Abstract:
A bicycle antitheft device includes an antitheft mechanism switchable between an antitheft state and a release state, wherein the antitheft mechanism includes a first member that moves relative to a second member to move the bicycle forward and backward. A movement controlling mechanism hinders the first member from moving relative to the second member when the antitheft mechanism is in the antitheft state, and a selection mechanism is provided for selecting one of the antitheft state and the release state. Alternatively, the antitheft mechanism may include a sound generator for generating a sound when the first member moves relative to the second member and the antitheft mechanism is in the antitheft state. The movement controlling mechanism and the sound generator may be combined into a single antitheft mechanism. The movement controlling mechanism and/or sound generator may be installed inside of an internal transmission such as a hub or crank transmission, or they could be installed inside a handlebar control for the transmission.

Description:
BACKGROUND OF THE INVENTION 
     The present invention is directed to bicycle accessories and, more particularly, to an antitheft control device for a bicycle. 
     Bicycles, particularly recreational bicycles referred to as city cruisers, are inexpensive and are easy to ride, and are thus widely used to commute to work or school. This type of recreational bicycle is sometimes equipped with an internal gear shifter to ride at high speeds over flat terrain or to ride uphill with minimal exertion. Such internal gear shifters commonly use planet reduction mechanisms, which are compactly housed in the wheel hub. 
     Unfortunately, such recreational bicycles are often stolen from bike stands or the like in front of train stations, not out of any particular ill will, but as a kind of “quick borrow.” Bicycles which are obviously equipped with internal gear shifters are a particular target of such thefts. To prevent this type of theft, bicycle locks such as box-shaped locks and horseshoe-shaped locks are attached to the front or back fork to lock the wheel. However, the simple structure of bicycle locks makes them easy to unlock and remove. Two bicycle locks are thus sometimes attached to the front and back forks. For example, a box-shaped lock is attached to the front fork, and a horseshoe-shaped lock or chain lock is attached to the back fork. When two bicycle locks are used, there is less of a probability of theft because it is more trouble for a potential thief to unlock and take off two locks than just one. On the other hand, it is a nuisance for the owner to lock and unlock them. Similarly, when a rider is in a hurry, it is a burden to lock two locks. And even when two locks are used, bicycles can still be pedaled away and stolen by unlocking and taking off the locks. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to an antitheft device for a bicycle wherein the antitheft device can be easily activated or deactivated by the owner while also being very difficult for a thief to defeat. In one embodiment of the present invention, a bicycle antitheft device includes an antitheft mechanism switchable between an antitheft state and a release state, wherein the antitheft mechanism includes a first member that moves relative to a second member to move the bicycle forward and backward. A movement controlling mechanism hinders the first member from moving relative to the second member when the antitheft mechanism is in the antitheft state, and a selection mechanism is provided for selecting one of the antitheft state and the release state. Alternatively, the antitheft mechanism may include a sound generator for generating a sound when the first member moves relative to the second member and the antitheft mechanism is in the antitheft state. Furthermore, if desired, the movement controlling mechanism and the sound generator may be combined into a single antitheft mechanism. The movement controlling mechanism and/or sound generator may be installed inside of an internal transmission such as a hub or crank transmission, or they could be installed inside a handlebar control for the transmission. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view of a bicycle in which a particular embodiment of an antitheft device according to the present invention may be employed; 
     FIG. 2 is an oblique view of a particular embodiment of a handlebar control mechanism used with an antitheft device according to the present invention; 
     FIG. 3 is a block diagram of a particular embodiment of an electronic control mechanism that may be used with the antitheft control device according to the present invention; 
     FIG. 4 is a partial cross sectional view of a bicycle hub transmission that incorporates a particular embodiment of an antitheft device according to the present invention; 
     FIG. 5 is a diagram showing the relationship between a first sun gear and drive pawls when the hub transmission shown in FIG. 4 is in a fourth gear; 
     FIG. 6 is a diagram showing the relationship between lock pawls, drive pawls and a third sun gear when the hub transmission shown in FIG. 4 is in the fourth gear; 
     FIG. 7 is a diagram showing the relationship between a first sun gear and drive pawls when the hub transmission shown in FIG. 4 is in a locked state; 
     FIG. 8 is a diagram showing the relationship between lock pawls, drive pawls and a third sun gear when the hub transmission shown in FIG. 4 is in the locked state; 
     FIG. 9 is a detailed cross-sectional view of a particular embodiment of a sound generating mechanism according to the present invention when the bicycle is in motion; 
     FIG. 10 is a detailed cross-sectional view of the antitheft device shown in FIG. 9 when the bicycle is in a locked state; 
     FIGS.  11 ( a )- 11 ( c ) are views showing the operation of the antitheft device of FIG. 9; 
     FIG. 12 is a flow chart of a particular embodiment of a main routine for shift processing in a shift control device that incorporates an antitheft device according to the present invention; 
     FIG. 13 is a flow chart showing overall password processing in a shift control device that incorporates an antitheft device according to the present invention; 
     FIG. 14 is a flow chart showing password registration processing in a shift control device that incorporates an antitheft device according to the present invention; 
     FIG. 15 is a flow chart showing automatic shift processing in a shift control device that incorporates an antitheft device according to the present invention; 
     FIG. 16 is a flow chart showing manual shift processing in a shift control device that incorporates an antitheft device according to the present invention; 
     FIG. 17 is a partial cross sectional view of a bicycle hub transmission that incorporates an alternative embodiment of an antitheft device according to the present invention; 
     FIG. 18 is a detailed cross-sectional view of a particular embodiment of the antitheft device shown in FIG. 17 when the bicycle is in motion; 
     FIG. 19 is a detailed cross-sectional view of the antitheft devce shown in FIG. 17 when the bicycle is in a locked state; 
     FIGS.  20 ( a )- 20 ( b ) are views showing the operation of the antitheft device of FIG.  17 ; 
     FIG. 21 is a front view of a lock ring used in the antitheft device of FIG. 17; 
     FIG. 22 is an oblique view of an alternative embodiment of a handlebar control mechanism used with an antitheft device according to the present invention; 
     FIGS.  23 ( a )- 23 ( c ) are cross sectional views of a particular embodiment of a locking mechanism used with the handlebar control mechanism shown in FIG. 22; 
     FIG. 24 is a partial cross sectional view of a bicycle hub transmission that incorporates another alternative embodiment of an antitheft device according to the present invention; 
     FIG. 25 is a partial cross sectional view of a front hub that incorporates an embodiment of an antitheft device according to the present invention; 
     FIG. 26 is a partial cross sectional view of a crank transmission that incorporates an embodiment of an antitheft device according to the present invention; 
     FIGS.  27 ( a )- 27 ( c ) are views showing the operation of the antitheft mechanism of FIG. 26; 
     FIG. 28 is an oblique view of another alternative embodiment of a handlebar control mechanism used with an antitheft device according to the present invention; 
     FIG. 29 is an oblique exploded view of a particular embodiment of a lock component used in the handlebar control mechanism shown in FIG. 28; and 
     FIGS.  30 ( a )- 30 ( b ) are views showing the operation of the antitheft mechanism of FIG.  29 . 
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     FIG. 1 is a side view of a bicycle in which a particular embodiment of an antitheft device according to the present invention may be employed. The bicycle includes a frame  1  with a double-loop type of frame unit  2  and a front fork  3 ; a handle component  4 ; a drive component  5 ; a front wheel  6 ; a rear wheel  7  in which a four-speed internal shifting hub  10  is mounted; front and rear brake devices  8  (only the front brake device is shown in figure); and a shift control element  9  for conveniently operating the internal shifting hub  10 . The drive component  5  has a gear crank  18  that is provided to the lower portion (bottom bracket portion) of the frame body  2 , a chain  19  that is wrapped around the gear crank  18 , and the internal gear hub  10 . 
