Abstract:
A bicycle speed control apparatus is provided with a pair of shifting levers to easily control a gear transmission mechanism via a drive cable. The bicycle speed control apparatus comprises a first seat connected to a bicycle handlebar and a second seat having a shaft used to connect to the first seat. A cylindrical sleeve member is used to connect to the drive cable and provided with first teeth, second teeth and third teeth in parallel. A first shifting lever and a second shifting lever are provided to pivot on the shaft so as to respectively shift a front and rear speed shifter. A first pawl and a second pawl are provided to movably mount on the first shifting lever and the second shifting lever, respectively. A resilient member is used to position on the shaft so as to engage the third teeth and disengage the first pawl from the first teeth and disengage the second pawl from the second teeth. The resilient member is formed with a first protrusion for pressing the first pawl to disengage from the first teeth and a second protrusion for pressing the second pawl to disengage from the second teeth and a third protrusion for engaging the third teeth. A regulator is connected to and adjusts the tension of the drive cable.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    This invention relates to a bicycle speed control apparatus. More particularly, this invention relates to a bicycle speed control apparatus provided with a pair of shifting levers to control a gear transmission mechanism via a drive cable.  
           [0003]    2. Description of Prior Art  
           [0004]    U.S. Pat. No. 5,287,766 is disclosed with a speed control apparatus that is provided with a shift lever attached to the handlebar of a bicycle so as to control a derailleur (not shown). It is quite simple to produce the shift lever and assemble it with other elements. Because the shifter is positioned by frictional force, the shifter is easily disengaged and the chain cannot be appropriately positioned when the bicycle passes over an uneven road. Thus, the rider often feels discomfort on his/her palm because of the excessive shifting range generated by the single shift lever during the shifting process.  
           [0005]    In U.S. Pat. No. 5,438,889, the driving force acted on the lever portion of the shifter has to be generated by the external pulley assembly (cable winding reel ( 16 ), drive reel portion ( 16 ) and the drive cable (K)), and therefore the driving force cannot be precisely controlled and the shifter cannot be properly positioned at a predetermined site when it is pushed outside the range.  
           [0006]    In Taiwan Patent No. 276229 discloses two complicate mechanisms, each connected to the shifter and used to determine the movement of the shifter. Because the assembled mechanisms can be provided with larger driving force, the cable connected between the shifter and the two complicate mechanisms gradually extends over time. Then, the tract of the shift gradually becomes insufficient and the shifting process may be interrupted unexpectedly.  
         SUMMARY OF THE INVENTION  
         [0007]    To solve the above problem, the primary object of this invention is to provide a bicycle speed control apparatus so as to shift precisely a gearbox or a gear transmission mechanism of a bicycle through a drive cable. The bicycle speed control apparatus of the present invention comprises a first seat connected to a bicycle handlebar, and a second seat provided with a shaft connected to the first seat so as to construct the main structure thereof. A cylindrical sleeve member is movably disposed about the shaft and connected to the end of a drive cable. The cylindrical sleeve member has an inner wall provided with first teeth, second teeth and third teeth, the third teeth located between the first teeth and the second teeth in parallel. A first shifting lever and a second shifting lever for respectively shifting a front and rear speed shifter of the gear transmission mechanism, are provided to pivot on the shaft, each of which having a hole used for receiving the shaft. A first pawl and a second pawl are provided to movably mount on the first shifting lever and the second shifting lever, respectively. The first pawl is formed with a first thrust end so as to engage the first teeth, and the second pawl is formed with a second thrust end so as to engage the second teeth. A resilient member positioned on the shaft so as to engage the third teeth and disengage the first pawl from the first teeth and disengaging the second pawl from the second teeth. The resilient member has a first protrusion for pressing the first pawl to disengage from the first teeth and a second protrusion for pressing the second pawl to disengage from the second teeth and a third protrusion for engaging the third teeth. A regulator is connected to and adjusts the tension of the drive cable. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    The present invention can be more fully understood by reading the subsequent detailed description and examples with reference made to accompanying drawings in which:  
