Seat support device and bicycle

Abstract

A seat support device (60) comprises a seat support (61) with a lower support (61A) mounted so that it can be centered forwards and backwards on a support shaft (64a), and an upper support (61B) that can be moved up and down relative to the lower support (61A). The seat position adjustment mechanism (M) switches between a locked state, in which a relative position between the upper support (61B) and the lower support (61A) is locked, and an unlocked state. The seat support device (60) includes a coupling arm (62) connected to the upper support (61B). A front portion of the coupling arm (62) is supported by a support shaft (62b), so that the coupling arm (62) and the upper support (61B) are movable up and down and center themselves on the support shaft (62b).According to this structure, it is possible to change the position of a seat not only in a vertical direction, but also in a forward-backward direction.

Description

BACKGROUND OF THE INVENTIONField of the InventionThe present disclosure relates to a support structure for a seat in a bicycle.DESCRIPTION OF THE RELATED ARTThe bicycle disclosed in JP 2003-104257 A includes a seat position adjusting mechanism having a gas spring in a seat post. The seat position adjustment mechanism includes an operation lever disposed at a lower side of the seat. Upon actuation of this lever, a piston and the seat are forced upward by gas pressure. When the operation of the operation lever is canceled, the positions (height) of the piston and the seat are locked. A bicycle in which the operation lever for adjusting the seat position is attached to a grip lever unlike JP 2003-104257 A is also used.In the seating position adjustment mechanism known in the related art, the seating position changes only in the vertical direction (drawing direction of a cylinder). However, there is a need to change the seat position in a front-rear direction. For example, when driving up a hill, it is easier for the driver to step the pedals when the seat is in a high position and closer to the front part of the vehicle. In contrast, when driving downhill, it is easier in some cases to operate the bicycle when the seat is in a low position and is closer to a rear part of the vehicle.SUMMARY OF THE INVENTION(1) An example of a seat support device proposed in the present disclosure includes a seat support including a lower support supported to move forward and rearward centered on a first support shaft and an upper support extending upward from the lower support, the upper support configured to support a seat located at an upper side of the upper support and movable upward and downward relative to the lower support, a seat position adjustment mechanism configured to switch between a locked state in which a relative position between the upper support and the lower support is locked and an unlocked state in which a change in the relative position between the upper support and the lower support is possible, and a coupling arm coupled to the upper support. A front part of the coupling arm is supported by a second support shaft located in front of the seat post, so that the coupling arm and the upper post are movable upward and downward and center on the second support shaft.With this seat support structure, it is possible to change the position of a seat not only in the vertical direction but also in a front-rear direction.(2) In the seat support device described in (1), the seat position adjustment mechanism includes a biasing unit configured to bias the upper support upward with respect to the lower support in the unlocked state, and configured to switch between the locked state and the unlocked state in accordance with an operation of an operation unit by a user. This allows the driver to easily perform the adjustment of the seat position.(3) In the seat support device described in (1) or (2), the seat support is configured to move between a high support state in which the upper support is disposed in a relatively high position and a low support state in which the upper support is disposed in a relatively low position. A position of the upper support in the low support state is rearward of a position of the upper support in the high support state. Accordingly, it is possible for the rider to smoothly step the pedals when, for example, climbing up a hill by arranging the seat post in the high post state. For example, when the rider descends a rough hill, it is easy for him to move the body in accordance with the unevenness by arranging the seat post in the low post state.(4) In the seat support device in (3), a position of the second support shaft supporting the coupling arm is lower than a height of an upper end of the upper support when the seat support is in a high support state. According to this position of the second support shaft, the upper support moves rearward upon lowering the position of the upper support.(5) In the seat support device described in any one of (1) to (4), a clamp member is fixed to the upper support, and a rear end of the coupling arm is connected to the clamp member via a coupling shaft.(6) In the seat support device in (5), the coupling arm bulges below a straight line connecting the coupling shaft and the second support shaft. This allows the driver to smoothly descend forward from the seat.(7) A bicycle proposed in the present disclosure includes the seat support device described in any one of (1) to (6).(8) The bicycle described in (7) further comprises a frame. The frame includes a head tube configured to support a steering shaft, a frame bottom configured to support a hanger bracket configured to support a crankshaft, and a main frame portion extending rearward from the head tube to be connected to the frame bottom. The lower column is connected to the main frame part via the first support shaft.(9) In the bicycle described in (8), the seat post is configured to be movable between a high post state in which the upper post is disposed in a relatively high position and a low post state in which the upper post is disposed in a relatively low position, and when the seat post is in the low post state, the seat post tilts rearward beyond the main frame part.(10) The bicycle described in any one of (7) to (9) further includes a frame, wherein the frame has a head tube configured to support a steering shaft and comprises a main frame part extending rearward from the head tube, and the coupling arm is connected to the main frame part via the second support shaft.(11) The bicycle described in any one of (7) to (10) further includes a frame, the frame having a head tube configured to support a steering shaft and including a main frame part extending rearward from the head tube, the main frame part including a right extension part and a left extension part separated in a left-right direction, and the coupling arm being at least partially disposed between the right extension part and the left extension part. By this structure, it becomes easy to avoid interference between the coupling arm and the main frame part, and it is possible to increase the degree of freedom in the position, shape, and range of movement of the coupling arm.