Patent Publication Number: US-2011072635-A1

Title: Bicycle handlebar stem securing device and method for securing bicycle handlebar stem to steering tube

Description:
FIELD OF THE INVENTION 
     The present invention relates to a securing method and a securing device for securing the handlebar stem to a non-thread steering tube. 
     BACKGROUND OF THE INVENTION 
     A conventional steering system for bicycles generally includes the steering tube, the hub and the wheel, and a handlebar connected to the top end of the steering tube, a handlebar stem, and two bearing sets located on two ends of the head tube of the bicycle. The steering tube extends through the head tube and the two bearing sets located between the steering tube and the head tube so that when turning the handlebar, the wheel and the steering tube turn while the bicycle frame is maintained forward. 
     The two bearing sets have their inner periphery contacting the steering tube and their outer periphery contacting the inner periphery of the head tube such that the steering tube is rotatable relative to the head tube. The two bearing sets have to be securely mounted to the two ends of the head tube by the handlebar. 
     A securing device is needed to provide a downward force to the handlebar stem which presses the bearing sets to set the whole assembly. For the non-thread steering tube, there are two securing devices to secure the steering tube and the handlebar stem. One of which includes expandable plates which are expanded outward to contact against the inner periphery of the steering tube and the other of the securing device includes an expandable frame. Both of the two securing devices are cooperated with a bolt which is rotated to expand the expandable plates and the expandable frame. 
     The first securing device is located in the top of the steering tube and includes a bolt which extends through the expandable plates and a head of the bolt protrudes out from the steering tube and presses on the handlebar stem so as to position the handlebars stem between the bearing sets and the securing device. 
     The second securing device includes a positioning frame, an urging member and a cap, wherein the positioning frame is a tubular member with a passage and grooves are defined in the outer surface of the positioning frame. The urging member is cooperated with the passage and includes tapered outer surface. The urging member is located in the passage of the positioning frame and has a threaded hole. The cap has a threaded rod which is threadedly connected with the threaded hole of the urging member. The cap includes a driving hole for being connected with a tool. 
     The two securing devices have to be put in the steering tube by special tools and then the threaded rod is then connected to the expandable plates or expandable frame. By rotating the threaded rod, the cap applies a downward force to position the bearing sets. 
     It is noted that the securing device is left within the steering tube after the handlebar stem is connected to the steering tube. It is difficult to remove the securing device from the steering tube so that the manufacturers generally leave the securing device in the steering tube. A cover is used to close the opening of the steering tube. The securing device left in the steering tube does not have any function and may affect the disengagement of the related parts when maintaining the steering system. Besides, the securing device needs multiple installation steps and requires higher level of precision so that the securing device increases the manufacturing cost. The securing device left in the steering tube also increases the weight of the bicycle and this does not meet the requirement of the market. 
     The present invention intends to provide a method for securing the handlebar stem to the steering tube and the securing device for doing the same. The securing device can be easily removed from the steering tube after the steering system is assembled. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a method for securing handlebar stem to steering tube and the method includes a step of placing a head tube, an upper bearing set and a stem tube on a top of a steering tube, and an underside of the stem tube being in contact with the upper bearing set; a step of using a securing device having an expandable portion inserted into the steering tube and applying a downward force to a top of the stem tube; a step of rotating the securing device to urge the expandable portion against an inner periphery of the steering tube and the downward force pressing the stem tube onto the upper bearing set, and a step of releasing the expandable portion and removing the securing device from the steering tube. The securing device can be used repeatedly and reduces the bicycle weight. 
     The primary object of the present invention is to provide a method for securing the handlebar stem to the steering tube, and the securing device can be removed from the steering tube after the steering system is completely assembled. There will be no part left in the steering tube. 
     Another object of the present invention is to provide a method for securing the handlebar stem to the steering tube, wherein the securing device can be used repeatedly and reduces the bicycle weight. 
     Yet another object of the present invention is to provide a method for securing the handlebar stem to the steering tube, wherein the securing device is not left in the steering tube so as to simplify maintenance steps for the steering system. 