         [0009]    [0009]FIG. 1A is a perspective view showing the assembly of a bicycle speed control apparatus (G) according to a first embodiment of the present invention, which is mounted on a bicycle handlebar (B) and used to control a gear transmission mechanism (GB) through a drive cable (W);  
         [0010]    [0010]FIG. 1B is an exploded perspective view of FIG. 1A;  
         [0011]    [0011]FIG. 1C is another perspective view with a different visual angle of FIG. 1B, for clearly seeing the structure of a first seat ( 10 ) and a second seat ( 14 );  
         [0012]    [0012]FIG. 2A is an enlarged perspective view of the first seat ( 10 ) of FIG. 1C;  
         [0013]    [0013]FIG. 2B is an enlarged perspective view of the second seat ( 14 ) of FIG. 1C;  
         [0014]    [0014]FIG. 3A is a perspective view of the first seat ( 10 ) with a different visual angle according to FIG. 2A;  
         [0015]    [0015]FIG. 3B is a perspective view of the second seat ( 10 ) with a different visual angle according to FIG. 2B;  
         [0016]    [0016]FIG. 4 is a perspective view showing the geometric relationship between the second seat ( 14 ) and the drive cable (W) which is control by a regulator ( 15 );  
         [0017]    [0017]FIG. 5 is an enlarged perspective view showing elements located in a dotted line (Z 1 ) with a different visual angle of FIG. 1C;  
         [0018]    [0018]FIG. 6A is an exploded perspective view showing all the element of a bicycle speed control apparatus (G′) according to a second embodiment of the present invention;  
         [0019]    [0019]FIG. 6B is an enlarged perspective view of elements in a dotted line (Z 2 ) of FIG. 6A;  
         [0020]    [0020]FIG. 6C is a perspective view with a different visual angle according to FIG. 6B;  
         [0021]    [0021]FIG. 7A is an exploded perspective view of all the elements of a bicycle speed control apparatus (G″) according to a third embodiment of the present invention;  
         [0022]    [0022]FIG. 7B is an enlarged perspective view of elements in a dotted line (Z 3 ) of FIG. 7A; and  
         [0023]    [0023]FIG. 7C is a perspective view with a different visual angle according to FIG. 7B. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     First embodiment  
       [0024]    [0024]FIG. 1A is a perspective view showing the assembly of a bicycle speed control apparatus G. The speed control apparatus G is mounted on a bicycle handlebar B and used to control a gear transmission mechanism GB through a drive cable W. The main structure of the bicycle speed control G is constructed by a first seat  10  and a second seat  14 , wherein the first seat  10  is connected to the bicycle handlebar B and secured thereon by a bolt T 2 . A first shifting lever  3  wrapped with a rubber cover  3 ′ and a second shifting lever  4  wrapped with a rubber cover  4 ′ are both pivotally mounted between the first seat  10  and the second seat  14 . The first shifting lever  3  and the second shifting lever  4  are respectively used to control a front shifter (not shown) and a rear speed shifter (not shown) of the gearbox GB. Therefore, the bicyclist can use two fingers to hold onto and move the first shifting lever  3  and the second shifting lever  4  about its axis, and the degree of the shift can be clearly seen by an opening  144  which is formed on the second seat  14 .  
         [0025]    Referring also to FIG. 1B, an exploded perspective view shows the element of the speed control apparatus G of FIG. 1A. In addition to the aforementioned elements, the bicycle speed control G further comprises a cylindrical sleeve member  7 , a first pawl  5  and a second pawl  6 , a resilient member  8 , a regulator  15 , and two types of springs (denoted by symbols  11 ,  12  and symbols  16 ,  17 ). In FIG. 1C, a perspective view with a different visual angle of FIG. 1B shows more clearly about the inner structure of the first seat  10  and the second seat  14 .  
         [0026]    Referring to FIG. 2A and FIG. 2B, two enlarged perspective views show the structure of the first seat  10  with different visual angles according to FIG. 1B and FIG. 1C, respectively.  
