Patent Publication Number: US-2023150304-A1

Title: Hub assembly for human-powered vehicle

Description:
BACKGROUND 
     Technical Field 
     The present disclosure generally relates to a hub assembly for a human-powered vehicle. More specifically, the present disclosure generally relates to a hub assembly that has a sprocket support body of supporting at least one sprocket. 
     Background Information 
     Generally, a wheel for a human-powered vehicle has a hub assembly, a plurality of spokes and an annular rim. Basically, the hub assembly has a hub axle and a hub body. The hub axle is non-rotatably mounted to a frame of the human-powered vehicle. The hub body that is coaxially coupled to the hub axle so that the hub body is disposed radially outwardly with respect to the hub axle. The bearings are configured and arranged to support the hub body so that the hub body can freely rotate around the hub axle. In some human-powered vehicle, such as bicycles, a wheel is provided with a sprocket support body that is rotatably disposed to the hub axle. The sprocket support body is usually coupled to hub body by a one-way clutch such that torque is transferred from the sprocket support body to the hub body in one direction. This type of sprocket support body is sometimes called a freewheel. 
     SUMMARY 
     Generally, the present disclosure is directed to various features of a hub assembly for a human-powered vehicle. The term “human-powered vehicle” as used herein refers to a vehicle that can be driven by at least human driving force, but does not include a vehicle using only a driving power other than human power. In particular, a vehicle solely using an internal combustion engine as a driving power is not included in the human-powered vehicle. The human-powered vehicle is generally assumed to be a compact, light vehicle that sometimes does not require a license for driving on a public road. The number of wheels on the human-powered vehicle is not limited. The human-powered vehicle includes, for example, a monocycle and a vehicle having three or more wheels. The human-powered vehicle includes, for example, various types of bicycles such as a mountain bike, a road bike, a city bike, a cargo bike, and a recumbent bike, and an electric assist bicycle (E-bike). 
     In view of the state of the known technology and in accordance with a first aspect of the present disclosure, a hub assembly is provided for a human-powered vehicle. The hub assembly basically comprises a hub axle, a hub body, a pawl support body, at least one pawl, a sprocket support body, at least one sprocket support bearing, a ratchet body and a plurality of ratchet teeth. The hub body is rotatably mounted on the hub axle to rotate around a rotational center axis of the hub assembly. The pawl support body is connected to the hub body. The at least one pawl is movably provided to the pawl support body to move between a driving position and a non-driving position. The sprocket support body is rotatably disposed to the hub axle to rotate around the rotational center axis. The at least one sprocket support bearing rotatably supports the sprocket support body on the hub axle. The ratchet body is connected to the sprocket support body. The ratchet teeth are provided to the ratchet body for engaging the at least one pawl to transmit a driving force from the sprocket support body to the hub body while rotating in a driving rotational direction around the rotational center axis. Each of the at least one sprocket support bearing is disposed opposite to the hub body with respect to the plurality of ratchet teeth in an axial direction with respect to the rotational center axis. 
     With the hub assembly according to the first aspect, the component force exerted on the sprocket support body from the at least one pawl is spread out and the compressive force on the at least one sprocket support bearing is reduced. 
     In accordance with a second aspect of the present disclosure, the hub assembly according to the first aspect is configured so that the plurality of ratchet teeth is provided on an outer peripheral side of the at least one pawl. 
     With the hub assembly according to the second aspect, the component force exerted on the sprocket support body is directed outwardly with respect to the rotational center axis. 
     In accordance with a third aspect of the present disclosure, the hub assembly according to the first aspect or the second aspect is configured so that the pawl support body is integrally formed with the hub body as a unitary, one-piece member. 
     With the hub assembly according to the third aspect, the hub body and the pawl support body can be simplified. 
     In accordance with a fourth aspect of the present disclosure, the hub assembly according to the first aspect or the second aspect is configured so that the pawl support body is a separate member from the hub body. 
     With the hub assembly according to the fourth aspect, the hub body and the pawl support body can be easily manufactured at a relatively low cost. 
     In accordance with a fifth aspect of the present disclosure, the hub assembly according to any one of the first aspect to the fourth aspect is configured so that the ratchet body is integrally formed with the sprocket support body as a unitary, one-piece member. 
     With the hub assembly according to the fifth aspect, the structure of the sprocket support body and the ratchet body can be simplified. 
     In accordance with a sixth aspect of the present disclosure, the hub assembly according to any one of the first aspect to the fourth aspect is configured so that the ratchet body is a separate member from the sprocket support body. 
     With the hub assembly according to the sixth aspect, it is possible to manufacture the ratchet body and the sprocket support body from different materials that are more suited for each of their functions. 
     In accordance with a seventh aspect of the present disclosure, the hub assembly according to any one of the first aspect to the sixth aspect is configured so that the sprocket support body has a splined region which includes a plurality of splines, and the ratchet teeth are disposed outside the splined region in the axial direction. 
     With the hub assembly according to the seventh aspect, one or more sprockets can be mounted to the splined region of the sprocket support body and the ratchet teeth are not directly subjected to a force from the one or more sprockets. 
     In accordance with an eighth aspect of the present disclosure, the hub assembly according to any one of the first aspect to the seventh aspect is configured so that at least one of the at least one pawl and the plurality of ratchet teeth are overlapped with the hub body as viewed in a radial direction with respect to the rotational center axis. 