(12) The bicycle described in any one of (7) to (11) further includes a frame, wherein the frame includes a head tube configured to support a steering shaft and a main frame part extending rearward from the head tube, wherein the main frame part includes a right extension part and a left extension part separated in a left-right direction, and the seat post is at least partially disposed between the right extension part and the left extension part. With this structure, it becomes easy to avoid interference between the seat post and the main frame part, and it is possible to increase the degree of freedom in the position and the range of movement of the seat post.BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 is a side view of a bicycle proposed in the present disclosure. FIG. 2 is a perspective view showing a rear part of the bicycle. FIG. 3 is a perspective view illustrating a supporting structure for a motor unit, a bottom bracket, and so forth.shows. In this drawing, a right extension portion of a main frame is omitted. FIG. 4 is a side view showing the rear part of the bicycle. FIG. 5 is a schematic side view showing the position of the motor unit, the bottom bracket, a battery, etc. FIG. 6 is a side view of a seat support structure. FIG. 7 is a side view showing a movement of the seat support structure.DESCRIPTION OF THE EMBODIMENTSThe present disclosure is to be considered an exemplary representation of the invention and is not intended to limit the invention to the specific embodiments illustrated in the figures or the following description. The present invention will now be described with reference to the accompanying drawings which illustrate embodiments.The terminology used herein is for the purpose of describing particular embodiments only and is not to be taken as limiting the invention. As used herein, the term "and / or" includes any combination of one or more of the listed items. As used herein, the singular forms "a", "an" and "the" include both the plural forms and the singular forms, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises," "comprises," "includes," and / or "including," when used in this specification, specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It will be further understood that terms, as defined in commonly used dictionaries, should be construed as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly defined herein.In describing the invention, it will be apparent that a number of technologies are disclosed. Each of them has individual advantages and each may also be used in conjunction with one or more, or in some cases all, of the other disclosed technologies. Accordingly, for reasons of clarity, it is omitted in this description to unnecessarily repeat each possible combination of the individual technologies. Nevertheless, the specification and claims should be read with the understanding that such combinations fall fully within the scope of the invention and claims.In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without these specific details.An electric assist bicycle as illustrated in FIG. 1 etc. will be described below as an example of the bicycle proposed in the present disclosure. Note that in the following description, the direction F and the direction B shown in FIG. 1, etc. are referred to as forward direction and rearward direction, respectively. Further, the direction U and the direction D illustrated in FIG. 1, etc. are referred to as an upward direction and a downward direction, respectively. Further, the direction L and the direction R illustrated in FIG. 3 are referred to as left and right directions, respectively.As illustrated in FIG. 1, a bicycle 10 includes a motor unit 20, a battery 13, and a frame 30.[Supporting Structure of Frame and Crankshaft]As shown in FIG. 1, the frame 30 includes a head pipe 31 for receiving a steering shaft 16 in the foremost part of the frame 30, and a steering handle 15 is fixed to an upper portion of the steering shaft 16. The steering handle 15 includes handles 15a in right and left portions. A front fork 14 is fixed to a lower portion of the steering shaft 16. A front wheel 11 is supported at a lower end of the front fork 14.As illustrated in FIG. 1, the bicycle 10 includes a pedal 51 (see FIG. 2 ) that rotatably supports a crankshaft 52. The hanger 51 has a substantially cylindrical shape, and the crankshaft 52 is inserted inside the hanger 51. The crankshaft 52 includes crank arms 52 dat right and left ends thereof. A pedal 53 is attached to an end portion of the crank arm 52 d.As shown in FIG. 2, the frame 30 includes a frame bottom 32 to which the bottom bracket 51 is fixed. The frame lower 32 is located in a lower end portion of the frame 30, and the hanger 51 is disposed, for example, on a lower surface of a rear portion of the frame lower 32. In the rearmost portion of the frame bottom 32, a recessed part 32a is formed. The bottom bracket 51 may be disposed in this recessed part 32 a. The bottom bracket 51 is fixed to a lower portion of the frame lower 32 by fastening members 71 aand 71 b(see FIG. 3 ) that are connecting means such as a bolt or a screw. The bottom bracket 51 can be welded to the frame bottom part 32.As shown in FIG. 1, the frame 30 includes a lower frame part 33 that extends obliquely rearward and downward from the head pipe 31 toward the frame lower part 32. An upper end (a front end) of the frame lower 33 is welded to the head pipe 31. Further, a lower end (a rear end) of the lower frame part 33 is welded to the frame lower part 32. The lower frame part 33 and the frame lower part 32 (a portion supporting the bottom bracket 51) may be formed integrally with each other.As shown in FIG. 1, the frame 30 includes a main frame portion 34 extending rearward from the head pipe 31. A front part 34 aof the main frame part 34 is located above the lower frame part 33. in the example illustrated in FIG. 1, the front part 34 aof the main frame part 34 extends obliquely rearward and downward from the head pipe 31. the main frame part 34 bends at a rear end of the front part 34 a, and a rear part 34 bof the main frame part 34 extends downward toward the frame lower part 32. the pedal 51 is located below the lower end of the main frame part 34 (extension parts 34R and 34L which will be described later).The shape of the main frame member 34 is not limited to the example shown in the drawing. For example, the main frame 34 may extend from the head pipe 31 toward the frame bottom 32 while being slightly bent.As illustrated in FIGS. 2 and 3, the lower end of the main frame member 34 is connected to an upper end 32 b(see FIG. 3 ) of a rear portion of the frame member 32. The lower end of the lower frame part 33 is connected to an upper end 32 c(see FIG. 3 ) of a front portion of the frame lower part 32. The bottom bracket 51 is fixed to a lower side of the rearmost portion of the frame bottom 32.The structure of the frame 30 is not limited to the example illustrated in FIG. 1 etc. For example, the frame bottom 32 may be provided with a through hole penetrating the frame bottom 32 in a left-right direction. Further, the hanger bearing 51 may be fitted into this through hole to be supported by the frame bottom 32. In this case, the frame bottom 32 may be a cylindrical portion. Further, the lower end of the main frame part 34 may be connected to an outer circumferential surface of the frame lower part 32, or the lower end (the rear end) of the lower frame part 33 may be connected to the outer circumferential surface of the frame lower part 32. Further, instead of the rear arm 48 described later, a stay for supporting an axle 12 aof a rear wheel 12 may be provided on the frame 30. This strut may also be connected to the cylindrically shaped frame bottom 32.Further, the main frame part 34 may be composed of a pipe extending rearward from the head pipe 31 and a pipe extending downward from a rear end of this pipe. In other words, the main frame part 34 may be formed of two tubes coupled to each other. Further, in the example shown in FIG. 2 and so forth, the lower frame part 33 extends straight from the head pipe 31, but may have a bent part at the center, for example, in contrast to the example. For example, the lower frame part 33 may extend obliquely rearward and downward from the head pipe 31 and then be bent rearward in a lowermost portion of the lower frame part 33 to be connected to the frame lower part 32.