         [0027]    As shown in FIG. 2A and FIG. 3A, the first seat  10  is composed of a disk-like connecting portion  10 - 1  and a cylindrical connecting portion  10 - 2 . The cylindrical connecting portion  10 - 2  is a clamping frame used to directly connect to the handlebar B, and the disk-like connecting portion  10 - 1  is integrally formed with the cylindrical connecting portion  10 - 2  and used to connect to the second seat  14 .  
         [0028]    The cylindrical connecting portion  10 - 2  has an inner surface  101 C 1 , an outer surface  101 C 2  and a slit  102  formed therebetween. The inner surface  101 C is a annular surface used to directly mount on the handlebar B, and a hole  104  is penetrated from the outer surface  101 C 2  to the inner surface  101 C 1 , and two holes  103 H 1  and  103 H 2  are penetrated from the outer surface  101 C 2  to the slit  102 .  
         [0029]    In FIG. 3A, the disk-like connecting portion  10 - 1  has a bottom surface  100  and an annular flange  100 C formed with a curved recess  10 G is formed on the circumferential of the bottom surface  100 . A through hole  105  is penetrated from the inner surface  101 C 1  to the bottom surface  100 , and the through hole  105  on bottom surface  100  is formed with a rectangular opening  100 H.  
         [0030]    Referring again to FIG. 1B, when the first seat  10  is properly fitted on the handlebar B, the handlebar B can be held tightly by screwing a bolt T 3  on the holes  103 H 1 ,  103 H 2  to minimize the size of the slit  102 . Further, a bolt T 2  is used to connect the first seat  10  and the handlebar B by screwing on the predetermined hole (not shown in Figs.) of the handlebar B through the hole  104  of the first seat  10 . Thus, the speed control apparatus G can be properly fixed on the handlebar B by the bolt T 2 , T 3  without movement or rotation.  
         [0031]    Referring to FIG. 2B and FIG. 3B, two enlarged perspective views show the structure of the second seat  14  with different visual angles according to FIG. 1B and FIG. 1C, respectively.  
         [0032]    In FIG. 2B, the second seat  14  comprises a cylindrical container  14 - 1  formed with a curved wall  140 C and a shaft  141  therein, and a bracket  14 - 2  extended outwardly from the curved wall  140 C. The curved wall  140 C is formed with an L-shaped slot  142  and two through holes  143 ,  144 . The shaft  141  is upwardly formed on the middle of the bottom surface  140  of the container  14 - 1 , and the curved wall  140 C is located on the circumference of the bottom surface  140  of the container  14 - 1 . The L-shaped slot  142  on the curved wall  140 C is located next to the bottom surface  140  and therefore a guiding slit  14 G is formed.  
         [0033]    The shaft  141  is a multi-step shaft used as a gyro shaft of the first shifting lever  3  and the second shifting lever  4 . From the root to the free end of the shaft  141 , the geometrical structure of the shaft  141  is defined as 1) to 7) as following. 1) a first step portion  141 P 1 ; 2) a first curved groove  141 G 1  and two positioning holes  141 H 1 ; 3) a second step portion  141 P 2  formed with a notch  141 G 0 ; 4) a third step portion  141 P 3 ; 5) a second curved groove  141 G 2  and two positioning holes  141 H 2 ; 6) a fourth step portion  141 P 4 ; 7) a rectangular end  141 P 5  formed with a threaded hole  141 H 3 . Owing to the visual angle, only one hole  141 H 1  and one hole  141 H 2  are shown in FIG. 2B.  
         [0034]    Referring to FIG. 4, a perspective view shows the geometric relationship between the second seat  14 , the regulator and the drive cable W.  
         [0035]    The bracket  14 - 2  is formed with a channel  145  for the installation of the regulator  15 . The regulator  15  has a threaded element  15 - 1  and a cylindrical sleeve  15 - 2  formed with a hole  150 . The threaded element  15 - 1  is installed in the through channel  145  and used to control the tension of the drive cable W, and the hole  150  of the cylindrical sleeve  15 - 2  is used to mount on the threaded element  15 - 1 . The drive cable W passes through the hole  150  of the cylindrical sleeve  15 - 2 , the threaded element  15 - 1 , and the channel  145  of the second seat  14 . Finally, the free end of the drive cable W is connected to the cylindrical sleeve member  7 .  