     With the hub assembly according to the eighth aspect, at least one of the at least one pawl and the plurality of ratchet teeth can be protected by the hub body. 
     In accordance with a ninth aspect of the present disclosure, the hub assembly according to any one of the first aspect to the eighth aspect is configured so that the plurality of ratchet teeth are disposed at an end portion of the sprocket support body on a hub body side. 
     With the hub assembly according to the ninth aspect, the rotation from the sprocket support body can be reliably transmitted to the hub body. 
     In accordance with a tenth aspect of the present disclosure, the hub assembly according to any one of the first aspect to the ninth aspect further comprises at least one hub bearing rotatably supporting the hub body on the hub axle. Each of the at least one hub bearing is disposed opposite the at least one sprocket support bearing with respect to the ratchet teeth in the axial direction. 
     With the hub assembly according to the tenth aspect, the hub body can be rotatably supported on the hub axle for smooth rotation of the hub body with respect to the hub axle. The hub assembly has a simple structure and is suitable for manufacturing. 
     In accordance with an eleventh aspect of the present disclosure, the hub assembly according to the tenth aspect is configured so that the at least one pawl is disposed axially between each of the at least one hub bearing and each of the at least one sprocket support bearing in the axial direction. 
     With the hub assembly according to the eleventh aspect, the sprocket support body can be easily separated from the hub body such that the at least one pawl can be easily serviced, replaced or repaired. 
     In accordance with a twelfth aspect of the present disclosure, the hub assembly according to any one of the first aspect to the eleventh aspect is configured so that the pawl support body is non-rotatably coupled to the hub body and supporting the at least one pawl. 
     With the hub assembly according to the twelfth aspect, the complicated structure of the pawl support body and the at least one pawl are provided to the hub body and the sprocket support body can be simplified. Thus, the replacement work can be easily performed, and the price of the replacement parts can be reduced. 
     In accordance with a thirteenth aspect of the present disclosure, the hub assembly according to the twelfth aspect is configured so that the pawl support body is non-rotatably coupled to the hub body with spline engagement. 
     With the hub assembly according to the thirteenth aspect, the pawl support body can be easily installed to the hub body. 
     In accordance with a fourteenth aspect of the present disclosure, the hub assembly according to any one of the first aspect to the thirteenth aspect is configured so that the at least one pawl includes a plurality of pawls. 
     With the hub assembly according to the fourteenth aspect, the component force transmitted to the sprocket support body can be more balanced. 
     In accordance with a fifteenth aspect of the present disclosure, the hub assembly according to any one of the first aspect to the fourteenth aspect is configured so that the plurality of ratchet teeth are provided on an inner surface of the ratchet body. 
     With the hub assembly according to the fifteenth aspect, the structure of the ratchet body can be simplified. 
     In accordance with a sixteenth aspect of the present disclosure, the hub assembly according to any one of the first aspect to the fifteenth aspect is configured so that the at least one pawl is located inside the hub body. 
     With the hub assembly according to the sixteenth aspect, rotation of the sprocket support body can be reliably transmitted to the hub body by the at least one pawl. 
     In accordance with a seventeenth aspect of the present disclosure, the hub assembly according to any one of the first aspect to the sixteenth aspect is configured so that the sprocket support body and the plurality of ratchet teeth are a single, one-piece member. 
     With the hub assembly according to the seventeenth aspect, the structure of the sprocket support body and the plurality of ratchet teeth can be simplified. 
     In accordance with an eighteenth aspect of the present disclosure, the hub assembly according to any one of the first aspect to the seventeenth aspect is configured so that the at least one sprocket support bearing includes a first sprocket support bearing and a second sprocket support bearing that are axially spaced apart along the hub axle. 
     With the hub assembly according to the eighteenth aspect, smooth rotation of the sprocket support body on the hub axle can be reliably achieved. 
     In accordance with a nineteenth aspect of the present disclosure, the hub assembly according to the eighteenth aspect further comprises an end cap threadedly coupled to a first end of the hub axle and contacting the first sprocket support bearing to retain the sprocket support body to the hub axle. 
     With the hub assembly according to the nineteenth aspect, it is possible to easily remove and replace the sprocket support body to the hub axle. 
     In accordance with a twentieth aspect of the present disclosure, the hub assembly according to the eighteenth aspect or the nineteenth aspect is configured so that the sprocket support body includes a first bearing abutment contacting a first outer race of the first sprocket support bearing and a second bearing abutment contacting a second outer race of the second sprocket support bearing. The first bearing abutment faces in an opposite direction from the second bearing abutment with respect to the rotational center axis. 
     With the hub assembly according to the twentieth aspect, the first sprocket support bearing and the second sprocket support bearing can be easily located at the appropriate axial locations with respect to the rotational center axis. 
