Abstract:
A gear shift control apparatus comprises a shift command input that receives shift commands indicating a desired gear shift operation, a control output that outputs controls signals that control a gear shift unit to shift the bicycle transmission, a gear shift monitor that monitors a progress of a gear shift operation by the gear shift unit, and a gear shift controller operatively coupled to the shift command input, to the control output, and to the gear shift monitor. The gear shift controller receives a shift command and outputs a control signal that controls the operation of the gear shift unit to shift the bicycle transmission to a target gear. The gear shift controller modifies the control signal when the gear shift controller receives a second shift command corresponding to a second target gear that differs from a first target gear corresponding to a first shift command and the gear shift operation initiated by the first shift command has not completed.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention is directed to bicycles and, more particularly, to various features of an apparatus for controlling a bicycle transmission.  
           [0002]    In recent years, some bicycle transmissions have been controlled by devices that operate via electric power or pneumatic power. Such transmissions may be shifted automatically according to the bicycle speed or manually by the rider. Typically, a shift command is generated according to the bicycle speed obtained by a speed sensor or according to manual input by the rider, the shift command is processed by a gear shift controller, and the appropriate gear of the transmission is set by a gear shift unit.  
           [0003]    Shift commands sometimes are generated while the gear shift unit is being operated, either manually by the rider or automatically when the bicycle speed changes quickly. When prior art systems receive shift commands at this time, either the shift commands are ignored by the gear shift controller, or else the shift commands are saved and executed sequentially by the gear shift controller after the current gear shift operation has completed. If shift commands are ignored in the case of manual shifting, then the rider&#39;s intentions are not carried out. Furthermore, in such a system the rider must personally keep track of the timing when shifting operations begin and end before he or she can repeat the desired shift command, which makes the shifting operation more complicated. On the other hand, when the shift commands are saved and executed sequentially after the pending gear shift operation has completed, there is a risk of wasted effort. Generally, there is not much difficulty if the series of shift commands correspond to all upshift commands or all downshift commands. However, sometimes the rider enters a mixed series of upshift and downshift commands, either because of changing conditions or because of initial misjudgment of the desired gear. If, for example, the rider wanted to enter a single upshift command but mistakenly entered two upshift commands and then entered a downshift command to correct the error, then in prior art systems the transmission would make a total of three shifts instead of one (two upshift operations and then one downshift operation to achieve the desired gear). Such a mode of operation creates unnecessary wear on the components, it requires more time to execute all of the shift commands, and it unnecessarily drains the power supply.  
           [0004]    One possible method to alleviate some of the foregoing problems is to calculate the target gear that would result if all of the shift commands were executed sequentially, and then shift to the resulting target gear after the pending gear shift operation has completed. However, waiting until the pending gear shift operation has completed may cause the new gear shift operation (which is the result of multiple shift commands) to be executed in a rough manner.  