[Support Structure of Rear Wheel]As illustrated in FIG. 2, the bicycle 10 has a rear arm 48, and a front end of the rear arm 48 is connected to the main frame member 34 via a pivot shaft 39. The front end of the rear arm 48 is disposed between the right extension part 34R and the later-described left extension part 34L (which will be described later) of the main frame part 34. The axle 12 aof the rear wheel 12 is supported by the rearmost part of the rear arm 48. The rear arm 48 can move up and down about the pivot shaft 39.As illustrated in FIG. 2, the bicycle 10 includes a rear suspension 47 and a link mechanism 40 for connecting the rear suspension 47 and the rear arm 48 to each other. The rear suspension 47 is disposed between the rear part 34 bof the main frame part 34 and the lower frame part 33, for example. A lower end of the rear suspension 47 is fixed to the lower frame member 33 via a bracket 35. The link mechanism 40 is connected to an upper end of the rear suspension 47.For example, as illustrated in FIG. 2, the link mechanism 40 includes a first link 41 and a second link 42. When the bicycle 10 runs on a rough road, an impact applied to the rear wheel 12 is transmitted to the rear suspension 47 via the links 41 and 42.As shown in FIG. 3, the foremost parts 41 aof the first link 41 are connected to an upper end of the rear suspension 47 via a coupling shaft 43 b. The rear portions 41b of the first link 41 are connected to the front portions 42b of the second link 42 via coupling shafts 43a. The first link member 41 can swing reciprocally while rotating about a support shaft 36 supported by the main frame member 34. The first link member 41 includes a right link part 41R and a left link part 41L that include the rearmost part 41 band the foremost part 41 a, respectively.As illustrated in FIG. 2, a rearmost part 42 aof the second link 42 supports the axle 12 aof the rear wheel 12. The second connecting member 42 extends obliquely upward and forward from the rearmost part 42 a. The second link member 42 includes a right link part 42R and a left link part 42L including the rearmost part 42 aand the foremost part 42 b, respectively.[Motor Unit]As illustrated in FIG. 3, the motor unit 20 includes an electric motor 21 (see FIG. 4 ), a housing 22 in which the electric motor 21 is accommodated, and an output shaft 23 for outputting the torque of the electric motor 21. A pinion 23a is fixed to the output shaft 23. In the motor unit 20, a reduction gear may be housed in addition to the electric motor 21. The rotational movement of the electric motor 21 can be transmitted to the output shaft 23 via the reduction gear.As shown in FIG. 3, the bottom bracket 51 and the motor unit 20 are spaced apart by a certain distance. In other words, the bottom bracket 51 is not a part accommodated in the housing 22. This makes it possible to increase the degree of freedom of the arrangement of the motor unit 20 as compared with the structure in which the hanger bearing 51 and the motor unit 20 are united, i.e., the structure in which the electric motor 21, the output shaft 23, and the hanger bearing 51 are accommodated in a single housing. In the example shown in FIG. 3, the motor unit 20 is disposed at a position away from and above the bottom bracket 51.[Structure for Torque Transmission]As illustrated in FIG. 1, the bicycle 10 includes a chain 18, and the chain 18 is wound around the sprocket 23 aprovided on the output shaft 23, a sprocket 52 aprovided on the crankshaft 52, and a sprocket 12 bprovided on the axle of the rear wheel 12. The torque of the crankshaft 52 and the torque of the output shaft 23 are transmitted to the rear wheel 12 via the chain 18.The number of teeth of the pinion 23 amounted on the output shaft 23 is smaller than the number of teeth of the pinion 12 bof the rear wheel 12, and the number of teeth of the pinion 23 ais smaller than the number of teeth of the pinion 52 aof the crankshaft 52, thereby reducing rotation of the output shaft 23 and transmitting it to the rear wheel 12 and the crankshaft 52.In the structure in which the engine unit and the pedal bearing form one unit, the rotation of the electric motor is transmitted to the crankshaft via a plurality of gears. In order to ensure a sufficient reduction ratio in this structure, it is necessary to fix a gear having a large number of teeth (a large-diameter gear) to the crankshaft. As a result, the structure around the crankshaft becomes large, i.e., the case in which the engine unit, etc., is accommodated becomes larger, and therefore it is necessary to increase the distance between the axis of the rear wheel and the crankshaft.In contrast, in the bicycle 10, since the rotation of the output shaft 23 is reduced by the sprockets 23 a, 12 b, and 52 aand the chain 18, it is not necessary to attach the above-described large-diameter sprocket to the crankshaft 52. Thereby, it is possible to shorten the distance between the axis 12 aof the rear wheel 12 and the crankshaft 52. Thereby, it is possible to reduce the moment of inertia about the axis of the rear wheel 12, and thus it is possible to easily perform posture switching (e.g., wheelie) of the bicycle 10. In the example shown in FIG. 1, the rear wheel 12 is located near the rear part 34 bof the main frame part 34, and the foremost portion of the rear wheel 12 overlaps the sprocket 52 aof the crankshaft 52 in a side view.It should be noted that the bicycle may be equipped with a gear shift. In this case, the axle 12 aof the rear wheel 12 may be provided with a plurality of pinions 12 bthat have different numbers of teeth from each other. Moreover, the bicycle 10 may include a derailleur for moving the chain 18 onto the sprocket 12 bcorresponding to the gear change set.[Control of Electric Motor]The battery 13 is electrically coupled to the electric motor 21, and the electric motor 21 is driven by a current of the battery 13. The bicycle 10 includes a control device for controlling the electric motor 21 and a driving device for supplying the electric motor 21 with power from the battery 13 (both devices are not illustrated). Further, the bicycle 10 includes a torque sensor for detecting the torque acting on the crankshaft 52 (pedaling force on the pedal 53) and a vehicle speed sensor for detecting the vehicle speed (both sensors are not shown). The torque sensor is attached to the crankshaft 52, for example. The vehicle speed sensor is connected to the front wheel 11 or the rear wheel 12.The controller calculates an assist rate based on an output of the vehicle speed sensor to calculate a target value of the current based on the assist rate and an output of the torque sensor. The driving device supplies the current corresponding to the target value to the electric motor 21, and the control device and the driving device are housed in an electric component housing 17 (see FIG. 1 ) attached to, for example, the lower end of the lower frame part 33. The arrangement of the control device and the drive device is not limited to the example described here.[Structure of Motor Unit and Battery]The battery 13 is fixed to the lower frame 33. As shown in FIG. 4, the battery 13 may be accommodated in the lower frame part 33. More specifically, the lower frame part 33 has a box-like shape elongated in its extending direction (obliquely rearward and downward), and the battery 13 may be disposed inside the lower frame part 33.To enable such arrangement of the battery 13, the frame 30 may have an opening for inserting the battery 13. For example, the lower frame part 33 and the frame lower part 32 may be provided with an opening at their lower side. In addition, the battery 13 can be inserted through the opening in the lower frame part 33. The opening can be closed by the electrical component housing 17.The arrangement of the battery 13 is not limited to the example illustrated in FIG. 4. The battery 13 may be mounted on a front surface 33 aof the lower frame part 33, for example. Conversely, the battery 13 may be mounted on a rear surface 33 bof the lower frame part 33. Further, the opening for inserting the battery 13 into the inside of the lower frame 33 may be provided on the rear surface 33 bof the lower frame 33.As another structure, the lower frame part 33 may be provided with a forwardly open recess. The battery 13 can be accommodated in this recess. Conversely, the lower frame part 33 may be provided with a recess opening to the rear. The battery 13 can be accommodated in this recessed part.The electric component housing 17 (see FIG. 1 ) is located below the motor unit 20 and the battery 13, and thereby the distance between a circuit board (the control device and / or the driving