Abstract:
A handlebar/stem attachment interface with minimal frontal area comprises a handlebar body and a stem between which is disposed a threaded element to screw or unscrew the stem. By such arrangements, it is convenient for the user to replace the handlebar as desired, and the smooth even configuration of the handlebar body can further reduce the drag coefficient of the bicycle while increasing the riding rate.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a bicycle, and more particularly to a handlebar/stem attachment interface with minimal frontal area. 
         [0003]    2. Description of the Prior Art 
         [0004]    Bicycling is a popular means of recreation, fitness and competition. There are three main sources of drag which a cyclist must overcome: friction, gravity, and aerodynamic drag. Since aerodynamic drag increases with the speed of the cyclist squared, aerodynamic drag becomes an increasingly important concern at higher speeds, especially for competitive cycling. Aerodynamic drag is related to the shape of the vehicle and the frontal area. Thus, it is desirable to reduce the frontal area of the bicycle and all components to give the bicycle and rider the greatest possible aerodynamic advantage. 
         [0005]    Take the bicycle handlebar as an example, a professional bicycle racer may have to use different handlebars according to different racing rules, or may need to adjust the fit of their bicycle through the course of the racing season. More importantly, since the bicycle handlebar is the upfront component of a bicycle, the configuration of the bicycle handlebar will largely affect the drag of the bicycle. As shown in  FIG. 10 , a conventional stem  80  for a bicycle handlebar is functionally designed without consideration of the aerodynamic drag, so that it might produce a larger aerodynamic drag during the riding process, seriously affecting the professional bicycle racer. 
         [0006]    In view of these considerations, the inventor of the present invention has developed a handlebar/stem attachment interface with minimal frontal area which facilitates the replacement of the handlebar and reduces the drag coefficient of the bicycle. 
       SUMMARY OF THE INVENTION 
       [0007]    The primary objective of the present invention is to provide a handlebar/stem attachment interface with minimal frontal area which facilitates the replacement of the handlebar body and reduces the drag coefficient of the bicycle. 
         [0008]    To achieve the above objective, a handlebar/stem attachment interface with minimal frontal area in accordance with the present invention comprises a handlebar body, a threaded element and a stem. 
         [0009]    The handlebar body includes a central portion and two arms, the two arms have first ends thereof connected at both sides of the central portion, each of the two arms is connected to an extension extending forwards adjacent to the central portion. The central portion is formed with an assembling hole and tapered. 
         [0010]    The threaded element includes a keyed hole and is further formed with external threads on an outer surface of a first end thereof. The threaded element is inserted in the assembling hole of the handlebar body, and the first end of the threaded element is located in a direction opposite a tapered direction of the central portion. 
         [0011]    The stem includes a screwing end and a connecting end. The screwing end includes an inner threaded hole. The connecting end includes a through hole for engagement with a steerer tube of a front fork. The stem further includes an operating through hole penetrating the screwing end. The stem is screwed on the threaded element by inserting the screwing end in the assembling hole of the handlebar body. 
         [0012]    With a single threaded element between the stem and the handlebar body, the user can easily replace the handlebar body, thus achieving the objective of facilitating replacement of the handlebar body, and further, the integrated streamlined appearance of the handlebar body reduces the drag coefficient of the bicycle. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is an exploded view of a handlebar/stem attachment interface with minimal frontal area in accordance with a first embodiment of the present invention; 
           [0014]      FIG. 2  is an assembly view of the handlebar/stem attachment interface with minimal frontal area in accordance with the first embodiment of the present invention; 
           [0015]      FIG. 3  is a cross-sectional view of the handlebar/stem attachment interface with minimal frontal area in accordance with the first embodiment of the present invention; 
           [0016]      FIG. 4  is an operational cross-sectional view of the handlebar/stem attachment interface with minimal frontal area in accordance with the first embodiment of the present invention; 
           [0017]      FIG. 5  is a perspective view showing that the handlebar/stem attachment interface with minimal frontal area in accordance with the present invention is installed on a bicycle; 
           [0018]      FIG. 6  is an exploded view of a handlebar/stem attachment interface with minimal frontal area in accordance with a second embodiment of the present invention; 
           [0019]      FIG. 7  is an assembly view of the handlebar/stem attachment interface with minimal frontal area of  FIG. 6  in accordance with the present invention; 
           [0020]      FIG. 8  is a cross-sectional view of the handlebar/stem attachment interface with minimal frontal area of  FIG. 6  in accordance with the present invention; 
           [0021]      FIG. 9  is an operational cross-sectional view of the handlebar/stem attachment interface with minimal frontal area of  FIG. 6  in accordance with the present invention; and 
           [0022]      FIG. 10  is a perspective view of a conventional stem for a bicycle handlebar. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0023]    The present invention will be clearer from the following description when viewed together with the accompanying drawings, which show, for purpose of illustrations only, the preferred embodiment in accordance with the present invention. 