     Various components, including a saddle  11  and a handle component  4 , are attached to the frame  1 . A bicycle speed sensor  12  furnished with a bicycle speed sensing lead switch is mounted on the front fork  3 . This bicycle speed sensor  12  outputs a bicycle speed signal by detecting a magnet  13  mounted on the front wheel  6 . The handle component  4  has a handle stem  14  that is fixed to the upper portion of the front fork  3  and a handlebar  15  that is fixed to the handle stem  14 . Brake levers  16  and grips  17  which constitute part of the brake devices  8  are mounted at either end of the handlebar  15 . A shift control element  9  is mounted on the right-side brake lever  16 . 
     As shown in FIG. 2, the shift control element  9  has a control panel  20  formed integrally with the right-side (front-wheel) brake lever  16 , two control buttons  21  and  22  disposed next to each other to the left and right on the lower portion of the control panel  20 , a control dial  23  disposed above the control buttons  21  and  22 , and a liquid-crystal display component  24  disposed to the left of the control dial  23 . The current riding speed is displayed on the liquid-crystal display component  24 , as is the speed step selected at the time of the shift. 
     The control buttons  21  and  22  are triangular push buttons. The control button  21  on the left side is used to perform shifts to a higher speed step, while the control button  22  on the right side is used to perform shifts to a lower speed step. The control dial  23  is used to switch among two shifting modes and a parking mode (P), and it has three stationary positions: P. A, and M. Here, the shift mode comprises an automatic shift (A) mode and a manual shift (M) mode. The automatic shift mode is for automatically shifting the internal shifting hub  10  by means of a bicycle speed signal from the bicycle speed sensor  12 , and the manual shift mode is for shifting the internal shifting hub  10  through the operation of the control buttons  21  and  22 . The parking mode is for locking the internal shifting hub  10  and controlling the rotation of the rear wheel  7 . 
     A shift control component  25  (FIG. 3) that is used to control shifting is housed inside the control panel  20 . The shift control component  25  comprises a microcomputer consisting of a CPU, a RAM, a ROM, and an I/O interface. As shown in FIG. 3, the shift control component  25  is connected to the bicycle speed sensor  12 , an actuation position sensor  26  composed of a potentiometer (for example, a potentiometer that senses the actuation position of the internal shifting hub  10 ), the control dial  23 , and the control buttons  21  and  22 . The shift control component  25  is also connected to a power supply  27  (consisting of a battery), a motor driver  28 , the liquid-crystal display component  24 , a memory component  30 , and another input/output component. A shift motor  29  is connected to the motor driver  28 . Various types of data, such as the password (PW) discussed below or the tire diameter, are stored in the memory component  30 . The relation between the speed step and the speed during the automatic shift mode is also stored. The shift control component  25  controls the motor  29  according to the various modes, and also controls the display of the liquid-crystal display component  24 . 
     As shown in FIG. 4, the internal gear hub  10  primarily has a hub axle  41  that is fixed to the rear portion of the bicycle frame  1 , a driver  42  that is located around the outer periphery at one end of the hub axle  41 , a hub shell  43  that is located around the outer periphery of the hub axle  41  and driver  42 , a planet gear mechanism  44  for transmitting motive power between the driver  42  and the hub shell  43 , and a sound-generating mechanism  100  for antitheft purposes. The planet gear mechanism  44  is made up of a total of four steps, one direct and three speed-increasing. 
     The driver  42  is a roughly cylindrical member, one end of which is rotatably supported by the hub axle  41  via balls  45  and a hub cone  46 . A hub cog  47  is fixed as an input element around the outer periphery at one end. A notch  42   a  that expands outward in the radial direction from the space in the center is formed in the driver  42 . Three of these notches  42   a  are formed at roughly equal angles in the circumferential direction. 
     The hub shell  43  is a cylindrical member having a plurality of steps in the axial direction, and the driver  42  is housed in a housing space  43   a  around the inner periphery thereof. One side of the hub shell  43  is rotatably supported around the outer periphery of the driver  42  via balls  50 , and the other by the hub axle  41  via balls  51  and a hub cone  52 . Flanges  53  and  54  for supporting the spokes  7   a  (FIG. 1) of the rear wheel  7  are fixed around the outer periphery at both ends of the hub shell  43 . A cover  55  is fixed to the outer side wall at one side of the driver  42 , and the distal end of the cover  55  extends so as to cover the outer peripheral surface at one end of the hub shell  43 . A sealing member  56  is positioned between the inner peripheral surface at the distal end of the cover  55 , and the outer peripheral surface of the hub shell  43 . 
     The planet gear mechanism  44  is housed in the housing space  43   a  inside the hub shell  43 , and has first, second, and third sun gears  60 ,  61 , and  62 , three planet gears  63 ( a-c ) (only one planet gear is shown in the figures) that mesh with these, and a ring gear  64 . The sun gears  60  to  62  are lined up in the axial direction around the inner periphery of the driver  42  and the outer periphery of the hub axle  41 , and furthermore are allowed to rotate relative to the hub axle  41 . The planet gears  63  are rotatably supported via a support pin  65  within the notches  42   a  in the driver  42 . A first gear  63   a , a second first gear  63   b , and a third gear  63   c  are formed integrally with the planet gears  63 . The first gear  63   a  meshes with the first sun gear  60 , the second gear  63   b  meshes with the second sun gear  61 , and the third gear  63   c  meshes with the third sun gear  62 . The ring gear  64  is located on the outer peripheral side of the planet gears  63 , and inner teeth are formed around the inner periphery. This ring gear  64  meshes with the second gear  63   b  of the planet gears  63 . 
     As shown in FIGS. 5 to  8 , a pair of stopping protrusions  41   a  are formed at the locations where the sun gears  60  to  62  are disposed. Four housing spaces  60   a  to  62   a  are formed apart from each other in the peripheral direction around the inner periphery of the sun gears  60  to  62 . The first sun gear  60  is depicted in FIGS. 5 and 7, whereas the third sun gear  62  is depicted in FIGS. 6 and 8. Between the hub axle  41  and the inner periphery of the sun gears  60  to  62  are positioned a selective clutch mechanism  70  for preventing the sun gears  60  to  62  from performing relative rotation in the forward direction or for allowing them to rotate relative to the hub axle  41 , a lock mechanism  90  for preventing the third sun gear  62  from performing relative rotation in the opposite direction from the forward direction or for allowing it to perform relative rotation, and an actuation mechanism  91  for actuating the selective clutch mechanism  70  and the lock mechanism  90 . These actuation mechanism  91 , lock mechanism  90 , and sound-generating mechanism  100  constitute an antitheft device. 
     The selective clutch mechanism  70  has a function whereby it selectively links one of the three sun gears  60  to  62  to the hub axle  41 , and a function whereby it does not link any of the sun gears  60  to  62  to the hub axle  41 . The selective clutch mechanism  70  has a plurality of drive pawls  71 ,  72 , and  73  that are disposed in the housing spaces  60   a  to  62   a  of the sun gears  60  to  62 , and the distal ends of which are able to mesh with the stopping protrusions  41   a  of the hub axle  41 , and has annular wire springs  74 ,  75 , and  76  for energizing the distal ends of the drive pawls  71  to  73  toward the hub axle  41 . The drive pawls  71  to  73  are swingably supported at their base ends in the pawl housing spaces  60   a  to  62   a  where they face each other, and are able to mesh at their distal ends with the stopping protrusions  41   a . When the drive pawls  71  to  73  are stopped by the stopping protrusions  41   a  of the hub axle  41  and thereby linked to the hub axle  41 , the sun gears  60  to  62  are no longer able to rotate in the forward direction (clockwise in FIG. 5) in relation to the hub axle  41  but can perform relative rotation in the opposite direction (counterclockwise in FIG.  5 ). When the drive pawls are released, relative rotation is possible in both directions. 
