Patent Publication Number: US-10780945-B2

Title: Gear changing control apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional application of U.S. patent application Ser. No. 14/661,419 filed on Mar. 18, 2015. The entire disclosure of U.S. patent application Ser. No. 14/661,419 is hereby incorporated herein by reference. This application claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2014-092903, filed Apr. 28, 2014. The entire disclosure of Japanese Patent Application No. Apr. 28, 2014 is hereby incorporated herein by reference. 
    
    
     BACKGROUND 
     Field of the Invention 
     This invention generally relates to a control apparatus. More specifically, the present invention relates to a gear changing control apparatus that controls a gear changing device of a bicycle according to a plurality of operation modes of an auxiliary power device that is provided to the bicycle and that assists a manual drive force. 
     Background Information 
     Assisted bicycles are provided with a drive unit having a motor for generating an auxiliary force. On example of a conventional assisted bicycle is disclosed in Japanese Patent No. 3,306,309. The assisted bicycle disclosed in this Japanese Patent can be switched between a plurality of types of auxiliary forces with a switch. 
     SUMMARY 
     One object of the present invention is to improve the riding comfort in an assisted bicycle. 
     The gear changing control apparatus according to the present invention is a device for controlling a gear changing device of a bicycle according to a plurality of operation modes of an auxiliary power device that assists a manual drive force of the bicycle. The gear changing control apparatus comprises a gear changing controller and a traveling state detecting unit. The gear changing controller controls the gear changing device and controls the auxiliary power device to operate in one of the plurality of operation modes. The traveling state detecting unit is configured to detect a traveling state of the bicycle. The gear changing controller is configured to select a gear changing range to be used according to a selected operation mode that was selected from the plurality of operation modes. The gear changing controller is further configured to control the gear changing device within the gear changing range that was selected. The gear changing controller is configured to control the gear changing device according to a detection result of the traveling state detecting unit. 
     In this gear changing control apparatus, the gear changing controller selects a gear changing arrangement that can be used according to a plurality of operation modes of the auxiliary power device and that controls the gear changing device within the selected gear changing range. Therefore, improving the riding comfort in an assisted bicycle is possible. 
     The plurality of operation modes comprises a first operation mode and a second operation mode. The gear changing controller varies at least one of a maximum gear ratio and a minimum gear ratio to be used in the first operation mode and at least one of a maximum gear ratio and a minimum gear ratio to be used in the second operation mode. 
     The gear changing controller can control the gear changing device so that a maximum gear ratio available during the second operation mode is larger than a maximum gear ratio available during the first operation mode. 
     The gear changing controller can control the gear changing device so that the minimum gear ratio to be used during the second operation mode is larger than the minimum gear ratio to be used during the first operation mode. 
     The first operation mode can be an operation mode that assists the manual drive force with a first auxiliary force, and the second operation mode can be an operation mode that assists the manual drive force with a second auxiliary force that is larger than the first auxiliary force. 
     The first operation mode can be an operation mode that does not make the auxiliary power device generate an auxiliary force, and the second operation mode can be an operation mode that does make the auxiliary power device generate an auxiliary force. 
     The gear changing range can be defined by one of a gear ratio and a shift position. In this case, the gear changing range becomes clear. 
     The gear changing controller can control the gear changing device according to a gear changing command. In this case, the controller can control the gear changing device based on a gear changing command that is generated by a gear changing operation or based on a gear changing command that is generated by the traveling state of the bicycle. 
     A gear changing control apparatus according to yet another aspect of the present invention is a device for controlling a gear changing device of a bicycle according to a plurality of operation modes of an auxiliary power device that assists a manual drive force. The plurality of operation modes comprises a first operation mode and a second operation mode. The gear changing control apparatus comprises a gear changing controller that controls the gear changing device, according to a first parameter related to time and the traveling state of the bicycle when in the first operation mode, and that controls the gear changing device, according to a second parameter related to time and that is different from the first parameter and the traveling state of the bicycle when in the second operation mode. 
     In this gear changing control apparatus, the gear changing device is controlled according to different parameters related to time when in the first operation mode and the second operation mode. For example, in the case that the auxiliary force of the second operation mode is larger than that of the first operation mode, by making the length of the first parameter related to time shorter than the length of the second parameter related to time, the gear changing frequency of the second operation mode with a larger auxiliary force can be reduced, and the gear changing frequency of the first operation mode with a small auxiliary force can be increased. With this, an optimum gear changing frequency according to the operation mode can be obtained, which will improve the riding comfort of the assisted bicycle. 
     The gear changing controller can shift the gear changing device when a prescribed condition is still being met even after a period of time expressed by the first parameter has elapsed from the time that the traveling state of the bicycle satisfies the prescribed condition when in the first operation mode. The controller can also shift the gear changing device when a prescribed condition is still being met even after a period of time expressed by the second parameter has elapsed from the time that the traveling state of the bicycle satisfies the prescribed condition when in the second operation mode. 
     The gear changing controller does not have to shift the gear changing device when a prescribed condition is not being met after a period of time expressed by the first parameter has elapsed from the time that the traveling state of the bicycle satisfies the prescribed condition when in the first operation mode. The controller also does not have to shift the gear changing device when a prescribed condition is not being met after a period of time expressed by the second parameter has elapsed from the time that the traveling state of the bicycle satisfies the prescribed condition when in the second operation mode. 
     The time expressed by the first parameter can be shorter than the time expressed by the second parameter. 
     The traveling state of the bicycle can be selected from a group comprising the speed of the bicycle, the cadence of the crank, the manual drive force, and the inclination of the bicycle in the traveling direction. In this case, the gear changing device will automatically shift gears according to the traveling state of the bicycle, so that a gear changing operation becomes unnecessary. 
     The gear changing controller can control the gear changing device according to the first parameter, the second parameter, and the traveling state of the bicycle, regarding shifting in the direction in which the gear ratio becomes smaller. In this case, in the so-called downshifting, the gear changing frequency can be changed according to the auxiliary force. 
     The first operation mode can be an operation mode that assists the manual drive force with a first auxiliary force, and the second operation mode can be an operation mode that assists the manual drive force with a second auxiliary force that is larger than the first auxiliary force. 
     The first operation mode can be an operation mode that does not make the auxiliary power device generate an auxiliary force, and the second operation mode can be an operation mode that does make the auxiliary power device generate an auxiliary force. 