         [0024]    Referring to  FIGS. 1-5 , a handlebar/stem attachment interface with minimal frontal area in accordance with a first embodiment of the present invention comprises a handlebar body  10 , an insert  20 ′, a stem  70 , and a threaded element  30 ′. 
         [0025]    The handlebar body  10  includes a central portion  11 ′ and two arms  12 . The two arms  12  have first ends connected at both sides of the central portion  11 ′. Two brake levers  121  are provided at two second ends of the two arms  12 , respectively. Each of the two arms  12  is connected to an extension  13  extending forwards adjacent to the central portion  11 ′, and each of the two arms  12  is further provided with an abutting seat  14  in alignment with the extension  13 . The central portion  11 ′ is formed with an assembling hole  111 ′ penetrating the handlebar body  10  along an extending direction of the extensions  13 . The assembling hole  111 ′ includes a second opening  113  open in a direction opposite the extending direction of the extensions  13 . The handlebar body  10  is made of carbon fiber, and the central portion  11 ′ is tapered toward the extensions  13 . 
         [0026]    The insert  20 ′ is hollow and shaped correspondingly to the assembling hole  111 ′. The insert  20 ′ includes a first opening  21  and a second opening  22  in both ends thereof. The insert  20 ′ is further formed on an inner surface thereof with an abutting flange  23  between the first opening  21  and a second opening  22 . The insert  20 ′ is inserted in the assembling hole  111 ′ of the central portion  11 ′ of the handlebar body  10  in such a manner that the second opening  22  of the insert  20 ′ is in communication with the second opening  113  of the central portion  11 ′. The insert  20  is made of aluminum. The insert  20 ′ is formed with an inner threaded hole  24 ′ extending from the abutting flange  23  toward a direction opposite the second opening  22 . 
         [0027]    The stem  70  includes a screwing end  71  and a connecting end  72  that are arranged in a stepped manner. Between the screwing end  71  and the connecting end  72  is formed an end surface  73 . The screwing end  71  is in the form of a rectangular cylinder and includes an inner threaded hole  711 . The connecting end  72  includes a through hole  721  for engagement with a steerer tube of a front fork. The stem  70  further includes an operating through hole  74  penetrating the screwing end  71 . The stem  70  is inserted in the insert  20  in the assembling hole  111 ′ of the handlebar body  10  by inserting the screwing end  71  from the second opening  22  of the insert  20 . 
         [0028]    The threaded element  30 ′ includes a keyed hole  31  allowing the engagement of a wrench. The threaded element  30 ′ is further formed with external threads  32  on an outer surface thereof. The threaded element  30 ′ consists of a first segment and a second segment that are connected to each other, and an outer diameter of the first segment is bigger than that of the second segment. The first and the second segments of the threaded element  30 ′ include a first outer threaded portion  321 ′ and a second outer threaded portion  322 ′, respectively. The first outer threaded portion  321 ′ and the second outer threaded portion  322 ′ of the threaded element  30 ′ are screwed with the inner threaded hole  711  of the stem  70  and the inner threaded hole  24 ′ of the insert  20 , respectively. A thread pitch of the first outer threaded portion  321 ′ is greater than that of the second outer threaded portion  322 ′. The threaded element  30 ′ is inserted through the second opening  22  of the insert  20 ′ from the operating hole  74  of the stem  7  in such a manner that the second threaded portion  322 ′ is screwed in the inner threaded hole  24 ′ of the insert  20 ′ while the first outer threaded portion  321 ′ is screwed in the inner treaded hole  711  of the stem  70 . 
         [0029]    The aforementioned is the summary of the positional and structural relationship of the respective components of the first embodiment in accordance with the present invention. 
         [0030]    As shown in  FIG. 5 , the stem  70  is bonded to the steerer tube X 1  of the front fork of the bicycle X. When in use, since the threaded element  30 ′ consists of the first segment and the second segment which include the first outer threaded portion  321 ′ and the second outer threaded portion  322 ′, respectively, and the first outer threaded portion  321 ′ and the second outer threaded portion  322 ′ are allowed to be screwed with the inner threaded hole  711  of the stem  70  and the inner threaded hole  24 ′ of the insert  20 ′, when being rotated, the threaded element  30 ′ will be screwed with both the stem  70  and the insert  20 ′, improving the convenience in operation. 
         [0031]    Referring to  FIGS. 6-9 , a handlebar/stem attachment interface in accordance with a second embodiment of the present invention comprises a handlebar body  10 , an insert  20 , a threaded element  30 , a first extracting cap  40 , a second extracting cap  50 , a plug  60 , and a stem  70 . 