     The lock mechanism  90 , as shown in FIG. 6, has a pair of lock pawls  92  which are capable of meshing at their distal ends with the stopping protrusions  41   a  of the hub axle  41  at the inner surface of the third sun gear  62  and which are positioned in the pawl housing space  62   a  of the third sun gear  62 . The distal ends of the lock pawls  92  are energized toward the hub axle  41  by the wire spring  76  that energizes the drive pawls  73 . The lock pawls  92  are swingably supported at their base ends in another pawl housing space  62   a  opposite from the pawl housing space  62   a  in which the drive pawl  73  is housed, and they are capable of meshing at their distal ends with the stopping protrusions  41   a  on the opposite side from the drive pawls  73 . When the lock pawls  92  are stopped by the stopping protrusions  41   a  of the hub axle  41  and thereby linked to the hub axle  41 , the third sun gear  62  is no longer able to rotate relatively in the opposite direction from the forward direction (counterclockwise in FIG.  6 ), but is able to rotate relatively in the forward direction (clockwise in FIG.  6 ). When the lock pawls are released, relative rotation is possible in both directions. 
     The actuation mechanism  91  has a sleeve  77 . The sleeve  77  is rotatably fitted over the outer periphery of the hub axle  41 , and has a plurality of drive cam components  94   a  and lock cam components  94   b  at the locations where the drive pawls  71  to  73  and the lock pawls  92  are disposed on the outer periphery. When these drive cam components  94   a  strike any of the drive pawls  71  to  73 , and the lock cam components  94   b  strike lock pawls  92 , the struck pawls are raised, and the linkage between the hub axle  41  and the sun gears  60  to  62  is released by these pawls. An operator  78  is fixed to one end of the sleeve  77 , and the sleeve  77  can be rotated by the rotation of the operator  78 . The rotation of the sleeve  77  then causes the cam components  94  to selectively actuate the drive pawls  71  to  73  and the lock pawls  92 , so that the linkage and locking of the sun gears  60  to  62  with the hub axle  41  are controlled. 
     As shown in FIG. 4, a reduction mechanism  95  is linked to the operator  78 . The reduction mechanism  95  reduces the speed of rotation of the shift motor  29 , and transmits rotation to the operator  78 . The actuation position sensor  26 , which is used to fix the sleeve  77  of the internal shifting hub  10  in one of the actuation positions VP (in one of the shift positions V 1  to V 4  of the speed steps or in the locked position PK), is disposed inside the reduction mechanism  95 . 
     With a structure such as this, a large speed-increasing power transmission path with the largest speed increasing ratio is created when the drive pawl  71  strikes a stopping protrusion  41   a  of the hub axle  41 , and the first sun gear  60  is selected; a medium speed-increasing power transmission path with the second-largest speed increasing ratio is created when the second sun gear  61  is selected; and a small speed-increasing power transmission path with the smallest speed increasing ratio is created when the third sun gear  62  is selected. If none of the sun gears has been selected, then a direct-coupled power transmission path is created. Also, when the lock pawls  92  strike the stopping protrusions  41   a  of the hub axle  41 , rotation of the third sun gear  62  is locked in the opposite direction from the forward direction, and when another sun gear (such as the first sun gear  60 ) is linked with the hub axle  41  by the drive pawls, the internal shifting hub  10  is locked. 
     A first one-way clutch  80  is provided between the inner peripheral surface of the hub shell  43  and the outer peripheral surface at the other end of the driver  42 . A second one-way clutch  81  is provided between the inner peripheral surface of the hub shell  43  and the outer peripheral surface of the ring gear  64 . These one-way clutches  80  and  81  are both roller-type, one-way clutches, which reduces noise during idle running when a shift is made, softens the shock when a shift is made, and allows for smoother shifting. 
     The sound-generating mechanism  100  is provided to the left end (in FIG. 4) of the hub axle  41  within the hub shell  43 . As shown in FIGS. 9 to  11 , the sound-generating mechanism  100  has a spring washer  101  that rotates integrally with the sleeve  77 , a noise-emitting cam  102  positioned on the hub axle  41  such that it is able to move in the axial direction but unable to rotate, a noise-emitting washer  103  that presses against the noise-emitting cam  102 , and a noise-emitting spring  104  disposed in a compressed state between the noise-emitting washer  103  and the hub cone  52 . 
     The spring washer  101  is a member that is nonrotatably stopped by the sleeve  77 , and it has around its outer periphery an engagement tab  105  that strikes the noise-emitting cam  102 . The noise-emitting cam  102  has a cylindrical cam body  106  and a stopping washer  107  that stops the cam body  106  and the hub axle  41  such that they can move in the axial direction but cannot rotate. A cam component  108  that strikes the engagement tab  105  is formed at the right end (in FIG. 11) of the cam body  106 . The cam component  108  is formed such that the cam body  106  is moved axially to the left by the rotation of the sleeve  77  toward the locked position PK. A large number of noise-emitting grooves  109  are formed at regular intervals in the circumferential direction at the left end of the cam body  106 . The noise-emitting grooves  109  are inclined in the forward direction. 
     The noise-emitting washer  103  has a disk-shaped washer body  110  and a ratchet pawl  111  that is swingably supported on the washer body  110 . Numerous noise-emitting tabs  112  that engage with the noise-emitting grooves  109  are formed around the outer periphery of the washer body  110 . The ratchet pawl  111  is able to mesh with ratchet teeth  113  formed in the inner peripheral surface of the hub shell  43  when the hub shell  43  rotates in the forward direction. This sound-generating mechanism  100  emits noise through the vibration of the noise-emitting washer  103  when the sleeve  77  is in the locked position and when the rear wheel  7  rotates in the forward direction. 
     Shifting and locking are performed by actuating the shift motor  29  through mode selection with the control dial  23  of the shift control element  9 , through shift operation with the control buttons  21  and  22 , and through rotating the sleeve  77  via the operator  78 . FIG. 12 is a flow chart illustrating the actuation and control of the shift control component  25 . 
     When the power is turned on, initialization is performed in step S 1 . Here, circumference data used for calculating speed is set to a diameter of 26 inches, and the speed step is set to second gear (V 2 ). In step S 2 , a decision is made as to whether the control dial  23  has been set to the parking mode. In step S 3 , a decision is made as to whether the control dial  23  has been set to the automatic shift mode. In step S 4 , a decision is made as to whether the control dial  23  has been set to the manual shift mode. In step S 5 , a decision is made as to whether some other processing, such as tire diameter input, has been selected. 
     When the control dial  23  is turned to position P and set to the parking mode, the flow goes from step S 2  to step S 10 . In step S 10 , the dial P processing shown in FIG. 13 is executed. When the control dial  23  is turned to position A and set to the automatic shift mode, the flow goes from step S 3  to step S 11 . In step S 11 , the automatic shift processing shown in FIG. 15 is executed. When the control dial  23  is turned to position M and set to the manual shift mode, the flow goes from step S 4  to step S 12 . In step S 12 , the manual shift processing shown in FIG. 16 is executed. When other processing is selected, the flow goes from step S 5  to step S 13 , and the selected processing is executed. 
     With the dial P processing in step S 10 , a decision is made as to whether 30 seconds has elapsed since the dial was turned to position P in step S 21  in FIG.  13 . In step S 22 , a decision is made as to whether the password PW has been registered. This decision is made on the basis of whether the password PW has already been stored in the memory component  30 . If the password has already been registered, the flow moves on to step S 23 . 