device) housed in the electric component housing 17 and the electric motor 21, and the distance between this circuit board and the battery 13, can be shortened. The positions of the control device and the driving device may be higher than the sprocket 52 aof the crankshaft 52.As illustrated in FIG. 2, the motor unit 20 is located above the hanger 51 and behind the battery 13. as illustrated in FIG. 4, at least a lower end 13 aof the battery 13 is located below the pivot point Cm of the electric motor 21. In FIG. 4, the lower end 13 aof the battery 13 is a lower end (corner) of the front surface of the battery 13.With such an arrangement of the motor unit 20, the battery 13, and the hanger bracket 51, it is possible to use a space formed at obliquely front and lower sides of the motor unit 20 for arrangement of the battery 13. Thereby, the distance between the crankshaft 52 disposed below the motor unit 20 and the battery 13 can be shortened to reduce the moment of inertia of the bicycle 10 about the crankshaft 52. As a result, the change in posture of the bicycle 10 can be facilitated by the operation of a rider when riding on uneven ground.As shown in FIG. 5, in the bicycle 10, not only the lower end 13 aof the battery 13, but also the entire lower surface 13 bis located below the rotation center Cm of the electric motor 21. By thus lowering the position of the battery 13, the distance between the battery 13 and the crankshaft 52 can be further shortened.As shown in FIG. 5, in the bicycle 10, the entire lower surface 13 bof the battery 13 is located lower than a lower end 21 aof the electric motor 21. Accordingly, the distance between the battery 13 and the crankshaft 52 can be further reduced.As described above, in the bicycle 10, the battery 13 is accommodated in the lower frame part 33 as illustrated in FIG. 4. Due to this structure, it is possible to make the distance between the battery 13 and the crankshaft 52 shorter than, for example, a structure in which the battery 13 is fixed to the front surface 33 aof the lower frame 33.Note that the positional relationship between the battery 13 and the motor unit 20 is not limited to the example illustrated in FIG. 3. For example, the position of a part of the lower surface 13 bof the battery 13 may be higher than the horizontal line H 2 passing through the lower end 21 aof the electric motor 21.Further, the battery 13 may be fixed to the rear surface 33 bof the lower frame member 33, and its lower end 13 amay be located below the rotation center Cm of the electric motor 21. In this case, the lower frame member 33 may be formed so as to allow such arrangement of the battery 13.As shown in FIG. 5, the distance W 1 from the center of the crankshaft 52 to an end portion 13 cof the battery 13 is smaller than the distance W 2 from the crankshaft 52 to the rotation center Cm of the electric motor 21 (In the present specification, the end portion 13 cof the battery 13 means a rear end of a lower portion of the battery 13).In the example shown in FIG. 5, the motor unit 20 is arranged such that the position of the output shaft 23 is higher than that of the electric motor 21.Note that the distance W 1 may be smaller than only one of the two distances W 2 from the crankshaft 52 to the rotation center Cm of the electric motor 21, and a distance from the crankshaft 52 to the output shaft 23, depending on the posture (the positional relationship between the electric motor 21 and the output shaft 23) of the motor unit 20.The space formed under the motor unit 20 is used for the arrangement of the battery 13 and the electric component housing 17. Therefore, as shown in FIG. 4, a vertical line V 1 passing through the front end of the motor unit 20 may cross the rear part of the battery 13. In addition, the vertical line V 1 may also cross the electrical component housing 17.As described above, the position of the battery 13 and the position of the motor unit 20 are close to each other. As shown in FIG. 5, the distance W 3 between the outer circumferential surface of the electric motor 21 and the battery 13 may be smaller than the radius of the electric motor 21.[Arrangement of Motor Unit and Rear Suspension]As illustrated in FIG. 4, the bracket 35 supporting a lower end of the rear suspension 47 is located between the motor unit 20 and the lower part of the battery 13. in particular, the horizontal line H 1 (see FIG. 5 ) passing through the pivot point Cm of the electric motor 21 crosses the bracket 35 and the lower part of the battery 13.As illustrated in FIG. 4, a lower end 47 aof the rear suspension 47 is located in front of the motor unit 20.As illustrated in FIG. 4, the motor unit 20 is disposed such that the output shaft 23 is located above the electric motor 21. This can lower the position of the electric motor 21, which is heavy, which can reduce the moment of inertia around the crankshaft 52. As a result, the change in posture of the bicycle 10 can be facilitated by the operation of a rider when riding on irregular ground.[Relative Position Between Motor Unit and Frame]As shown in FIG. 2, the main frame portion 34 is divided into two at the center. In other words, the main frame part 34 includes the right extension part 34R and the left extension part 34L separated in the left-right direction. The main frame part 34 includes a first extension part 34A connected to the head pipe 31. The left and right extension parts 34L and 34R extend obliquely rearward and downward from the first extension part 34A. Subsequently, the extension parts 34L and 34R respectively bend and extend downward. The extension parts 34L and 34R form a part of the front part 34 a(see FIG. 1 ) and the rear part 34 b(see FIG. 1 ) of the main frame part 34 described above.The motor unit 20 may be disposed to overlap a part of one or both of the extension parts 34R and 34L in a side view of the bicycle 10. As shown in FIG. 4, the motor unit 20 is disposed in the bicycle 10 such that the rearmost part of the electric motor 21 overlaps the right extension part 34R.With this arrangement of the motor unit 20, it is possible to shift the position of the motor unit 20 rearward up to the positions of the extension parts 34R and 34L. In this way, it becomes easy to shorten the distance between the battery 13 disposed at the front of the engine unit 20 and the crankshaft 52.The positional relationship between the motor unit 20 and the extension parts 34R and 34L is not limited to the above-described example. For example, a recessed part may be provided on a front surface 34 c(see FIG. 4 ) of one or both extension parts 34R and 34L, and a part of the motor unit 20 may be provided on the recessed part. For example, the recessed part may be provided at the left extension part 34L, and a part of the motor unit 20 may be provided at the recessed part. This structure can also displace the position of the motor unit 20 rearward. Also in this case, the right extension part 34R can overlap the rearmost part of the electric motor 21 without providing such a recessed part to the right extension part 34R.Unlike above, the rearmost part of the motor unit 20 may be disposed between the left and right extension parts 34L and 34R. In other words, the rearmost part of the engine unit 20 may overlap both the left and right extension parts 34L and 34R in the side view of the vehicle. In contrast to the above, the recessed portion may be provided on both the left and right extension portions 34L and 34R.As a result, since the position of the motor unit 20 is displaced rearward in this manner, the vertical line V 2 (see FIG. 5 ) passing through the rear end of the electric motor 21 crosses the pedal bearing 51. As illustrated in FIG. 1, the entire engine unit 20 may be disposed in front of a rear end of the gear 52 aof the crankshaft 52. Further, the entire motor unit 20 may be disposed in front of the rear surface of the extension parts 34R and 34L.