal directions of the crankshaft 51 is indicated by a white arrow in Figure 6.

[0233] The first opening S1 and the second opening S2 are configured such that the crankshaft 51 can be inserted into the bicycle chassis assembly 253 by moving the crankshaft 51 axially from the first opening S1 toward the second opening S2.

[0234] The first opening S1 and the second opening S2 are configured such that the crankshaft 51 can be removed from the bicycle chassis assembly 253 by moving the crankshaft 51 axially from the second opening S2 toward the first opening S1.

[0235] In this embodiment, as shown in FIG6, the inner diameter of one of the first bearing units 261 of the bicycle base bracket assembly 253 is equal to the inner diameter of one of the second bearing units 262 of the bicycle base bracket assembly 253.

[0236] For example, the inner diameter of the first radial innermost surface 61e of the first inner ring 61b is equal to the inner diameter of the second radial innermost surface 62e of the second inner ring 62b. In other words, the diameter of the first opening S1 is equal to the diameter of the second opening S2.

[0237] Specifically, a first radial inner ring distance D231 is defined in the axial direction from the rotation center axis C1 to the first radial innermost surface 61e. A second radial inner ring distance D232 is defined in the axial direction from the rotation center axis C1 to the second radial innermost surface 62e. The first radial inner ring distance D231 is equal to the second radial inner ring distance D232.

[0238] The third radial inner ring distance D231 corresponds to "a first radial inner ring distance" in claim 15. The fourth radial inner ring distance D232 corresponds to "a second radial inner ring distance" in claim 15. [Sixth Embodiment] []

[0239] The bicycle 1 in the fourth embodiment has a configuration similar to that in the above embodiments. In the sixth embodiment, the explanation of the same configuration is omitted. The same symbols as in the above embodiments are added to the components with the same configuration.

[0240] As shown in Figure 7, the bicycle crank assembly 27 is mounted to the crankshaft 51. The crankshaft 51 for the bicycle crank assembly 27 is rotatably supported by a first bearing unit 361 via a sealing shield 67. The crankshaft 51 for the bicycle crank assembly 27 is rotatably supported by a second bearing unit 362. In this embodiment, a bushing member 168 is radially disposed between the second bearing unit 362 and the sealing shield 68. The sealing shield 68 can be disposed on a radially inner portion of the second radially innermost surface 62e of the second bearing unit 362 without the bushing member 168.

[0241] The crankshaft 51 of the bicycle crank assembly 27 has an elongated shape in one direction. The crankshaft 51 of the bicycle crank assembly 27 has a rotation center shaft C2. The rotation center shaft C2 of the crankshaft 51 is coaxially mounted with the rotation center shaft C1 of the bicycle chassis assembly 53 in the installed state of the bicycle crank assembly 27.

[0242] The crankshaft 51 for the bicycle crank assembly 27 includes a large-diameter portion 51a, a small-diameter portion 51b, and a transition step 51c. The crankshaft 51 for the bicycle crank assembly 27 has a diameter difference.

[0243] The large-diameter portion 51a is preferably formed in a cylindrical or tubular shape. The large-diameter portion 51a includes a first bearing mounting section 51d. The first bearing mounting section 51d has a first bearing mounting diameter.

[0244] The first bearing mounting section 51d faces the first inner ring 61b in the radial direction relative to the rotation center axis C1 of the bicycle chassis assembly 53, for example, the first radial innermost surface 61e of the first inner ring 61b. Specifically, the first bearing mounting section 51d is press-fitted to the first radial innermost surface 61e of the first inner ring 61b.

[0245] The small-diameter portion 51b is preferably formed in a cylindrical or tubular shape. The small-diameter portion 51b includes a second bearing mounting section 51e. The second bearing mounting section 51e has a second bearing mounting diameter that is smaller than that of the first bearing mounting diameter.

[0246] The second bearing mounting section 51e faces the second inner ring 62b in the radial direction relative to the rotation center axis C1 of the bicycle chassis assembly 53, for example, the second radial innermost surface 62e of the second inner ring 62b. Specifically, the second bearing mounting section 51e is press-fitted to the second radial innermost surface 62e of the first inner ring 61b via a sealing shield 67.