     Also, other objects, features, aspects and advantages of the disclosed hub assembly will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses preferred embodiments of the hub assembly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Referring now to the attached drawings which form a part of this original disclosure: 
         FIG.  1    is a side elevational view of a human-powered vehicle (e.g., a bicycle) equipped with a rear wheel having a hub assembly in accordance with a first embodiment; 
         FIG.  2    is an elevational view of the hub assembly attached to the vehicle body of the human-powered vehicle illustrated in  FIG.  1   ; 
         FIG.  3    is a partially exploded perspective view of the hub assembly illustrated in  FIGS.  1  and  2    where two sprocket support body can be selectively installed onto the hub axle; 
         FIG.  4    is a longitudinal cross-sectional view of the hub assembly illustrated in  FIGS.  2  to  4   ; 
         FIG.  5    is an enlarged cross sectional view of a portion of the hub assembly illustrated in  FIG.  4   ; 
         FIG.  6    is a transverse cross-sectional view of the hub assembly illustrated in  FIGS.  2  to  4    as seen along section line  6 - 6  in  FIG.  2   ; 
         FIG.  7    is a transverse cross-sectional view, similar to  FIG.  6   , of the hub assembly, but where the sprocket support body has been rotated so that the pawls have moved from the driving position of  FIG.  6    to a non-driving position; 
         FIG.  8    is an enlarged cross sectional view of a portion of a hub assembly in accordance with a second embodiment; and 
         FIG.  9    is an enlarged cross sectional view of a portion of a hub assembly in accordance with a third embodiment. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Selected embodiments will now be explained with reference to the drawings. It will be apparent to those skilled in the human-powered vehicle field (e.g., the bicycle field) from this disclosure that the following descriptions of the embodiments are provided for illustration only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents. 
     Referring initially to  FIG.  1   , a hub assembly  10  is provided for a human-powered vehicle V. In other words, the human-powered vehicle V (i.e., a bicycle) is illustrated that is equipped with the hub assembly  10  in accordance with the illustrated embodiments. Here, in the illustrated embodiment, the hub assembly  10  is a bicycle hub. More specifically, the hub assembly  10  is a bicycle rear hub. Here, the bicycle V is an electric assist bicycle (E-bike). Alternatively, the bicycle V can be a road bicycle, a city bike, a cargo bike, and a recumbent bike, or another type of off-road bicycle such as a cyclocross bicycle. 
     As seen in  FIG.  1   , the bicycle V includes a vehicle body VB that is supported by a rear wheel RW and a front wheel FW. The vehicle body VB basically includes a front frame body FB and a rear frame body RB (a swing arm). The vehicle body VB is also provided with a handlebar H and a front fork FF for steering the front wheel FW. The rear frame body RB is swingably mounted to a rear section of the front frame body FB such that the rear frame body RB can pivot with respect to the front frame body FB. The rear wheel RW is mounted to a rear end of the rear frame body RB. A rear shock absorber RS is operatively disposed between the front frame body FB and rear frame body RB. The rear shock absorber RS is provided between the front frame body FB and the rear frame body RB to control the movement of the rear frame body RB with respect to the front frame body FB. Namely, the rear shock absorber RS absorbs shock transmitted from the rear wheel RW. The rear wheel RW is rotatably mounted to the rear frame body RB. The front wheel FW is mounted to the front frame body FB via the front fork FF. Namely, the front wheel FW is mounted to a lower end of the front fork FF. A bicycle seat or saddle S is mounted to a seat tube of the front frame body FB in a conventional manner. The front fork FF is pivotally mounted to a head tube of the front frame body FB. The handlebar H is mounted to an upper end of a steering column or a steerer tube of the front fork FF. The front fork FF absorbs shock transmitted from the front wheel FW. Preferably, the rear shock absorber RS and the front fork FF are electrically adjustable suspensions. For example, the stiffness and/or stoke length of the rear shock absorber RS and the front fork FF can be adjusted. 
     The bicycle V further includes an electric drive unit DU that has an electric motor that provides a drive assist force to a front sprocket FS. The electric drive unit DU can be actuated to assist in the propulsion of the bicycle V in a conventional manner. The electric drive unit DU is actuated, for example, in accordance with a human driving force applied to the pedals PD. The electric drive unit DU is actuated by electric power supplied from a main battery pack BP that is mounted on a downtube of the bicycle V. Here, for example, the drivetrain is a chain-drive type that includes a crank C, a front sprocket FS, a plurality of rear sprockets CS and a chain CN. The crank C includes a crank axle CA 1  and a pair of crank arms CA 2 . The crank axle CA 1  is rotatably supported to the front frame body FB via the electric drive unit DU. The crank arms CA 2  are provided on opposite ends of the crank axle CAL A pedal PD is rotatably coupled to the distal end of each of the crank arms CA 2 . The drivetrain can be selected from any type, and can be a belt-drive type or a shaft-drive type. 
     The structure of the hub assembly  10  will now be described with particular reference to  FIGS.  2  to  6   . The hub assembly  10  basically comprises a hub axle  12  and a hub body  14 . The hub axle  12  is configured to be non-rotatably attached to the vehicle body VB. In this embodiment, the hub axle  12  is configured to be non-rotatably attached to the rear frame body RB. The hub body  14  is rotatably mounted on the hub axle  12  to rotate around a rotational center axis A 1  of the hub assembly  10 . The hub axle  12  has a center axis coaxial with the rotational center axis A 1 . The hub body  14  is rotatably disposed around the rotational center axis A 1 . In other words, the hub body  14  is rotatably mounted around the hub axle  12 . 
     As seen in  FIGS.  5  to  7   , the hub axle  12  is a rigid member made of a suitable material such as a metallic material. The hub axle  12  has a first end  12   a  and a second end  12   b . Here, the hub axle  12  is a tubular member that is a one-piece member. Thus, the hub axle  12  has an axial bore  12   c  that extends between the first end  12   a  and the second end  12   b . The hub axle  12  can be a one-piece member or made of several pieces. 