     According to the present invention, the riding comfort of an assisted bicycle can be improved in an assisted bicycle having an auxiliary power device that operates in a plurality of operation modes since the gear changing range, the gear changing state, or the gear changing frequency will change for each of the operation modes. Also other objects, features, aspects and advantages of the disclosed gear changing control apparatus will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses one embodiment of the gear changing control apparatus. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Referring now to the attached drawings which form a part of this original disclosure: 
         FIG. 1  is a side elevational view of a bicycle drive train of a power-assisted bicycle that that is equipped with a gear changing control apparatus in accordance with a first embodiment; 
         FIG. 2  is a block diagram showing an overall configuration of the gear changing control apparatus comprising a drive unit; 
         FIG. 3  is a table showing one example of an upshifting threshold value and a downshifting threshold value for each shift position of an internal gear changing mechanism; 
         FIG. 4  is a flowchart showing one example of a control process executed by the gear changing controller according to the first embodiment of the present invention; 
         FIG. 5  is a flowchart showing one example an automatic shifting process of the control process when a gear changing range is defined by the shift position; 
         FIG. 6  is a flowchart showing one example of a manual shifting process of the control process when a gear changing range is defined by the shift position; 
         FIG. 7  is a diagram showing one example of a gear ratio in the case that the gear changing range is defined by the gear ratio in a gear changing device having three front sprockets and ten rear sprockets; 
         FIG. 8  is a diagram corresponding to  FIG. 5  of a modified example of the first embodiment in the case that the gear changing range is defined by the gear ratio; and 
         FIG. 9  is a diagram corresponding to  FIG. 5 , showing one example of an automatic shifting process of the control process according to a second embodiment. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Selected embodiments will now be explained with reference to the drawings. It will be apparent to those skilled in the bicycle field from this disclosure that the following descriptions of the embodiments are provided for illustration only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents. 
     First Embodiment 
     Referring initially to  FIG. 1 , a power-assisted bicycle drive train is illustrated that incorporates a bicycle control apparatus  1  according to a first embodiment. The power-assisted bicycle drive train includes a drive unit  2  that is controlled by the bicycle control apparatus  1 . The drive unit  2  assists a pedaling force that acts on a pair of pedals  100 . One of the pedals  100  is mounted on a crank arm  101   a , while the other pedal  100  is mounted on a crank arm  101   b . The crank arms  101   a  and  101   b  are mounted on a crankshaft  102 . A front sprocket  103  is also mounted on the crankshaft  102  via the drive unit  2 . A chain  104  is engaged with the front sprocket  103  and a rear sprocket  105  that is attached to an axle  106  of a rear wheel (not shown). An electric transmission  107  is mounted to the rear sprocket  105 . Thus, the power-assisted bicycle drive train transmits the pedaling force that acts on the pedals  100  to the internal gear changing mechanism  107   a  of the electric transmission  107 . Specifically, the internal gear changing mechanism  107   a  is provided around the axle  106  of the rear wheel. The internal gear changing mechanism  107   a  receives the pedaling (drive) force via a path from the crank arm  101   a  (or the crank arm  101   b )→the crankshaft  102 →the drive unit  2 →the front sprocket  103 →the chain  104 →the rear sprocket  105 . The pedaling force is one example of the manual drive force. The drive unit  2  is one example of the auxiliary power device. The bicycle control apparatus  1  is one example of a bicycle gear changing control apparatus. 
     The drive unit  2  comprises a casing  11  and a motor  20 . The motor is disposed in the casing  11  (refer to  FIG. 2 ). The motor  20  is provided to assist the pedaling force. The crankshaft  102  is rotatably supported by the casing  11 . The drive unit  2  transmits the driving force of the motor  20  to the front sprocket  103 . For example, the electric transmission  107  basically comprises an internal gear changing mechanism  107   a  and a gear shift motor  107   b . The internal gear changing mechanism  107   a  shifts gears using the gear shift motor  1071 . The electric transmission  107  is one example of the gear changing mechanism. Also, as shown in  FIG. 2 , the electric transmission  107  further comprises a gear number sensor  107   c  that is configured to detect the shift position of the internal gear changing mechanism  107   a . The internal gear changing mechanism  107   a  comprises a plurality of shift positions. The internal gear changing mechanism  107   a  comprises five shift positions in the present embodiment. For each shift position in the internal gear changing mechanism  107   a , the gear ratio is, for example, about 0.5 for the first shift position, about 0.8 for the second shift position, about 1.2 for the third shift position, about 1.6 for the fourth shift position, and about 2.1 for the fifth shift position. 
     The power-assisted bicycle combines the output of the motor  20  with the pedaling force as the auxiliary force and assists riding in the present embodiment, a sensor  50  detects the pedaling force of the rider. When the detected value exceeds a set value. The sensor  50  activates the motor  20 , which generates a force corresponding to the pedaling force as the auxiliary force. The motor  20  of the drive unit  2  for assisting is generally disposed near a connection portion of a bottom end portion of a seat tube and a rear end portion of a down tube of a frame for assisting in the pedaling force. The drive unit  2  is fixed to the frame by bolts that are not shown. A battery is disposed along a rear carrier, the down tube, or the seat tube for supplying electrical power for driving the motor. 
     Electric Configuration 
       FIG. 2  is a block diagram showing an electric configuration of a power-assisted bicycle comprising the drive unit  2 . The power-assisted bicycle comprises the bicycle control apparatus  1 , the drive unit  2  and the electric transmission  107 , as well as an inverter  6 , a gear shifting unit  10  and an assist operating unit  12 . The bicycle control apparatus  1  comprises a gear changing control apparatus. The bicycle control apparatus  1  and the inverter  6  can be disposed in the drive unit  2 . Additionally, at least one of the bicycle control apparatus  1  and the inverter  6  can be provided in the inner or the outer peripheral part of the casing  11  of the drive unit  2 . 
     The bicycle control apparatus  1  comprises a controller  4 , a traveling state detecting unit  8  and the sensor  50 . The controller  4  comprises, for example, a central processing unit (CPU) and a memory that stores a prescribed control program. The controller  4  has information regarding the correlation between a command that is output to the inverter  6  for driving the motor  20  and a torque that the motor  20  outputs in response to this command. The correlation information can be represented in the form of a table or a formula. With this, the controller  4  can determine the output torque of the motor  20 . The sensor  50  detects a torque that combines the output of the motor  20  and a torque of the crankshaft  102 . Therefore, the controller  4  can calculate just the pedaling force based on the torque that combines the output of the motor  20  detected by the sensor  50  and a torque of the crankshaft  102 , as well as the output torque of the motor  20 . With this, the controller  4  can control the drive unit  2  according to the pedaling force. The controller  4  can estimate the driving force for the motor  20  by measuring the electric current flowing through the motor  20 . Alternatively, the controller  4  can estimate the driving force of the motor  20  based on the command value to the motor  20 . The sensor  50  can be configured to detect the torque of the crankshaft  102 , i.e., the manual drive force. 
     The controller  4  controls the motor  20  via the inverter  6  according to the pedaling force and a detection result of the traveling state detecting unit  8 . In the first embodiment, the controller  4  controls the motor  20  via the inverter  6  in one of the plurality of operation modes. In the present embodiment, the operation modes comprises a first operation mode and a second operation mode. The first operation mode is an operation mode that assists driving with a first auxiliary force. The second operation mode is an operation mode that assists driving with a second auxiliary force that is larger than the first auxiliary force of the first operation mode. The first auxiliary force increases to the maximum, for example, to the same value as the pedaling force. The second auxiliary force also increases to the maximum, for example, to twice the pedaling force. Meanwhile, the first auxiliary force can be 0. That is, in the first operation mode, an auxiliary force by the motor  20  does not have to be generated. 