         SUMMARY OF THE INVENTION  
         [0005]    The present invention is directed to inventive features of an apparatus for controlling a bicycle transmission. In one embodiment of the present invention, a gear shift control apparatus comprises a shift command input that receives shift commands indicating a desired gear shift operation, a control output that outputs control signals that control a gear shift unit to shift the bicycle transmission, a gear shift monitor that monitors a progress of a gear shift operation by the gear shift unit, and a gear shift controller operatively coupled to the shift command input, to the control output, and to the gear shift monitor. The gear shift controller receives a shift command and outputs a control signal that controls the operation of the gear shift unit to shift the bicycle transmission to a target gear. The gear shift controller modifies the control signal when the gear shift controller receives a second shift command corresponding to a second target gear that differs from a first target gear corresponding to a first shift command and the gear shift operation initiated by the first shift command has not completed. Additional inventive features will become apparent from the description below, and such features alone or in combination with the above features may form the basis of further inventions as recited in the claims and their equivalents.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    [0006]FIG. 1 is a side view of a bicycle that includes a particular embodiment of an electrically controlled bicycle transmission;  
         [0007]    [0007]FIG. 2 is a detailed view of particular embodiments of handlebar mounted components of the bicycle shown in FIG. 1;  
         [0008]    [0008]FIG. 3 is a block diagram of a particular embodiment of electrical components used with the electrically controlled bicycle transmission;  
         [0009]    [0009]FIG. 4 is a flow chart of a particular embodiment of a main routine used to control the bicycle transmission;  
         [0010]    [0010]FIG. 5 is a flow chart of a particular embodiment of an upshift routine used to upshift the bicycle transmission;  
         [0011]    [0011]FIG. 6 is a flow chart of a particular embodiment of a downshift routine used to downshift the bicycle transmission;  
         [0012]    FIGS.  7 (A)- 7 (C) are graphs showing the effects of the described embodiment compared to the prior art;  
         [0013]    [0013]FIG. 8 is a side view of a bicycle that includes a second embodiment of an electrically controlled bicycle transmission;  
         [0014]    [0014]FIG. 9 is a block diagram of a particular embodiment of electrical components used with the second embodiment shown in FIG. 8;  
         [0015]    [0015]FIG. 10 is a flow chart of a particular embodiment of a routine used to control the bicycle transmission in the second embodiment;  
         [0016]    [0016]FIG. 11 is a flow chart of a particular embodiment of a second gear routine used to control the bicycle transmission in the second embodiment;  
         [0017]    [0017]FIG. 12 is a side view of a bicycle that includes a third embodiment of an electrically controlled bicycle transmission;  
         [0018]    [0018]FIG. 13 is a block diagram of a particular embodiment of electrical components used with the third embodiment shown in FIG. 12; and  
         [0019]    [0019]FIG. 14 is a flow chart of a particular embodiment of a routine used to control the bicycle transmission in the third embodiment. 
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0020]    [0020]FIG. 1 is a side view of a bicycle that includes a particular embodiment of an electrically controlled bicycle transmission. The bicycle  1  is a sport bicycle of a mountain bike type, and it comprises a frame  2 , a front fork  3  rotatably mounted to frame  2  in slanted manner, a handlebar assembly  4  mounted to the upper part of fork  3 , a front wheel  5  rotatably attached to the lower part of fork  3 , a rear wheel  6  rotatably attached to the rear of frame  2 , a chain  7 , a front external gear transmission  8 , a rear external gear transmission  9 , and a saddle  11  on which the rider sits. A front wheel brake  16  is provided for braking the front wheel  5 , and a rear wheel brake  17  is provided for braking the rear wheel  6 . As shown in FIG. 2, respective grips  12   a ,  12   b  and brake levers  13   a ,  13   b  are provided on both ends of handlebar assembly  4 . Brake lever  13   b  is connected to the front wheel brake  16  for braking front wheel  5 , and brake lever  13   a  is connected to the rear wheel brake  17  for braking rear wheel  6 .  
         [0021]    The front external gear transmission  8  is a mechanical unit attached in the central lower part of frame  2  for transmitting the drive force generated by the rider to the rear external gear transmission  9  via the chain  7 . In this embodiment, the front external gear transmission  8  comprises three sprockets  37  of various sizes, and a front derailleur  33 . The three sprockets  37  are installed on a gear crank  31  that is rotated when the rider pushes pedals  32   a  and  32   b . The gear crank  31  comprises a crankshaft  34  that passes horizontally and rotatably through the central lower part of frame  2 , a right crank  35 , and a left crank  36 . One end of the right crank  35  is nonrotatably connected to the right side of crankshaft  34 , and the three sprockets  37  are nonrotatably attached to the right crank  35 . One end of the left crank  36  is nonrotatably connected to the left side of crankshaft  34 . The other ends of right crank  35  and left crank  36  rotatably support pedals  32   a  and  32   b , respectively. The front derailleur  33  engages the chain  7  with one of the three sprockets  37  and can be moved by a gear shift unit in the form of a motor, solenoid, or some other actuator (not shown in the figures) that is controlled by a gear shift controller  15  described below. A front derailleur position sensor (not shown in the figures) detects the position of front derailleur  33 , and hence the current gear of front transmission  8 .  