     In step S 23  a decision is made as to whether the left control button  21  has been operated. The purpose of operating the control buttons  21  and  22  here is to input the password for unlocking the locked internal shifting hub  10 . In step S 24  a decision is made as to whether the right control button  22  has been operated. In step S 25  a decision is made as to whether the password LR inputted by operation of the two control buttons  21  and  22  matches the registered password PW. If there is no match, the flow moves on to step S 26 . In step S 26  a decision is made as to whether the password still does not match after it has been inputted three times. If it has yet to be inputted three times, the flow returns to step S 23 , and the re-inputting of the password is permitted. If the password does not match the registered password PW after three inputs, the flow moves on to step S 27 . In step S 27 , the system waits for 10 minutes to pass, and when 10 minutes have elapsed, the flow returns to step S 23 , and the re-inputting of the password is permitted. 
     Once 30 seconds have elapsed since the dial was turned to the P position, the flow moves from step S 21  to step S 30 . In step S 30 , the shift motor  29  is driven by the motor driver  28 , and the actuation position VP is set to the locked position PK. As a result, the sleeve  77  is rotated via the operator  78 , the drive pawl  71  is raised as shown in FIGS. 7 and 8 so that the first sun gear  60  and the hub axle  41  are locked in just the forward direction, and the lock pawls  92  are raised so that the third sun gear  62  and the hub axle  41  are nonrotatably locked in the opposite direction from the forward direction. When the two sun gears  60  and  62  are thus locked, if an attempt is made to rotate the driver  42  by rotating the crank gear  18 , the system will try to make the largest upshift since the first sun gear  60  is locked in the forward direction, but since the third sun gear  62  cannot turn backward, the planet gear mechanism  44  is locked and cannot move. Accordingly, the bicycle cannot be pedaled away, making its theft more difficult. 
     If the bicycle is pushed by hand at this point, the one-way clutch  80  will allow it to move forward even if the planet gear mechanism  44  is locked. If, however, the sleeve  77  is rotated to the locked position PK, the cam body  106  of the sound-generating mechanism  100  will be pressed by the engagement tab  105  of the spring washer  101  that rotates along with the sleeve  77 , and will move from the position indicated by (A) in FIGS. 9 and 11 to the positions indicated by (B) and (C) in FIGS. 10 and 11 (that is, will move to the left in the axial direction). As a result, the ratchet pawl  111  of the noise-emitting washer  103  meshes with the ratchet teeth  113  of the hub shell  43 , and rotates integrally with the hub shell  43  only in the forward direction. At this point, the noise-emitting tabs  112  of the noise-emitting washer  103  go in and out of the noise-emitting grooves  109  of the noise-emitting cam  102 , creating a loud impact sound. Consequently, a loud noise is produced when the bicycle is pushed by hand in a locked state, and this also deters theft. 
     If the password PW has not been registered, the flow moves from step S 22  to step S 31 . In step S 31 , the code registration processing illustrated in FIG. 14 is executed. Here, a decision is made as to whether the control button  21  was operated in step S 41  in FIG.  14 . If the control button  21  was operated, the flow moves to step S 42 , and the left number L (a 10-digit number) is increased by one. In step S 43  a decision is made as to whether the control button  22  was operated. The flow returns to step S 41  until the control button  22  is pushed, and the left number L is increased by one. When the control button  22  is operated, the flow moves to step S 44 , and the right number R (a 1-digit number) is increased by one. In step S 45  a decision is made as to whether the control button  21  was operated again. The flow returns to step S 43  until the control button  21  is operated, and the right number R is increased by one. When the control button  21  is operated, the flow moves to step S 46 , and the inputted number LR is stored as the password PW in the memory component  30 . A password PW is thus registered after being selected from among 100 two-digit numbers LR ranging from “00” to “99.” 
     In step S 23 , if it is decided that the control button  21  was operated during unlocking, the flow moves on to step S 32 . In step S 32  the left number L is increased by one, just as when the password was registered. If it is decided that the control button  22  was operated, the flow moves from step S 24  to step S 33 . In step S 32 , the right number R is increased by one, just as when the password was registered. If the inputted number LR matches the password PW in step S 25 , the flow moves to step S 34 , and the actuation position VP is set to first gear V 1 . As a result, the sleeve  77  is rotated by the shift motor  29  and positioned at the first gear V 1 , the lock pawl  92  of the third sun gear  62  comes out, and all of the drive pawls  71  to  73  come out. This means that all of the sun gears  60  to  62  are free to rotate with respect to the hub axle  41 . As a result, when the bicycle is pedaled, the rotation of the driver  42  is transmitted directly to the hub shell  43  via the first one-way clutch  80 . 
     With the automatic shift processing of step S 11 , the actuation position VP is set to a speed step corresponding to the bicycle speed SP. When the position is different from this, shifts are made one gear at a time toward this. Here, in step S 51  in FIG. 15, a decision is made as to whether the bicycle speed SP is at or below the speed S 1  on the basis of the speed signal from the bicycle speed sensor  12 . In step S 52  a decision is made as to whether the bicycle speed SP is over the speed S 1  and at or below the speed S 2 . In step S 53  a decision is made as to whether the bicycle speed SP is over the speed S 2  and at or below the speed S 3 . In step S 54  a decision is made as to whether the bicycle speed SP is over the speed S 3 . 
     When the bicycle speed SP is low (at or below the speed S 1 ), the flow moves from step S 51  to step S 55 . In step S 55  a decision is made as to whether the current actuation position VP is first gear V 1 . If the actuation position VP is not first gear V 1 , the flow moves on to step S 56 , and the actuation position VP is adjusted to first gear V 1  one speed step at a time. If the bicycle speed SP is medium low (over the speed S 1  and at or below the speed S 2 ), the flow moves from step S 52  to step S 57 . In step S 57  a decision is made as to whether the current actuation position VP is second gear V 2 . If the actuation position VP is not second gear V 2 , the flow moves on to step S 58 , and the actuation position VP is adjusted to second gear V 2  one speed step at a time. If the bicycle speed SP is medium high (over the speed S 2  and at or below the speed S 3 ), the flow moves from step S 53  to step S 59 . In step S 59  a decision is made as to whether the current actuation position VP is third gear V 3 . If the actuation position VP is not third gear V 3 , the flow moves on to step S 60 , and the actuation position VP is adjusted to third gear V 3  one speed step at a time. If the bicycle speed SP is high (over the speed S 3 ), the flow moves from step S 54  to step S 61 . In step S 61  a decision is made as to whether the current actuation position VP is fourth gear V 4 . If the actuation position VP is not fourth gear V 4 , the flow moves on to step S 62 , and the actuation position VP is adjusted to fourth gear V 4  one speed step at a time. 
     Here, when the first sun gear  60  and the hub axle  41  are linked by the shift motor  29 , the bicycle is in fourth gear V 4 , the rotation inputted from the chain wheel to the driver  42  is increased by the largest gear ratio determined by the number of teeth on the first sun gear  60 , the first gear  63   a  and second gear  63   b  of the planet gears  63 , and the ring gear  64 , and this rotation is transmitted to the hub shell  43  via the second one-way clutch  81 . When the second sun gear  61  is selected and linked to the hub axle  41 , the bicycle is in third gear V 3 , the rotation of the driver  42  is increased by a medium (the second largest) gear ratio determined by the number of teeth on the second sun gear  61 , the second gear  63   b  of the planet gears  63 , and the ring gear  64 , and this rotation is transmitted to the hub shell  43  via the second one-way clutch  81 . When the third sun gear  62  is selected and linked to the hub axle  41 , the bicycle is in second gear V 2 , the rotation of the driver  42  is increased by the smallest gear ratio determined by the number of teeth on the third sun gear  62 , the second gear  63   b  and third gear  63   c  of the planet gears  63 , and the ring gear  64 , and this rotation is transmitted to the hub shell  43  via the second one-way clutch  81 . If none of the sun gears  60  through  62  is selected, first gear V 1  is engaged, and the rotation of the driver  42  is transmitted directly to the hub shell  43 , as above. Unselected sun gears perform relative rotation in the opposite direction from the forward direction with respect to the hub axle  41 . When any one of the sun gears is selected and speed is stepped up by the planet gear mechanism  44 , the driver  42  and the hub shell  43  perform relative rotation in the direction in which meshing with the first one-way clutch  80  is released. 