     The controller  4  also controls the electric transmission  107  according to the operation mode of the drive unit  2 , the output of the traveling state detecting unit  8 , and the detection result of the gear number sensor  107   c , The controller  4  is one example of the gear changing controller. In the first embodiment, the controller selects a gear changing range of the electric transmission  107  that can be used according to the first operation mode and the second operation mode. The controller controls the electric transmission  107  within the selected gear changing range. The controller  4  varies at least a part of the gear changing range that can be used in the first operation mode and the gear changing range that can be used in the second operation mode. The controller  4  controls the electric transmission  107  so that the maximum gear ratio that can be used during the second operation mode is larger than the maximum gear ratio that can be used during the first operation mode. The controller  4  controls the electric transmission  107  so that the minimum gear ratio that can be used during the second operation mode is larger than the minimum gear ratio that can be used during the first operation mode. The gear changing range is defined by the shift position or the gear ratio. In the first embodiment, the gear changing range is defined by the shift position. The controller  4  controls the electric transmission  107  by the gear changing command. The gear changing command is output in response to a switch operation or the traveling state of the bicycle. 
     The traveling state detecting unit  8  detects a traveling state selected from a group comprising the speed of the bicycle, the cadence of the crank, the pedaling force (the manual drive force), and the inclination of the bicycle in the traveling direction. In the first embodiment, the traveling state detecting unit  8  detects the speed of the bicycle. The traveling state detecting unit  8  comprises, for example, a magnet that is provided to the front wheel or the rear wheel, as well as a magnetic sensor that is provided to the frame and that detects the magnet. In this case, the speed of the bicycle is detected from the timing at which the magnetic sensor detects the magnet and the circumference of the wheel. Meanwhile, the traveling state detecting unit  8  may detect the rotational speed of the crankshaft  102 . For example, the traveling state detecting unit  8  comprises a magnet that is provided to crank arms  101   a  and  101   b  or the crankshaft, as well as a magnetic sensor that is disposed to the drive unit  2  in the periphery of the crankshaft  102 . In this case, the cadence of the crank can be detected from the output of the magnetic sensor. Meanwhile, since the rotational speed of the wheel is calculated from a value that multiplies the gear ratio to the cadence, the speed of the bicycle can be detected by multiplying the circumference of the rear wheel by the rotational speed. Conversely, the cadence can be detected by dividing the speed of the bicycle by the circumference of the rear wheel and the gear ratio. 
     The motor  20  is realized by, for example, a three-phase brushless DC motor and is driven by the inverter  6 . The inverter  6  converts DC to three-phase AC by a switching control, based on a command from the controller  4 . 
     The electric transmission  107  comprises a gear changing mechanism and an electric actuator. In the first embodiment, the internal gear changing mechanism  107   a , and the motor  107   b  (e.g. an electric actuator) constitutes the gear changing mechanism. The gear changing mechanism can be an exterior gear changing mechanism. The electric actuator can be a solenoid. The gear shift motor  107   b  operates the internal gear changing mechanism  107   a  in response to a gear changing command from the controller  4 . 
     The gear shifting unit  10  comprises, for example, three switches, a first switch SW 1 , a second switch SW 2 , and a third switch SW 3 . The gear shifting unit  10  gives a gear changing command and a switching command between manual shifting and automatic shifting. The controller  4  controls the electric transmission  107  by two gear shifting modes, a manual shifting mode and an automatic shifting mode. The first switch SW 1  is used for outputting an upshifting gear changing command in which the gear ratio becomes larger when in, for example, the manual shifting mode. The second switch SW 2  is used for outputting a downshifting gear changing command to the controller  4  so that the gear ratio becomes smaller when in, for example, the manual shifting mode. The third switch SW 3  is used for outputting a command to switch modes between, for example, the manual shifting mode and the automatic shifting mode to the controller  4 . The third switch SW 3  is also used for changing parameters used in the control. Meanwhile, the function of each switch from SW 1  to SW 3  can be freely set by software. In the manual shifting mode, the controller  4  controls the gear shifting motor  107   b  in response to the gear changing command from the gear shifting unit  10  and the operation mode of the drive unit  2 . In the automatic shifting mode, the controller  4  controls the electric transmission  107  in response to the detection result of the traveling state detecting unit  8  and the operation mode of the drive unit  2 . 
     In the automatic shifting mode, for example, a gear changing command is generated by comparing an upshifting threshold value TU and a downshifting threshold value TD for each shift position, as shown by way of an example in  FIG. 3 , and the gear changing command is output to the electric transmission  107 . Here, the upshifting threshold values TU( 1 )-TU( 4 ) from the first shift position to the fourth shift position are, for example, 8 km/h, 12.2 km/h, 16.4 km/h, and 20.5 km/h. The downshifting threshold values TD( 5 )-TD( 2 ) from the fifth shift position to the second shift position are, for example, 18.5 km/h, 14.6 km/h, 10.7 km/h, and 8.5 km/h. The upshifting threshold values and the downshifting threshold values can be freely set according to the physical strength of the rider, the use of the bicycle, the number of shift positions, etc. Upshifting in the present embodiment is a gear shift that increases the gear ratio, and downshifting is a gear shift that decreases the gear ratio. 
     In the first embodiment, the controller  4  selects a gear changing range of the electric transmission  107  that can be used according to the detected value of the traveling state detecting unit  8  and the operation mode, and the controller controls the electric transmission  107  to be within the selected gear changing range. The controller  4  varies at least a part of the gear changing range that can be used in the first operation mode and the gear changing range that can be used in the second operation mode. Specifically, the controller  4  controls the electric transmission  107  so that the maximum gear ratio that can be used during the second operation mode is larger than the maximum gear ratio that can be used during the first operation mode. Additionally, the controller  4  controls the electric transmission  107  so that the minimum gear ratio that can be used during the second operation mode is larger than the minimum gear ratio that can be used during the first operation mode. 
     For example, in the second operation mode, the controller  4  is programmed to control the internal gear changing mechanism  107   a  in a gear changing range between the second shift position and the fifth shift position of the five shift positions of the internal gear changing mechanism  107   a . For example, in the first operation mode, the controller  4  is programmed to control the internal gear changing mechanism  107   a  within a gear changing range between the first shift position and the fourth shift position of the five shift positions of the internal gear changing mechanism  107   a.    
     Additionally, the controller  4  controls the gear changing state in response to the operation mode when the speed of the bicycle becomes less than or equal to a prescribed value. The prescribed value includes zero, which is a stopped state. Meanwhile, the prescribed value can be a value other than zero. For example, this value can be a value that is less than or equal to 5 km per hour. When the speed of the bicycle becomes less than or equal to the prescribed value, the controller  4  controls the electric transmission  107  to be in a first gear changing state corresponding to the first operation mode when in the first operation mode. The controller also controls the electric transmission  107  to be in a second gear changing state that is different from the first gear changing state and corresponding to the second operation mode when in the second operation mode. The first gear changing state is a gear changing state in which the gear ratio is smaller than the second gear changing state. 
     In the first embodiment, the first gear changing state is, for example, the first shift position, and the second gear changing state is, for example, the third shift position. The settings of at least one of the shift position corresponding to the first gear changing state and the shift position corresponding to the second gear changing state can be selectively changed by a user. For example, one of the switches of either the gear shifting unit  10  or the assist operating unit  12  can configured to act as an input unit, which can change at least either the shift position corresponding to the first gear changing state or the shift position corresponding to the second gear changing state by operating the switch. Additionally, an external settings device serving as the input unit can be connected to the controller  4  via an interface, and the shift positions corresponding to each of the gear changing states can be freely changed by the external settings device. The external settings device can be, for example, a cycle computer, a small portable electronic device such as a smartphone, or a personal computer. 