[Supporting Structure of Motor Unit with Frame]The motor unit 20 is supported by the frame 30. As shown in FIG. 3, the housing 22 of the motor unit 20 includes a fastening target part 22 bin an uppermost part of the housing 22, and the fastening target part 22 bis fastened to the left and right extension parts 34L and 34R with a fastening part (e.g., a bolt) via a bracket 37. Further, the housing 22 includes a fixing target part 22 cin its lowermost part. The attachment target part 22 cis attached to the frame lower part 32 by an attachment part (e.g., a screw). The attachment target part 22 cof the housing 22 can be attached to the lower frame part 33.[Arrangement of Rear Arm]As described above, the bicycle 10 includes the rear arm 48 (see FIG. 2 ). The rear arm 48 is connected to the main frame member 34 via the pivot shaft 39. Therefore, the rear arm 48 is movable up and down and centers on the pivot shaft 39. as shown in FIG. 5, the position of the pivot shaft 39 is above the rotation center Cm of the electric motor 21. When the position of the pivot shaft 39 is high as described above, this results in the moving direction of the rear wheel 12 being inclined rearward with respect to the vertical direction as indicated by the arrow D 1 in FIGS. 1 and 4 when the rear wheel 12 enters a protruding part on a road. As a result, an impact when the rear wheel 12 collides with the protruding part can be relaxed, and thus it is possible for the rear wheel 12 to smoothly ride on the protruding part.As illustrated in FIG. 5, both the pivot shaft 39 and the output shaft 23 of the motor unit 20 are located higher than the pivot point Cm of the electric motor 21, and the output shaft 23 is located in front of the pivot shaft 39. For example, the pivot shaft 39 and the output shaft 23 may be disposed at substantially the same height. With this arrangement, the distance between the pivot shaft 39 and the output shaft 23 can be shortened. In the example shown in FIG. 5, the distance W 3 between the output shaft 23 of the motor unit 20 and the pivot shaft 39 is shorter than the distance W 4 between the output shaft 23 and the crankshaft 52. This point will be described below.As shown in FIG. 4, the axle 12 aof the rear wheel 12 is supported by the rearmost part 42 aof the second link member 42 located rearward of the rear end of the rear arm 48. The rearmost part 42a is connected to the rear end of the rear arm 48 via the coupling shaft 43c. When the bicycle 10 travels on the rough road, the rear wheel 12 moves up and down centering on a center of swing Cs (see FIG. 4 ) located slightly forward of the pivot shaft 39. When the distance between the pivot shaft 39 and the output shaft 23 is shortened, the distance between the pivot center Cs and the output shaft 23 can also be shortened.As described above, since the position of the pivot shaft 39 is set higher than the axis 12 aof the rear wheel 12, the rear wheel 12, when riding on the protruding part of the road, is urged to move obliquely rearward and upward (the direction D 1 shown in FIG. 4 ). When the distance between the center of vibration Cs (see FIG. 4 ) of the rear wheel 12 and the output shaft 23 is large, the distance between the axis 12 aof the rear wheel 12 and the output shaft 23 increases as the position of the rear wheel 12 increases. This increases the tension on the chain 18 and impedes the movement of the rear wheel 12. In contrast, the tension acting on the chain 18 can be prevented from becoming too large by setting both the pivot shaft 39 and the output shaft 23 higher than the pivot point Cm of the electric motor 21 to shorten the distance between the pivot point Cs and the output shaft 23. Note that the position of the center of vibration Cs may coincide with the position of the output shaft 23.[Seat Support Device]The bicycle 10 includes the seat support device 60. as illustrated in FIG. 2, the seat support device 60 includes a seat post 61 and a coupling arm 62.As illustrated in FIG. 6, the seat post 61 includes a lower post 61A and an upper post 61B. The lower support 61A can move forward and backward centering on a support shaft 64 athat has an axis line along the left-right direction. The support shaft 64 ais located in a lower portion of the lower support 61A. As shown in FIG. 3, a clamping member 64 is fixed to the lower part of the lower bracket 61A. The clamping member 64 has an annular shape. The lower bracket 61A is held by being fitted into the clamp member 64. The bracket member 64 is supported by the main frame member 34 via the support shaft 64a. Therefore, the lower support 61A can move forward and backward relative to the main frame member 34, centering on the support shaft 64 a. The fixing position of the clamp member 64 is not limited to the example illustrated in FIG. 6. The clamp member 64 may be disposed in or around a central portion in the vertical direction of the lower bracket 61A.As illustrated in FIG. 6, the upper support 61B extends upward from the lower support 61A. The upper support 61B supports the seat 19 (see FIG. 1 ) at its upper side. A seat stay 65 is attached to an upper end of the upper bracket 61B, and the seat 19 is fixed to the seat stay 65. The upper support 61B can move up and down relative to the lower column 61A. In other words, the upper support 61B can move relative to the lower support 61A in a drawing direction of the seat post 61. The lower support 61A has a cylindrical shape, and the upper support 61B is inserted into the inside thereof. Conversely, the lower support 61A may be inserted inside the upper support 61B.[Seat Position Adjustment]The seat post 61 includes a seat position adjustment mechanism M in the interior thereof. As shown in FIG. 6, the seat position adjustment mechanism M switches between a locked state in which the relative position between the upper support 61B and the lower support 61A is locked and an unlocked state in which a change in the relative position between the upper support 61B and the lower support 61A is possible. A user sets the position (height) of the seat 19 in the unlocked state of the seat position adjustment mechanism M and then brings the seat position adjustment mechanism M into the locked state.The seat position adjustment mechanism M includes a biasing unit that biases the upper bracket 61B upward relative to the lower bracket 61A in the unlocked state. The biasing unit is realized by, for example, a gas chamber 61 ein which a high-pressure gas described later is sealed and an oil chamber 61 fbeing filled with an operating oil. Further, the seat position adjusting mechanism M includes an operation unit 66 that can be operated by the user. The seat position adjusting mechanism M is switched between the locked state and the unlocked state by operation of the operation unit 66.The seat post 61 is referred to as a lowerable seat post, and the seat position adjustment mechanism M functions as follows, for example. When the seat post 61 is placed in the unlocked state by the operation of the operation unit 66, the upper post 61B automatically moves upward due to the operation of the biasing unit, thereby increasing the position of the seat 19. In this unlocked state, when the user presses down the seat 19 in the teeth of the biasing force, the position of the upper support 61B (the position of the seat 19) falls. When the seat post 61 is placed in the locked state by the operation of the operation unit 66, the height of the upper post 61B is fixed.As illustrated in FIG. 6, the seat position adjusting mechanism M includes the gas chamber 61 e, the first oil chamber 61 f, and a second oil chamber 61 gwithin the seat post 61. the gas chamber 61 eand the oil chambers 61 fand 61 gare zoned by a free piston 61 h. Further, the first oil chamber 61f and the second oil chamber 61g are zoned by a piston 61i. The piston 61 iis provided with an oil flow path. The oil can move between the first oil chamber 61 fand the second oil chamber 61 gvia the oil flow path. On the piston 61i, a valve 61m for opening and closing the oil flow path is attached. The piston 61 iis fixed to a tip of a piston rod 61 j. The piston rod 61j passes through the second oil chamber 61g in the ascending direction. The piston rod 61 jis cylindrical in shape, and a push rod 61 kis disposed