     The present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, a preferred embodiment in accordance with the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows the steps of the method of the present invention; 
         FIG. 2  is a perspective view to show the steering system of a bicycle assembled by the method of the present invention; 
         FIG. 3  is an exploded view to show the securing device of the present invention; 
         FIG. 4  is a cross sectional view of the securing device of the present invention located in the steering tube; 
         FIG. 5  is a cross sectional view to show that the securing device of the present invention is removed from the steering tube; 
         FIG. 6  is a cross sectional view to show that a tool is used to rotate the driving member to expand the expandable member in the steering tube; 
         FIG. 7  is a cross sectional view to show that a pressing unit is pressed on the stem tube; 
         FIG. 8  is a cross sectional view to show that the pressing member presses onto the stem tube; 
         FIG. 9  shows that a bolt is used to fasten the two lugs on the stem tube; 
         FIG. 10  shows that the pressing member is first removed from the steering tube; 
         FIG. 11  shows that a tool is used to rotate and loosen the driving member and the wedge-shaped member moves downward and a gap is formed between the driving member and the steering tube; 
         FIG. 12  shows that the securing device is removed from the steering tube; 
         FIG. 13  is a perspective view to show a second embodiment of the steering system of a bicycle assembled by the method of the present invention; 
         FIG. 14  is an exploded view to show the securing device of the second embodiment of the present invention; 
         FIG. 15  is a cross sectional view of the securing device of the second embodiment of the present invention located in the steering tube; 
         FIG. 16  is a cross sectional view to show that the driving rod of the securing device of the present invention is rotated to move the upper and bottom wedges; 
         FIG. 17  is a cross sectional view to show that the upper and bottom wedges of the second embodiment of the present invention contact the steering tube and the lever is then pivoted to lock the status; 
         FIG. 18  is a cross sectional view to show that the lever is pivoted in order to loosen the securing device of the second embodiment of the present invention; 
         FIG. 19  is a cross sectional view to show that the lever is rotated to loosen the securing device of the second embodiment of the present invention, and 
         FIG. 20  shows that the securing device of the second embodiment of the present invention is removed from the steering tube and a cap seals the opening of the steering tube. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIGS. 1 to 4 , the method for securing handlebar stem to steering tube comprises the following steps: 
     step (a): placing a head tube  71 , an upper bearing set  72  and a stem tube  73  on a top of a steering tube  74 , an underside of the stem tube  73  being in contact with the upper bearing set  71 ; 
     step (b): using a securing device  10  having an expandable portion inserted into the steering tube  74  and applying a downward force to a top of the stem tube  73 ; 
     step (c): rotating the securing device  10  to urge the expandable portion against an inner periphery of the steering tube  74  and the downward force pressing the stem tube  74  onto the upper bearing set  72 , and 
     step (d): releasing the expandable portion and removing the securing device  10  from the steering tube  74 . 
     The method is completely proceeded by using the securing device  10  which includes an expandable unit  20  and a pressing unit  30 . 
     The expandable unit  20  has an expandable member  21  and the pressing unit  30  activates the expandable member  21  to expand and contact the inner periphery of the steering tube  74 . The expandable member  21  is a tubular member and includes a first upper tapered surface  211  and a first bottom tapered surface  212  on two ends thereof. A driving member  22  extends through the expandable member  21  and includes a second upper tapered surface  221  which is engaged with the first upper tapered surface  211  of the expandable member  21 . A wedge-shaped member  23  is located beneath the driving member  22  and able to linearly move when the driving member  22  rotates. The wedge-shaped member  23  includes a second bottom tapered surface  231  which is engaged with the first bottom tapered surface  212 . The driving member  22  includes a pressing surface  222  which contacts the top of the steering tube  74 . 
     The pressing unit  30  applies a force to press the top of the stem tube  73  which is moved and presses onto the upper bearing set  72 . The pressing unit  30  includes a pressing member  31  which contacts the top of the stem tube  73  and the pressing member  31  further includes a driving rod  32  which is inserted into the driving member  22 . 
     When assembling, the driving member  22  is inserted into the driving member  21  and is threadedly connected with the wedge-shaped member  23 . The first upper tapered surface  211  and the first bottom tapered surface  212  are respectively engaged with the second upper tapered surface  221  and the second bottom tapered surface  231 . The pressing member  31  has its driving rod  32  to be inserted in the driving member  22  to set the assembly. 
     As shown in  FIG. 5 , in step (a), the head tube  71 , the upper bearing set  72 , the stem tube  73  and the steering tube  74  are arranged in sequence, but are not securely connected to each other. The top of the stem tube  73  protrudes above the steering tube  74 . 
     As shown in  FIG. 6 , in step (b), the expandable portion of the securing device  10  is inserted into the steering tube  74  and the pressing surface  222  of the driving member  22  contacts the top of the steering tube  74 , and a gap is defined between the expandable member  21  and the inner periphery of the steering tube  74 . 