     In the first embodiment, controlling the gear changing range is applied to both shifting modes, the manual shifting mode and the automatic shifting mode. Meanwhile, controlling the gear changing range according to the operation mode can be applied to only one of the shifting modes, either the manual shifting mode or the automatic shifting mode. The controlling the gear changing state according to the operation mode is applied to the manual shifting mode. 
     The assist operating unit  12  is configured, for example, to comprise a fourth switch SW 4 , and this unit gives a command to switch the operation mode to the controller  4 . For example, the first operation mode and the second operation mode are switched every time the fourth switch SW 4  is operated. Meanwhile, the first switch SW 1  to the fourth switch SW 4  can be switches that the rider can directly operate, such as a push button or a toggle switch, etc. However, they can also be switches that the rider can operate via an operating member, or a touch panel. 
     The operation mode and the shifting mode are, for example, displayed on a display device that is provided to a handle bar. The display device can be, for example, a liquid crystal display device that is provided to a cycle computer or a light emitting device, such as a light emitting diode. In the case of a light emitting device, the configuration can allow for the display of various modes (for example, the operation mode and the shifting mode) by color or blinking, etc. 
     Next, referring to the control flowcharts shown in  FIGS. 4 to 6  and  FIGS. 8 and 9 , one example of a specific gear changing control process that is executed by the controller  4  will be explained in accordance with the first embodiment. Meanwhile, the gear changing control process is not limited to the processes shown in these control flowcharts. 
     In  FIG. 4 , when power is supplied to the bicycle control apparatus  1  and the controller  4  goes into an operable state, in Step S 1 , the controller  4  conducts an initialization process, in which various flags and values are reset. Here, at least two types of flags are prepared, a flag AM and a flag SM. Flag AM is a flag to identify whether the operation mode is the first operation mode or the second operation mode. The flag AM is set when the second operation mode is selected by the fourth switch SW 4 , and the flag AM is reset if the flag AM is selected. Meanwhile, in the explanation below, setting a flag is presented with a “1”, and resetting a flag is represented with a “0”. The flag SM is a flag to identify whether or not the shifting mode is the manual shifting mode or the automatic shifting mode. The flag SM is set when the automatic shifting mode is selected by the third switch SW 3 , and the flag SM is reset when the manual shifting mode has been selected. Therefore, by default, when the power is turned on, the operation mode will be the first operation mode, and the shifting mode will be the manual shifting mode. Here, the operation mode is the first operation mode, and the shifting mode is the manual shifting mode when the power is turned on. However, the flags that are set immediately before turning the power off can be stored, and those flags can be set when turning the power on. 
     In Step S 2 , the controller  4  determines whether or not the fourth switch SW 4  has been operated. If the controller  4  determines that the fourth switch SW 4  has not been operated, then the operation proceeds to Step S 3 . In Step S 3 , the controller  4  determines whether or not the third switch SW 3  has been operated. If the controller  4  determines that the third switch SW 3  has not been operated, then the operation proceeds to Step S 4 . In Step S 4 , the controller reads the speed VS from the traveling state detecting unit  8 . In Step S 5 , the controller  4  determines whether or not the automatic shifting mode has been set. 
     If the controller  4  determines that the fourth switch SW 4  has been operated, then the operation proceeds from Step S 2  to Step S 6 . In Step S 6 , the controller  4  determines whether or not the flag AM has been set, that is, whether or not the current operation mode is the second operation mode. In the case that the current operation mode is not the second operation mode, the controller proceeds from Step S 6  to Step S 7 , sets the flag AM, and changes the operation mode to the second operation mode. In the case that the flag AM has been set, the controller  4  proceeds from Step S 6  to Step S 8 , resets the flag AM, and changes the operation mode to the first operation mode. Once these settings are completed, the controller  4  proceeds to Step S 3 . 
     If the controller  4  determines that the third switch SW 3  has been operated, then the operation proceeds from Step S 3  to Step S 9 . In Step S 9 , the controller  4  determines whether or not the flag SM has been set, that is, whether or not the current shifting mode is the automatic shifting mode. In the case that the current shifting mode is not the automatic shifting mode, the controller  4  advances the operation from Step S 9  to Step S 10 , sets the flag SM, and changes the shifting mode to the automatic shifting mode. In the case that the flag SM has been set, the controller  4  advances the operation from Step S 9  to Step S 11 , resets the flag SM, and changes the shifting mode to the automatic shifting mode. Once these settings have been completed, the controller  4  proceeds to Step S 4 . 
     In Step S 5 , if the controller  4  determines that the current mode is in the automatic shifting mode, then the operation proceeds to the Step S 12 . In Step S 12 , the controller  4  executes the automatic shifting operation, as shown in  FIG. 5 . In Step S 5 , when a determination is made that the current mode is in the manual shifting mode, the operation proceeds to the Step S 14 . Once the automatic shifting process of Step S 12  has been completed, the controller  4  proceeds to Step S 2 . 
     In Step S 14 , the controller  4  determines whether or not the speed VS of the bicycle is less than or equal to V 1  km/h. Here, V 1  shall be zero, so that the controller  4  determines whether or not the bicycle is stopped. If the controller  4  determines that the bicycle is not stopped in Step S 14 , that is, that the bicycle is not stopped, then the operation proceeds from Step S 14  to Step S 15 . In Step S 15 , the controller  4  executes the manual shifting process, as shown in  FIG. 6 . Once the automatic shifting process of Step S 13  has been completed, the controller  4  proceeds to Step S 2 . 
     If the controller  4  determines that the speed of the bicycle is less than or equal to V 1  km/h in Step S 14 , then the operation proceeds from Step S 14  to Step S 19 . In Step S 19 , the controller  4  determines whether or not the flag AM has been set. If the flag AM has been set and the operation mode has been set to the second mode, then the controller  4  advances the operation to Step S 20 . In Step S 20 , the controller  4  outputs a gear changing command that puts the shift position SP in the X 1  shift position to the electric transmission  107 . With this, when the current mode is in the second operation mode with a large auxiliary force, when the bicycle stops, shifting to the X 1  shift position will occur. When starting to travel after having been stopped, the gear shifting will be started from the X 1  shift position. If the flag AM has been reset and the operation mode has been set to the first operation mode in Step S 19 , then the controller  4  proceeds to the Step S 21 . In Step S 21 , the controller  4  outputs a gear changing command to the electric transmission  107  that puts the shift position SP in the X 2  shift position. With this, when the current mode is in the first operation mode with a small auxiliary force or with no auxiliary force, when the bicycle stops, shifting to the X 2  shift position will occur. When starting to travel after having been stopped, the gear shifting will be started from the X 2  shift position. The gear ratio of the X 1  shift position is larger than the gear ratio of the X 2  shift position. 