         [0022]    The rear external gear transmission  9  serves to transmit the driving force transmitted by the chain  7  to the rear wheel  6 . The rear external gear transmission  9  comprises a rear sprocket wheel  41  and a rear derailleur  42 . In this embodiment, rear sprocket wheel  41  comprises seven sprockets  43  of different sizes that are mounted concentrically with the hub portion of rear wheel  6 . Rear derailleur  42  engages chain  7  with one of the seven sprockets  43  and can be moved by a gear shift unit in the form of a motor, solenoid, or some other actuator (not shown in the figures) that is controlled by gear shift controller  15 . A rear derailleur position sensor (not shown in the figures) detects the position of rear derailleur  42  and hence the current gear of rear external gear transmission  9 . The rear derailleur position sensor provides position signals SH that are used in a manner described below.  
         [0023]    As shown in FIG. 2, shift command units  14   a ,  14   b  are provided inwardly of grips  12   a ,  12   b  and brake levers  13   a ,  13   b , respectively. Gear shift controller  15  is attached to the central portion of handlebar assembly  4 , and it is operatively connected to the shift command units  14   a ,  14   b . The shift command units  14   a ,  14   b  are used for manually shifting the front external gear transmission  8  and rear external gear transmission  9 . A front upshift button  18   a  and a front downshift button  19   a  are provided in the shift command unit  14   a , and a rear upshift button  18   b  and a rear downshift button  19   b  are provided in the shift command unit  14   b . In this embodiment, the upshift buttons  18   a  and  18   b  provide signals for upshifting the front and rear external gear transmissions  8  and  9  by one speed step. Similarly, the downshift buttons  19   a  and  19   b  provide signals for downshifting the front and rear external gear transmissions  8  and  9  by one speed step. This arrangement facilitates shift command computation and facilitates operation by the rider.  
         [0024]    As shown in FIG. 3, the gear shift controller  15  includes a controller  23  comprising a CPU  21  and a memory  22 , a display unit  24  that displays the current active gear and other information, a power switch  25  and a mode switch  26 . The controller  23  is programmed to perform gear shift control and display control via the CPU  21 . The upshift and downshift buttons  18   a ,  18   b ,  19   a  and  19   b , and a rotation speed sensor  10 , are connected to the controller  23 . Gear shift controller  15  is connected to the gear shift units for front derailleur  33  and rear derailleur  42  via a connector  28 , and it performs gear shift control for both mechanisms. In the case of manual gear shift mode, such control is executed in response to the manual operation of shift command units  14   a  and  14   b . In the case of automatic gear shift mode, such control is executed in response to gear shift signals generated in response to speed signals from a rotation speed sensor  10 . The display unit  24  comprises a liquid crystal display device that uses the segment method, for example, and can display the current bicycle speed, the total distance traveled, the current gear, and so on. The power switch  25  turns the display unit  24  ON and OFF. The mode switch  26  changes the mode between automatic gear shift mode and manual gear shift mode. In addition, the gear shift controller  15  is disposed in a box-shaped control case  27 , and the display unit  24 , the power switch  25 , and the mode switch  26  are disposed on the top surface thereof.  
         [0025]    FIGS.  4 - 6  are flowcharts illustrating particular embodiments of the operation of the rear external gear shift mechanism  9  using gear shift controller  15 . The operation of the front external gear shift mechanism  8  is the same (except the front external gear shift mechanism  8  has only three sprockets), so the description of the operation of the front external gear shift mechanism  8  is omitted.  