[0247] The transition step 51c is positioned between the large diameter portion 51a and the small diameter portion 51b in the axial direction relative to the rotation center axis C2 of the crankshaft 51.

[0248] The transition step 51c is disposed on a plane intersecting the rotation center axis C2 of the crankshaft 51. For example, the transition step 51c is disposed on a plane orthogonal to the rotation center axis C2 of the crankshaft 51. The transition step 51c may be disposed on a plane inclined toward the rotation center axis C2 of the crankshaft 51.

[0249] The transition step 51c is spaced apart from the second bearing mounting section 51e in the axial direction. In other words, the second bearing mounting section 51e is spaced apart from the transition step 51c in the axial direction. An axial distance is provided between the transition step 51c and the second bearing mounting section 51e in the axial direction.

[0250] Preferably, the axial distance between the second bearing mounting section 51e and the transition step 51c, defined in the axial direction, is within the range of 0.1 mm to 70 mm. Preferably, the diameter difference between the first bearing mounting diameter and the second bearing mounting diameter is equal to or greater than 2 mm. The diameter difference is equal to or less than 60 mm.

[0251] 1: Bicycle 9: Bicycle chain 11: Bicycle frame 11a: Hanger components 12a: First axial end 12b: Second axial end 12c: Main body component 12d: Third bearing mounting section 12e: Fourth bearing mounting section 13: Handlebars 17: Front wheel 17a: Front tire 19: Rear wheel 19a: Rear tire 20: Front fork 24: Gear shifting device 25: Transmission System 26: Rear derailleur of a bicycle 27: Bicycle crank assembly 28: Bicycle rear sprocket assembly 29: Bicycle rear wheel hub assembly 35: Bicycle front sprocket 51: Crankshaft 51a: Large diameter section 51b: Small diameter portion 51c: Transitional stage 51d: First bearing installation section 51e: Second bearing installation section 53: Bicycle chassis assembly 55: First supporting component 55a: First hanger installation section 55b: First bearing mounting section 55d: First adjacent surface 55c: First axial inner end 55d: First adjacent surface 55e: First threaded section 57: Second support component 57a: Second hanger installation section 57b: Second bearing mounting section 57c: Second axial inner end 57d: Second adjacent surface 57e: Second threaded portion 59: Connection part 60: Second connecting tubular member / Connecting tubular member 61: First bearing unit 61a: First outer ring 61b: First Inner Ring 61c: First rolling element 61d: First radial outermost surface 61e: First radial innermost surface 62: Second bearing unit 62a: Second outer ring 62b: Second Inner Ring 62c: Second rolling element 62d: Second radial outermost surface 62e: Second radial innermost surface 63: Elastic sealing component 67: Sealed protective cover 68: Sealed protective cover 69: Tubular sealing component 70: Locking component 70a: Adjacent components 70b: Protruding component 153: Bicycle chassis assembly 161: First bearing unit 161a: First outer ring 161b: First Inner Ring 161c: First rolling element 161e: First radial innermost surface 162: Second bearing unit 162a: Second outer ring 162b: Second Inner Ring 162c: Second rolling element 162e: Second radial innermost surface 168: Bushing Components 253: Bicycle chassis assembly 261: First bearing unit 262: Second bearing unit 361: First bearing unit 362: Second bearing unit C1: Rotation center axis C2: Rotation center axis D11: First radial outer ring distance D12: Second radial outer ring distance D21: Distance between the first radial rolling element D22: Distance between the second radial rolling element D31: First radial inner ring distance D32: Second radial inner ring distance D131: First radial inner ring distance D132: Second radial inner ring distance D231: First radial inner ring distance / Third radial inner ring distance D232: Second radial inner ring distance / Fourth radial inner ring distance DS1: Diameter DS2: Diameter P1: First center point P2: Second center point S1: First opening S2: Second opening