     In the automatic shifting process of  FIG. 5 , in Step S 22 , the controller  4  reads the current shift position SP from the gear number sensor  107   c . In Step S 23 , the controller  4  determines whether or not the speed VS that was read in Step S 4  exceeds an upshifting threshold value TU (SP) of the shift position SP that was read in Step S 22 . In the case that the speed VS does not exceed the upshifting threshold value TU (SP), the controller  4  proceeds from Step S 23  to Step S 24 . In Step S 24 , the controller  4  determines whether or not the speed VS that was read in Step S 4  is less than a downshifting threshold value ID (SP) of the shift position SP that was read in. In the case that the speed VS is not less than the downshifting threshold value TD (SP), since gear shifting is not necessary, the controller  4  proceeds to the shifting control Step S 14  of  FIG. 4 . 
     In the case that the speed VS that was read in exceeds the upshifting threshold value TU (SP) of the shift position SP that was read in, the controller  4  proceeds from Step S 23  to Step S 25 . In Step S 25 , the controller  4  determines whether or not the flag AM has been set, that is, whether or not the operation mode is the second operation mode. In the case that the operation mode is the second operation mode, the controller  4  proceeds from Step S 25  to Step S 26 . In Step S 26 , a determination is made regarding whether or not the current shift position SP of the electric transmission  107  is greater than or equal to an Xa 1  shift position. The Xa 1  shift position is a shift position with the largest gear ratio within the gear changing range in the second operation mode. Xa 1  is a positive integer that, in the present embodiment, is five and is the shift position with which the gear ratio becomes largest. In the case that the current shift position SP is greater than or equal to the Xa 1  shift position, the controller  4  proceeds from Step S 26  to Step S 24  without further processing. In the case that the current shift position SP is not greater than or equal to the Xa 1  shift position, the controller  4  proceeds from Step S 26  to Step S 27 . In Step S 27 , the controller  4  outputs a command to the electric transmission  107  to shift the gears from the current shift position SP to a shift position that is upshifted one gear (SP+1) and proceeds to Step S 24 . In the case that the operation mode is the first operation mode, the controller  4  proceeds from Step S 25  to Step S 28 . In Step S 28 , a determination is made regarding whether or not the current shift position SP is greater than or equal to an Xa 2  shift position. The Xa 2  shift position is a shift position with the largest gear ratio within the gear changing range in the first operation mode. Xa 2  is a positive integer that, in the present embodiment, is four. In the first operation mode, since the gear changing range is limited from the first shift position to the fourth shift position, in the case that the current shift position SP is greater than or equal to the fourth shift position, the controller  4  proceeds from Step S 28  to Step S 24  without further processing. In the case that the current shift position SP is not greater than or equal to the fourth shift position, the controller  4  proceeds from Step S 28  to Step S 27  and outputs a gear changing command that upshifts one gear to the electric transmission  107 . 
     In the case that the speed VS that was read in is less than the downshifting threshold value TD (SP) of the shift position SP that was read in, the controller  4  proceeds from Step S 24  to Step S 30 . In Step S 30 , the controller  4  determines whether or not the flag AM has been set, that is, whether or not the operation mode is the second operation mode. In the case that the operation mode is the second operation mode, the controller  4  proceeds from Step S 30  to Step S 31 . In Step S 31 , a determination is made regarding whether or not the current shift position SP of the electric transmission  107  is greater than or equal to an Xa 3  shift position. The Xa 3  shift position is a shift position with the smallest gear ratio within the gear changing range in the second operation mode. Xa 3  is a positive integer that, in the present embodiment, is two. In the case that the current shift position SP is less than or equal to the Xa 3  shift position, the controller  4  proceeds from Step S 31  to Step S 2  in  FIG. 4  without further processing. In the case that the current shift position SP is not in the first shift position, the controller  4  proceeds from Step S 31  to Step S 32 . In Step S 32 , the controller  4  outputs a command to the electric transmission  107  to shift gears from the current shift position to a shift position that is downshifted one gear and proceeds to Step S 2  in  FIG. 4 . In the case that the operation mode is the first operation mode instead of the second operation mode, the controller  4  proceeds from Step S 30  to Step S 33 . In Step S 33 , a determination is made regarding whether or not the current shift position SP is less than or equal to an Xa 4  shift position. The Xa 4  shift position is a shift position with the smallest gear ratio within the gear changing range in the first operation mode. Xa 4  is a positive integer that, in the present embodiment, is one. In the first operation mode, since the gear changing range is limited from the first shift position to the fourth shift position, in the case that the current shift position SP is less than or equal to the Xa 4  shift position, the controller  4  proceeds from Step S 33  to Step S 2  in  FIG. 4  without further processing. In the case that the current shift position SP is not less than or equal to the Xa 4  shift position, the controller  4  proceeds from Step S 33  to Step S 32  and outputs a gear changing command to the electric transmission  107  to downshift one gear. 
     In this way, the controller  4  controls the gear changing mechanism so that the minimum gear ratio of the gear changing range in the second operation mode with a large auxiliary force is larger than the minimum gear ratio of the gear changing range in the first operation mode during automatic shifting. The controller  4  also controls the gear changing mechanism so that the maximum gear ratio of the gear changing range in the second operation mode with a large auxiliary force is larger than the maximum gear changing ratio of the gear changing range in the first operation mode during automatic shifting. With this, improving the riding comfort is possible. 
     In another embodiment, the controller  4  can control the gear changing mechanism so that the minimum gear ratio of the gear changing range in the second operation mode is larger than the minimum gear ratio of the gear changing range in the first operation mode. The controller can also control the gear changing mechanism so that the maximum gear ratio of the gear changing range in the second operation mode and the maximum gear ratio of the gear changing range in the first operation mode are the same. Additionally, the controller  4  can control the gear changing mechanism so that the minimum gear ratio of the gear changing range in the second operation mode and the minimum gear ratio of the gear changing range in the first operation mode are the same. The controller can also control the gear changing mechanism so that the maximum gear ratio of the gear changing range in the second operation mode is larger than the maximum gear ratio of the gear changing range in the first operation mode. 
     In the manual shifting process of  FIG. 6 , in Step S 41 , the controller  4  reads the current shift position SP from the gear number sensor  107   c . In Step S 42 , the controller  4  determines whether or not the first switch SW 1  for the upshifting operation has been operated. In the case that the first switch SW 1  has not been operated, the controller  4  proceeds from Step S 42  to Step S 43 . In Step S 43 , the controller  4  determines whether or not the second switch SW 2  for downshifting has been operated. In the case that the second switch SW 2  has not been operated, the controller  4  proceeds to Step S 2  in  FIG. 4 . 
     In the case that the first switch SW 1  has been operated, the controller  4  proceeds from Step S 42  to Step S 45 . Step S 45  corresponds to Step S 25  in the automatic shifting control of  FIG. 5 . Step S 46  corresponds to Step S 26  in the automatic shifting control of  FIG. 5 . Step S 47  corresponds to Step S 27  in the automatic shifting control of  FIG. 5 . Step S 48  corresponds to Step S 28  in the automatic shifting control of  FIG. 5 . Thus, the redundant explanations have been omitted. In Step S 46 , in the case that the controller  4  determines that the current shift position SP is greater than or equal to the Xa 1  shift position, the operation proceeds to Step S 43  without further processing. In Step S 48 , in the case that the controller  4  determines that the current shift position SP is greater than or equal to the Xa 2  shift position, the operation proceeds to Step S 43 . Once Step S 47  has been completed, the controller  4  proceeds to Step S 43 . 
