Abstract:
A bicycle including a main frame, a front wheel mounted for rotation relative to the main frame. a rear dropout, and a rear wheel mounted for rotation relative to the rear dropout about an axis. The rear wheel defines a center plane of the bicycle and is driven by a chain. The bicycle also includes a seat stay coupling the rear dropout to the main frame. The seat stay has an inner surface facing the rear wheel and an outer surface facing away from the rear wheel. The seat stay includes a steep portion having an outer surface disposed at a steep angle of between about 25 degrees and about 75 degrees relative to the center plane, and at least a portion of the steep portion is disposed outboard of the chain.

Description:
BACKGROUND 
     The present invention relates to bicycles, and more particularly to frames for bicycles. 
     Bicycle frames typically include a top tube, a down tube, a seat tube, and a head tube. The top tube and the down tube are typically interconnected near the front of the bicycle by the head tube. The seat tube interconnects the down tube and the top tube behind the head tube typically near a middle portion of the bicycle. A bottom bracket that supports a crank set is often located near an intersection of the down tube and the seat tube. The crank set is utilized by the rider to drive the rear wheel. In many bicycles, a seat post is received in the seat tube, above the top tube. The seat post is secured to a seat that supports the rider on the bicycle. A typical bicycle frame also includes rear dropouts for receiving a rear wheel. The rear dropouts are commonly connected to the remainder of the frame by stays, such as seatstays and chainstays, as is known in the art. 
     SUMMARY 
     In one embodiment, the invention provides a bicycle that includes a main frame, a front wheel mounted for rotation relative to the main frame, a rear dropout, and a rear wheel mounted for rotation relative to the rear dropout. The rear wheel defines a center plane of the bicycle. The bicycle further includes a rear stay that couples the rear dropout to the main frame. The rear stay has an inner surface facing the rear wheel and an outer surface facing away from the rear wheel. The rear stay includes a steep portion having an outer surface at a steep angle of between about 25 degrees and about 75 degrees relative to the center plane. 
     In another embodiment, the invention provides a bicycle where the front and rear wheels support the bicycle on a ground surface. A rear stay couples the rear dropout to the main frame. The rear stay has a rear portion adjacent the dropout and at a first angle relative to the center plane and a front portion adjacent the main frame and at a second angle relative to the center plane and a steep portion between the front and rear portions and at a steep angle relative to the center plane. The steep angle is larger than the first angle and the second angle. The steep portion includes an elongated cross-section defining a major axis that is substantially parallel to the ground surface. 
     In yet another embodiment, the invention provides a bicycle that includes a rear stay coupling the rear dropout to the main frame. The rear stay includes a rear portion adjacent the dropout and at a first angle relative to the center plane, a front portion adjacent the main frame and at a second angle relative to the center plane, and a steep portion between the first and second portions and at a steep angle relative to the center plane. The steep angle is larger than the first angle and the second angle. The steep portion includes an elongated cross-section having a leading edge and a trailing edge. The leading edge is directly in front of the trailing edge. 
     Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of a bicycle that includes a frame embodying the present invention. 
         FIG. 2A  is a view of the frame of  FIG. 1  taken along line  2 A- 2 A of  FIG. 1 . 
         FIG. 2B  is an enlarged view of a portion of  FIG. 2A . 
         FIG. 3  is a view of the frame of  FIG. 1  taken along line  3 - 3  of  FIG. 1 . 
         FIG. 4  is a perspective view of a front portion of the frame of  FIG. 1  and a front fork of the bicycle of  FIG. 1 . 
         FIG. 5  is a perspective view similar to  FIG. 4  with the front fork removed. 
         FIG. 6  is a perspective view of portions of rear stays of the frame of  FIG. 1  illustrating a dropout exploded from the rear stays. 
         FIG. 7  is a side view of a portion of the frame of  FIG. 1 . 
         FIG. 8  is a cross-sectional view of a top tube of the frame taken along line  8 - 8  of  FIG. 1 . 
         FIG. 9  is a cross-sectional view of a seatstay of the bicycle taken along line  9 - 9  of  FIG. 1 . 