Claims

1. A bicycle chassis assembly, comprising: A first support member comprising a first hanger mounting portion and a first bearing mounting portion, the first hanger mounting portion being configured to be mounted to a first axial end of a hanger component of a bicycle frame; a second support member comprising a second hanger mounting portion and a second bearing mounting portion, the second hanger mounting portion being configured to be mounted to a second axial end of the hanger component of the bicycle frame, the second axial end of the hanger component being opposite to the first axial end of the hanger component in an axial direction relative to a rotation center axis of a bicycle chassis assembly; A first bearing unit includes a first outer ring, a first inner ring, and at least one first rolling element disposed between the first outer ring and the first inner ring in a radial direction relative to a rotational axis. The first outer ring is configured to be fixed to a first bearing mounting portion of a first support member. The first outer ring has a first radially outermost surface facing the radial direction, and the first inner ring has a first radially innermost surface facing the radial direction. The at least one first rolling element has a first center point. A second bearing unit includes a second outer ring, a second inner ring, and at least one second rolling element disposed between the second outer ring and the second inner ring in a radial direction. The second outer ring is configured to be fixed to a second bearing mounting portion of a second support member. The second outer ring has a second radially outermost surface facing the radial direction, and the second inner ring has a second radially innermost surface facing the radial direction. The at least one second rolling element has a second center point. A first radial outer ring distance is defined in the radial direction from the rotational axis to the first radially outermost surface. A second radial outer ring distance is defined in the radial direction from the rotation center axis to the second radial outermost surface, and the first radial outer ring distance and the second radial outer ring distance are compared as corresponding items; a first radial rolling element distance is defined from the rotation center axis to the first center point; a second radial rolling element distance is defined from the rotation center axis to the second center point, and the first radial rolling element distance and the second radial rolling element distance are compared as corresponding items; a first radial inner ring distance is defined in the radial direction from the rotation center axis to the first radial innermost surface; a second radial inner ring distance is defined in the radial direction from the rotation center axis to the second radial innermost surface, and the first radial inner ring distance and the second radial inner ring distance are compared as corresponding items; at least one of the first radial outer ring distance and the first radial rolling element distance is different from one of the corresponding items of the second radial outer ring distance and the second radial rolling element distance; The first radial inner ring distance is different from the second radial inner ring distance; and the first support member and the second support member are formed as an integral single component.

2. The bicycle chassis assembly of claim 1, wherein the first support member has a first axial inner end configured to be disposed within the hanger component of the bicycle frame in an installed state in which the bicycle chassis assembly is mounted to the hanger component of the bicycle frame; and the second support member has a second axial inner end configured to be disposed within the hanger component of the bicycle frame in the installed state.

3. The bicycle chassis assembly of claim 2, wherein the first axial inner end of the first support member and the second axial inner end of the second support member are separated from each other in the axial direction in the installed state.

4. The bicycle chassis assembly as claimed in claim 3, further comprising: A connecting tubular member configured to bridge an axial gap between the first axial inner end of the first support member and the second axial inner end of the second support member in the installed state.

5. The bicycle chassis assembly of claim 2, wherein the first axial inner end of the first support member has a first threaded portion; and the second axial inner end of the second support member has a second threaded portion configured to thread-engage with the first threaded portion of the first axial inner end in the installed state.

6. The bicycle chassis assembly of claim 2, wherein the first axial inner end of the first support member and the second axial inner end of the second support member overlap each other in a press-fit manner in the installed state.

7. The bicycle chassis assembly of claim 2, wherein the first axial inner end of the first support member and the second axial inner end of the second support member overlap each other in the installed state; and an elastic sealing member is disposed in the radial direction between the first axial inner end of the first support member and the second axial inner end of the second support member in the installed state.

8. The bicycle chassis assembly of claim 1, further comprising: A tubular sealing member configured to bridge an axial gap between the first inner ring of the first bearing unit and the second inner ring of the second bearing unit in an installed state where the bicycle chassis assembly is mounted to one of the hanger components of the bicycle frame.

9. The bicycle chassis assembly of claim 1, wherein the first radial inner ring distance is greater than the second radial inner ring distance; the first radial innermost surface defines a first opening; the second radial innermost surface defines a second opening; and the first opening and the second opening are configured such that a crankshaft can be inserted into the bicycle chassis assembly by moving a crankshaft in the axial direction from the first opening toward the second opening and can be removed from the bicycle chassis assembly by moving the crankshaft in the axial direction from the second opening toward the first opening.