         [0026]    The installation of a battery in the gear shift controller  15  by the rider as a power supply enables gear shift control of the bicycle  1 . When such installation is carried out, initialization is first executed with regard to the gear shift controller  15  in step S 1  shown in FIG. 4. In this initialization, a variable OP is set to “1” and stored in the memory  22 . OP is a gear value set via a shift command using the shift command unit  14   b . OP is incremented or decremented in accordance with the operation of the shift command unit  14   b . In addition, the gear shift mode is set to manual gear shift mode.  
         [0027]    In step S 2 , it is determined whether or not the current gear shift mode is manual gear shift mode. Determining the content of the setting made via the mode switch  26 , for example, makes this determination. In step S 3 , it is determined whether or not the current gear shift mode is automatic gear shift mode. In step S 4 , it is determined whether or not the gear shift controller is in some other mode so that other operations may be performed.  
         [0028]    If it is determined in step S 2  that the current gear shift mode is manual gear shift mode, then controller  23  advances from step S 2  to step S 5 . In step S 5 , it is determined whether or not the rear upshift button  18   b  has been operated. In step S 6 , it is determined whether or not the rear downshift button  19   b  has been operated. If the rear upshift button  18   b  has been operated, the controller  23  advances from step S 5  to step S 7 , and the upshift routine shown in FIG. 5 is executed. If the rear downshift button  19   b  has been operated, the controller  23  advances from step S 6  to step S 8 , and the downshift routine shown in FIG. 6 is executed.  
         [0029]    If it is determined in step S 3  that the current gear shift mode is the automatic gear shift mode, the controller  23  advances from step S 3  to step S 9 . In step S 9 , a bicycle speed V is calculated based on signals from the rotation speed sensor  10 . In step S 10 , the currently set gear value OP is obtained. In step S 11 , it is determined whether or not the bicycle speed V is greater than an upshift threshold value U(OP) (stored in memory  22 ) for the current gear. In step S 12 , it is determined whether or not the bicycle speed V is lower than a downshift threshold value D(OP) for the current gear. If it is determined in step S 11  that the bicycle speed V is higher than the upshift threshold value U(OP) for the current gear, then controller  23  advances from step S 11  to step S 13 , and the upshift routine shown in FIG. 5 is executed. If it is determined in step S 12  that the bicycle speed V is lower than the downshift threshold value D(OP) for the current gear, then the controller  23  advances from step S 12  to step S 14 , and the downshift routine shown in FIG. 6 is executed.  
         [0030]    If it is determined that other operations are to be performed, then the controller  23  advances from step S 4  to step S 15 . In step S 15 , the selected other operations are executed, whereupon the controller  23  returns to step S 2 .  
         [0031]    In this main routine, when the manual, automatic or other operation modes are selected, the operations associated with the selected mode are executed. If none of these modes are selected, then controller  23  returns to step S 2  and repeats the main routine.  
         [0032]    A particular embodiment of an upshift routine executed in steps S 7  or S 13  in FIG. 4 is shown in FIG. 5. In step S 21 , the current gear OP is incremented by one gear, and the resulting gear is set as the target gear. In step S 22 , it is determined whether or not the gear shift motor is operating in the direction of forward rotation (which may be determined by changes in value of the position data SH and monitored by the programming in controller  23 ). In other words, it is determined whether or not the rear derailleur  42  is undergoing a gear shift operation in the upshift direction. If the gear shift motor is not operating in the direction of forward rotation (i.e., if an upshift gear shift operation is not underway), then the controller  23  proceeds to step S 23 , wherein the gear shift motor is caused to operate in the direction of forward rotation and position data SH is obtained from the gear position sensor. If the gear shift motor is already operating in the direction of forward rotation, this operation is skipped.  
         [0033]    In step S 24 , it is determined whether or not the position data SH indicates that the rear derailleur  42  has arrived at the set target gear and the gear shift operation can end. If it is determined that the gear shift operation can end, then the controller  23  proceeds to step S 25 , wherein the gear shift motor is turned OFF and the obtaining of the position data SH from the gear position sensor is ended. In this routine, a new target gear is first set in step S 21  even when a gear shift operation is already underway. The new target gear replaces the previously set target gear.  