         [0032]    The handlebar body  10  includes a central portion  11  and two arms  12 . The two arms  12  have first ends connected at both sides of the central portion  11 . Two brake levers  121  are provided at two second ends of the two arms  12 , respectively. Each of the two arms  12  is connected to an extension  13  extending forwards adjacent to the central portion  11 , and each of the two arms  12  is further provided with an abutting seat  14  in alignment with the extension  13 . The central portion  11  is formed with an assembling hole  111  penetrating the handlebar body  10  along an extending direction of the extensions  13 . The assembling hole  111  includes a first opening  112  open in the extending direction of the extensions  13 , and a second opening  113  open in a direction opposite the extending direction of the extensions  13 . The handlebar body  10  is made of carbon fiber, and the central portion  11  is tapered toward the extensions  13 . 
         [0033]    The insert  20  is hollow and shaped correspondingly to the assembling hole  111 . The insert  20  includes a first opening  21  and a second opening  22  in both ends thereof. The insert  20  is further formed on an inner surface thereof with an abutting flange  23  between the first opening  21  and a second opening  22 . The insert  20  is inserted in the assembling hole  111  of the central portion  11  of the handlebar body  10  in such a manner that the first opening  21  of the insert  20  is in communication with the first opening  112  of the central portion  11  while the second opening  22  of the insert  20  is in communication with the second opening  113  of the central portion  11 . The insert  20  is made of aluminum. 
         [0034]    The threaded element  30  includes a keyed hole  31  allowing the engagement of a wrench. The threaded element  30  is further formed with external threads  32  on an outer surface of a first end thereof, and a second end of the threaded element  30  is formed with an outwards-extended flange  33 . The threaded element  30  is inserted into the insert  20  in the assembling hole  111  of the handlebar body  10  from the first opening  112  of the central portion  11  in such a manner that the first end of the threaded element  30  is located in a direction opposite the extending direction of the extensions  13 , and the second end of the threaded element  30  is located in the extending direction of the extensions  13 . The flange  33  of the threaded element  30  abuts against the abutting flange  23  of the insert  20 . 
         [0035]    The first extracting cap  40  is disposed in the insert  20  from the first openings  112 ,  21  of the handlebar body  10  and the insert  20  and abuts against the flange  33  of the threaded element  30 . 
         [0036]    The second extracting cap  50  includes a receiving groove  51  in one side thereof. The second extracting cap  50  is disposed in the insert  20  from the first openings  112 ,  21  of the handlebar body  10  and the insert  20  in such a manner that the first extracting cap  40  and the flange  33  of the threaded element  30  are received in the receiving groove  51  of the second extracting cap  50 . 
         [0037]    The plug  60  includes an inserting end  61  and a decorating end  62 . The inserting end  61  of the plug  60  is inserted into the insert  20  from the first openings  112 ,  21  of the handlebar body  10  and the insert  20  and abuts against the second extracting cap  50  while the decorating end  62  covers the first opening  112  of the central portion  11  of the handlebar body  10 . The decorating end  62  is tapered in a direction opposite the central portion  11  and shaped correspondingly to the central portion  11  of the handlebar body  10 . 
         [0038]    The stem  70  includes a screwing end  71  and a connecting end  72  that are arranged in a stepped manner. Between the screwing end  71  and the connecting end  72  is formed an end surface  73 . The screwing end  71  is in the form of a rectangular cylinder and includes an inner threaded hole  711 . The connecting end  72  includes a through hole  721  for engagement with a steerer tube of a front fork. The stem  70  further includes an operating through hole  74  penetrating the screwing end  71 . The stem  70  is screwed on the threaded element  30  by inserting the screwing end  71  into the insert  20  in the assembling hole  111  of the handlebar body  10  from the second opening  22  of the insert  20  in the handlebar body  10  and then rotating the threaded element  30 . 
         [0039]    The aforementioned is the summary of the positional and structural relationship of the respective components of the second embodiment in accordance with the present invention. 
         [0040]    As shown in  FIG. 5 , the stem  70  is bonded to the steerer tube X 1  of the front fork of the bicycle X. To assemble the handlebar body  10 , the stem  70  is inserted into the insert  20  first, as shown in  FIG. 9 , and then the plug  60  is pulled away to open the first opening  112  of the handlebar body  10 , so that the user can insert an operating tool A through the second extracting cap  50 , the first extracting cap  40  and the threaded element  30  and into the insert  20  in the assembling hole  111 . Then the user can fix the stem  70  to the handlebar body  10  by rotating the threaded element  30  with the operating tool A. And vice versa, rotating the threaded element  30  can also disassemble the stem  70  from the handlebar body  10  easily. To change the distance between the handlebar body and the rider, the stem  70  will be disassembled from the handlebar body  10  in the same method and replaced with a stem  70  having a different length. 
         [0041]    Furthermore, after assembly, since the central portion  11  of the handlebar body  10  is sealed by the plug  60 , which makes the handlebar body  10  tapered and streamlined, thus reducing the drag coefficient of the bicycle. 
         [0042]    While we have shown and described various embodiments in accordance with the present invention, it is clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.