Abstract:
A bicycle including a front wheel, a rear wheel, and a frameset supported by the front wheel and the rear wheel. The rear wheel includes a first end cap and a second end cap, and each end cap has an aligned hole extending through the end cap. The rear wheel includes an axle that is positioned in the holes in the end caps and that defines an axial direction. The frameset includes a first dropout and a second dropout, each including an opening. The axle is positioned in the opening of each dropout. Each drop out has a lip that defines a slot aligned with and larger than the openings. Each of the lips is dimensioned to receive a corresponding end cap of the rear wheel. The lip of the first dropout has an axial length less than the lip of the second dropout.

Description:
BACKGROUND 
       [0001]    The present invention relates to rear axle systems for bicycles. 
         [0002]    Prior art bicycles have employed through-axle systems for both front and rear axles. For example, U.S. Pat. No. 7,654,548 and U.S. Patent Publication No. 2009/0072613 each disclose an axle securing structure that includes two lips that define slots for receiving a portion of a wheel hub, and holes in the frame dropouts for receiving a axle. The axle is inserted through the hole in one of the dropouts, through an opening on the hub, and is then threaded into the other dropout. The axle can include a quick-release mechanism that facilitates toolless insertion and removing of the axle. 
         [0003]    When utilized on a rear wheel of a bicycle, the slots define a hub spacing, and the lips (which define the slots) determine a clearance width less than the hub spacing. For example, in one conventional arrangement, the hub spacing is 142 mm and the clearance width is 135 mm, due to the fact that the lips each have a length (parallel to the axle) of 3.5 mm. 
       SUMMARY 
       [0004]    The present invention provides a bicycle that includes a front wheel, a rear wheel, and a frameset supported by the front wheel and the rear wheel. The rear wheel includes a first end cap (e.g., a right end cap) and a second end cap (e.g., a left end cap), and each end cap has an aligned hole extending through the end cap. The rear wheel also includes an axle that is positioned in the holes in the end caps and that defines an axial direction. The frameset includes a first dropout (e.g., a right dropout) and a second dropout (e.g., a left dropout). Each dropout has an opening aligned with the holes in the end caps. The axle is positioned in the opening of each dropout. Each drop out also has a lip that defines a slot aligned with and larger than the openings. Each of the lips is dimensioned to receive a corresponding end cap of the rear wheel. The lip of the first dropout has an axial length less than the lip of the second dropout. For example, the axial length of the lip of the first dropout can be less than 75% (preferably less than 60% and more preferably less than 50%) of an axial length of the lip of the second dropout. 
         [0005]    In another embodiment, the first and second end caps are spaced from each other to define a hub spacing, and the rear wheel further includes an outer cog adapted to drive the rear wheel (e.g., by a chain driven by a crankset pedaled by the rider). In this embodiment the slot defines a recessed surface of the dropout, and a cog spacing from a center of the cog to the recessed surface is less than 5% (preferably less than 4.5% and more preferably less than 4%) of the hub spacing. 
         [0006]    Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is a right side view of a bicycle according to one embodiment of the invention. 
           [0008]      FIG. 2  is an exploded view of a rear axle system of the bicycle of  FIG. 1 . 
           [0009]      FIG. 3  is a perspective view of a right dropout of the rear axle system of  FIG. 2 . 
           [0010]      FIG. 4  is a perspective view of a left dropout of the rear axle system of  FIG. 2 . 
           [0011]      FIG. 5  is a section view of the rear axle system taken along line  5 - 5  of  FIG. 1 . 
           [0012]      FIG. 6  is an enlarged section view of a right portion of  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. 
         [0014]      FIG. 1  shows a bicycle  10  that includes a frameset or frame  14 , a front wheel  18 , a rear wheel  22 , and a drive train  26 . The frame  14  includes a top tube  30 , a head tube  34 , a down tube  38 , and a seat tube  42 . A top tube mount  46  is disposed on the underside of the top tube  30  and a seat tube mount  50  is disposed on the front side of the seat tube  42 . A saddle  54  including a seat post  58  is mounted to the frame  14  with a clamp  62 . 