         [0034]    A particular embodiment of a downshift routine executed in steps S 8  or S 14  in FIG. 4 is shown in FIG. 6. In this routine, the current gear OP is decremented by one gear, and the resulting gear is set as the target gear in step S 31 . In step S 32 , it is determined whether or not the gear shift motor is operating in the direction of reverse rotation. In other words, it is determined whether or not the rear derailleur  42  is undergoing a gear shift operation in the downshift direction. If the gear shift motor is not operating in the direction of reverse rotation, (i.e., if a downshift gear shift operation is not underway), then the controller  23  proceeds to step S 33 , wherein the gear shift motor is made to operate in the direction of reverse rotation and position data SH is obtained from the gear position sensor. If the gear shift motor is already operating in the direction of reverse rotation, this operation is skipped.  
         [0035]    In step S 34 , it is determined whether or not the position data SH indicates that the rear derailleur  42  has arrived at the set target gear and the gear shift operation can end. If it is determined that the gear shift operation can end, then the controller  23  proceeds to step S 35 , wherein the gear shift motor is turned OFF and the obtaining of the position data SH from the gear position sensor is ended. In this routine as well, as with the upshift routine, a new target gear is first set in step S 31  even when a gear shift operation is already underway, the new target gear replaces the previously set target gear.  
         [0036]    Where the gear shift mode is manual gear shift mode, the rider can shift to a desired gear by pressing the upshift buttons  18   a  or  18   b  or the downshift buttons  19   a  or  19   b  of the shift command units  14   a  and  14   b  at the desired timing. In automatic gear shift mode, the gear shift operation is performed automatically based on the bicycle speed V. During manual gear shift mode, if the shift command unit  14   a  is operated while the front external gear shift mechanism  8  is undergoing a gear shift operation or if the shift command unit  14   b  is operated while the rear external gear shift mechanism  9  is undergoing a gear shift operation, or if the bicycle speed V is higher than the upshift threshold value for the current active gear or is lower than the downshift threshold value for that gear, the target gear OP is incremented or decremented accordingly and a new target gear is set.  
         [0037]    For example, if an upshift button  18   a  or  18   b  is pressed, or if the bicycle speed exceeds the upshift threshold value for the current gear, the value of OP in the memory  22  is increased by 1, and conversely, if a downshift button  19   a  or  19   b  is pressed, or if the bicycle speed is lower than the downshift threshold value for the current gear, the value of OP in the memory  22  is decreased by 1. If multiple shift commands are issued using the shift command units  14   a  or  14   b , the value of OP is increased or decreased via addition or subtraction in accordance with the multiple actions carried out using the shift command units  14   a  or  14   b . This addition/subtraction operation is carried out regardless of whether a gear shift operation is already underway, and the target gear value is updated based on the newly output gear shift signals. As a result, even where gear shift signals are output or generated while a gear shift operation is underway, the gear shift operation is always carried out for the most current target gear. This carries out the intent of the rider and enhances smoothness in the gear shift operation.  
         [0038]    FIGS.  7 (A)- 7 (C) illustrate a situation where the rider presses the rear upshift button  18   b  twice after pressing the rear downshift button  19   b  once while a gear shift operation to shift from third gear to fourth gear is underway. In this embodiment, the target gear is updated when needed, and gear shifting to the final destination gear is carried out even while an existing gear shift operation is underway as shown in FIG. 7(A). In other words, the gear shifting motor rotates forward or backward by a precise amount while the gear shifting operation is underway, and the gear is shifted to the final destination gear via a single gear shift operation (effectively canceling the intermediate gear shift commands). As a result, needless gear shift operations can be eliminated, and the gear shifting to the final destination gear can be carried out smoothly and quickly without ignoring shift commands. Furthermore, where the front derailleur  33  and the rear derailleur  42  are battery-driven, the elimination of needless gear shift operations helps to prevent wasteful battery consumption.  