     With the manual shift processing of step S 11 , gear shifts are made one at a time by operation of the control buttons  21  and  22 . In step S 71  in FIG. 16 a decision is made as to whether the control button  21  was operated. In step S 72  a decision is made as to whether the control button  22  was operated. When the control button  21  is operated, the flow moves from step S 71  to step S 73 . In step S 73  a decision is made as to whether the current actuation position VP is fourth gear V 4 . If the current actuation position VP is fourth gear V 4 , the flow moves on to step S 74 , and fourth gear V 4  is maintained without a shift being made. If the current actuation position VP is not fourth gear V 4 , then the flow moves to step S 75 , and the actuation position VP is moved one speed step higher. When the control button  22  is operated, the flow moves from step S 71  to step S 73 . In step S 73  a decision is made as to whether current actuation position VP is first gear V 1 . If the current actuation position VP is first gear V 1 , the flow moves on to step S 77 , and first gear V 1  is maintained without a shift being made. If the current actuation position VP is not first gear V 1 , the flow moves to step S 78 , and the actuation position VP is moved one speed step lower. During these shifts, the sensing results from the actuation position sensor  26  are compared with the positional data for each actuation position stored ahead of time in the memory component  30 , the results of which are used to perform positioning control of the shift motor  29 . 
     Thus, according to this embodiment, entering the parking mode with the aid of the control dial  23  allows this mode to be maintained as long as the entered password does not match the registered password, and hence impedes the unlocking of the antitheft device containing the lock mechanism  90 . In addition, entering the parking mode with the aid of the control dial  23  allows the planetary gear mechanism  44  to be locked by the lock mechanism  90  and the sound-generating mechanism  100  to produce a sound, making it impossible for an unauthorized person to pedal the bicycle away and generating a sound when the bicycle is pushed. This arrangement can minimize bicycle theft. 
     In the above-described embodiment, a lock mechanism  90  was provided between a hub axle  41  and a sun gear  62  that performed relative rotation, and a sound-generating mechanism  100  was separately provided between the hub axle  41  and the hub shell  43  to prevent theft. It is also possible, however, to position an antitheft device  85  endowed with sound-generating and locking functions between the hub axle  41  and the hub shell  43 , that is, to provide the device to a running component that performs relative rotation as shown in FIG.  17 . 
     As shown in FIG. 17, an internal shifting hub  10   a  has an antitheft device  85  in which the sound-generating mechanism  100  in FIG. 4 is endowed with a locking function in addition to a sound-generating function. The sun gear  62  is therefore devoid of any lock pawls. Except for the presence of the antitheft device  85 , this embodiment has the same structure and operation as embodiment shown in FIG. 4, and the corresponding description will therefore be omitted. 
     The antitheft device  85  is provided to the left end (in FIG. 17) of the hub axle  41  within the hub shell  43 . As shown in FIGS. 18 through 20, the antitheft device  85  has a spring washer  101   a  that rotates integrally with the sleeve  77 , a moving cam  102   a , a moving member  103   a , a moving spring  104   a , and a lock ring  114 . The moving cam  102   a  is nonrotatably installed while allowed to move axially in relation to the hub axle  41 . The moving member  103   a  presses against the moving cam  102   a , the moving spring  104   a  is disposed in a compressed state between the moving member  103   a  and a hub cone  52 , and the lock ring  114  is pressed against the moving member  103   a.    
     The spring washer  101   a  is a member that is nonrotatably stopped by the sleeve  77 , and it has around its outer periphery an engagement tab  105   a  that strikes the moving cam  102   a . The moving cam  102   a  has a cylindrical cam body  106   a  and a stopping washer  107   a  that stops the cam body  106   a  and the hub axle  41  such that they can move in the axial direction but cannot rotate. A cam component  108   a  that strikes the engagement tab  105   a  is formed at the right end (in FIG. 20) of the cam body  106   a . The cam component  108   a  is formed such that the cam body  106   a  is moved axially to the right by the rotation of the sleeve  77  toward the locked position PK. 
     The moving member  103   a  has a disk-shaped flange component  115  and a cylindrical component  116  integrally formed along the inner periphery of the flange component  115 . A step  1   15   a  is formed on the flange component  115  in its midportion as viewed in the radial direction. A lock ring  114  is rotatably supported by the step  115   a . As shown in FIG. 21, respective radial irregularities  114   a  (only those located on the side of the lock ring  114  are shown) are formed on the surface of the flange component  115  facing the lock ring  114  and on the surface of the lock ring  114  facing the flange component  115 . The presence of such irregularities  114   a  increases the frictional force between the lock ring  114  and the moving member  103   a  and causes these components to vibrate and to produce sound during relative rotation. Serration teeth  114   b  are formed in the outer peripheral portion of the lock ring  114 , as shown in FIG.  21 . These serration teeth  114   b  can engage with serration teeth  113   a  formed in the inner peripheral surface of the hub shell  43 . 
     Four protrusions  116   a  are formed on the inner peripheral surface of the cylindrical component  116  as shown in FIG.  21 . The protrusions  116   a  engage four grooves  41   c  formed in the outer peripheral surface of the hub axle  41 . As a result of this arrangement, the moving member  103   a  is nonrotatably supported by the hub axle  41  while allowed to move in the axial direction. A thread and a stopping groove are formed in the outer peripheral surface of the cylindrical component  116 . A pressure ring  117  is mounted around the outside of the cylindrical component  116  as shown in FIG.  18 . The pressure ring  117 , which is nonrotatably supported on the cylindrical component  116  while allowed to move in the axial direction, is allowed to come into contact with the lock ring  114 . In addition, a pressure nut  118  is screwed on the outer periphery at the right end of the cylindrical component  116 . A coned disk spring  119  is disposed between the pressure nut  118  and the pressure ring  117 . 
     The pressure exerted by the coned disk spring  119  can be adjusted by adjusting the fastening of the pressure nut  118 ; the frictional force between the lock ring  114  and the flange component  115  of the moving member  103   a  can be adjusted via the pressure ring  117 ; and the rotation of the hub shell  43  can be controlled arbitrarily. For example, maximizing the frictional force produced by the coned disk spring  119  makes it possible to bring the system into a locked state with minimal rotation of the hub shell  43 . Furthermore, reducing the frictional force weakens the force with which the rotation of the hub shell  43  is controlled and allows the hub shell  43  to rotate in relation to the hub axle  41 . In this case as well, a frictional force is generated when the coned disk spring  119  is energized, and the rotation is controlled, unlike in a free-rotating state. This embodiment allows the rotation of the hub shell  43  (that is, the rotation of the rear wheel  7 ) to be freely controlled by adjusting the energizing force of the coned disk spring  119  within a range that extends essentially from the locked state to the free-rotating state. 
     In the antitheft device  85  thus configured, the engagement tab  105   a  of the spring washer  101   a  rotating along the sleeve  77  moves into the cam component  108   a  when the sleeve  77  is rotated from a shift position to the locked position PK. When the engagement tab  105  moves into the cam component  108   a , the moving cam  102   a  and the moving member  103   a  energized by the moving spring  104   a  move to the right from the position designated as (A) in FIGS. 18 and 20 to the position designated as (B) in FIGS. 19 and 20. As a result of this, the serration teeth  114   b  of the lock ring  114  engage with the serration teeth  113   a  of the hub shell  43 , and the rotation of the hub shell  43  is controlled by the force of friction between the lock ring  114  and the moving member  103   a . The corresponding frictional force can be altered as needed by adjusting the energizing force of the coned disk spring  119  through the tightening of the pressure nut  118 . Therefore, pedaling fails to rotate the rear wheel  7  or rotates it only slightly. 