     As indicated in  FIGS.  1  and  3   , the hub body  14  is rotatably mounted around the hub axle  12  to rotate in a driving rotational direction D 1 . The driving rotational direction D 1  corresponds to a forward driving direction of the rear wheel RW. The hub body  14  is configured to support the rear wheel RW in a conventional manner. More specifically, in the illustrated embodiment, the hub body  14  includes a first outer flange  14   a  and a second outer flange  14   b . The first outer flange  14   a  and the second outer flange  14   b  extend radially outward with respect to the rotational center axis A 1  from a peripheral surface of the hub body  14 . The first outer flange  14   a  and the second outer flange  14   b  are configured to receive a plurality of spokes ( FIG.  1   ) for attaching a rim ( FIG.  1   ) of the rear wheel RW to the hub body  14 . In this way, the hub body  14  and the rear wheel RW are coupled to rotate together. 
     The hub assembly  10  further comprises at least one hub bearing rotatably supporting the hub body  14  on the hub axle  12 . In the illustrated embodiment as seen in  FIG.  4   , the hub assembly  10  further comprises a first hub body bearing  20  and a second hub body bearing  22 . The first hub body bearing  20  rotatably supports a first end of the hub body  14  with respect to the rotational center axis A 1 . The second hub body bearing  22  rotatably supports a second end of the hub body  14  with respect to the rotational center axis A 1 . The first hub body bearing  20  includes a first inner race  20   a , a first outer race  20   b  and a plurality of first roller elements  20   c . The first roller elements  20   c  are disposed between the first inner race  20   a  and the first outer race  20   b . The second hub body bearing  22  includes a second inner race  22   a , a second outer race  22   b  and a plurality of second roller elements  22   c . The second roller elements  22   c  are disposed between the second inner race  22   a  and the second outer race  22   b.    
     The first hub body bearing  20  and the second hub body bearing  22  are radial ball bearings. Radial ball bearings support force in the direction perpendicular to the axis. Further, a radial roller bearing can be adopted instead of the radial ball bearing for one or both of the first hub body bearing  20  and the second hub body bearing  22 . Radial roller bearings include cylindrical roller bearings and needle roller bearings. Alternatively, an angular contact ball bearing can be adopted instead of a radial ball bearing for one or both of the first hub body bearing  20  and the second hub body bearing  22 . Angular contact ball bearings have inner and outer ring raceways that are displaced relative to each other in the direction of the bearing axis. In other words, angular contact bearings are designed to accommodate combined loads, i.e., simultaneously acting radial and axial loads. Further, an angular contact roller bearing (i.e., tapered roller bearing) can be adopted instead of a radial ball bearing one or both of the first hub body bearing  20  and the second hub body bearing  22 . Angular contact roller bearings include cylindrical roller bearings and needle roller bearings. 
     Here, the hub assembly  10  further comprises a sprocket support body  26 . In the illustrated embodiment, the sprocket support body  26  supports the rear sprockets CS as seen in  FIG.  2   . The sprocket support body  26  is rotatably disposed to the hub axle  12  to rotate around the rotational center axis A 1 . The sprocket support body  26  transmits a driving force to the hub body  14  while rotating in a driving rotational direction D 1  around the rotational center axis A 1 . As explained below, the sprocket support body  26  does not transmit a driving force to the hub body  14  while rotating in a non-driving rotational direction D 2  around the rotational center axis A 1 . The non-driving rotational direction D 2  is opposite to the driving rotational direction D 1  with respect to the rotational center axis A 1 . The rotational center axis of the sprocket support body  26  is disposed concentrically with the rotational center axis A 1  of the hub assembly  10 . 
     While the sprocket support body  26  is configured to non-rotatably support the rear sprockets CS, the sprocket support body  26  is not limited to the illustrated embodiment. Alternatively, one or more of the rear sprockets CS can be integrally formed with the sprocket support body  26 . In any case, the sprocket support body  26  and the rear sprockets CS are coupled together to rotate together in both the driving rotational direction D 1  and the non-driving rotational direction D 2 . 
     As seen in  FIGS.  3  and  4   , the sprocket support body  26  has a splined region  26   a  which includes a plurality of splines  26   a   1 . The splines  26   a   1  are external splines that are configured to engage the rear sprockets CS. In this way, the rear sprockets CS are non-rotatably coupled to the sprocket support body  26 . The sprocket support body  26  also has a non-splined region  26   b  that is configured to be at least partially disposed inside the hub body  14 . Thus, the hub body  14  and the sprocket support body  26  partially overlap. 
     Referring to  FIG.  3   , the hub assembly  10  is configured such that the sprocket support body  26  can be easily replaced with a sprocket support body  28 , as explained below. The sprocket support body  28  is identical to the sprocket support body  26  except for the exterior configuration. In particular, the sprocket support body  28  has a splined region  28   a  which includes a plurality of splines  28   a   1 . In the sprocket support body  28 , the splines  28   a   1  are narrower than the splines  26   a   1 . Also, the total number of the splines  28   a   1  of the sprocket support body  28  is greater than the total number of the splines  26   a   1  of the sprocket support body  26 . Finally, the sprocket support body  28  also has a non-splined region  28   b  that is configured to be at least partially disposed inside the hub body  14 . In the sprocket support body  28 , the non-splined region  28   b  has an axial length longer than an axial length of the non-splined region  26   b  of the sprocket support body  26 . 