     In the case that the second switch SW 2  has been operated, the controller  4  proceeds from Step S 43  to Step S 50 . Step S 50  corresponds to Step S 30  in the automatic shifting control of  FIG. 5 . Step S 51  corresponds to Step S 31  in the automatic shifting control of  FIG. 5 . Step S 52  corresponds to Step S 32  in the automatic shifting control of  FIG. 5 . Step S 53  corresponds to Step S 33  in the automatic shifting control of  FIG. 5 . Thus, the redundant explanations have been omitted. In Step S 51 , in the case that the controller  4  determines that the current shift position SP is less than or equal to the Xa 3  shift position, the operation proceeds to Step S 2  in  FIG. 4  without further processing. In Step S 53 , in the case that the controller  4  determines that the current shift position SP is less than or equal to the Xa 4  shift position, the operation proceeds to Step S 2  in  FIG. 4  without further processing. Once Step S 52  has been completed, the controller  4  proceeds to Step S 2  in  FIG. 4 . 
     Modified Example of the First Embodiment 
     The modified example differs from the first embodiment in the configuration of the gear changing mechanism and the operations of automatic shifting and manual shifting. In the modified example, the gear changing range is defined by the gear ratio. This shows a front sprocket FC, a rear sprocket CS, the number of teeth for each sprocket, and the gear ratios obtained by their combinations. The modified example uses an electric transmission comprising an electric front derailleur (not shown) that is configured to hang the chain to the front sprocket, as well as an electric rear derailleur (not shown) that is configured to hang the chain to, for example, ten rear sprockets. The electric front derailleur and the electric rear derailleur both comprise a gear number sensor that detects to which sprocket a chain guide is positioned, that is, the shift position. Here, there are three front sprockets, which comprise a first front sprocket Low, a second front sprocket Mid, and a third front sprocket Top gears. The rear sprocket comprises the first to the tenth rear sprockets RS 1 -RS 10 . 
     In the modified example, from combinations of the three front sprockets and the ten rear sprockets, as a whole, there are 30 shift positions. However, since there are many combinations with similar gear ratios, as well as combinations in which the chain will be greatly inclined, a prescribed shifting route is set by taking into consideration the change in the gear ratio, the inclination of the chain, and smooth usage frequency. 
     In the example shown in  FIG. 7 , the controller  4  will manually shift and will automatically shift the gear changing device in, for example, 14 gear ratios. For example, as shown in  FIG. 7 , when upshifting in order from the minimum gear ratio, the rear sprocket is changed in order from the first rear sprocket RS 1  to the fifth rear sprocket RS 5  while keeping the front sprocket at first front sprocket Low. If further upshifting occurs, then the front sprocket goes to the second front sprocket Mid, and the rear sprocket is changed in order from the fourth rear sprocket RS 4  to the seventh rear sprocket RS 7 . If further upshifting occurs, then the front sprocket goes to the third front sprocket Top, and the rear sprocket is changed in order from the sixth rear sprocket RS 6  to the tenth rear sprocket RS 10 . When downshifting, the sprockets are changed in the reverse order of the order for upshifting. 
     However, the prescribed shifting route shown in  FIG. 7  is one example, and the prescribed shifting route can be set to various routes according to the number of shift positions and the gear changing range, etc. In this kind of modified example, since there are 14 shift positions, 13 upshifting threshold values are set corresponding to each shift position excluding the shift position with the maximum gear ratio, and 13 downshifting threshold values are set corresponding to each shift position excluding the shift position with the minimum gear ratio. In the same way as in the first embodiment, the upshifting threshold value from a certain gear ratio to a larger gear ratio is set to a gear ratio that is larger than the downshifting threshold value from the larger gear ratio to the certain gear ratio. 
     Additionally, the first operation mode is an operation mode in which, for example, the auxiliary force is “0”, that is, in which an auxiliary force is not generated in the drive unit  2 . The second operation mode is a mode that does generate an auxiliary force in the drive unit  2 . The gear changing range differs between the first operation mode and the second operation mode. For example, in the first operation mode, the gear changing range is limited to eleven steps from, for example, gear ratio 0.67 to gear ratio 2.47. Also, in the second operation mode, the range is limited, for example, from gear ratio 1.00 to the maximum gear ratio 3.82. Meanwhile, in an exterior gear changing mechanism comprising a derailleur, since the gears in the gear changing device cannot be shifted when stopped, in the modified example, Steps S 14  to S 21  in  FIG. 4  are not conducted. 
     An automatic gear shift control of the modified example is shown in  FIG. 8 . In  FIG. 8 , in Step S 61 , the controller  4  reads information regarding the current shift position of the electric front derailleur (the front shift position FSP) and information regarding the current shift position of the electric rear derailleur (the rear shift position RSP), with a gear number sensor that is provided to the electric front derailleur and the electric rear derailleur. In Step S 62 , the controller  4  calculates the gear ratio GR based on the front shift position FSP and the rear shift position RSP. In Step S 63 , the controller  4  determines whether or not the speed VS that was read in Step S 4  exceeds an upshifting threshold value TU (OR) of the gear ratio GR that was read in. In the case that the speed VS does not exceed the upshifting threshold value TU (GR), the controller  4  proceeds from Step S 63  to Step S 64 . In Step S 64 , the controller  4  determines whether or not the speed VS that was read in Step S 4  is less than a downshifting threshold value TD (OR) of the gear ratio GR that was read in. In the case that the speed VS is not less than the downshifting threshold value TD (GR), since gear shifting is not necessary, the controller  4  proceeds to the shifting control Step S 14  of  FIG. 4 . Meanwhile, the calculation of the gear ratio can be done through arithmetic, and the gear ratio that is obtained by the combination of the front sprocket and the rear sprocket can be stored to a memory in the controller  4  beforehand and can be read out from the memory according to the combination. 
     In the case that the speed VS that was read in exceeds the upshifting threshold value TU (GR) of the gear ratio GR that was read in, the controller  4  proceeds from Step S 63  to Step S 65 . In Step S 65 , the controller  4  determines whether or not the flag AM has been set, that is, whether or not the operation mode is the second operation mode. In the case that the operation mode is the second operation mode, the controller  4  proceeds from Step S 65  to Step S 66 . In Step S 66 , a determination is made regarding whether or not the current gear ratio GR is greater than or equal to the maximum gear ratio Ya 1  of the gear changing range of the second operation mode. In this modified example, Ya 1  is “3.82”. In the case that the current gear ratio GR is greater than or equal to “3.82”, the controller proceeds from Step S 66  to Step S 64  without further processing. In the case that the current gear ratio is not greater than or equal to Ya 1 , the controller  4  proceeds from Step S 66  to Step S 67 . In Step S 67 , the controller  4  outputs a command to the electric transmission to shift gears from the current gear ratio to a gear ratio that is upshifted by one gear and proceeds to Step S 64 . In the case that the operation mode is the first operation mode, the controller  4  proceeds from Step S 65  to Step S 68 . In Step S 68 , a determination is made regarding whether or not the gear ratio GR is greater than or equal to the maximum gear ratio Ya 2  of the gear changing range of the first operation mode. In this modified example, Ya 2  is “2.47”. In the case that the current gear ratio GR is greater than or equal to “2.47”, the controller  4  proceeds from Step S 68  to Step S 64  without further processing. In the case that the current gear ratio GR is not greater than or equal to Ya 2 , the controller  4  proceeds from Step S 68  to Step S 67 , outputs a gear changing command that shifts to a gear ratio that is upshifted one gear to the electric transmission, and proceeds to Step S 14  of  FIG. 4 . 