     At this time, an attempt to forcefully turn the hub shell  43  results in the relative rotation of the moving member  103   a  and the lock ring  114  and causes the lock ring  114  and the moving member  103   a  to vibrate and to emit a loud vibrating noise under the action of the irregularities  114   a . Thus, loud noise is produced when the bicycle is pressed by hand or the pedals are pressed and the hub shell  43  is rotated in the locked state, making the bicycle more difficult to steal. Another feature is that even when the sleeve  77  is mistakenly placed in the locked position by an accidental action during riding, the rear wheel  7  is still prevented from being locked abruptly because the rotation of the rear wheel  7  is controlled by friction. 
     In the first embodiment described above, the sun gears are locked to prevent the bicycle from being pedaled away when the sleeve  77  is in the locked position. However, the bicycle can still be moved by pushing. By contrast, this embodiment entails directly coupling the hub shell  43  with the hub axle  41  to achieve locking. This controls the rotation of the hub shell  43  (and rear wheel  7 ) even when an attempt is made to push the bicycle, making it more difficult to push the bicycle and reducing the likelihood of a theft. 
     Although the two embodiments described above referred to internal shifting hubs  10  and  10   a  in which an operator  78  was actuated by a motor, it is also possible to rotate a sleeve and to perform shifting and antitheft locking by linking a shift control element and an operator with the aid of a shifting cable, and by mechanically operating the shift control element. For example, in FIG. 22 the shift control element  9   a  has a body unit  160  formed integrally with the right-side brake lever  16  and a control element  161  rotatably mounted on the body unit  160 . The body unit  160  has a circular display component  162  for displaying a shift position or the parking position and a lock component  163  for maintaining the control element  161  in the parking position when this position has been reached. 
     The display component  162  has a transparent dial  164  on which numbers indicating shift positions 1 through 4 and a letter indicating parking position P are marked at regular intervals in the circumferential direction, and an indicator  165  that rotates in conjunction with the rotation of the control element  161  on the reverse side of the dial  165 . The indicator  165  points to one of the five positions comprising a parking position and four shift positions. 
     As shown in FIG. 23, the lock component  163  has a cylindrical lock  170 , a lock cam  171  that rotates in conjunction with the cylindrical lock  170 , a lock body  172  actuated by the lock cam  171 , and a leaf spring  173  for energizing the lock body  172  to the right in FIG.  23 . 
     The lock cam  171  is an oval member that is rotated by the rotating cylindrical lock  170 , assuming a normal position achieved during shifting and shown in FIG. 23A as a straight-up position, an open position achieved by a 45-degree turn to the left from the normal position and shown in FIG. 23B, and a locked position achieved by a 90-degree turn to the right from the normal position and shown in FIG.  23 C. 
     The lock body  172  is a rectangular member provided with a rectangular opening  172   a  in the center and supported while allowed to move to the left and right in FIG. 23 inside a rectangular opening  160   a  formed within the body unit  160 . The outer peripheral surface of the lock cam  171  presses against the inner peripheral surface of the opening  172   a  in the lock body  172 . The vertical dimension of the opening  172   a  [is] considerably greater than the lengthwise dimension of the lock cam  171 . In addition, the transverse dimension is slightly greater than the medium lengthwise dimension of the lock cam  171  so that the lock body  172  cannot move in any significant way to the right or left when the lock cam  171  is in the locked position. A rectangular stopping protrusion  174  is formed on the lateral surface of the lock body  172  facing the control element  161 . 
     The end face of the control element  161  facing the body unit is provided with a stopping groove  166  that is stopped by the stopping protrusion  174  in the locked position and with a movement groove  167  that faces the stopping protrusion  174  in the normal position. A protrusion  168  between the movement groove  167  and the stopping groove  166  functions as a stopper for preventing the system from leaving a shift position and moving to the parking position in the normal running state even when the control element  161  is actuated by striking the stopping protrusion  174 . 
     The control element  161  is supported by the body unit  160  while allowed to be placed in five positions: a parking position and four shift positions. The shift positions can be changed by the rotation of the control element  161  with the thumb and the index finger. The control element  161  is linked to a cable winder (not shown) provided to the body unit  160 , and the inner cable of a shifting cable  180  whose tip is fixed to the cable winder is taken up or paid out by rotation. The tip of the inner cable of the shifting cable  180  is linked to the operator  78 . 
     When the shift control element  9   a  is in the normal position (FIG.  23 A), that is, when the cylindrical lock  170  is not engaged, the control element  161  can be turned to one of the four shift positions because the stopping protrusion  174  is positioned in the movement groove  167 . When a key is inserted into the cylindrical lock and turned 45 degrees to the left, the lock cam  171  is rotated in the same manner, and the open position is reached. At this time, the lock body  172  is allowed to move to the left in FIG. 23 in opposition to the energizing force of the leaf spring  173  (FIG.  23 B). This releases the stopped state formed by the striking of the protrusion  168  and the stopping protrusion  174 , and allows the control element  161  to rotate to the parking position. The stopping protrusion  174  faces the stopping groove  166  when the control element  161  is rotated to the parking position. When the key is turned 135 degrees to the right from the open position in this state, the lock cam  171  is rotated in the same manner and is moved to the locked position. At this time, the lock body  172  is moved to the left in FIG. 23 by the energizing force of the leaf spring  173  (FIG.  23 C). As a result, the stopping protrusion  174  engages the stopping groove  166 , and the control element  161  is nonrotatably locked. The lock cam  171  is maintained in the parking state in the locked position if the key is removed from the cylindrical lock  170  in this state. 
     Conversely, to release the parking state the key is inserted into the cylindrical lock  170  and turned 135 degrees to the left, placing the lock cam  171  in the open position. When this is done, the lock body is moved to the left, allowing the control element  161  to be rotated. The lock cam  171  is placed in the normal position when the key is turned 45 degrees to the right after the control element  161  has been placed in one of the shift positions. In this state, the lock body  172  is moved to the right by the energizing force of the leaf spring  173 , and the stopping protrusion  174  is placed into the movement groove  167 . In this state, the control element  161  can move solely among the four shift positions, as described above. As a result, the parking position cannot be engaged even by mistake. In this state, the key is removed and riding is started. 
     As shown in FIG. 24, an internal shifting hub  10   b  has essentially the same structure as the one shown in FIG. 17, the difference being that a shifting cable is directly linked to the operator  78 . The embodiment shown in FIG. 17 contemplates an arrangement in which the operator  78  is turned by the motor  29 , whereas the embodiment shown in FIG. 24 contemplates an arrangement in which the operator  78  is turned by the shifting cable. In all other respects the structure is the same as in the embodiment shown in FIG. 17, and the corresponding description will therefore be omitted. 
     This embodiment contemplates an arrangement in which rotating the control element  161  of the shift control element  9   a  into the parking position results in the rotation of the operator  78 , in the corresponding rotation of the sleeve  77  to the locked position PK, and in the controlled rotation of the internal shifting hub  10   b  so that a sound is produced when the hub shell  43  is rotated. As a result, the likelihood of a theft is reduced and bicycle theft is prevented in the same manner as in the two embodiments described above. In addition, placing the control element  161  in the parking position makes it possible for this state to be maintained by the cylindrical lock  170 , so a return to a shift position is impossible until the cylindrical lock  170  is unlocked. This impedes the unlocking of the antitheft device  85  in the antitheft position and makes theft less likely. 
     Although the three embodiments described above referred to an internal shifting hub  10  for a rear wheel  7 , it is also possible to mount the antitheft device  85  inside a front hub  120  for a front wheel  6  as shown in FIG.  25 . In this embodiment the front hub  120  has a hub axle  41   b  and a hub shell  43   b  rotatably supported on the hub axle  41   b . Serration teeth  113   b  are formed in the inner peripheral surface of the hub shell  43   b . A sleeve  77   a  is rotatably mounted around the outside of the hub axle  41   b , and a lock lever  121  is rotatably mounted in the base-end portion of the sleeve  77   a . The structure of the antitheft device  85  is the same as in the second embodiment above, and the corresponding description will therefore be omitted. 
