Abstract:
A bicycle frame including a head tube and a bottom bracket adapted to support a crankset. The frame also includes a tubular frame member that is coupled to the head tube and that has a concave section disposed on an underside of the frame member and spaced from the head tube.

Description:
BACKGROUND 
     The present invention relates generally to bicycles, and more specifically to bicycle frames. 
     Bicycles commonly have a main frame and a front fork pivotally secured to the main frame. The main frame typically includes a top tube, a down tube, a seat tube, and a rear wheel mount for receiving a rear wheel axle. The front fork typically includes a front wheel mount for receiving a front wheel axle. Steering control of the bicycle is provided by a handlebar that is usually secured to the front fork via a handlebar stem. 
     In some situations, it is desirable to carry a bicycle. For example, it is often necessary to lift and carry a bicycle over an obstacle, such as a curb, fallen tree, or other obstruction. In fact, in competitive events known as cyclocross racing, obstacles are deliberately placed on the race course in order to force the rider to dismount the bicycle and carry the bicycle over the obstacle. 
     SUMMARY 
     The present invention provides a bicycle having a frame that facilitates carrying the bicycle. In one construction, the present invention provides a bicycle frame including a head tube, a bottom bracket that supports a crankset, and a tubular frame member that is coupled to the head tube and that includes a concave section disposed on an underside of the frame member and spaced from the head tube. 
     In another construction, the present invention provides a bicycle frame including a head tube, a bottom bracket adapted to support a crankset, and a tubular frame member that is coupled to the head tube and that defines a longitudinal axis. The frame member has a first length along the axis and includes a concave section disposed on an underside of the frame member. The concave section has a second length that is at most 40 percent of the first length. 
     In another construction, the present invention provides a bicycle frame including a head tube, a bottom bracket adapted to support a crankset, and a tubular frame member that is coupled to the head tube and that defines a longitudinal axis. The tubular frame member includes a concave section disposed on an underside of the tubular frame member. The concave section has a central recess and a curved ridge disposed along the central recess such that the central recess and the curved ridge cooperate to define a substantially oval-shaped depression in the tubular frame member. 
     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 having a frame embodying the present invention. 
         FIG. 2  is a lower perspective view of a portion of the frame of the bicycle illustrated in  FIG. 1 , including a top tube, a seat tube, and a down tube. 
         FIG. 3 . is an underside view of the down tube of  FIG. 2  illustrating a concave section. 
         FIG. 4  is a cross-section of the down tube taken along line  4 - 4  in  FIG. 3 . 
         FIG. 5  is a cross-section of the down tube taken along line  5 - 5  in  FIG. 3 . 
         FIG. 6  is a cross-section of the down tube taken along line  6 - 6  in  FIG. 3 . 
         FIG. 7  is a cross-section of the down tube taken along line  7 - 7  in  FIG. 3 . 
         FIG. 8  is a cross-section of the down tube taken along line  8 - 8  in  FIG. 3 . 
         FIG. 9  is a perspective view of a portion of the down tube taken along line  9 - 9  in  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION 
     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. 
       FIG. 1  shows a bicycle  10  (e.g., a cyclocross bicycle) that includes a front wheel  15 , a rear wheel  20 , and a frame  25 . The frame  25  has a head tube  30  and a front fork  35  rotationally supported by the head tube  30  and that secures the front wheel  15  to the frame  25 . A handlebar  40  and a stem assembly  45  secures the handlebar  40  to the front fork  35  such that movement of the handlebar  40  results in movement of the stem assembly  45  and the fork  35 . 
       FIGS. 1 and 2  show that the frame  25  also has a top tube  50  connected to and extending rearward from the head tube  30 , and a down tube  55  connected to the head tube  30  below the top tube  50  and extending generally downward toward a bottom bracket  60  of the frame  25 . A seat tube  65  extends upward from the bottom bracket  60  and is connected to the top tube  50 , and a seat  70  is supported by the seat tube  65 . 
     The illustrated down tube  55  is coupled to the head tube  30  and to the bottom bracket  60 , and extends in a generally downward and rearward direction from the head tube  30  to the bottom bracket  60 . Referring to  FIGS. 1-3 , the down tube  55  defines a longitudinal axis  75 . The down tube  55  has a length L 1  that is measured along the axis  75  and a width W 1  that is measured across the axis  75 . Generally, the length L 1  is measured from the intersection of the head tube  30  and the down tube  55  to the center of the bottom bracket  60  along the axis  75 . The down tube  55  illustrated in  FIGS. 1-3  has a length L 1  of approximately 650 mm, although the length L 1  can be any other suitable length. 
     With reference to  FIGS. 2 and 3 , the down tube  55  includes a concave section  80  that is disposed on an underside (i.e., facing generally downward toward the ground) of the down tube  55  to accommodate a hand of a bicycle rider. Alternatively, or in addition, the top tube  50  can include a concave section (not shown) that is similar to the concave section  80 . 
     The illustrated concave section  80  is located between and spaced from the head tube  30  and the bottom bracket  60 . As shown in  FIG. 2 , the concave section  80  is located closer to the head tube  30  than the bottom bracket  60 , although the concave section  80  can be located near the middle portion of the down tube  55 , or even closer to the bottom bracket  60  than the head tube  30 , if desired. With reference to  FIG. 3 , the concave section  80  is substantially symmetrical about a vertical plane P 1  (as viewed in  FIG. 3 ) passing through the longitudinal axis  75 , and is substantially symmetrical about a transverse plane P 2  (as viewed in  FIG. 3 ) that is perpendicular to the longitudinal axis  75 . 