         [0015]    The frame  14  is connected to the front wheel  18  by a front fork  66  rotatably received within the head tube  34 . A handle bar assembly  104  is clamped to the front fork  66  and may be manipulated by the user to steer the bicycle  10 , apply the brakes, adjust the drive train  26 , and perform other duties, as desired. 
         [0016]    The frame  14  further includes a rear triangle  108  connected to the rear wheel  22 . The rear triangle  108  includes a left seat stay  112  (see  FIG. 4 ), a right seat stay  116 , a seat stay bridge that connects the left seat stay  112  and the right seat stay  116 , a left chain stay  122 , a right chain stay  126 , and a shock mounting portion  130 . 
         [0017]    A rear left dropout  146  is disposed at a lower end of the left seat stay  112  and a rear right dropout  150  is disposed at the end of the right seat stay  116 . A rear brake mount  154  is disposed on the upper side of the left seat stay  112  (see  FIG. 4 ), and is adapted to support a rear brake in the form of a rear disk brake caliper  158 . A rear axle  162  rotatably secures the rear wheel  22  in the dropouts to rotatably secure the rear wheel  22  to the frame  14 . The rear axle  162  defines an axial direction along an axis A about which the rear wheel  22  rotates. A lateral direction B is defined as a direction perpendicular to the axis A. 
         [0018]    The drive train  26  includes a crankset  166  rotatably mounted to the bottom bracket. The crankset  166  includes two crank arms  170 , two pedals  174 , and three chain rings  178 . In other constructions a different number of chain rings  178  may be used, as desired. A front derailleur  182  shifts a chain  186  between the different chain rings  178 , and is actuated by the handle bar assembly  104 . A plurality of rear cogs  190  are mounted to the rear wheel  22  and connected to the crankset  166  by the chain  186 . A rear derailleur  194  shifts the chain  186  between the different rear cogs  190 , and is actuated by the handle bar assembly  104 . 
         [0019]    Turning to  FIG. 2 , the rear axle system will be described in detail. The left chain stay  122  connects to the left seat stay  112  with a fastener  198 . Likewise, the right chain stay  126  connects to the right seat stay  116  with a fastener  202 . A rear derailleur hanger  206  is connected to the rear right dropout  150  with a fastener  210 . In other constructions, the rear derailleur hanger  206  may be formed as a single piece with the rear right dropout  150 , may be connected in a different way (e.g., welding, brazing, adhesive) or may be attached to a different component (e.g., the rear right chain stay  126 , the right seat stay  116 ). Additionally, the left chain stay  122  and the left seat stay  112  may be formed as a single piece or be coupled together differently. Likewise, the right chain stay  126  and the right seat stay  116  may be formed as a single piece or be coupled together differently, as desired. 
         [0020]    The rear wheel  22  includes a hub  214  with a body  218 , spoke flanges  222  for attaching spokes, a rear brake disk flange  226  for attaching the rear brake disk (not visible) to the hub  214 , a cogset spline portion  230  for receiving the rear cogs  190 , a left end cap  234 , and a right end cap  238 . Inside the body  218 , a bearing set (not shown) couples the hub  214  to the rear axle  162  such that the rear wheel  22  can freely rotate about the rear axle  162 . The left end cap  234  and the right end cap  238  are spaced apart from one another to define a hub spacing C (see  FIG. 5 ). Each of the left end cap  234  and the right end cap  238  defines an outer diameter and lateral dimension D of nineteen millimeters and includes an aperture  242  or hole extending through the respective end cap  234 ,  238 . Each aperture  242  is aligned and parallel with respect to the axis A when installed on the bicycle  10 . In other constructions, the lateral dimension D of the end caps may be more or less than nineteen millimeters, as desired. It should also be appreciated that the end caps can be separate parts or can be formed integrally with each other (e.g., each defined by an opposing end of a common shaft). 
         [0021]    The rear axle  162  includes a quick connect cam  248 , a threaded portion  252 , and a bearing portion  256  between the quick connect cam  248  and the threaded portion  252 . In the illustrated embodiment, the rear axle  162  has a diameter of twelve millimeters (12 mm) that defines a lateral dimension E of the rear axle  162 . In other constructions the lateral dimension E of the rear axle  162  may be more or less than twelve millimeters, as desired. 