         [0039]    The actions of prior art systems that perform sequential gear shift operations for each shift command are shown in FIG. 7(B). In such systems, after the gear shift operation from third gear to fourth gear is completed, a gear shift operation from fourth gear to third gear is executed, and then gear shift operations to shift from third to fourth gear and from fourth gear to fifth gear are executed. This results in a total of four gear shift operations. However, the rider&#39;s shift commands were based on a desire to shift only one gear (from fourth gear into fifth gear). In other words, the operations to switch from fourth gear to third gear and then from third gear back into fourth gear are unnecessary.  
         [0040]    In another prior art method shown in FIG. 7(C), shift commands are combined such that gear shifts are performed one at a time, with each gear shift being executed after the previous gear shift has completed. In this method, the gear is shifted from third gear into fourth gear, and then from fourth gear into fifth gear, thus resulting in a total of two separate and distinct gear shift operations. Unfortunately, such separate and distinct gear shift operations may result in jerkiness between the two gear shift operations, and the smoothness of the transition between the gears may be lost.  
         [0041]    In the first embodiment, downshift and upshift signals were output directly from the shift command units  14   a  and  14   b  in manual gear shift mode, but it is also acceptable if the gear shift command units have buttons corresponding to each gear, and downshift and upshift signals are generated based on a comparison between the gear selected by a given button and the current gear. FIG. 8 is a side view of such a bicycle that includes a second embodiment of an electrically controlled bicycle transmission. As shown in FIG. 8, the bicycle  51  is an ordinary recreational bicycle, and it includes as its main components a frame  52 , a fork  53  rotatably mounted to the front of frame  52 , a handlebar assembly  54  mounted to the upper portion of fork  53 , a front wheel  55  rotatably mounted to the lower portion of fork  53 , a rear wheel  56  rotatably mounted to the rear of frame  52 , and a saddle  61  on which the rider sits disposed at the top center part of the frame  52 .  
         [0042]    The front wheel  55  includes a generator hub  60  that forms the hub of front wheel  55  and is mounted at the bottom of the front fork  53 . The generator hub  60  serves both as a power supply for a front lamp  58  mounted to the front fork  53  and may function as a speed sensor that detects the speed of the bicycle. A front wheel brake  66  that performs braking of the front wheel  55  is disposed at the top of fork  53 . A chain  57  is suspended over a front sprocket (shown schematically) and over a rear sprocket (not shown) disposed on the internal gear shift hub  59 . Chain  57  transmits the drive power from one of the front sprocket to the rear sprocket. The internal gear shift hub  59  forms the hub part of the rear wheel  6  and transmits the drive power from the chain  57  to the rear wheel  56 . The internal gear shift hub  59  can change among three gears via a gear shift unit such as a gear shift motor (not shown). Furthermore, the internal gear shift hub  59  can detect the position of the current gear based on position data SH from a gear position sensor (not shown).  
         [0043]    Grips  62   a  and  62   b  (only  62   a  is shown) and brake levers  63   a  and  63   b  (only  63   a  is shown) are located at either end of the handlebar  54 , much like in the first embodiment. Furthermore, a gear shift control apparatus  65  having a shift command unit  64  is mounted to the handlebar  4  inboard of the grip  62   a  and the brake lever  63   a.  First-gear through third-gear gear shift buttons  67 - 69  (FIG. 9) corresponding to first through third gears of the internal gear shift hub  59  are disposed on the shift command unit  64 .  
         [0044]    As shown in FIG. 9, the gear shift control apparatus  65  includes a controller  23  comprising a CPU  21  and a memory  22 , a display unit  24  that displays the current active gear and other information, a power switch  25  and a mode switch  26 . The controller  23  performs gear shift control and display control via the CPU  21 . First-gear through third-gear gear shift buttons  67 - 69  are connected to the controller  23 , as well as generator hub  60  and internal gear shift hub  59 . The display unit  24  comprises a liquid crystal display device that uses the segment method, for example, and can display the current bicycle speed, the total distance traveled the current gear, and so on. The power switch  25  turns the display unit  24  ON and OFF, and the mode switch  26  changes the mode of the gear shift control apparatus  65  between automatic gear shift mode and manual gear shift mode.  