     The concave section  80  has a length L 2  (e.g., 75-110 mm) measured along the longitudinal axis  75 , and a width W 2  (e.g., 10-27 mm) measured laterally across the axis  75 . Generally, a ratio of the width W 2  relative to the length L 2  (W 2 /L 2 ) for the concave section  80  is equal to or less than 0.25 to substantially correspond or conform to the ratio of the length of a portion of a person&#39;s fingers (e.g., the approximate length of one node of the fingers) relative to the width of the person&#39;s hand as measured across the fingers when the hand is loosely clenched. As illustrated, the width W 2  of the concave section  80  is approximately 16 mm such that the ratio W 2 /L 2  is approximately 0.15. Also, the length L 2  of the concave section  80  depicted in  FIG. 3  is approximately 105 mm such that the length L 2  is approximately 16 percent of the length L 1  of the down tube  55 . Preferably, the length L 2  of the concave section  80  is at most 40 percent of the length L 1  of the down tube  55  to accommodate a person&#39;s hand while maintaining stiffness of the down tube  55 . In some constructions, the length L 2  is at most 30 percent of the length L 1 . In other constructions, the length L 2  is at most 20 percent of the length L 1 . 
     With reference to  FIGS. 2 ,  3 , and  9 , the concave section  80  has a central recess  85  and a curved ridge  90  that defines a transition or boundary between the central recess  85  on the underside of the down tube  55  and the other surfaces of the down tube  55 . Stated another way, the central recess  85  is formed in the down tube  55  such that concave section  80  defines a depression in the underside of the down tube  55 . As illustrated, the curved ridge  90  extends circumferentially around the central recess  85  to define a substantially oval-shaped depression, as best shown in  FIG. 3 . Generally, the oval shape of the illustrated depression encompasses any smoothly-rounded, closed, convex shape (e.g., an ellipse). 
     As illustrated in  FIG. 4 , the illustrated down tube  55  has an oblong or rounded trapezoidal (e.g., pentagonal) cross-sectional profile in the area between the head tube  30  and the concave section  80 . In particular, the upper side of the down tube  55  at this location is rounded and is at least partially defined by a convex radius of curvature R 1 . The underside of the down tube  55  is slightly less rounded than the upper side, which is at least partially defined by a convex radius of curvature R 2 . At the location shown in  FIG. 4 , the down tube  55  has a first height H 1  (e.g., 53 mm). 
       FIG. 5  illustrates the cross-sectional profile of the down tube  55  near a forward end of the concave section  80  (i.e., the area of the concave section  80  toward the head tube  30 ). At this location, the down tube  55  transitions from the oblong cross-sectional profile to a profile that has a rounded profile on the upper side and a substantially flat or slightly inwardly curved (i.e., concave) profile on the underside due to the central recess  85 . In  FIG. 5 , the central recess  85  and the ridge  90  cooperate to define the profile of the underside of the down tube  55 . As illustrated, at least a portion of the upper side has a convex radius of curvature R 1  at this location, at least a portion of the central recess  85  has a concave radius of curvature R 2 , and at least a portion of the laterally opposed portions of the curved ridge  90  each has a convex radius of curvature R 3 . 
       FIG. 6  illustrates that, at a longitudinal center of the concave section  80 , at least a portion of the upper side of the down tube  55  has a convex radius of curvature R 1 , at least a portion of the central recess  85  defines a concave radius of curvature R 2 , and at least a portion of the laterally opposed portions of the curved ridge  90  define convex radii of curvature R 3  such that the down tube  55  has a substantially kidney bean profile in cross-section. Stated another way, the radius of curvature R 1  is larger than the radius of curvature R 2 , and the radii of curvature R 1  and R 2  are each larger than the radii of curvature R 3 . At the location shown in  FIG. 6 , the down tube  55  has a second height H 2  (e.g., 50 mm) that is smaller than the first height H 1 . 
       FIG. 7  illustrates the cross-sectional profile of the down tube  55  near a rearward end of the concave section  80  (i.e., the area of the concave section  80  toward the bottom bracket  60  and farthest from the head tube  30 ). At this location, the down tube  55  transitions from the kidney bean profile defined by the concave section  80  ( FIG. 6 ) to an oblong cross-sectional profile that is very similar to the profile illustrated and described with regard to  FIG. 5 . As illustrated, at least a portion of the upper side has a convex radius of curvature R 1  at this location, at least a portion of the central recess  85  has a concave radius of curvature R 2 , and at least a portion of the laterally opposed portions of the curved ridge  90  each has a convex radius of curvature R 3 . 
       FIG. 8  shows that the down tube  55  has a substantially outwardly rounded or convex cross-sectional profile in the area between the concave section  80  and the bottom bracket  60 . At the location illustrated in  FIG. 8 , at least a portion of the upper side of the down tube  55  has a convex radius of curvature R 1 , and at least a portion of the underside has a convex radius of curvature R 2 . At the location shown in  FIG. 8 , the down tube  55  has a third height H 3  (e.g., 49 mm) that is smaller than the second height. 
     Table 1, produced below, sets forth the approximate dimensions and the relationship between the radii of curvature R 1 , R 2 , R 3  for the cross-sectional profile of the down tube  55  as illustrated in  FIGS. 4-8 , which correspond to locations  4 - 8 . 
     