     In this embodiment, a lock control element is disposed, for example, on the handlebar  15 . This lock control element may have essentially the same structure as the shift control element  9   a . Specifically, the lock control element may be equipped with a body unit and a control element. The control element may move among the parking position and riding positions. These riding positions correspond to the plurality of shift positions. The lock control element is provided with a means that allows a cylindrical lock or the like to be locked with a key in the parking position and that prevents a return from the parking position to a riding position unless a numeric password has been inputted, a key inserted, or another such unlocking operation performed. It is possible to link such a lock control element and the lock lever  121  with the aid of a cable, to allow the lock control element to rotate the sleeve  77   a , and to move the moving member between a locked position and an unlocked position. 
     Although the embodiments described above involved providing a wheel hub with an antitheft device, it is also possible to mount the antitheft device  85   a  inside the internal shift crank  130  of a drive component  5 , as shown in FIG.  26 . In this embodiment the internal shift crank  130  can be locked or shifted between two steps (high and low). The internal shift crank  130  has a bottom bracket  132  (which has a crank axle  131  that is mounted on the bottom bracket component  2   a  of the bicycle frame body  2 ), left and right crank arms  133   a  and  133   b , a planetary gear mechanism  134 , a crank gear  135  linked to the planetary gear mechanism  134 , and an antitheft device  85   a  provided to the planetary gear mechanism  134 . 
     The crank axle  131  is rotatably supported on the cylindrical bottom bracket  132 , and the crank arms  133   a  and  133   b  are nonrotatably mounted at both ends with the aid of a mounting bolt  140 . The bottom bracket  132  has a cylindrical bracket body  141  for supporting the crank axle  131 , a case component  142  integrally formed at the right end of the bracket body  141 , and an attaching bolt  143  mounted on the left end of the bracket body  141 . The bottom bracket  132  is mounted on the bottom bracket component  2   a  by tightening, with the aid of the attaching bolt  143 , the bracket body  141  inserted into the bottom bracket component  2   a , and is nonrotatably stopped in relation to the frame body  2  by a fixing arm  144  mounted on the case component  142 . The case component  142 , which is designed to house the planetary gear mechanism  134  in its interior, has a disk component  142   a  disposed at the right end of the bracket body  141  and a cylindrical component  142   b  extending to the right in FIG. 26 away from the outer peripheral portion of the disk component  142   a.    
     As shown in FIG. 27, the planetary gear mechanism  134  has a ring gear  145  formed on the inner peripheral surface of the cylindrical component  142   b , three planetary gears  146  (only one is shown in FIG. 27) that mesh with this ring gear  145 , and a sun gear  147  that meshes with the planetary gears  146 . 
     The planetary gears  146  are arranged at regular intervals in the circumferential direction around an annular frame body  148  fixed to the crank gear  135 , and they are rotatably supported on the frame body  148 . The frame body  148  is rotatably supported by a crank arm  133   b  and the case component  142 , and a swingable drive pawl  155  is disposed around the inside of this frame body. Only the forward rotation of the crank axle  131  is transmitted by the drive pawl  155  to the frame body  148 . 
     The frame body  148  can be rotated by the drive pawl  155  only in the forward direction integrally with the crank axle  131 . In addition, a large number of stopping grooves  148   a  are radially formed in the left-side surface of the frame body  148 . The planetary gears  146  have a large gear tooth  146   a  and a small gear tooth  146   b . The large gear tooth  146   a  meshes with the ring gear  145 , and the small gear tooth  146   b  meshes with the sun gear  147 . The sun gear  147  is rotatably mounted on the crank axle  131 . A drive pawl  149  is disposed inside the sun gear  147 , which is rotated by the drive pawl  149  in conjunction solely with the forward rotation of the crank axle  131 . 
     A switching disk  151  is nonrotatably mounted around the inside of the cylindrical component  142   b  of the case component  142  while allowed to move in the axial direction. The switching disk  151  is axially moved by the turning of a switching lever  152 . The switching disk  151  is also energized to the left in FIG. 27 by an energizing means (not shown). The switching lever  152  is swingably supported by the case component  142 , an inclined cam (not shown) is formed on the lateral surface that strikes this switching disk  151 , and the switching disk  151  is moved in the axial direction by turning. A shifting cable is mounted on the upper end. The shift control element has, for example, three positions (high-speed position, low-speed position, and parking position) and can be locked in the parking position to allow this position to be preserved. This shift control element may be essentially the same as that disclosed in relation to the third embodiment. 
     A radial stopping groove  151   a  capable of meshing with the stopping grooves  148   a  formed in the frame body  148  are formed in the right-side surface of the switching disk  151 . Together with the switching disk  151 , these stopping grooves  148   a  and  151   a  constitute the antitheft device  85   a . In addition, a switching pawl  151   b  designed to turn the drive pawl  155  without driving is formed at the right end around the inside of the switching disk  151 . Furthermore, a tooth component  151   c  for meshing with the cylindrical component  142   b  is formed around the outside of the switching disk  151 . 
     The crank gear  135  rotates integrally with the frame body  148 . The crank gear  135  is rotatably supported by the crank arm  133   b  and the case component  142  via the frame body  148 . When the shift control element is turned to the high-speed position in the internal shift crank  130  thus configured, the switching lever  152  is turned via the shifting cable (as shown in FIG.  27 A), and the switching disk  151  is moved to the high-speed position on the left side. In this state, the frame body  148  and the crank axle  131  are linked by the drive pawl  155 . As a result, the forward rotation of the crank axle  131  is directly transmitted to the frame body  148 , and the crank gear  135  is rotated at the same rotational speed as the crank axle  131 . 
     When the shift control element is turned to the low-speed position, the switching lever  152  is turned via the shifting cable as shown in FIG. 27B, and the switching disk  151  is moved to the low-speed position in the center. In this state, the drive pawl  155  is turned by the switching pawl  151   b  of the switching disk  151 , and the drive pawl  155  cannot perform driving. As a result, the link between the frame body  148  and the crank axle  131  is released. When this is done, the forward rotation of the crank axle  131  is transmitted to the sun gear  147  via the drive pawl  149 . When the sun gear  147  is rotated in the forward direction, the planetary gear  146  rotates around its axis in the opposite direction and revolves around the sun gear in the forward direction at a reduced speed. As a result, the crank gear  135  rotates at a reduced speed via the frame body  148 . 
     When the shift control element is turned to the parking position, this state is preserved by the input of a password, the use of a key, or the like. When the shift control element is placed in this parking position, the switching lever  152  is turned via the shifting cable, and the switching disk  151  is placed in the locked position on the right, as shown in FIG.  27 C. In this state, the drive pawl  155  is turned by the switching pawl  151   b  of the switching disk  151 , and cannot be driven any longer. In addition, the stopping groove  151   a  and the stopping grooves  148   a  engage with each other, and the frame body  148  is linked to the case component  142  and locked via the switching disk  151 . Consequently, the crank axle  131  is locked and the crank gear  135  does not rotate when an attempt is made to rotate the crank arms  133   a  and  133   b  in the forward direction. When, however, the crank arms  133   a  and  133   b  are caused to rotate in the backward direction, the drive pawl  149  disengages from the sun gear  147 , and the crank axle  131  is able to rotate even if the frame body  148  has been locked. However, the rotation of the crank axle  131  is not transmitted to the crank gear. Consequently, the bicycle cannot be pedaled away in this locked state, making its theft less likely. 