         [0036]    Referring to FIG. 5, a perspective view shows the elements located in a dotted line Z 1  with a different visual angle of FIG. 1C.  
         [0037]    As shown in FIG. 1C, the cylindrical sleeve member  7  is used to dispose in the container  14 - 1  and rotated about the shaft  141 . The cylindrical sleeve member  7  has an inner wall  70  formed with three rows of teeth: first, second and third teeth  71 ,  72  and  73 . The first teeth  71  and the second teeth  72  are spaced each other and regularly designed at all round of the inner wall  70 , and the third teeth  73  located between the first teeth  71  and the second teeth  72  are partially designed at the inner wall  70 . An annular slot  74  is formed on the outer wall of the cylindrical sleeve member  7 , and a recess  740  and a positioning hole  741  is formed on the annular slot  74 . The drive cable W guided in the hole  150  (FIG. 4) of the cylindrical sleeve  15 - 2  is rounded on the annular slot  74 , and then the end of the drive cable W is knotted and fixed in the positioning hole  741  (not shown in Figs.). The knotted drive cable W (not shown) can be received in the recess  740  so that possible interference, such as friction, can be prevented. A series of numbers from “1” to “7” marked with numeral  75  represent the shifting degrees of the present embodiment.  
         [0038]    In FIG. 1C and FIG. 5, the resilient member  8 , preferably made of rubber or other flexible material, is a traveling compensator that is pivoted about the shaft  141  and kept in the inner space of the cylindrical sleeve member  7 . The resilient member  8  has a cylindrical body  80  formed with two through holes  80 H 1 ,  80 H 2 , which are penetrated from its bottom surface  80 S 1  to the top surface  80 S 2 . The through hole  80 H 1  is located at the middle of the cylindrical body  80 , and the through hole  80 H 2  is a curved hole located between the through hole  80 H 1  and the sidewall of the cylindrical body  80 . A first protrusion  81  and a second protrusion  82  are protruded from the bottom surface  80 S 1  and the top surface  80 S 2 , respectively. A third protrusion  83  shown in FIG. 1C is formed on the sidewall of the cylindrical body  80  nearby the curved through hole  80 H 2 . A fourth protrusion  84  shown in FIG. 5 protrudes from the bottom surface  80 S 1  and next to the through hole  80 H 1 .  
         [0039]    In FIG. 1C(FIG. 5), the first (second) shifting lever  3 ( 4 ) is composed of a base plate  31 ( 41 ) and an extension bar  32 ( 42 ). The extension bar  32 ( 42 ) can be wrapped by fitting itself in an opening  30 ′( 40 ′) of the rubber cover  3 ′( 4 ′). A post  310 ( 410 ) protrudes from the base plate  31 ( 41 ), and a through hole  311 ( 411 ) is penetrated from a first surface  310 S 1 ( 410 S 1 ) to a second surface  310 S 2 ( 410 S 2 ) of the base plate  31 ( 41 ). The sidewall of the post  310 ( 410 ) is formed with a curved recess  313 ( 413 ) and a curved slot  315 ( 415 ). In FIG. 1C, a positioning hole  316 ( 416 ) is formed on the first (second) surface  310 S 1 ( 410 S 2 ) next to the through hole  311 ( 411 ).  
         [0040]    In FIG. 1C(FIG. 5), the first (second) pawl  5 ( 6 ) is formed with an inner curved surface  50 S 1 ( 60 S 1 ) and an outer is curved surface  50 S 2 ( 60 S 2 ), and two slots  52 ( 62 ) is formed on the outer curved surface  50 S 2 ( 60 S 2 ) and formed on the inner curved surface  50 S 1 ( 60 S 1 ), respectively. The two intersections of the inner curved surface  50 S 1 ( 60 S 1 ) and the outer curved surface  50 S 2 ( 60 S 2 ) are formed with first thrust ends  53 ( 63 ) and second thrust ends  54 ( 64 ), respectively.  