         [0022]      FIGS. 3 and 6  show the rear right dropout  150  in more detail. The rear right dropout  150  defines a right inner surface  264  and includes an aperture  268  and a nut  260  held via compression fit within the aperture  268  due to tightening of the fastener  210 . The nut  260  includes an internally threaded hole. A right lip  272  defines a right slot  276  sized to receive the right end cap  238  of the hub  214 . The right slot  276  defines a right recessed surface  280 , and the axial length F or depth of the illustrated right lip  272 , defined between the right inner surface  264  and the right recessed surface  280 , is about one and one-half millimeters (1.5 mm). 
         [0023]    Turning back to  FIG. 2 , the rear left dropout  146  includes an opening in the form of an aperture  284  and an insert  288  sized to be received by the aperture  284 . In the illustrated construction, the insert  288  is press fit into the aperture  284 . Alternatively, the insert  288  could be formed as a single piece with the rear left dropout  146  or attached in another way, as desired.  FIG. 4  shows the rear left dropout  146  in more detail. The insert  288  defines a left inner surface  292  and includes an aperture  296  sized to receive the rear axle  162 . A left lip  300  defines a left slot  304  sized to receive the left end cap  234  of the hub  214 . The left slot  304  defines a left recessed surface  308 , and the axial length G or depth of the illustrated left lip  300 , defined between the left inner surface  292  and the left recessed surface  308 , is about three and one-half millimeters (3.5 mm). 
         [0024]    As shown in  FIGS. 3 ,  4 , and  5 , the right lip  272  has an axial length F or depth that is less than the axial length G of the left lip  300 . In the illustrated construction, the axial length F of the right lip  272  is about forty-two percent (42%) of the axial length G of the left lip  300 . 
         [0025]    Turning to  FIG. 5 , the hub spacing C is clearly shown. In the illustrated construction, the hub spacing C is substantially equal to the space between the right recessed surface  280  and the left recessed surface  308  when the hub  214  is secured to the dropouts  146 ,  150 . The illustrated hub spacing C is about one-hundred-forty-two millimeters (142 mm). The illustrated axial length F of the right lip  272  is about one percent (1.1%) of the hub spacing C. 
         [0026]    The right slot  276  has a lateral dimension H (see  FIG. 3 ) about equal to the right end cap diameter D such that the lateral dimension H of the right slot  276  is about nineteen millimeters (19 mm). The illustrated right lip  272  has an axial length F about eight percent (8%) of the lateral dimension H of the right slot  276 . 
         [0027]    To assemble the rear axle system, the hub  214  is positioned between the rear left dropout  146  and the rear right dropout  150 , with the apertures  242  in the end caps aligned with the openings in the dropouts. The rear axle  162  is then inserted through the rear left dropout  146 , the hub  214 , and the rear right dropout  150 . The threaded portion  252  of the rear axle  162  threads into the nut  260  and the quick connect cam  248  is rotated to secure the rear axle  162  in place. 
         [0028]    One advantage of the inventive rear axle system is an increased space between the right inner surface  264  and the left inner surface  292  (dimension C minus G minus F). The illustrated space is about one-hundred-thirty-seven millimeters (137 mm) compared to one-hundred-thirty-five millimeters (135 mm) without the inventive concepts. The extra space allows for a wider hub  214  with a more stable rear wheel  22  because the rear cogs  190  can be moved outward (i.e. to the right in  FIGS. 5 and 6 ) to allow more room between the spoke flanges  222 . As illustrated in  FIG. 6 , a cog spacing I between the rightmost rear cog  190  and the right recessed surface  280  (or the rightmost rear cog  190  and the end of the right end cap  238 ) is decreased when compared to prior art arrangements. The illustrated cog spacing I is about 5.5 millimeters, compared to 7.5 mm in the prior art. As a result, it can be seen that this spacing I is about 3.9% of the hub spacing (142 mm). This feature is also a feature of the rear wheel hub by comparing the spacing Ito the hub spacing C. 
         [0029]    Various features and advantages of the invention are set forth in the following claims.