Patent Publication Number: US-2003221509-A1

Title: Handlebar stem

Description:
FIELD OF THE INVENTION  
       [0001] The present invention relates to a handlebar stem for mountain bike and a plurality of concavities defined in an outer surface of the handlebar stem so that the user may observe tiny cracks before the handlebar stem is severely damaged.  
       BACKGROUND OF THE INVENTION  
       [0002] A conventional handlebar stem for mountain bikes or heavy-duty bikes is required to have better structural strength so that the modern handlebar stem for mountain bikes is made to have larger diameter and thicker wall. In order to reduce the total weight of the whole bicycle, the handlebar stem is usually made of Aluminum and has one end thereof fixed to the steerer tube extending from the head tube and the other end of the handlebar stem is connected with the cross bar of the handlebar. For mountain bikes, they are operated to jump up and down on the serrated road and the handlebar stem is applied by a large and sudden stress. It is dangerous if the handlebar stem is broken during operation of the mountain bike. The possible damage could happen at the position where the cross bar of the handlebar and the stem, and/or the position where the steerer tube and the handlebar stem. This damage can hardly be seen because it starts with tiny cracks and could be covered by the coating on the handlebar stem.  
       SUMMARY OF THE INVENTION  
       [0003] In accordance with one aspect of the present invention, there is provided a handlebar stem which comprises a main passage defined therethrough and a first end piece is connected to a first end of the body and a second end piece is connected to the first end piece. A first passage is defined between the first end piece and the second end piece so as to receive a handlebar. Two lugs extend from a second end of the body and a second passage is defined between the two lugs so as to receive a steerer tube therethrough. A plurality of concavities are defined in an outer surface of each of the two lugs.  
       [0004] The primary object of the present invention is to provide a handlebar stem that has concavities in the outer surface and the cracks will be happened at the positions of the concavities because the positions are the weak portion of the handlebar stem.  
       [0005] 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  
     [0006]FIG. 1 is an exploded view to show the handlebar stem of the present invention;  
     [0007]FIG. 2 is a perspective view to show the handlebar stem of the present invention;  
     [0008]FIG. 3 is a cross sectional view to show the handlebar stem of the present invention, and  
     [0009]FIG. 4 shows the steerer tube and the handlebar are respectively connected to two ends of the handlebar stem of the present invention.  
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0010] Referring to FIGS.  1  to  3 , the handlebar stem  10  of the present invention is an elongated body  10  having a main passage  100  defined therethrough. A first end piece  21  is connected to a first end of the body  10  and a second end piece  20  is connected to the first end piece  21  by four bolts extending through four corners of the second end piece  20  and threadedly engaged with the first end piece  21 . A first passage  11  is defined between the first end piece  21  and the second end piece  20  so as to receive a handlebar  30  as shown in FIG. 4.  
     [0011] Two lugs  12  extend from a second end of the body  10  and each lug  12  has a concave inner surface so as to define a second passage  13  between the two lugs  12 . A steerer tube  40  extending through the head tube (not shown) is securely mounted by the two lugs  12  and extends through the second passage  13 . A plurality of concavities  14  are defined in an outer surface of each of the two lugs  12  so as to form a fatigue detection area at each of the two lugs  12 . The concavities  14  are located at radial and longitudinal positions corresponding to the main passage  100 . The concavities  14  are located radially corresponding to the main passage and majority of the concavities  14  are located at the longitudinal positions. The concavities  14  extend inward the body  10  and form a fatigue detection area.  
     [0012] A plurality of first grooves  15  are defined in a conjunction portion between the inner periphery of the main passage  100  and an opening in the first end piece  21 . The first grooves  15  are located in an inner periphery of the main passage  100  and extend longitudinally toward the second end of the body  10 .  
     [0013] A plurality of second grooves  150  are defined in a conjunction portion between the inner periphery of the main passage  100  and an opening in the second end of the body  10 . The second grooves  150  are located in an inner periphery of the second passage  13  and in a form of a circular groove.  
     [0014] The areas that the first grooves  15  and the second grooves  150  are located also form two fatigue detection areas where cracks could be happened at the fatigue detection areas and can be seen easily.  
     [0015] The fatigue detection areas of the handlebar stem  10  of the present invention provide an early-warning convenience and the cracks can be seen in the fatigue detection areas so that the riders may replace the handlebar stem  10  before it is severely damaged.  
     [0016] 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.