         [0045]    In manual gear shift mode, the shift command unit  64  performs gear shifting with respect to the internal gear shift hub  59  using gear shift buttons  67 - 69 . In automatic gear shift mode, gear shift signals are generated in accordance with speed signals from the generator hub  60 . FIGS. 10 and 11 are flowcharts illustrating the operation of this embodiment. Control operations identical to those executed in connection with the first embodiment will not be described. Gear shift control of the bicycle  51  is enabled when the rider installs a battery in the gear shift control apparatus  65  as a power supply, or when electric power is supplied from the generator hub  60 . When such installation or power supply occurs, first, the operations of steps S 41  through S 44  shown in FIG. 10 are performed in the same fashion as steps S 1  through S 4  shown in FIG. 4.  
         [0046]    If it is determined in step S 42  that the gear shift mode is manual gear shift mode, then the controller  23  advances from step S 42  to step S 45 . In step S 45 , it is determined whether or not the first-gear gear shift button  67  has been pressed. In step S 46 , it is determined whether or not the second-gear gear shift button  68  has been pressed. In step S 47 , it is determined whether or not the third-gear gear shift button  68  has been pressed. If the first-gear gear shift button  67  has been pressed, the controller  23  advances from step S 45  to step S 48 , and the first-gear routine is executed. If the second-gear gear shift button  68  has been pressed, the controller  23  advances from step S 46  to step S 49 , and the second-gear routine is executed. If the third-gear gear shift button  69  has been pressed, the controller  23  advances from step S 47  to step S 50 , and the third-gear routine is executed.  
         [0047]    If it is determined that the gear shift mode is automatic gear shift mode, then the controller  23  advances from step S 43  to step S 51 , and the same operations that were executed in connection with the first embodiment are executed up to step S 56 . If it is determined that other operations are to be executed, then the controller  23  advances from step S 44  to step S 57 , the selected operations are executed, and the controller  23  advances to step S 42 .  
         [0048]    In the second-gear routine shown in FIG. 11, the current gear OP is read in a step S 61 . In step S 62 , it is determined whether or not the current gear OP is first gear (low gear). In step S 63 , it is determined whether or not the gear OP is third gear (high gear). If the current gear OP is first gear (low gear), then the controller  23  advances from step S 62  to step S 64 , and the shift-up routine shown in FIG. 5 is executed. If the current gear OP is third gear (high gear), the controller  23  advances from step S 63  to step S 65 , and the shift-down routine shown in FIG. 6 is executed. In the second-gear routine, gear shift control is performed when the current gear is not second gear (middle gear). Therefore, in the case of the first-gear routine, the downshift routine may be executed where the current gear is not first gear, and in the case of the third-gear routine, the upshift routine may be executed where the current gear is not third gear. Furthermore, when the third-gear routine is executed from first gear or the first-gear routine is executed from third gear, then two shift-up or shift-down routines may be executed.  
         [0049]    In the two embodiments described above, gear shifting was based on the bicycle speed in automatic gear shift mode, but it may also be based on the crank rotation speed. This allows the rider to maintain cadence in a desired range. FIG. 12 shows such an embodiment. As shown in FIG. 12, the bicycle  51  is an ordinary recreational bicycle identical to that described in connection with the second embodiment, and it includes a frame  52 , a front fork  53 , a handlebar  54 , a front wheel  55 , a rear wheel  56 , a chain  57 , and an internal gear shift hub  59  having three gears. A detailed description of the construction will be omitted.  