     It is also possible for the switching disk to be energized by a suitable energizing means from the left side in FIG. 27, and for the switching disk and the frame body  148  to perform relative rotation in the locked position. In this case, the rotation is controlled, and sound is produced by relative rotation. 
     FIG. 28 depicts another embodiment, which is a modification of the third embodiment described above. In this embodiment, as with the third embodiment, a shift control element  9   b  is locked in the parking position by a key  181 . 
     In FIG. 28, the shift control element  9   b  has a body unit  160   b  formed integrally with the right-side brake lever  16  and a control element  161   a  rotatably mounted on the body unit  160   b . The body unit  160   b  has a circular display component  162   a  for displaying a shift position or the parking position and a lock component  163   a  for maintaining the control element  161   a  in the parking position when this position has been reached. The display component  162   a  is rotatably supported on the body unit  160   b , and is allowed to rotate in conjunction with the control element  161   a . An indicator  165   a  for displaying [I] numbers indicating the four shift positions 1 through 4 drawn on the body unit  160   b  and [ii] a letter indicating parking position P is mounted on the surface of the display component  162   a . The indicator  165   a  points to the parking position or to one of the shift positions (four operating positions). 
     As shown in FIGS. 29 and 30, the lock component  163   a  has a cylindrical lock  170   a  that can be rotated with the key  181 , a lock member  172   b  that moves rectilinearly in conjunction with the cylindrical lock  170   a , and a coil spring  173   a  for energizing the lock member  172   b  to the right in FIG.  29 . The cylindrical lock  170   a  is used, for example, in a bicycle horseshoe-shaped lock, and contains in its interior a cylindrical component  170   b  rotatable by the key  181 . This cylindrical component  170   b  can be rotated by the insertion of the key  181  between the first horizontal position shown in FIG. 28 and a second position (shown in FIG. 29) obtained by turning the key 90 degrees counterclockwise from the first position. A protruding pin  171   a  extends into the back surface (reverse surface in relation to the key-insertion surface) of the cylindrical component  170   b  of the cylindrical lock  170   a.    
     The lock member  172   b , which is a channel steel shape, is supported by the body unit  160   b  while allowed to move in the axial direction of the handle assembly. A slot  172   c  for stopping the protruding pin  171   a  of the cylindrical component  170   b  is formed in the lateral surface of the lock member  172   b  facing the cylindrical lock. Due to the stopping of the protruding pin  171   a  by the slot  172   c , the lock member  172   b  is advanced to or retracted from [I] the forward position shown in FIG.  30 A and [ii] the unlocking position shown in FIG. 30B (and reached by retraction from the forward position) by the rotation of the cylindrical component  170   b  between the first and second positions. 
     The coil spring  173   a , which is stopped by a stopping tab  160   c  whose base portion is disposed on the body unit  160   b  and by a stopping tab  172   d  whose tip is disposed on the lock member  172   b , energizes the lock member  172   b  in the direction of the control element  161   a . The end face of the control element  161   a  that is opposite the body unit  160   b  is provided with a stopping groove  166   a  that faces the tip of the lock member  172   b  when the control element  161   a  has been moved to the parking position, and with a moving groove  167   a  that faces the tip of the lock member  172   b  when the shift positions of gears 1 to 4 have been reached. The stopping groove  166   a  has a C-shape to enable the tip of the lock member  172   b  to be stopped in accordance with the parking position, and the moving groove  167   a  has a fan shape in accordance with the shift positions of gears 1 to 4. A wall component  168   a  between the moving groove  167   a  and the stopping groove  166   a  presses against the tip of the lock member  172   b  in a normal riding state, and thus functions as a stopper for preventing the system from being switched from a shift position to the parking position or vice versa by the operation of the control element  161   a.    
     The control element  161   a  is supported by the body unit  160   b  while allowed to be placed in five positions: four shift positions and a parking position. The operating positions can be changed by the grasping and rotation of the control element  161   a  with the thumb and the index finger. The control element  161   a  is linked to a cable winder (not shown) provided to the body unit  160   b , and the inner cable of a shifting cable  180  whose tip is fixed to the cable winder is taken up or paid out by rotation. The tip of the inner cable of the shifting cable  180  is linked to the operator  78  of the internal shifting hub  10   b  (FIG.  24 ). 
     When the key  181  is inserted into the cylindrical lock  170   a  of the shift control element  9   b , the coil spring  173   a  energizes the lock member  172   b  in the direction of the control element  161   a , so the cylindrical component  170   b  is also placed in the first position (FIG.  30 A). The result of this is that when the control element  161   a  is placed in one of the four shift positions, the tip of the lock member  172   b  protrudes into the moving groove  167   a , and the control element  161   a  can be rotated solely among the shift positions of gears 1 to 4. When the control element  161   a  is in the parking position, the tip of the lock member  172   b  protrudes into the stopping groove  166   a , and the control element  161   a  is locked in the parking position. 
     Inserting the key  181  into the cylindrical lock  170   a  turns the cylindrical component  170   b  90 degrees from the first position to the second position (shown in FIG. 30B) when the system is moved from the parking position to a shift position or vice versa. As a result, the lock member  172   b  retracts in opposition to the energizing force of the coil spring  173   a , and the tip of the lock member  172   b  disengages from the moving groove  167   a  or the stopping groove  166   a . This arrangement allows the control element  161   a  to be rotated among the shift positions and the parking position. The control element  161   a  can therefore be moved from the parking position to a shift position or vice versa when, for example, the control element  161   a  is turned with the right hand while the key  181  is held in the left hand and the cylindrical component  170   b  is turned to the second position. When the force exerted by the left hand is released after the operation of the control element  161   a  has been completed, the lock member  172   b  is advanced by the energizing force of the coil spring  173   a , and the cylindrical component  170   b  turns from the second position to the first position. The tip of the lock member  172   b  is thus stopped by the moving groove  167   a  or the stopping groove  166   a , and the control element  161   a  is rotated solely among the four shift positions or is locked in the parking position. 
     The key  181  is removed from the cylindrical lock  170   a  in the normal riding state, and the key  181  is inserted into the cylindrical lock  170   a  (and the cylindrical component  170   b  is turned from the first position to the shift position) only when the bicycle is locked during parking or is unlocked at the start of riding. This arrangement makes it possible to retract the lock member  172   b  and to turn the control element  161   a  from a selected state to the parking state or vice versa. When the control element  161   a  is turned to the parking position, the operator  78  linked to an inner cable is rotated, the sleeve  77  is turned to the locked position PK in a corresponding manner, the rotation of the internal shifting hub  10   b  is controlled, and the hub shell  43  rotates and produces sound. As a result, theft can be impeded and bicycle theft prevented in the same manner as in the embodiments described above. In addition, this state is maintained when the control element  161   a  is placed in the parking position, making a return to a shift position impossible as long as the lock member  172   b  is not retracted by the cylindrical lock  170   a . This impedes the unlocking of the antitheft device  85  in the antitheft position and makes theft less likely. 
     In addition, the key  181  is not used during riding and should be inserted into the cylindrical lock  170   a  solely during locking or unlocking, making it possible to keep this key in a key holder together with the bicycle lock key inserted into the lock during riding, and thus reducing the likelihood of the key  181  being lost. 
     While the above is a description of various embodiments of the present invention, further modifications may be employed without departing from the spirit and scope of the present invention. For example, the size, shape, location or orientation of the various components may be changed as desired. The functions of one element may be performed by two, and vice versa. In the embodiments described above, the antitheft device was provided to an internal shifting hub, a front hub, or a crank, but the present invention is not limited to these options alone, and the antitheft device may be provided to any component as long as this component can rotate during riding. Four-step gear shifters were used in the embodiments described above, but the gear shifter having a plurality of speed steps also encompasses continuously variable gear shifters. Thus, the scope of the invention should not be limited by the specific structures disclosed. Instead, the true scope of the invention should be determined by the following claims.