         [0041]    In FIG. 1C, a first (second) spring  11 ( 12 ) is a wire spring composed of a circular wire body  110 ( 120 ) and a gap  111 ( 121 ). A third (fourth) spring  16 ( 17 ) is also made of wire spring which has a circular wire body  160 ( 170 ) and two distal ends  161 ( 171 ),  162 ( 172 ). As shown in FIG. 5, the extension direction of the distal end  171  is different from the one of the distal end  172  of the fourth spring  17 . The distal end  171  is extended toward the geometrical center of the circular wire body  170 , and the extension direction of the distal end  172  is substantially perpendicular to the one of the distal end  171 . The third spring  16  has the same structure as the fourth spring  17  but it&#39;s a small one.  
         [0042]    In FIG. 5, the second pawl  6  is mounted on the second shifting lever  4  by the second spring  12 , comprising the steps of: a) Disposing the second pawl  6  to the curved recess  413  of the second shifting lever  4  by contacting its inner curved surface  60 S 1  thereon. b) Adjusting the slot  62  of the second pawl  6  to align to the curved slot  415  of the second shifting lever  4 . c) Enlarging the gap  121  of the second spring  12  with a predetermined range to allow it slides along the slot  62  of the second pawl  6  and the curved slot  415  of the second shifting lever  4 . d) Finally, the second pawl  6  can be surely clamped on the post  410  by the second spring  12 . With the constrain of the second spring  12 , the outer curved surface  60 S 2  near the second thrust end  64  is juxtaposed to the circumferential surface is of the post  410 , and the first thrust ends  63  is partially projected from the circumferential surface of the post  410 . Relatively, the first pawl  5  also can be mounted on the first shifting lever  3  by the first spring  11  with the same way. The outer curved surface  50 S 2  near the second thrust end  54  is juxtaposed to the circumferential surface of the post  510 , and the first thrust end  53  is partially projected from the circumferential surface of the post  310 .  
         [0043]    The installation of the aforementioned elements is depicted as following steps with reference to FIG. 1C.  
         [0044]    First, the first shifting lever  3  is clamped with the first pawl  5  and the first spring  11  on the second seat  14 . The first shifting lever  3  with its through hole  311  is fitted on the first step portion  141 P 1  of the shaft  141 . The second surface  310 S 2  of the first shifting lever  3  contacts the bottom surface  140 , and the first curved groove  141 G 1  and two holes  141 H 1 (only one being shown) of the shaft  141  are just next to the first surface  310 S 1  of the first shifting lever  3 . Thus, the L-shaped slot  142  (guiding slit  14 G) as shown in FIG. 1A can use to limit the traveling of the shifting first shifting lever  3  (extension bar  32 ).  
         [0045]    Second, the first shifting lever  3  is connected to the shaft  141  by the third spring  16 . After fitting the circular wire body  160  of the third spring  16  on the shaft  141 , the third spring  16  is tensed and then properly fitted on the first curved groove  141 G 1  of the shaft  141 . One distal end  161  of the third spring  16  is positioned in the positioning hole  316  of the first shifting lever  3 , and then another distal end  162  is tensely moved and fitted in the hole  141 H 1  of the shaft  141 . Thus, the first shifting lever  3  can be tensely controlled by the third spring  16 .  
         [0046]    Third, the cylindrical sleeve member  7  is connected with the drive cable W (not shown in Figs.) in the container  14 - 1 . The cylindrical sleeve member  7  is disposed in the container  14 - 1  with its first teeth  71  engaging with the first thrust end  53  of the first pawl  5  clamped on the first shifting lever  3 .  
         [0047]    Fourth, the resilient member  8  is placed in the container  14 - 1 . The resilient member  8  with its through hole  80 H 1  is fitted on the third step portion  141 P 3  of the shaft  141 , and the fourth protrusion  84  of the resilient member  8  is positioned in the notch  141 G 0 . The first protrusion  81  of the resilient member  8  is located around the post  310  of the first shifting lever  3 , and the third protrusion  83  is engaged with the third teeth  73  of the cylindrical sleeve member  7 .  