         [0050]    A magnet  76  that functions as a detection element for detecting the rotation of a crank  75  that is rotatably mounted to the bottom center area of frame  52 . In addition, a crank rotation sensor  80  that detects the number of crank rotations based on detection of the magnet  76  is fixed to the seat tube  52   a  of the frame  52 . The gear shift controller  85  controls the operation of the internal gear shift hub  59  based on gear shift signals generated in response to the operation of the shift command unit  64  in manual gear shift mode, and based on gear shift signals generated in accordance with crank rotation signals from the crank rotation sensor  80  in automatic gear shift mode.  
         [0051]    As shown in FIG. 13, the gear shift control apparatus  85  includes a controller  23  comprising a CPU  21  and a memory  22 , a display unit  24  that displays the current active gear and other information, a power switch  25  and a mode switch  26 . The controller  23  performs gear shift control and display control via the CPU  21 . First-gear through third-gear gear shift buttons  67 - 69  and the crank rotation sensor  80  are connected to the controller  23 . The display unit  24  comprises a liquid crystal display device that uses the segment method, for example, and can display the current bicycle speed, the total distance traveled, the current gear, and so on. The power switch  25  turns the display unit  24  ON and OFF, and the mode switch  26  changes the mode of the shift controller  85  between automatic gear shift mode and manual gear shift mode. The shift controller  85  is connected to the internal gear shift hub  59 .  
         [0052]    [0052]FIG. 14 is a flow chart illustrating the operation of this embodiment. Control operations identical to those executed in connection with the second embodiment will not be described.  
         [0053]    Gear shift control of the bicycle  1  is enabled when the rider installs a battery in the shift controller  85  as a power supply. When such installation occurs, first, the operations of steps S 71  through S 80  shown in FIG. 14 are performed in the same fashion as steps S 41  through S 50  shown in FIG. 10.  
         [0054]    If it is determined that the gear shift mode is automatic gear shift mode, the controller  23  advances from step S 73  to step S 81 , and the crank rotation speed R is obtained. In step S 82 , it is determined whether or not the obtained crank rotation speed R exceeds the upshift threshold value (for example, 65 rpm, stored in memory  22 ). In step S 83 , it is determined whether or not the obtained crank rotation speed R is lower than the downshift threshold value DR (for example, 40 rpm). In this third embodiment, the crank rotation rate threshold values are fixed regardless of the gear, but it is acceptable if the threshold values vary depending on the gear. If it is determined that the obtained crank rotation speed R exceeds the shift-up threshold value, then the controller  23  advances from step S 82  to step S 84 , and the upshift routine shown in FIG. 5 is executed. Similarly, if it is determined that the obtained crank rotation speed R is lower than the shift-down threshold value, then the controller  23  advances from step S 83  to step S 85 , and the downshift routine shown in FIG. 6 is executed. If it is determined that other operations are to be executed, then the controller  23  advances from step S 74  to step S 86 , and the selected other operations are executed. The controller  23  then returns to step S 72 .  
         [0055]    While the above is a description of various embodiments of inventive features, further modifications may be employed without departing from the spirit and scope of the present invention. For example, in the above embodiments, automatic gear shifting was carried out via electric power, but the foregoing inventive features can be implemented using pneumatic driving or some other type of drive power. Furthermore, the gear shifting action was carried out by pressing a button in manual gear shift mode, but the action can also be carried out by operating a lever-type switch or other type of switch.  
         [0056]    In the above embodiments, inventive features were described using the example of a gear shift control apparatus having both a manual gear shift mode and an automatic gear shift mode, but inventive features may exist where the gear shift control apparatus has only one of such modes.  
         [0057]    The size, shape, location or orientation of the various components may be changed as desired. Components that are shown directly connected or contacting each other may have intermediate structures disposed between them. The functions of one element may be performed by two, and vice versa. The structures and functions of one embodiment may be adopted in another embodiment. It is not necessary for all advantages to be present in a particular embodiment at the same time. Every feature which is unique from the prior art, alone or in combination with other features, also should be considered a separate description of further inventions by the applicant, including the structural and/or functional concepts embodied by such feature(s). Thus, the scope of the invention should not be limited by the specific structures disclosed or the apparent initial focus on a particular structure or feature.