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Location 4 
                 Location 5 
                 Location 6 
                 Location 7 
                 Location 8 
               
               
                   
                 (FIG. 4) 
                 (FIG. 5) 
                 (FIG. 6) 
                 (FIG. 7) 
                 (FIG. 8) 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 R1 
                 31 mm 
                 26 mm 
                 23 mm 
                 25 mm 
                 37 mm 
               
               
                 R2 
                 94 mm 
                 108 mm  
                 56 mm 
                 108 mm  
                 53 mm 
               
               
                 R3 
                 NA 
                 15 mm 
                 10 mm 
                 10 mm 
                 NA 
               
               
                   
               
             
          
         
       
     
     With reference to  FIG. 6 , at the longitudinal center of the concave section  80 , the radius of curvature R 2  for the curved ridge  90  is preferably between about 5 mm and 15 mm, and the width W 1  of the down tube  55  is preferably between about 30 mm and 75 mm. Generally, the radius of curvature R 2  of the curved ridge  90  at the longitudinal center is preferably between about 8 percent and 35 percent of the width W 1  of the down tube  55  to avoid relatively sharp edges on the down tube  55 . The illustrated down tube  55  at the longitudinal center has a radius of curvature R 2  of approximately 10 mm, and a width W 1  that is approximately 59 mm. As such, the illustrated radius of curvature is approximately 17 percent of the width W 1 . 
     As illustrated in  FIGS. 4-9 , the upper side surface profile of the down tube  55  has a substantially rounded profile that is maintained along the entire length of the down tube  55 . The underside of the down tube  55  transitions from the less-rounded profile between the head tube  30  and the concave section  80  to the inwardly curved or kidney bean profile defined by the central recess  85 , and then to the more-rounded profile between the concave section  80  and the bottom bracket  60 . 
     With reference to  FIGS. 1-3  and  9 , the depression defined by the central recess  85  provides an area of the down tube  55  that a user, such as a cyclocross rider, can securely and comfortably grasp. Stated another way, the profile of the down tube  55  at the concave section  80  is ergonomically designed to substantially conform to the profile of the rider&#39;s hand so that the bicycle  10  can be comfortably and stably lifted (e.g., over an obstacle, or so that the top tube  50  rests on the rider&#39;s shoulder) by the rider. In particular, the upper rounded profile of the down tube  55  conforms to the area between the rider&#39;s index finger and the thumb, whereas the central recess  85  and the ridge  90  conform to the profile of the padded side of the rider&#39;s fingers. The illustrated concave section  80  is located closer to the head tube  30  than the bottom bracket  60  (i.e., substantially forward of a longitudinal center of the down tube  55 ) so that the rider does not have to reach too far to firmly grasp the down tube  55 . 
     Various features and advantages of the invention are set forth in the following claims.