         [0048]    Fifth, the second shifting lever  4  is clamped with the second pawl  6  and the second spring  12  on the second seat  14 . The second shifting lever  4  with its through hole  411  is fitted on the third step portion  141 P 3  of the shaft  141 . The first surface  410 S 1  (FIG. 5) of the second shifting lever  4  contacts the top surface  80 S 2  of the resilient member  8 . Then, the second thrust end  63  of the second pawl  6  clamped on the second shifting lever  4  is engaged with the second teeth  72  of the cylindrical sleeve member  7 . The second protrusion  82  of the resilient member  8  is located around the post  410  of the second shifting lever  4  as well as the clamped second pawl  6 . The second curved groove  141 G 2  and two holes  141 H 2  (only one being shown) of the shaft  141  are just next to the second surface  410 S 2  of the first shifting lever  3 .  
         [0049]    Sixth, the second shifting lever  4  is connected to the shaft  141  by the fourth spring  17 . After fitting the circular wire body  170  of the fourth spring  17  on the shaft  141 , the fourth spring  16  is tensed and then properly is fitted on the second curved groove  141 G 2  of the shaft  141 . One distal end  171  of the fourth spring  17  is positioned in the positioning hole  416  of the second shifting lever  4 , and then another distal end  172  is tensely moved and fitted in the hole  141 H 2  of the shaft  141 . Thus, the second shifting lever  4  can be tensely controlled by the fourth spring  17 .  
         [0050]    Last, the first seat  10  is connected to the second seat  14  as shown in FIG. 1A. The first seat  10  with its rectangular opening  100 H is fitted on the rectangular end  141 P 5  of the shaft  141 , and the annular flange  100 C of the disk-like connecting portion  10 - 1  is disposed on the top end of the curved wall  140 C of the second seat  14 . Then, the first seat  10  can be fixedly connected to the second seat  14  by the bolt T 1  screwing on the threaded hole  141 H 3  of the shaft  141  via the through hole  105  thereon. Thus, the traveling of the shifting second shifting lever  4  (extension bar  42 ) is limited by the curved recess  10 G of the first seat  10 , as shown in FIG. 1A.  
         [0051]    After the above steps are completed, the relationships among the first pawl  5 , the second pawl  6 , the cylindrical sleeve member  7  and the resilient member  8  are shown as following. The first pawl  5  engaged with the first teeth  71  is pressed by the first protrusion  81 , and the second pawl  6  engaged with the second teeth  72  is pressed by the second protrusion  82 . As the shifting process is proceed, the first protrusion  81  is used to press the first pawl  5  to disengage from the first teeth  71 , and the second protrusion  82  is used to press the second pawl  6  to disengage from the second teeth  72 .  
         [0052]    The assembly of the first teeth  71  of the cylindrical sleeve member  7  and the first pawl  5  clamped on the first shifting lever  3  is used as a ratchet mechanism for a high gear of the bicycle speed control apparatus of the present invention. The assembly of the second teeth  72  of the cylindrical sleeve member  7  and the second pawl  6  clamped on the second shifting lever  4  is used as another ratchet mechanism for a low gear of the bicycle speed control apparatus of the present invention. The third teeth  73  of the cylindrical sleeve member  7  function as the positioning slot so as to prevent the third protrusion  83  of the resilient member  8  from being disengaged while the degree of shifting is determined.  
         [0053]    In FIG. 5, the annular slot  74  is used as a path to guide the drive cable W, and the design of the annular slot  74  can precisely determine the tract feed of the drive cable W and effectively reduce the frictional resistance from the cylindrical sleeve member  7 . A cylindrical base  742  is formed on the bottom of the annular slot  74  of the cylindrical sleeve member  7 . The radius of the cylindrical base  742  precisely determines the tract feed of the drive cable W. The intervals of the degree of shifting, tract force of the drive cable W, and the lever portion of shifting.  