     The hub assembly  10  further comprises at least one sprocket support bearing. The at least one sprocket support bearing rotatably supports the sprocket support body  26  on the hub axle  12 . Here, the at least one sprocket support bearing includes a first sprocket support bearing  30  and a second sprocket support bearing  32  that are axially spaced apart along the hub axle  12 . The first sprocket support bearing  30  rotatably supports a first end of the sprocket support body  26 . The second sprocket support bearing  32  rotatably supports a second end of the sprocket support body  26 . Each of the at least one sprocket support bearing is disposed opposite to the hub body  14  with respect to the plurality of ratchet teeth  56  in an axial direction with respect to the rotational center axis A 1 . 
     The first sprocket support bearing  30  and the second sprocket support bearing  32  have outer diameters that are smaller than the first hub body bearing  20  and the second hub body bearing  22 . Here, the inner diameter of the first sprocket support bearing  30  is smaller than the inner diameter of the second sprocket support bearing  32 . The first sprocket support bearing  30  and the second sprocket support bearing  32  are mounted on the hub axle  12  from the first end  12   a  of the hub axle  12 . 
     The first sprocket support bearing  30  includes a first inner race  30   a , a first outer race  30   b  and a plurality of first roller elements  30   c . The first roller elements  30   c  are disposed between the first inner race  30   a  and the first outer race  30   b . The second sprocket support bearing  32  includes a second inner race  32   a , a second outer race  32   b  and a plurality of second roller elements  32   c . The second roller elements  32   c  are disposed between the second inner race  32   a  and the second outer race  32   b . Here, the first sprocket support bearing  30  and the second sprocket support bearing  32  are radial ball bearings. As mentioned above, radial ball bearings support force in the direction perpendicular to the axis. Further, one of an angular contact ball bearing, a radial roller bearing and an angular contact roller bearing can be adopted instead of a radial ball bearing for one or both of the first sprocket support bearing  30  and the second sprocket support bearing  32 . 
     Here, the sprocket support body  26  includes a first bearing abutment  26   c  contacting the first outer race  30   b  of the first sprocket support bearing  30  and a second bearing abutment  26   d  contacting a second outer race  32   b  of the second sprocket support bearing  32 . The first bearing abutment  26   c  faces in an opposite direction from the second bearing abutment  26   d  with respect to the rotational center axis A 1 . 
     A first tubular spacing element  34  is disposed on the hub axle  12  between the first sprocket support bearing  30  and the second sprocket support bearing  32 . The first tubular spacing element  34  axially spaces the first sprocket support bearing  30  and the second sprocket support bearing  32  on the hub axle  12 . Also, a second tubular spacing element  36  is disposed on the hub axle  12  between the first tubular spacing element  34  and the first hub body bearing  20 . The second sprocket support bearing  32  is supported on the second tubular spacing element  36 , and is axially sandwiched between an abutment of the second tubular spacing element  36  and an end of the first tubular spacing element  34 . The second tubular spacing element  36  abuts the first hub body bearing  20 . In this way, the second tubular spacing element  36  axially spaces the second sprocket support bearing  32  and the first hub body bearing  20 . 
     In the first embodiment, the hub assembly  10  further comprises an end cap  38  threadedly coupled to the first end  12   a  of the hub axle  12  and contacting the first sprocket support bearing  30  to retain the sprocket support body  26  to the hub axle  12 . The hub axle  12  also an end cap  40  that is threadedly coupled to the second end  12   b  of the hub axle  12 . The end cap  40  contacts the second hub body bearing  22 . In this way, the end cap  38  and the end cap  40  retain the hub body  16  to the hub axle  12 . Also, the first end cap  38  and the second end cap  40  are configured to be received in mounting openings of the rear frame body RB as seen in  FIG.  2   . Here, the first end cap  38  has a first opening  38   a  and the second end cap  40  has a second opening  40   a.    
     Here, as seen in  FIGS.  2  and  5   , the hub assembly  10  further comprises a wheel holding mechanism  42  for securing the hub axle  12  of the hub assembly  10  to the rear frame body RB. The wheel holding mechanism  42  basically includes a shaft or skewer  42   a , a cam body  42   b , a cam lever  42   c  and an adjusting nut  42   d . The cam lever  42   c  is attached to one end of the skewer  42   a  via the cam body  42   b , while the adjusting nut  42   d  is threaded on the other end of the skewer  42   a . The lever  42   c  is attached to the cam body  42   b . The cam body  42   b  is coupled between the skewer  42   a  and the cam lever  42   c  to move the skewer  42   a  relative to the cam body  42   b . Thus, the lever  42   c  is operated to move the skewer  42   a  in the axial direction of the rotational center axis A 1  with respect to the cam body  42   b  to change the distance between the cam body  42   b  and the adjusting nut  42   d . Preferably, a compression spring is provided at each end of the skewer  42   a . Alternatively, the hub axle  12  can be non-rotatably attached to the rear frame body RB with other attachment structures as needed and/or desired. 