     In the case that the speed VS that was read in is less than the downshifting threshold value TD (GR) of the gear ratio GR that was read in, the controller  4  proceeds from Step S 64  to Step S 69 . In Step S 69 , the controller  4  determines whether or not the flag AM has been set, that is, whether or not the operation mode is the second operation mode. In the case that the operation mode is the second operation mode, the controller  4  proceeds from Step S 69  to Step S 70 . In Step S 70 , a determination is made regarding whether or not the current gear ratio GR is less than or equal to the minimum gear ratio Ya 3  of the gear changing range of the first operation mode of a prescribed shifting route. In this modified example, Ya 3  is “1.00”. In the case that the current gear ratio GR is less than or equal to “1.00”, the controller  4  proceeds from Step S 70  to Step S 14  of  FIG. 4  without further processing. In the case that the current gear ratio is not less than or equal to Ya 3 , the controller  4  proceeds from Step S 70  to Step S 71 . In Step S 71 , the controller  4  outputs a command that shifts gears from the current gear ratio to a gear ratio that is downshifted one gear to the electric transmission in a prescribed shifting route, and then the controller proceeds to Step S 14  of  FIG. 4 . In the case that the operation mode is the first operation mode, the controller  4  proceeds from Step S 69  to Step S 72 . In Step S 72 , a determination is made regarding whether or not the current gear ratio GR is less than or equal to the minimum gear ratio Ya 4  of the gear changing range of the first operation mode. In this modified example, Ya 4  is “0.67”. In the case that the current gear ratio GR is less than or equal to “0.67”, the controller  4  proceeds from Step S 72  to Step S 14  of  FIG. 4  without further processing. In the case that the current gear ratio GR is not less than or equal to Ya 4 , the controller  4  proceeds from Step S 72  to Step S 71  and outputs a gear changing command that shifts to a gear ratio that is downshifted one gear to the electric transmission. 
     Second Embodiment 
     In the second embodiment, in the automatic shifting mode, the gear changing frequency, rather than the gear changing range, is varied in the first operation mode and the second operation mode. Meanwhile, in the second embodiment, the automatic shifting process is executed by the shift position in the same way as in the first embodiment. Specifically, in order to vary the gear changing frequency according to the operation mode, in the case of automatic shifting, a first no-response time and a second no-response time from when a shifting condition is met to when gear shifting is actually conducted in relation to the operation mode are provided. The first no-response time T 1  of the first operation mode is set to, for example, two seconds, and the second no-response time T 2  of the second operation mode is set to, for example, five seconds. The first no-response time T 1  is one example of a first parameter, and the second no-response time T 2  is one example of a second parameter. With this, the gear changing frequency becomes lower when in the second operation mode than when in the first operation mode. The times of the first no-response time T 1  and the second no-response time T 2  (two seconds or five seconds) is one example, and the present invention is not limited to these values. A no-response time according to the operation mode is appropriately set according to the gear changing frequency of the bicycle. However, the second no-response time T 2  of the second operation mode with a large auxiliary force is preferably longer than the first no-response time T 1  of the first operation mode with a small auxiliary force. 
     In  FIG. 9 , in the automatic shifting mode according to the second embodiment of the present invention, in Step S 76 , the controller  4  reads the current shift position SP from the gear number sensor  107   c . In Step S 77 , the controller  4  determines whether or not the speed VS that was read in Step S 4  exceeds an upshifting threshold value TU (SP) of the shift position SP that was read in. In the case that the speed VS does not exceed the upshifting threshold value TU (SP), the controller  4  proceeds from Step S 77  to Step S 78 . In Step S 78 , the controller  4  determines whether or not the speed VS that was read in Step S 4  is less than a downshifting threshold value TD (SP) of the shift position SP that was read in. In the case that the speed VS is not less than the downshifting threshold value ID (SP), since gear shifting is not necessary, the controller  4  proceeds to the shifting control Step S 14  of  FIG. 4 . 
     In the case that the speed VS that was read in exceeds the upshifting threshold value TU (SP) of the shift position SP that was read in, the controller  4  proceeds from Step S 77  to Step S 79 . In Step S 79 , the controller  4  determines whether or not the flag AM has been set, that is, whether or not the operation mode is the second operation mode. In the case that the operation mode is the second operation mode, the controller  4  proceeds from Step S 79  to Step S 80 . In Step S 80 , the controller  4  determines whether or not a timer UT 2  that determines the shifting timing for upshifting when in the second operation mode has already started. The controller  4  comprises a timer UT 2 . The timer UT 2  is provided to measure the second no-response time T 2  of the upshifting when in the second operation mode. In the case that the timer UT 2  has not yet started, the controller  4  proceeds from Step S 80  to Step S 81 , starts the timer UT 2 , and proceeds to Step S 82 . In the case that the timer UT 2  has already started, the controller  4  proceeds from Step S 80  to Step S 82 , skipping Step S 81 . In Step S 82 , the controller  4  determines whether or not the timer UT 2  has already started. In the case that the timer UT 2  has not started, the controller  4  proceeds from Step S 82  to Step S 78  without further processing. In the case that the timer UT 2  has already started, the controller  4  proceeds from Step S 82  to Step S 83  and determines whether or not the current shift position SP is greater than or equal to the Xa 1  shift position. Meanwhile, the timer is reset when the timer starts. In the case that the shift position SP is greater than or equal to the Xa 1  shift position, the controller  4  proceeds from Step S 83  to Step S 78  without further processing. In the case that the current shift position SP is not greater than or equal to the Xa 1  shift position, the controller  4  proceeds from Step S 83  to Step S 84 . In Step S 84 , the controller  4  outputs a command to the electric transmission  107  to shift gears from the current shift position SP to a shift position that is upshifted by one gear (SP+1) and proceeds to Step S 14  of  FIG. 4 . 
     In the case that the operation mode is the first operation mode, the controller  4  proceeds from Step S 79  to Step S 85 . In Step S 85 , the controller  4  determines whether or not a timer UT 1  that determines the shifting timing for upshifting when in the first operation mode has already started. The controller  4  comprises a timer Urn. The timer UT 1  is provided to measure the first no-response time T 1  of the upshifting when in the first operation mode. In the case that the timer UT 1  has not yet started, the controller  4  proceeds from Step S 85  to Step S 87 , starts the timer UT 1 , and proceeds to Step S 87 . In the case that the timer UT 1  has already started, the controller  4  proceeds from Step S 85  to Step S 87 , skipping Step S 86 . In Step S 87 , the controller  4  determines whether or not the timer UT 1  has already started. In the case that the timer UT 1  has not started, the controller  4  proceeds from Step S 87  to Step S 78  without further processing. In the case that the timer UT 1  has already started, the controller  4  proceeds from Step S 87  to Step S 83  and, henceforth, executes the same procedure as the second operation mode. 