       Second Embodiment  
       [0054]    [0054]FIG. 6A is an exploded perspective view showing all the elements of a bicycle speed control apparatus G′.  
         [0055]    The second embodiment is identical to the first embodiment except as follows. In FIG. 6A, the bicycle speed control apparatus G′ is further provided with a thrusting element  18 ′, another cylindrical sleeve member  7 ′ and another resilient member  8 ′. The thrusting element  18 ′ is used to support the axial force and is composed of two disk-like springs  18 ′- 1 ( 18 ′- 2 ), which are juxtaposed and disposed between the resilient member  8 ′ and the second shifting lever  4  and fixed on the shaft  141  by a bolt  20 . The other elements shown in FIG. 6A are all the same as the corresponding elements shown in FIG. 1A and also the corresponding symbols of these elements are adopted.  
         [0056]    [0056]FIG. 6B is an enlarged perspective view showing the elements in a dotted line Z 2  of FIG. 6A, and FIG. 6C is a perspective view with a different visual angle according to FIG. 6B.  
         [0057]    In FIG. 6B and FIG. 6C, the resilient member  8 ′ comprises a cylindrical body  80 ′, a first protrusion  81 ′, a second protrusion  82 ′, a third protrusion  83 ′, a fourth protrusion  84 ′(FIG. 6C), a fifth protrusion  88 ′ and a sixth protrusion  89 ′. The cylindrical body  80 ′ has a bottom surface  80 S 1 , a top surface  80 S 2  and a step surface  80 S 3 , and a through hole  80 H 1  is centrally penetrated from the bottom surface  80 S 1  to top surface  80 S 2 . The step surface  80 S 3  is extended from the sidewall of the cylindrical body  80 ′ and is located between the bottom surface  80 S 1  to the top surface  80 S 2 . The first protrusion  81 ′ and the second protrusion  82 ′ are respectively protruded from the bottom surface  80 S 1  and the top surface  80 S 2 , and the third protrusion  83 ′ is upwardly protruded from the step surface  80 S 3 . The fourth protrusion  84 ′(shown in FIG. 6C) protrudes from the bottom surface  80 S 1  and next to the through hole  80 H 1 . The fifth protrusion  88 ′ and the sixth protrusion  89 ′ in FIG. 6B are corresponding and protruded from the bottom surface  80 S 1  next to the through hole  80 H 1 . The function of the first protrusion  81 ′, the second protrusion  82 ′, the third protrusion  83 ′ and the fourth protrusion  84 ′ are the same as the first protrusion  81 , the second protrusion  82 , the third protrusion  83  and the fourth protrusion  84  of the resilient member  8  of the first embodiment.  
         [0058]    In FIG. 6B, the two disk-like springs  18 ′- 1 ( 18 ′- 2 ) are the same one and has a bottom surface  183 S 1  and a top surface  183 S 2 . Each of two disk-like springs  18 ′- 1 ( 18 ′- 2 ) has a central hole  18 ′H 1 , two spaced curved holes  18 ′H 2  and two punching portions  183 ( 183 ), and the two punching portions  183 ( 183 ) are indented on the bottom surface  183 S 1  and next to the flange thereof.  
         [0059]    In FIG. 6B, the cylindrical sleeve member  7 ′ differs from the cylindrical sleeve member  7  in that the third teeth  73  in the cylindrical sleeve member  7  replace recesses  73 ′. A step surface  70 S is provided in the inner wall  70  of the cylindrical sleeve member  77 , and the spaced recess  73 ′ are formed on the step surface  70 S.  
         [0060]    As all the elements of the bicycle speed control apparatus G′ are assembled, the third protrusion  83 ′ of the resilient member  8 ′ is received in one of the recesses  73 ′. The two disk-like springs  18 ′- 1 ( 18 ′- 2 ) are juxtaposed with the engagement of the corresponding punching portions  183 ( 183 ) and disposed together on the top surface  80 S 2  of the resilient member  8 ′. The central holes  18 ′H 1  of the two disk-like springs  18 ′- 1 ( 18 ′- 2 ) are fitted with the fifth protrusion  88 ′ and the sixth protrusion  89 ′, the second protrusion  82 ′ is received in one curved hole  18 ′H 2  of each two disk-like springs  18 ′- 1 ( 18 ′- 2 ).  