     The hub assembly  10  further comprises a pawl support body  50 , at least one pawl  52 , a ratchet body  54  and a plurality of ratchet teeth  56 . Basically, the pawl support body  50 , the at least one pawl  52 , the ratchet body  54  and the ratchet teeth  56  form a one-way clutch  58  operatively disposed between the hub body  14  and the sprocket support body  26 . In this way, the sprocket support body  26  is coupled to the hub body  14  to rotate together in the driving rotational direction D 1  around the rotational center axis A 1 , and the sprocket support body  26  is coupled to the hub body  14  to rotate relative to the hub body  14  in the non-driving rotational direction D 2  around the rotational center axis A 1 . Also, with the one-way clutch  58 , the hub body  14  can rotate relative to the sprocket support body  26  in the case where the sprocket support body  26  is stopped or rotating slower than hub body  14 . In this way, the sprocket support body  26  and the one-way clutch  58  form a freewheel that is commonly used in bicycles. Since the basic operation of the freewheel is relatively conventional, the operation of the freewheel will not be discussed or illustrated in further detail. 
     Basically, the pawl support body  50  is non-rotatably coupled to the hub body  14  and supporting the at least one pawl  52 . Thus, the hub body  14  and the pawl support body  50  are configured to rotate together around the rotational center axis A 1 . Here, as seen in  FIG.  5   , the pawl support body  50  is non-rotatably coupled to the hub body  14  with spline engagement. In the first embodiment, the pawl support body  50  is connected to the hub body  14 . In particular, the pawl support body  50  has a plurality of outer splines that engage a plurality of inner splines of the hub body  14 . The outer splines of the pawl support body  50  and the inner splines of the hub body  14  extend axially, and are parallel to the rotational center axis A 1 . In this way, the pawl support body  50  can be easily attached to the hub body  14  and detached from the hub body  14 . Thus, in the first embodiment, the pawl support body  50  is a separate member from the hub body  14 . 
     The at least one pawl  52  is movably provided to the pawl support body  50  to move between a driving position ( FIG.  6   ) and a non-driving position ( FIG.  7   ). In the driving position ( FIG.  6   ), the at least one pawl  52  is engaged with one of the ratchet teeth  56  that is provided to the ratchet body  54 . In this way, the driving position, rotation of the ratchet body  54  can be transmitted to the pawl support body  50  and the hub body  14 . In the non-driving position ( FIG.  7   ), the at least one pawl  52  becomes disengaged with the ratchet teeth  56 . In this way, the non-driving position, the rotation of the ratchet body  54  is not transmitted to the pawl support body  50  and the hub body  14 . In the first embodiment, the at least one pawl  52  is located inside the hub body  14 . In particular, the at least one pawl  52  is disposed axially between each of the at least one hub bearing  20 ,  22  and each of the at least one sprocket support bearing  30 ,  32  in the axial direction. In other words, the first hub body bearing  20  and the second hub body bearing  22  are disposed on one axial side of the at least one pawl  52 , and the first sprocket support bearing  30  and the second sprocket support bearing  32  are disposed on the other axial side of the at least one pawl  52 . With this arrangement, the complicated structure of the pawl support body  50  and the at least one pawl  52  are provided to the hub body  14  and the sprocket support body  26  can be simplified. Thus, the sprocket support body  26  can be easily separated from the hub body  14  so that the replacement work can be easily performed. 
     Here, the at least one pawl  52  includes a plurality of pawls  53 A,  52 B and  52 C. The pawls  53 A,  52 B and  52 C are equally spaced apart in a circumferential direction on the pawl support body  50  around the rotational center axis A 1 . While a total of three pawls are shown, one or more pawls can be used as needed and/or desired. The one-way clutch  58  further includes a biasing element  60  that couples the pawls  53 A,  52 B and  52 C to the pawl support body  50  such that each of the pawls  53 A,  52 B and  52 C can move between the driving position ( FIG.  6   ) and the non-driving position ( FIG.  7   ). In particular, the biasing element  60  biases the pawls  53 A,  52 B and  52 C into engagement with the ratchet teeth  56  of the ratchet body  54 . The biasing element  60  squeezes the pawls  53 A,  52 B and  52 C against the pawl support body  50  such that the pawls  53 A,  52 B and  52 C pivot towards engagement with the ratchet teeth  56  of the ratchet body  54 . In a case where the sprocket support body  26  is rotated in the non-driving rotational direction D 2 , the ratchet teeth  56  push pawls  53 A,  52 B and  52 C and pivot pawls  53 A,  52 B and  52 C to the non-driving (retracted) position against the pawl support body  50 . Thus, the sprocket support body  26  is configured to rotate relative to the hub body  14  in the non-driving rotational direction D 2  around the rotational center axis A 1 . 
     Also, at least one of the at least one pawl  52  and the plurality of ratchet teeth  56  are overlapped with the hub body  14  as viewed in a radial direction with respect to the rotational center axis A 1 . In the first embodiment, each of the pawls  53 A,  52 B and  52 C and the ratchet teeth  56  both overlapped with the hub body  14  as viewed in a radial direction with respect to the rotational center axis A 1 . 
     As seen in  FIGS.  5  to  8   , the ratchet body  54  is connected to the sprocket support body  26 . As a result, the ratchet body  54  is configured to rotate together with the sprocket support body  26  with respect to the rotational center axis A 1 . Here, the ratchet body  54  is integrally formed with the sprocket support body  26  as a unitary, one-piece member. Thus, the sprocket support body  26  and the ratchet body  54  is a single member that transmits the torque from the sprocket support body  26  to the pawl support body  50  via the pawls  53 A,  52 B and  52 C. Typically, the sprocket support body  26  and the ratchet body  54  is made of a suitable hard and rigid material such as a metallic material or a fiber reinforced plastic material. 