         FIG. 10  is a cross-sectional view of a chainstay of the bicycle taken along line  10 - 10  of  FIG. 1 . 
         FIG. 11  is a cross-sectional view of the chainstay taken along line  11 - 11  of  FIG. 3 . 
     
    
    
     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. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings. 
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a bicycle  12  that includes a main frame  16  and a front wheel  18  and a rear wheel  22  that support the main frame  16  above a ground surface  26 . As best seen in  FIGS. 1 and 2A , the bicycle  12  further includes rear stays  30  and rear dropouts  34 . The rear stays  30  couple the rear dropouts  34  to the main frame  16 . The rear dropouts  34  rotatably support the rear wheel  22  and couple the rear wheel  22  to the rear stays  30 . The rear wheel  22  defines a central plane  36  of the bicycle  12 . 
     Referring to  FIG. 1 , the main frame  16  includes a head tube  38 , a down tube  40 , a top tube  42 , and a seat tube  44 . The head tube  38  interconnects the down tube  40  and the top tube  42 , and the head tube  38  rotatably supports a front fork  48 . As would be understood by one of skill in the art, a headset, which typically includes bearings, seals, etc., is received within the head tube  38  to rotatably support the front fork  48  with respect to the head tube  38 . The front fork  48  includes two fork blades  52  and a fork crown  56  that interconnects the fork blades  52  above the front wheel  18 . A front dropout  60  is received within each of the fork blades  52  to couple the front wheel  18  to the fork  48  and to rotatably support the front wheel  18  with respect to front fork  48 . A steerer tube  64  extends from the crown  56  of the front fork  48  and extends through the head tube  38 . A stem  68  is coupled to the steerer tube  64 . The stem  68  interconnects front handlebars  70  and the steerer tube  64 . The front handlebars  70  are rotatable with respect to the head tube  38  to pivot the front wheel  18 . 
     Referring to  FIGS. 4 and 5 , in the illustrated construction, the main frame  16  includes an aerodynamic transition portion  72  between the crown  56  of the front fork  48  and the down tube  40 . The transition portion  72  includes outer surfaces  74  that generally conform to the curvature of respective outer surfaces  76  of the fork crown  56 . The transition portion  72  further includes a concave inner surface  80  that generally conforms to the curvature of an inner surface  84  of the fork crown  56 . The aerodynamic transition portion  72  reduces wind resistance or drag created behind the fork crown  56 . 
     Referring to  FIGS. 1 and 8 , the top tube  42  includes a front portion  90  adjacent the head tube  38  and a rear portion  92  adjacent the seat tube  44 . The top tube  42  defines a thickness T 1  measured along a major axis  96  of the top tube  42  and a width W 1  measured along a minor axis  98  of the top tube  42 . In the illustrated construction, the thickness T 1  decreases from the front portion  90  toward the rear portion  92  or generally from the head tube  38  toward the seat tube  44 . The thickness T 1  of the front portion  90  is such that the front portion  90  includes an aerodynamic transition portion  102  that extend above the head tube  38  and located directly behind the stem  68 . The aerodynamic transition portion  102  reduces wind resistance or drag created behind the stem  68 . 
     Referring to  FIGS. 1 and 7 , the seat tube  44  includes an upper portion  110 , a lower portion  114  and a curved transition  118  that interconnects the upper and lower portions  110  and  114 . The upper portion  110  receives a seat post  122  that interconnects a saddle or seat  124  to the main frame  16 . The curved transition  118  is curved such that a trailing end  126  and a leading end  128  of the transition  118  are curved to generally conform to the curvature of the rear wheel  22 . 
     A bottom bracket  132  is coupled to the seat tube  44  adjacent the lower portion  114  of the seat tube  44 . The bottom bracket  132  interconnects the seat tube  44  and the down tube  40 . The bottom bracket  132  rotatably supports a crank set  136 . As would be understood by one of skill in the art, the crank set  136  and a cassette  138  or set of rear sprockets (schematically illustrated in  FIG. 2A ) are interconnected using a chain, and the crank set  136  is utilized by a rider of the bicycle  12  to drive the rear wheel  22 . 