       Third Embodiment  
       [0061]    [0061]FIG. 7A is an exploded perspective view of all the elements of a bicycle speed control apparatus G″.  
         [0062]    The second embodiment is identical to the first embodiment except as follows. In FIG. 7A, the bicycle speed control apparatus G″ is further provided with two rolling elements  19 - 1 ( 19 - 2 ) and another resilient member  8 ″. The other elements shown in FIG. 8A are all the same as the corresponding elements shown in FIG. 6A and also the corresponding symbols of these elements are adopted. Each of the rolling elements  19 - 1 ( 19 - 2 ) is made of steel ball and formed with the same size.  
         [0063]    [0063]FIG. 6B is an enlarged perspective view showing the elements in a dotted line Z 3  of FIG. 7A, and FIG. 7C is a perspective view with a different visual angle according to FIG. 7B.  
         [0064]    The resilient member  8 ″ differs from the resilient member  8 ′ in that the third protrusion  83 ′ of the resilient member  8 ′ is removed and replaced with two openings  86 ″( 87 ″). The openings  86 ″( 87 ″) are spaced each other and formed by penetrating on the top surface  80 S 2  to the step surface  80 S 3 , and the size of each openings  86 ″( 87 ″) is small than the diameter of each of the rolling elements  19 - 1 ( 19 - 2 ). The rolling elements  19 - 1 ( 19 - 2 ) are respectively used to received in two openings  86 ″( 87 ″) from the top surface  80 S 2  of the resilient member  8 ″.  
         [0065]    As all the elements of the bicycle speed control apparatus G″ are assembled, the two rolling elements  19 - 1 ( 19 - 2 ) received in the two openings  86 ″( 87 ″) respectively are clamped by the thrusting element  18 ′ and the resilient member  8 ″, and the two rolling elements  19 - 1 ( 19 - 2 ) are respectively pressed and accommodated by the two punching portions  183  and  183  of the disk-like spring  18 ′- 1 . Thus, the two rolling elements  19 - 1 ( 19 - 2 ) can be held tightly by the two juxtaposed disk-like spring  18 ′- 1 ( 18 ′- 2 ) while they are moved. The positioned rolling elements  19 - 1 ( 19 - 2 ) are protruded from the step surface  80 S 3 . The several recesses  73 ′ of the cylindrical sleeve member  7 ′ can be alternatively positioned by the two positioned rolling elements  19 - 1 ( 19 - 2 ) when undergoing the shifting process, and unpredictable abnormal shifting can be avoided.  
         [0066]    As the rider starts to shift by pushing or pulling the first shifting lever  3  and the second shifting lever  4 , the cylindrical sleeve member  7 ′ is actuated by the acting pawl (first pawl  5  or second pawl  6 ), the cylindrical sleeve member  7 ′ is rotated and when the two rolling elements  19 - 1 ( 19 - 2 ) held by the juxtaposed disk-like springs  18 ′- 1 ( 18 ′- 2 ) are disengaged from the initial recesses  73 ′ they are received by the rotating cylindrical sleeve member  7 ′ and temporarily located at the step surface  70 S before they arrive the another two recesses  73 ′. The juxtaposed disk-like springs  18 ′- 1 ( 18 ′- 2 ) are deformedly pressed and rotated by the two rolling elements  19 - 1 ( 19 - 2 ), and they will be positioned again and restored to the initial state when the two positioned rolling elements  19 - 1 ( 19 - 2 ) are engaged with the next two recesses  73 ′.  
         [0067]    Because most elements of the present invention are simply assembled on the shaft  141  along its axial direction, the assembled speed control apparatus has high-rigidity, and therefore the coupling force between the resilient member and the positioning recesses can be engaged.  
         [0068]    While this invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.