     In step (c), the securing device  10  is rotated to drive the wedge-shaped member  23  to move linearly and upward to allow the second bottom tapered surface  231  contact the first upper tapered surface  211 . The outer surface of the expandable member  21  is in contact with the inner periphery of the steering tube  74  to set the expandable unit  20  in position. As shown in  FIG. 7 , the driving rod  32  of the pressing member  31  is then inserted into the driving member  22 . 
     As shown in  FIG. 8 , a downward force is applied to the pressing member  31  to move the stem tube  73  downward and push the upper bearing  72  to a secured status. The top of the steering tube  74  now is located above the stem tube  73 . As shown in  FIG. 9 , a bolt  75  is used to fasten the two lugs on the stem tube in radial direction to securely mount the stem tube  73  onto the steering tube  74 . 
     Referring to  FIGS. 10 and 11 , in step (d), the pressing member  31  is first removed from the steering tube  74  and driving member  22  is rotated to drive the wedge-shaped member  23  to move linearly and downward, a gap is defined between the second bottom tapered surface  231  and the first bottom tapered surface  212 , so that the expandable portion can be moved downward and the expandable member  21  is loosened relative to the steering tube  74 . The whole expandable unit  20  can be removed from the steering tube  74  and the stem tube  73 , the upper bearing  72 , the head tube  71  and the steering tube  74  are securely assembled together as shown in  FIG. 12 . 
     The present invention provides the method which does not leave the securing device  10  in the steering tube  74  so that when the steering system is assembled, no part is left in the steering tube  74 . 
     The securing device  10  can be repeatedly used and is easily manufactured. The assembling steps are simplified and can be completed within short period of time. The steering system of the bicycle is light in weight because the no part is left in the steering tube  74 . 
     The stem tube  73  is secured by the bolt  75  and the secured stem tube  73  ensures that the upper bearing  72 , the head tube  71  and the steering tube  74  are well positioned. When maintaining the steering system, simply loosening the bolt  75  and because the securing device  10  is not left in the steering tube  74 , the maintaining processes will be easy and simplified. 
       FIGS. 13 to 20  disclose a second embodiment of the present invention, wherein the expandable member  21  includes an upper wedge  24  and a lower wedge  25 . The upper wedge  24  includes a third upper tapered surface  241  and the lower wedge  25  includes a third bottom tapered surface  251  which slidably contacts the third upper tapered surface  241 . A driving member  26  is inserted into the expandable member  21  and includes a pressing surface  261  which contacts the top of the steering tube  74 . A nut  27  is located beneath the lower wedge  25 . 
     The pressing unit  30  includes a pressing member  31  which contacts the top of the stem tube  73 . The pressing member  31  includes a driving rod  32  which has a first end extending through the driving member  22  and is threadedly connected with the nut  27  and a second end of the driving rod  32  is pivotably connected with a lever  33 . The lever  33  includes a cap portion  331  which presses the pressing member  31  to move the driving rod  32  linearly. 
     As shown in  FIG. 16 , after the step (a) is completed, in the step (b), the expandable unit  20  is inserted into the steering tube  74  and the pressing surface  261  contacts the top of the steering tube  74 . 
     In step (c), the driving member  26  is rotated and the lower wedge  25  slides along the third bottom tapered surface  251  and pushes the upper wedge  24  until the upper and lower wedges  24 ,  25  contact the inner periphery of the steering tube  74 . As shown in  FIGS. 17 and 18 , the pressing member  31  and the driving rod  32  are pressed downward until the bottom of the pressing member  31  presses on the top of the stem tube  31 . The lever  33  is pivoted upward and the cam portion  331  is rotated to push the stem tube  73  downward to secure the upper bearing  72 . 
     As shown in  FIG. 19 , in step (d), the lever  33  and the pressing member  31  are moved upward and then rotate the driving member  26  in opposite direction, the lower wedge  25  is moved downward and disengaged form the upper wedge  24 . Two respective gaps are defined between the upper and lower wedges  24 ,  25  and the inner periphery of the steering tube  74 . The securing device  10  is then able to be removed from the steering tube  74 , and the stem tube  73 , the upper bearing  72 , the head tube  71  and the steering tube  74  are securely assembled as shown in  FIG. 20 . 
     A cap  76  is used to seal the opening in the top of the steering  74  to prevent dust or rain from entering the steering tube  74 . 
     While we have shown and described the embodiment in accordance with the present invention, it should be clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.