     Referring to  FIGS. 1 and 2A , the rear stays  30  include left and right seatstays  140 ,  142  and left and right chainstays  146 ,  148 . The seatstays  140 ,  142  are coupled to the upper portion  110  of the seat tube  44  and interconnect the seat tube  44  and the rear dropouts  34 . The seatstays  140 ,  142  are similar, and therefore, only the left seatstay  140  will be described in detail below and like components and portions have been given the same reference number. 
     Referring to  FIGS. 1 ,  2 A,  2 B, and  9 , the seatstay  140  includes an inner surface  152  that generally faces toward the rear wheel  22  and an outer surface  156  that generally faces opposite the inner surface  152  or away from the rear wheel  22 . The inner surface  152  and the outer surface  156  converge to define a leading edge  160  and a trailing edge  162 . The leading edge  160  is directed toward the front of the bicycle  12  and the trailing edge  162  is directed toward the rear of the bicycle  12 . The seatstay  140  is aerodynamically shaped, and the leading edge  160  has a larger radius of curvature than the trailing edge  162 . The seatstay  140  defines a major axis  164  that extends through the leading and trailing edges  160  and  162  as illustrated in  FIG. 9 . 
     Referring to  FIGS. 2A and 2B , the seatstay  140  further includes a front portion  166 , a rear portion  170 , and a steep portion  174  between the front and rear portions  166  and  170 . The front portion  166  has a length  176  and the outer surface  156  of the front portion  166  defines a front angle  178  with respect to the center plane  36  of the bicycle  12 . In the illustrated construction, the front angle  178  is approximately 10 degrees. In other constructions, the front angle  178  can range from about 5 degrees to about 25 degrees. In yet other constructions, the front angle  178  can range from about 0 degrees (i.e., parallel to the center plane  36 ) to about 50 degrees. 
     In the illustrated construction, the outer surface  156  of the rear portion  170  is generally parallel to the center plane  36  of bicycle  12 . In other constructions, the outer surface  156  of the rear portion  170  can be angled with respect to the center plane  36 . Referring to  FIG. 6 , the rear portion  170  receives the rear dropout  34 . The dropout  34  includes a seatstay bonding plug  184  and a chainstay bonding plug  186 . In the illustrated construction, the seatstay bonding plug  184  is aero-shaped such that the plug  184  can be inserted into the aero-shaped seatstay  140  (see  FIG. 3 ). 
     Referring to  FIGS. 2A and 2B , the steep portion  174  of the seatstay  140  includes a front end  190  coupled to the front portion  166  of the seatstay  140  and a rear end  192  coupled to the rear portion  170  of the seatstay  140 . A front transition bend  194  is located between the steep portion  174  and the front portion  166  of the seatstay  140  and a rear transition bend  198  is located between the steep portion  174  and the rear portion  170  of the seatstay  140 . The front transition bend  194  defines a front bend axis  200  and the rear transition bend  198  defines a rear bend axis  202 . In the illustrated construction, the front and rear bend axes  200  and  202  are parallel to the ground surface  26  (see  FIG. 7 ). Because the front and rear bend axes  200  and  202  are parallel to the ground surface  26 , the leading edge  160  of the steep portion  174  is directly in front of the trailing edge  162 . Alternatively stated, the major axes of the seatstay  140  at the steep portion  174  (see  FIG. 9 ) are parallel to the ground surface  26 . Accordingly, the leading edge  160  and the trailing edge  162  are properly positioned with respect to oncoming wind to reduce the amount of wind resistance or drag created by the seatstay  140 , particularly the steep portion  174 . 
     Referring to  FIGS. 2A and 2B , the steep portion  174  defines a length  204  measured from the front bend axis  200  to the rear bend axis  202 . In the illustrated construction the length  204  of the steep portion  174  is approximately 15 percent of the length  176  of the front portion  166 . In other constructions, the length  204  of the steep portion  174  can range from about 10 percent to about 20 percent of the length  176  of the front portion  166 . In yet other constructions, the length  204  of the steep portion  174  can range from about 5 percent to about 30 percent of the length  176  of the front portion  166 . 