inside the piston rod 61 j. By moving the push rod 61 kin an axial direction of the seat post 61, the valve 61 marranged in the oil flow path of the piston 61 ican be operated. The push rod 61 kand the operation unit 66 are coupled to each other via, for example, a cable 67, and the user can operate the push rod 61 kvia the operation unit 66. The operating unit 66 can be, for example, a button or a lever which is attached to the steering handle 15.The seat position adjusting mechanism M functions as follows. When the push rod 61 kis pushed via the operation unit 66 to open the valve 61 m, the seat post 61 rotates to the unlocked state. On this occasion, the first oil chamber 61 fand the second oil chamber 61 gcommunicate with each other via the oil flow path formed in the piston 61 i. The oil moves from the second oil chamber 61 gto the first oil chamber 61 fvia the oil flow path due to the pressure in the gas chamber 61 e, and the upper support 61B moves upward. Conversely, when the user presses down the seat 19 in the teeth of the pressure in the gas chamber 61 e, the oil moves from the first oil chamber 61 fvia the oil flow path to the second oil chamber 61 g, and the upper support 61B moves down.The structure of the seat position adjusting mechanism M is not limited to the example illustrated in FIG. 6. The seat position adjustment mechanism M may have other structures as long as the structure is capable of switching the seat post 61 between the unlocked state and the locked state, and has a function of biasing the upper post 61B upward at least in the unlocked state.[Coupling arm]As illustrated in FIG. 6, a rear part of the coupling arm 62 is connected to the upper bracket 61B. Specifically, a clamping member 68 (see FIG. 2 ) is fixed to the upper bracket 61B. The upper support 61B is held by being fitted into the clamping member 68. The clamp member 68 is connected to a rear end of the coupling arm 62 via a coupling shaft 62a. The clutch shaft 62 ahas an axis line along the right-left direction. Due to this coupling structure, an angle between the upper support 61B and the coupling arm 62 may change depending on the position (height) of the upper support 61B.As shown in FIG. 6, a support shaft 62 bis disposed in front of the seat post 61. The support shaft 62 bhas an axis line along the left-right direction. The foremost part of the coupling arm 62 is supported by the support shaft 62b so that the coupling arm 62 can move up and down centered on the support shaft 62b. The support shaft 62 bis supported by the main frame member 34. In other words, the foremost part of the coupling arm 62 is connected to the main frame part 34 via the support shaft 62b.[Movement of Seat Support Device]The seat post 61 can move between a high post state and a low post state. The high support state state is a state in which the upper support 61B and the seat 19 are disposed at relatively high positions, and is, for example, the state (the position and the length) of the seat support 61 illustrated by the two dotted broken lines in FIG. 7. The low support state is a state in which the upper support 61B and the seat 19 are disposed at relatively low positions, and is, for example, the state (the position and the length) of the seat support 61 illustrated by the solid lines in FIG. 7. The seat post 61 may be disposed in an intermediate state therebetween.As described above, the lower support 61A is supported by the support shaft 64 a, and the foremost part of the coupling arm 62 is supported by the support shaft 62 b. Therefore, when the seat post 61 moves between the high post state and the low post state, the position (the position in the front-rear direction of the seat 19) also changes in the front-rear direction of the upper post 61B. As shown in FIG. 7, the position of the upper support 61B in the low support state is rearward of the position of the upper support 61B in the high support state.According to such a seat support device 60, it is possible for the rider to step the pedals 53 comfortably when, for example, driving up a hill by arranging the seat post 61 in the high support state. Further, for example, when a rough hill is driven down, it becomes easy for the rider to move the body in accordance with the asperities by the arrangement of the seat post 61 in the low post state.As described above, the lower support 61A is held by the clamp member 64 and supported by the support shaft 64 a. The clamping member 64 may be fixed to the lower bracket 61A with a screw, for example. In addition, the position of the clamping member 64 in the lower bracket 61A can be adjusted by loosening the bolt in the vertical direction. By adjusting the position of the clamping member 64, it is possible to raise and lower both the position of the seat post 61 in the high support state and the position of the seat post 61 in the low support state.The clamping member 68 is fixed to the upper bracket 61B. As illustrated by the solid lines in FIG. 7, the clamping member 68 may be in contact with an upper end of the lower support 61A when the seat post 61 is in the low support state. In other words, a movable range of the upper support 61B can be regulated by the clamping member 68. The clamping member 68 may be fixed to an upper portion of the upper support 61B, for example. This can ensure a sufficient range of movement with respect to the seat 19.The clamping member 68 may also be fixed to the upper support 61B, for example, with a screw. In addition, the position of the clamping member 68 in the upper bracket 61B can be adjusted by loosening the bolt in the vertical direction. By adjusting the position of the clamp member 68, it is possible to raise and lower the position of the upper support 61B in the lower position, i.e., the lowest position of the upper support 61B.As shown in FIG. 6, the position of the support shaft 62 bsupporting the coupling arm 62 is lower than the height of the upper end of the upper support 61B when the seat post 61 is in the high support state. Due to this positional relationship, the positions of the upper end of the upper support 61B and the seat 19 move rearward as shown in FIG. 7 when the seat post 61 moves from the high support state to the low support state.[Shape of Coupling Arm]As shown in FIG. 6, the coupling arm 62 is bent to bulge under a straight line L 1 connecting the coupling shaft 62 alocated in the rear part of the coupling arm 62 and the support shaft 62 blocated in the front part of the coupling arm 62 to each other. Due to this shape of the coupling arm 62, it is easy for the rider to descend in front of the seat 19 when the seat post 61 is in the raised state, for example.As shown in FIG. 6, the coupling arm 62 includes a rear extension part 62 cand a front extension part 62 dextending from the rear extension part 62 c. When the seat post 61 is in the raised state, the rear extension part 62 cextends obliquely forward and downward from a portion (the coupling shaft 62 a) connected to the clamping member 68. The front extension part 62d bends from the rear extension part 62c. The front extension part 62 dextends substantially forward. The front extension part 62 dmay extend obliquely upward.[Supporting Structure of Coupling Arm]As described above, the main frame part 34 includes the right extension part 34R and the left extension part 34L. As illustrated in FIG. 2, the frontmost part of the coupling arm 62 is disposed between the right extension part 34R and the left extension part 34L, and the support shaft 62 bis supported by the extension parts 34R and 34L. In the plan view of the bicycle 10, the coupling arm 62 is located between the right extension part 34R and the left extension part 34L. With this configuration, it is possible to increase the degree of freedom in the position and shape of the coupling arm 62. For example, it is possible to arrange the coupling arm 62 so as to partially overlap the extension parts 34R and 34L in the side view.In the bicycle 10 shown in FIG. 7, it is possible to arrange the coupling arm 62 such that the front extension part 62 dof the coupling arm 62 overlaps the extension parts 34R and 34L when the seat post 61 is in the low-support state. Further, by disposing the front extension part 62 dto overlap the extension parts 34R and 34L, it is possible to reduce the influence of the clutch arm 62 on the rider's getting-up and down operations.Note that the positional relationship between the coupling arm 62 and the main frame part 34 is not limited to the example illustrated in FIGS. 6, 7, etc. For example, the rear extension part 62 cof the coupling arm 62 may partially overlap the extension parts 34R and 34L depending on the shape of the coupling arm 62 and the position (height) of the main frame part 34.