     In the case that the speed VS that was read in is less than the downshifting threshold value TD (SP) of the shift position SP that was read in, the controller  4  proceeds from Step S 78  to Step S 89 . In Step S 89 , the controller  4  determines whether or not the flag AM has been set, that is, whether or not the operation mode is the second operation mode. In the case that the operation mode is the second operation mode, the controller  4  proceeds from Step S 89  to Step S 90 . In Step S 90 , the controller  4  determines whether or not a timer DT 1  that determines the shifting timing for downshifting when in the second operation mode has already started. The controller  4  comprises a timer DT 2 . The timer DT 2  is provided to measure the second no-response time T 2  of the downshifting when in the second operation mode. In the case that the timer DT 2  has not yet started, the controller  4  proceeds from Step S 90  to Step S 91 , starts the timer DT 2 , and proceeds to Step S 92 . In the case that the timer DT 2  has already started, the controller  4  proceeds from Step S 90  to Step S 92 , skipping Step S 91 . In Step S 92 , the controller  4  determines whether or not the timer DT 2  has already started. In the case that the timer DT 2  has not started, the controller  4  proceeds from Step S 92  to Step S 14  of  FIG. 4  without further processing. In the case that the timer DT 2  has already started, the controller  4  proceeds from Step S 92  to Step S 93  and determines whether or not the current shift position SP is less than or equal to the Xa 3  shift position. In the case that the shift position SP is less than or equal to the Xa 3  shift position, the controller  4  proceeds from Step S 93  to Step S 14  in  FIG. 4  without further processing. In the case that the current shift position SP is not less than or equal to the first shift position, the controller  4  proceeds from Step S 93  to Step S 94 . In Step S 94 , the controller  4  outputs a command to the electric transmission  107  to shift gears from the current shift position SP to a shift position that is downshifted by one gear (SP−1) and then proceeds to Step S 14  of  FIG. 4 . 
     In the case that the operation mode is the first operation mode, the controller  4  proceeds from Step S 89  to Step S 95 . In Step S 95 , the controller  4  determines whether or not a timer DT 1  that determines the shifting timing for downshifting when in the first operation mode has already started. The controller  4  comprises a timer DT 1 . The timer DT 1  is provided to measure the first no-response time T 1  of the downshifting when in the first operation mode. In the case that the timer DT 1  has not yet started, the controller  4  proceeds from Step S 95  to Step S 97 , starts the timer DT 1 , and proceeds to Step S 97 . In the case that the timer DT 1  has already started, the controller  4  proceeds from Step S 95  to Step S 97 , skipping Step S 96 . In Step S 77 , the controller  4  determines whether or not the timer DT 1  has already started. In the case that the timer DT 1  has not started, the controller  4  proceeds from Step S 97  to Step S 14  of  FIG. 4  without further processing. In the case that the timer DT 1  has already started, the controller  4  proceeds from Step S 97  to Step S 93  and, henceforth, executes the same procedure as the second operation mode. 
     Here, when automatic shifting, in the first operation mode and the second operation mode, the controller  4  configures the delay time (the no-response time) so that the gear ratio in the second operation mode with a large auxiliary force is larger than the first operation mode and so that the gear changing frequency of the second operation mode was decreased. With this, unnecessary gear shifting will be less likely to occur during automatic shifting, and improving the riding comfort in an assisted bicycle is possible. 
     Other Embodiments 
     (a) In the first embodiment, limiting the gear changing range according to the operation mode is carried out in both shifting modes, automatic shifting and manual shifting, but the present invention is not limited to this configuration. For example, the gear changing range can be limited only to the case of automatic shifting. The gear changing range is shifted by the same number of gears in the first operation mode and the second operation mode, but the number of gears of the gear changing range can be different between the first operation mode and the second operation mode. 
     (b) In the first embodiment, the gear changing range is shifted by same number of gears in the first operation mode and the second operation mode, but the number of gears of the gear changing range can be different between the first operation mode and the second operation mode. The gear changing range can also be varied between the automatic shifting mode and the manual shifting mode. 
     (c) In the modified example of the first embodiment, the gear changing range is made to be different for the first operation mode and the second operation mode by the gear ratio, with the automatic shifting mode as an example. However, also in the manual shifting mode, in the case of manual shifting in which the gear changing range can be made different between the first operation mode and the second operation mode, Step S 63  in  FIG. 8  should be made to be the same process as Step S 42  in  FIG. 6 , and Step S 64  in  FIG. 8  should be made to be the same process as Step S 43  in  FIG. 6 . 
     (d) In the second embodiment, the gear changing frequency was changed according to the operation mode by conducting the actual gear shifting with a delay after the shifting conditions were met in both shifting directions of downshifting and upshifting with an automatic shifting. However, the present invention is not limited to this configuration. For example, the gear changing frequency can be changed according to the operation mode in only one shifting direction of the automatic shifting (for example, in downshifting only). 
     (e) In the above-described first embodiment and second embodiment, there were two operation modes, but the present invention is not limited to this. There can be three or more operation modes. The operation mode can be, for example, a mode with no assisting, a mode with a weak auxiliary force, and a mode with a strong auxiliary force. In this case, the gear changing range (or the gear changing frequency) can be different in all of the operation modes, or at least one operation mode can have a different gear changing range (or gear changing frequency) from the rest of the plurality of operation modes. 
     (f) In the above-described first embodiment and second embodiment, the speed of the bicycle was selected as the traveling state, but the traveling state is not limited to the speed of the bicycle. For example, the cadence of the crank (the rotational speed of the crank), the pedaling force, and the inclination of the bicycle in the traveling direction can be made to be the traveling state. In the case of selecting the pedaling force as the traveling state, the controller  4  can control the gear changing device so that the gear ratio will become smaller as the pedaling force becomes larger. Additionally, in the case of selecting the cadence as the traveling state, the controller  4  can control the gear ratio of the gear changing device so that the cadence will be within a prescribed range. In the case of selecting the inclination as the traveling state, the controller  4  can control the gear changing device so that the gear ratio will become smaller as the inclination becomes larger. 
     (g) In the second embodiment, times have been set for the first no-response time T 1  and the second no-response time T 2  for upshifting and downshifting. However, a different time setting can be carried out for the downshifting and the upshifting. In this case, the no-response time during downshifting can be made to be longer than the no-response time during upshifting. 
     (h) In the above-described embodiment, the controller  4  is configured to switch between the automatic gear shift control and the manual gear shift control. However, the configuration can be such that the controller  4  comprises only the automatic gear shift control or such that the controller comprises only the manual gear shift control. 
     While only selected embodiments have been chosen to illustrate the present invention, it will be apparent to those skilled in the art from this disclosure that various changes and modifications can be made herein without departing from the scope of the invention as defined in the appended claims. Thus, the foregoing descriptions of the embodiments according to the present invention are provided for illustration only, and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.