     The outer surface  156  of the steep portion  174  defines a steep angle  210  with respect to the center plane  36 . In the illustrated construction, the steep angle  210  is approximately 50 degrees. In other constructions, the steep angle  210  can range from about 35 degrees to about 65 degrees. In yet other constructions, the steep angle  210  can range from about 25 degree to about 75 degrees. The steep angle  210  and the proximity of the steep portion  174  to the rear dropouts  34  and cassette  138  position the front portions  166  of the seatstays  140  and  142  relatively close to the center plane  36 , and therefore, reduce the amount of drag or wind resistance created by the seatstays  140  and  142 . 
     Referring to  FIGS. 1 and 3 , the chainstays  146  and  148  are coupled to the bottom bracket  132  and interconnect the bottom bracket  132  and the rear dropout  34 . The chainstays  146  and  148  are similar, and therefore, only the left chainstay  146  will be described in detail below and like components and portions have been given the same reference number. 
     The chainstay  146  includes an inner surface  218  that generally faces toward the rear wheel  22  and an outer surface  222  that generally faces opposite the inner surface  218  or away from the rear wheel  22 . 
     The chainstay  146  further includes a front portion  226 , a rear portion  230 , and a steep portion  234  between the front and rear portions  226  and  230 . The front portion  226  has a length  238  and the outer surface  222  of the front portion  226  defines a front angle  242  with respect to the center plane  36  of the bicycle  12 . In the illustrated construction, the front angle  242  is approximately 5 degrees. In other constructions, the front angle  242  can range from about 5 degrees to about 25 degrees. In yet other constructions, the front angle  242  can range from about 0 degrees (i.e., parallel to the center plane  36 ) to about 50 degrees. 
     The outer surface  222  of the rear portion  230  defines a rear angle  246  with respect to the center plane  36  of the bicycle  12 . In the illustrated construction, the rear angle  246  is approximately 15 degrees. In other constructions, the rear angle  246  can range from about 0 degrees to about 30 degrees. Referring to  FIG. 6 , the rear portion  230  receives the chainstay bonding plug  186  of the rear dropout  34  to couple the rear dropout  34  to the chainstay  148 . 
     Referring to  FIG. 3 , the steep portion  234  of the chainstay  146  includes a front end  250  coupled to the front portion  226  of the chainstay  146  and a rear end  254  coupled to the rear portion  230  of the chainstay  146 . A front transition bend  258  is located between the steep portion  234  and the front portion  226  of the chainstay  146  and a rear transition bend  262  is located between the steep portion  234  and the rear portion  230  of the chainstay  146 . The front transition bend  258  defines a front bend axis  266  and the rear transition bend  262  defines a rear bend axis  268 . Referring to  FIGS. 1 and 7 , in the illustrated construction, the front and rear bend axes  266  and  268  are normal to the ground surface  26 . 
     Referring to  FIGS. 2A and 2B , the steep portion  234  defines a length  272  measured from the front bend axis  266  to the rear bend axis  268 . In the illustrated construction the length  272  of the steep portion  234  is approximately 10 percent of the length  238  of the front portion  166 . In other constructions, the length  272  of the steep portion  234  can range from about 5 percent to about 30 percent of the length  238  of the front portion  226 . 
     Referring to  FIG. 3 , the outer surface  222  of the steep portion  234  defines a steep angle  276  with respect to the center plane  36 . In the illustrated construction, the steep angle  276  is approximately 45 degrees. In other constructions, the steep angle  276  can range from about 35 degrees to about 65 degrees. In yet other constructions, the steep angle  276  can range from about 25 degree to about 75 degrees. The steep angle  276  and the proximity of the steep portion  234  to the rear dropouts  34  and cassette  138  position the front portions  226  of the chainstays  146  and  148  relatively close to the central plane  36  in order to reduce the amount of drag or wind resistance created by the chainstays  146  and  148 . 
     Various features and advantages of the invention are set forth in the following claims.