[Support Structure of Seat Post]As shown in FIGS. 2 and 3, the support shaft 64 aof the clamping member 64 for supporting the seat post 61 is disposed between the left extension part 34L and the right extension part 34R of the main frame part 34, and is supported by these extension parts 34L and 34R. Further, a lower portion of the seat post 61 is disposed between the right extension part 34R and the left extension part 34L.With this arrangement of the seat post 61 and the main frame member 34, it becomes easy to increase the degree of freedom in the position of the seat post 61. For example, it becomes possible to arrange the seat post 61 at a position overlapping the left and right extension parts 34L, 34R in the side view. Thereby, it becomes possible to increase the degree of freedom of the position in the front and rear direction of the seat 19. In the example shown in FIGS. 6 and 7, the lowermost part of the lower bracket 61A overlaps a bent part between the front part 34 aand the rear part 34 bof the main frame part 34.As shown in FIG. 7, the rear part 34 b(rear portions of the extension parts 34R and 34L) of the main frame part 34 extends substantially downward toward the frame lower part 32. when the seat post 61 is in the low-support state, the seat post 61 inclines more rearward than the extension direction of the rear part 34 bof the main frame part 34. thereby it is possible to move the seat 19 rearward beyond the main frame part 34 when the seat post 61 is in the low-support state.As illustrated in FIG. 2, the second link member 42 includes the right link part 42R and the left link part 42L of the link member. The right link part 42R and the left link part 42L include the rearmost part 42 aand the foremost part 42 b(see FIG. 3 ), respectively, as described above. As shown in FIG. 3, the foremost part 42 bof the right link part 42R and the foremost part 42 bof the left link part 42L are bridged by a cross part 42 c. Further, the first connecting member 41 also includes the right link part 41R and the left link part 41L. The rearmost part 41 bof the right link part 41R and the rearmost part 41 bof the left link part 41L of the first link member 41 are respectively coupled to the foremost part 42 bof the right link part 42R and the foremost part 42 bof the left link part 42L of the second link 42 via the coupling shafts 43 a. The foremost part 41 aof the right link part 41R and the foremost part 41 aof the left link part 41L of the first link member 41 are coupled to the upper end 47 bof the rear suspension 47 via the coupling shaft 43 b.The seat post 61 is disposed between the right link part 41R and the left link part 41L of the first link 41. Further, the seat post 61 is located between the upper end 47 bof the rear suspension 47 and the cross part 42 cof the second link member 42 and can move in the front-rear direction between the upper end 47 band the cross part 42 c.[Conclusion](1) The seat support device 60 proposed in the present disclosure includes the seat support 61 including the lower support 61A supported to center forward and rearward on the support shaft 64 aand the upper support 61B extending upward from the lower support 61A, the upper support 61B being configured to support the seat disposed at the upper side of the upper support 61B and movable upward and downward relative to the lower support 61A, the seat position adjustment mechanism M is configured to be interposed between the locked state in which the relative position between the upper support 61B and the lower support 61A is locked and the unlocked state in which the change of the relative position between the upper support 61B and the lower support 61A is allowed, switching over and the coupling arm 62 being coupled to the upper support 61B. The foremost part of the coupling arm 62 is supported by the support shaft 62b so that the coupling arm 62 and the upper support 61B can move up and down centering on the support shaft 62b located in front of the seat post 61.With this construction, it is possible to change the position of the seat 19 not only in the vertical direction but also in the front-rear direction.(2) In the seat support device 60 described in (1), the seat position adjustment mechanism M includes the biasing unit configured to bias the upper support 61B upward with respect to the lower support 61A in the unlocked state, and configured to switch between the locked state and the unlocked state in accordance with an operation of the operation unit 66 by the user. In this way, the adjustment of the seat position can be easily performed.(3) In the seat support device 60 described in (1) or (2), the seat support 61 is configured to move between the Z high support state in which the upper support 61B is disposed in a relatively high position and the low support state in which the upper support 61B is disposed in a relatively low position. The position of the upper support 61B in the low support state is rearward of the position of the upper support 61B in the high support state. Accordingly, it is possible for the rider to smoothly step the pedals when, for example, driving up a hill by arranging the seat post 61 in the high post state. Further, for example, when driving down a rough hill, it becomes easy for the rider to move the body in accordance with the unevenness by arranging the seat post 61 in the low post state.(4) In the seat support device 60 in (3), the position of the support shaft 62 bthat supports the coupling arm 62 is lower than the height of the upper end of the upper support 61B when the seat support 61 is in the high support state. According to this position of the support shaft 62b, when the position of the upper support 61B is lowered, the position of the upper support 61B is slid rearward.(5) In the seat support device 60 described in any one of (1) to (4), the clamp member 68 is fixed to the upper support 61B, and the rear end of the coupling arm 62 is coupled to the clamp member 68 via the coupling shaft 62 a.(6) In the seat support device 60 in (5), the coupling arm 62 bulges below the straight line L 1 connecting the coupling shaft 62 aand the support shaft 62 b. This allows the driver to smoothly descend forward from the seat 19.(7) The bicycle 10 proposed in the present disclosure includes the seat support device 60 described in any one of (1) to (6).(8) The bicycle 10 described in (7) further includes the frame 30. the frame 30 includes the head tube 31 configured to support the steering shaft 16, the frame bottom 32 configured to support the hanger 51 configured to support the crankshaft 52, and the main frame portion 34 extending rearward from the head tube 31 to be connected to the frame bottom 32. The lower support 61A is connected to the main frame member 34 via the support shaft 64 a.(9) In the bicycle 10 described in (8), the seat post 61 is configured to move between the high post state in which the upper post 61B is disposed in a relatively high position and the low post state in which the upper post 61B is disposed in a relatively low position, and when the seat post 61 is disposed in the low post state, the seat post 61 tilts rearward beyond the main frame part 34.(10) In the bicycle 10 described in any one of (7) to (9), the bicycle 10 further includes the frame 30, the frame 30 includes the head tube 31 configured to support the steering shaft 16, and the main frame part 34 extending rearward from the head tube 31, and the coupling arm 62 is connected to the main frame part 34 via the support shaft 62 b.