     Basically, the ratchet teeth  56  are provided to the ratchet body  54  for engaging the at least one pawl  52  to transmit a driving force from the sprocket support body  26  to the hub body  14  while rotating in the driving rotational direction D 1  around the rotational center axis A 1 . Also, here, in the first embodiment, the plurality of ratchet teeth  56  are provided on an inner surface of the ratchet body  54 . Thus, the plurality of ratchet teeth  56  is provided on an outer peripheral side of the at least one pawl  52 . 
     Moreover, the sprocket support body  26  and the plurality of ratchet teeth  56  are a single, one-piece member. In particular, as mentioned above, the ratchet body  54  is integrally formed with the sprocket support body  26  as a unitary, one-piece member. Thus, the ratchet teeth  56  are integrally formed with the sprocket support body  26  as a unitary, one-piece member. Preferably, the ratchet teeth  56  are disposed outside the splined region  26   a  in the axial direction. Also, preferably, the plurality of ratchet teeth  56  are disposed at an end portion of the sprocket support body  26  on a hub body side. 
     Referring now to  FIG.  8   , a hub assembly  110  is illustrated in accordance with a second embodiment. In view of the similarity between the first and second embodiments, the descriptions of the parts of the second embodiment that are identical to the parts of the first embodiment may be omitted for the sake of brevity. 
     The hub assembly  110  basically comprises a hub axle  112  and a hub body  114 . The hub axle  112  is identical to the hub axle  12  of the first embodiment. The hub body  114  has been slightly modified from the hub body  14  as explained below. The hub assembly  110  further comprises at least one hub body bearing  120  rotatably supporting the hub body  114  on the hub axle  112 . Preferably, the hub body  114  is rotatably supported on the hub axle  112  by a pair of hub bearings in the same manner as the first embodiment. 
     The hub assembly  110  further comprises a sprocket support body  126  rotatably disposed to the hub axle  112  to rotate around the rotational center axis A 1 . The sprocket support body  126  is identical to the sprocket support body  26  of the first embodiment. The hub assembly  110  further comprises at least one sprocket support bearing that rotatably supports the sprocket support body  126  to the hub axle  112 . Here, the sprocket support body  126  is rotatably supported to the hub axle  112  by a first sprocket support bearing  130  and a second sprocket support bearing  132 . The first sprocket support bearing  130  is identical to the first sprocket support bearing  30  of the first embodiment. The second sprocket support bearing  132  is identical to the second sprocket support bearing  32  of the first embodiment. A first tubular spacing element  134  is disposed on the hub axle  112  between the first sprocket support bearing  130  and the second sprocket support bearing  132 . The first tubular spacing element  134  is identical to the first tubular spacing element  34  of the first embodiment. A second tubular spacing element  136  is disposed on the hub axle  112  between the first tubular spacing element  134  and the first hub body bearing  120 . The second tubular spacing element  136  is identical to the second tubular spacing element  36  of the first embodiment. 
     The hub assembly  110  further comprises an end cap  138  threadedly coupled to one end of the hub axle  112  and contacting the first sprocket support bearing  130  to retain the sprocket support body  126  to the hub axle  112  similar to the first embodiment. Also, a second end cap is mounted to the other end of the hub axle  112  similar to the first embodiment. 
     The hub assembly  110  further comprises a pawl support body  150 , at least one pawl  152 , a ratchet body  154  and a plurality of ratchet teeth  156 . Basically, similar to the first embodiment, the pawl support body  150 , the at least one pawl  152 , the ratchet body  154  and the ratchet teeth  156  form a one-way clutch  158  operatively disposed between the hub body  114  and the sprocket support body  126 . However, the second embodiment differs from the first embodiment in that the pawl support body  150  is integrally formed with the hub body  114  as a unitary, one-piece member. Similar to the first embodiment, the at least one pawl  152  includes a plurality of pawls movably coupled to the pawl support body  150  in the same manner as the first embodiment. The remaining parts (e.g., a biasing element  160 ) of the one-way clutch  158  are the same as the first embodiment. 
     Referring now to  FIG.  9   , a hub assembly  210  is illustrated in accordance with a third embodiment. In view of the similarity between the first and third embodiments, the descriptions of the parts of the third embodiment that are identical to the parts of the first embodiment may be omitted for the sake of brevity. 
     The hub assembly  210  basically comprises a hub axle  212  and a hub body  214 . The hub axle  212  is identical to the hub axle  12  of the first embodiment. The hub body  214  is identical to the hub body  14  of the first embodiment. The hub assembly  210  further comprises at least one hub body bearing  220  rotatably supporting the hub body  214  on the hub axle  212 . Preferably, the hub body  214  is rotatably supported on the hub axle  212  by a pair of hub bearings in the same manner as the first embodiment. 
     The hub assembly  210  further comprises a sprocket support body  226  rotatably disposed to the hub axle  212  to rotate around the rotational center axis A 1 . The sprocket support body  226  has been slightly modified from the sprocket support body  26  of the first embodiment as discussed below. The hub assembly  210  further comprises at least one sprocket support bearing that rotatably supports the sprocket support body  226  to the hub axle  212 . Here, the sprocket support body  226  is rotatably supported to the hub axle  212  by a first sprocket support bearing  230  and a second sprocket support bearing  232 . The first sprocket support bearing  230  is identical to the first sprocket support bearing  30  of the first embodiment. The second sprocket support bearing  232  is identical to the second sprocket support bearing  32  of the first embodiment. A first tubular spacing element  234  is disposed on the hub axle  212  between the first sprocket support bearing  230  and the second sprocket support bearing  232 . The first tubular spacing element  234  is identical to the first tubular spacing element  34  of the first embodiment. A second tubular spacing element  236  is disposed on the hub axle  212  between the first tubular spacing element  234  and the first hub body bearing  220 . The second tubular spacing element  236  is identical to the second tubular spacing element  36  of the first embodiment. 