10. A bicycle chassis assembly, comprising: A first bearing unit includes a first outer ring, a first inner ring, and at least one first rolling element disposed between the first outer ring and the first inner ring in a radial direction relative to a rotational axis of a bicycle frame assembly. The first outer ring is configured to be fixed to a first axial end of a hanger component of a bicycle frame. The first inner ring has a first radially innermost surface facing the radial direction. A second bearing unit includes a second outer ring, a second inner ring, and at least one second rolling element disposed between the second outer ring and the second inner ring in a radial direction. The second outer ring is configured to be fixed to a second axial end of a hanger component of the bicycle frame. The second axial end of the hanger component is opposite to the first axial end of the hanger component in an axial direction relative to a rotational axis of the bicycle frame assembly. The second inner ring has a second radially innermost surface facing the radial direction. A first radial inner ring distance is defined in the radial direction from the rotational axis to the first radially innermost surface. A second radial inner ring distance is defined in the radial direction from the rotation center axis to the innermost surface of the second radial direction; and the first radial inner ring distance is different from the second radial inner ring distance.

11. The bicycle chassis assembly of claim 10, wherein the first radial inner ring distance is greater than the second radial inner ring distance; the first radial innermost surface defines a first opening; the second radial innermost surface defines a second opening; and the first opening and the second opening are configured such that a crankshaft can be inserted into the bicycle chassis assembly by moving a crankshaft in the axial direction from the first opening toward the second opening and can be removed from the bicycle chassis assembly by moving the crankshaft in the axial direction from the second opening toward the first opening.

12. The bicycle chassis assembly of claim 10, wherein the first outer ring is configured to be press-fitted to the first axial end of the hanger component of the bicycle frame; and the second outer ring is configured to be press-fitted to the second axial end of the hanger component of the bicycle frame.

13. A bicycle chassis assembly, comprising: A first support member comprising a first hanger mounting portion and a first bearing mounting portion, the first hanger mounting portion being configured to be mounted to a first axial end of a hanger component of a bicycle frame; a second support member comprising a second hanger mounting portion and a second bearing mounting portion, the second hanger mounting portion being configured to be mounted to a second axial end of the hanger component of the bicycle frame, the second axial end of the hanger component being opposite to the first axial end of the hanger component in an axial direction relative to a rotation center axis of a bicycle chassis assembly; A first bearing unit includes a first outer ring, a first inner ring, and at least one first rolling element disposed between the first outer ring and the first inner ring in a radial direction relative to a rotational central axis of the bicycle chassis assembly. The first outer ring is configured to be fixed to the first bearing mounting portion of the first support member. The first inner ring has a first radially innermost surface facing the radial direction, the first radially innermost surface defining a first opening. A second bearing unit includes a second outer ring, a second inner ring, and at least one second rolling element disposed between the second outer ring and the second inner ring in a radial direction. The second outer ring is configured to be fixed to the second bearing mounting portion of the second support member. The second inner ring has a second radially innermost surface facing the radial direction, the second radially innermost surface defining a second opening. The first opening and the second opening are configured such that a crankshaft can be inserted into the bicycle chassis assembly from one of the first opening and the second opening toward the other of the first opening and the second opening in the axial direction, and the crankshaft can be removed from the bicycle chassis assembly by moving the crankshaft from the other of the first opening and the second opening toward the first opening and the second opening in the axial direction; and the first support member and the second support member are formed as an integral single component.

14. The bicycle chassis assembly of claim 13, wherein a first radial inner ring distance is defined in the axial direction from the rotation center axis to the first radial innermost surface; a second radial inner ring distance is defined in the axial direction from the rotation center axis to the second radial innermost surface; and the first radial inner ring distance is equal to the second radial inner ring distance.

15. The bicycle chassis assembly of claim 13, wherein a first radial inner ring distance is defined in the radial direction from the rotation center axis to the first radial innermost surface; a second radial inner ring distance is defined in the radial direction from the rotation center axis to the second radial innermost surface; and the first radial inner ring distance is different from the second radial inner ring distance.

16. The bicycle chassis assembly of claim 15, wherein the first radial inner ring distance is greater than the second radial inner ring distance; and the first opening and the second opening are configured such that a crankshaft can be inserted into the bicycle chassis assembly by moving a crankshaft in the axial direction from the first opening toward the second opening and can be removed from the bicycle chassis assembly by moving the crankshaft in the axial direction from the second opening toward the first opening.

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