(11) In the bicycle 10 described in any one of (7) to (10), the bicycle 10 further includes the frame 30, the frame 30 includes the head tube 31 configured to support the steering shaft 16, and the main frame part 34 extending rearward from the head tube 31, the main frame part 34 includes the right extension part 34R and the left extension part 34L separated in the left-right direction, and the coupling arm 62 is at least partially disposed between the right extension part 34R and the left extension part 34L. By this structure, it becomes easy to avoid interference between the coupling arm 62 and the main frame part 34, and it is possible to increase the degree of freedom in the position, shape, and range of movement of the coupling arm 62.(12) In the bicycle 10 described in any one of (7) to (11), the bicycle 10 further includes the frame 30, the frame 30 includes the head tube 31 configured to support the steering shaft 16 and the main frame part 34 extending rearward from the head tube 31, the main frame part 34 includes the right extension part 34R and the left extension part 34L separated in the left-right direction, and the seat post 61 is at least partially disposed between the right extension part 34R and the left extension part 34L. With this configuration, it becomes easy to avoid interference between the seat post 61 and the main frame part 34, and it is possible to increase the degree of freedom in the position and the range of movement of the seat post 61.[Other Issues]The bicycle proposed in the present disclosure is not limited to the electric assist bicycle 10 described with reference to FIG. 1 and so forth.For example, the bicycle proposed in the present disclosure may not necessarily be an electric assisted bicycle. In other words, the bicycle proposed in the present disclosure is not required to include the motor unit 20 and the battery 13.For example, the main frame part 34 may not necessarily be divided into two parts. In other words, the main frame part 34 does not necessarily have to include the right and left extension parts 34R, 34L.The seat position adjustment mechanism M does not necessarily have to include the biasing unit (the gas chamber 61 f, the oil chambers 61 f, 61 g, etc.) that biases the upper bracket 61B upward. In this case, it may be possible to change the relative position between the upper support 61B and the lower support 61A in the vertical direction with a device such as a screw mechanism or to lock the relative position between the upper support 61B and the lower support 61A.Although the present invention has been illustrated and described herein with reference to embodiments and specific examples, it will be readily apparent to those skilled in the art that other embodiments and examples may perform similar functions and / or achieve similar results. All such equivalent embodiments and examples are intended to be within the spirit and scope of the present invention, and are intended to be covered by the following claims.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedJP 2003-104257 A

[0002]

Claims

A seat support device (60) comprising: a seat post (61) including a lower support (61A) supported to move forward and rearward centering on a first support shaft (64a); and an upper support (61B) extending upward from the lower support (61A), the upper support (61B) being configured to support a seat (19) located on an upper side of the upper support (61B) and movable upward and downward relative to the lower support (61A); a seat position adjustment mechanism (M) configured to switch between a locked state in which a relative position between the upper support (61B) and the lower support (61A) is locked and an unlocked state in which a change in the relative position between the upper support (61B) and the lower support (61A) is possible; and a coupling arm (62) connected to the upper support (61B), wherein a front part of the coupling arm (62) is supported by a second support shaft (62b) located in front of the seat support (61), such that the coupling arm (62) and the upper support (61B) are movable upward and downward and are centered on the second support shaft (62b).The seat support device (60) according to claim 1, wherein the seat position adjustment mechanism (M) includes a biasing unit configured to bias the upper support (61B) upward with respect to the lower support (61A) in the unlocked state, and configured to switch between the locked state and the unlocked state in accordance with an operation of an operation unit (66) by a user.The seat support device (60) according to claim 1 or 2, wherein the seat post (61) is configured to move between a high post state in which the upper post (61B) is disposed in a relatively high position and a low post state in which the upper post (61B) is disposed in a relatively low position, and a position of the upper post (61B) in the low post state is rearward of a position of the upper post (61B) in the high post state.The seat support device (60) according to claim 3, wherein when the seat post (61) is in the high support state, a position of the second support shaft (62b) supporting the coupling arm (62) is lower than a height of an upper end of the upper support (61B).The seat support device (60) according to any one of claims 1 to 4, wherein a clamping member (68) is fixed to the upper support (61B), and a rear end of the coupling arm (62) is connected to the clamping member (68) via a coupling shaft (62a).The seat support device (60) according to claim 5, wherein the coupling arm (62) bulges below a straight line connecting the coupling shaft (62a) and the second support shaft (62b).A bicycle (10) comprising: the seat support device (60) according to claim 1.The bicycle (10) according to claim 7, further comprising: a frame (30), wherein the frame (30) has a head tube (31) configured to support a steering shaft (16), a frame bottom (32) configured to support a bottom bracket (51) configured to support a crankshaft (52), and a main frame part (34) extending rearward from the head tube (31) to be connected to the frame bottom (32), and the lower support (61A) is connected to the main frame part (34) via the first support shaft (64a).The bicycle (10) according to claim 8, wherein the seat post (61) is configured to move between a high post state in which the upper post (61B) is disposed in a relatively high position and a low post state in which the upper post (61B) is disposed in a relatively low position, and when the seat post (61) is in the low post state, the seat post (61) inclines rearward beyond the main frame part (34).The bicycle (10) according to any one of claims 7 to 9, further comprising: a frame (30), wherein the frame (30) has a head tube (31) configured to support a steering shaft (16), and a main frame part (32) extending rearward from the head tube (31), and the coupling arm (62) is connected to the main frame part (32) via the second support shaft (62b).The bicycle (10) according to any one of claims 7 to 10, further comprising: a frame (30), wherein the frame (30) has a head tube (31) configured to support a steering shaft (16), and a main frame part (32) extending rearward from the head tube (31), the main frame part (32) has a right extension part (34R) and a left extension part (34L) separated in a left-right direction, and the coupling arm (62) is at least partially disposed between the right extension part (34R) and the left extension part (34L).The bicycle (10) according to any one of claims 7 to 11, further comprising: a frame (30), wherein the frame (30) has a head tube (31) configured to support a steering shaft (16) and has a main frame part (32) extending rearward from the head tube (31), the main frame part (32) has a right extension part (34R) and a left extension part (34L) separated in a left-right direction, and the seat post (61) is at least partially disposed between the right extension part (34R) and the left extension part (34L).

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