     The hub assembly  210  further comprises an end cap  238  threadedly coupled to one end of the hub axle  212  and contacting the first sprocket support bearing  230  to retain the sprocket support body  226  to the hub axle  212  similar to the first embodiment. Also, a second end cap is mounted to the other end of the hub axle  112  similar to the first embodiment. 
     The hub assembly  210  further comprises a pawl support body  250 , at least one pawl  252 , a ratchet body  254  and a plurality of ratchet teeth  256 . Basically, similar to the first embodiment, the pawl support body  250 , the at least one pawl  252 , the ratchet body  254  and the ratchet teeth  256  form a one-way clutch  258  operatively disposed between the hub body  214  and the sprocket support body  226 . However, the second embodiment differs from the first embodiment in that the ratchet body  254  is a separate member from the sprocket support body  226 . For example, the ratchet body  254  is threadedly attached to the sprocket support body  226 . Similar to the first embodiment, the at least one pawl  252  includes a plurality of pawls movably coupled to the pawl support body  250  in the same manner as the first embodiment. The remaining parts (e.g., a biasing element  260 ) of the one-way clutch  258  are the same as the first embodiment. 
     In understanding the scope of the present invention, the term “comprising” and its derivatives, as used herein, are intended to be open ended terms that specify the presence of the stated features, elements, components, groups, integers, and/or steps, but do not exclude the presence of other unstated features, elements, components, groups, integers and/or steps. The foregoing also applies to words having similar meanings such as the terms, “including”, “having” and their derivatives. Also, the terms “part,” “section,” “portion,” “member” or “element” when used in the singular can have the dual meaning of a single part or a plurality of parts unless otherwise stated. 
     As used herein, the following directional terms “frame facing side”, “non-frame facing side”, “forward”, “rearward”, “front”, “rear”, “up”, “down”, “above”, “below”, “upward”, “downward”, “top”, “bottom”, “side”, “vertical”, “horizontal”, “perpendicular” and “transverse” as well as any other similar directional terms refer to those directions of a human-powered vehicle (e.g., bicycle) in an upright, riding position and equipped with the hub assembly. Accordingly, these directional terms, as utilized to describe the hub assembly should be interpreted relative to a human-powered vehicle (e.g., bicycle) in an upright riding position on a horizontal surface and that is equipped with the hub assembly. The terms “left” and “right” are used to indicate the “right” when referencing from the right side as viewed from the rear of the human-powered vehicle (e.g., bicycle), and the “left” when referencing from the left side as viewed from the rear of the human-powered vehicle (e.g., bicycle). 
     The phrase “at least one of” as used in this disclosure means “one or more” of a desired choice. For one example, the phrase “at least one of” as used in this disclosure means “only one single choice” or “both of two choices” if the number of its choices is two. For another example, the phrase “at least one of” as used in this disclosure means “only one single choice” or “any combination of equal to or more than two choices” if the number of its choices is equal to or more than three. Also, the term “and/or” as used in this disclosure means “either one or both of”. 
     Also, it will be understood that although the terms “first” and “second” may be used herein to describe various components, these components should not be limited by these terms. These terms are only used to distinguish one component from another. Thus, for example, a first component discussed above could be termed a second component and vice versa without departing from the teachings of the present invention. 
     The term “attached” or “attaching”, as used herein, encompasses configurations in which an element is directly secured to another element by affixing the element directly to the other element; configurations in which the element is indirectly secured to the other element by affixing the element to the intermediate member(s) which in turn are affixed to the other element; and configurations in which one element is integral with another element, i.e. one element is essentially part of the other element. This definition also applies to words of similar meaning, for example, “joined”, “connected”, “coupled”, “mounted”, “bonded”, “fixed” and their derivatives. Finally, terms of degree such as “substantially”, “about” and “approximately” as used herein mean an amount of deviation of the modified term such that the end result is not significantly changed. 
     While only selected embodiments have been chosen to illustrate the present invention, it will be apparent to those skilled in the art from this disclosure that various changes and modifications can be made herein without departing from the scope of the invention as defined in the appended claims. For example, unless specifically stated otherwise, the size, shape, location or orientation of the various components can be changed as needed and/or desired so long as the changes do not substantially affect their intended function. Unless specifically stated otherwise, components that are shown directly connected or contacting each other can have intermediate structures disposed between them so long as the changes do not substantially affect their intended function. The functions of one element can be performed by two, and vice versa unless specifically stated otherwise. The structures and functions of one embodiment can be adopted in another embodiment. It is not necessary for all advantages to be present in a particular embodiment at the same time. Every feature which is unique from the prior art, alone or in combination with other features, also should be considered a separate description of further inventions by the applicant, including the structural and/or functional concepts embodied by such feature(s). Thus, the foregoing descriptions of the embodiments according to the present invention are provided for illustration only, and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.