JP2014097755A - Bicycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve operability.SOLUTION: A bicycle comprises an operation part 40, a head tube 11 supporting the operation part 40, a front wheel shaft 46 provided below the head tube 11 and rotatably supported, and a plurality of front wheels 20 installed on both sides of the front wheel shaft 46. The head tube 11 forms a predetermined caster angle θ with respect to the vertical direction, and the caster angle θ ranges from 12 degrees to 26 degrees.

Description

  The present invention relates to a bicycle.

  Conventionally, many bicycles having a pair of front wheels have been proposed (for example, Patent Document 1). Such a conventional bicycle stabilizes by stopping the pair of front wheels on the ground when stopping or going straight, and when the handle is turned off, one of the front wheels floats to eliminate the problem of inner ring difference, Is possible. However, the conventional bicycle has no or small caster angle, which is an inclination angle of the frame head tube with respect to the vertical, and needs to take a slightly forward tilted posture, and is difficult to operate, for example, for elderly people.

Japanese Patent No. 4875405

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a bicycle having improved operability.

  The bicycle according to the present invention includes an operation unit, a head tube that supports the operation unit, a front wheel shaft that is provided below the head tube and is rotatably supported, and a plurality of front wheels that are provided on both sides of the front wheel shaft. The head tube has a predetermined caster angle with respect to the vertical direction, and the caster angle is 12 to 26 degrees.

  Furthermore, in the bicycle according to the present invention, the distance from the rear end of the saddle to the grip center of the operation unit may be 300 mm to 600 mm.

  Furthermore, the bicycle according to the present invention may be provided with a footrest member for placing a foot on the down tube of the frame when the user gets on and off.

  Further, a front fork that rotatably supports the front wheel shaft is provided below the head tube, and a reinforcing portion that reinforces the front fork may be provided.

Furthermore, the bicycle according to the present invention may have a GD value of 0.8 to 2.0, preferably 1.5.

  In the present invention, the head tube of the frame is inclined with respect to the vertical so as to have a caster angle of 12 degrees to 26 degrees. Therefore, according to the present invention, when the handle is cut to a predetermined angle, one of the pair of front wheels provided on both sides of one front wheel shaft rotatably supported below the head tube can be floated. Therefore, this invention can reduce the operation load of the handle when cutting the handle, and can improve the operability.

  Further, according to the present invention, since the head tube of the frame is inclined with respect to the vertical so as to have a caster angle of 12 degrees to 26 degrees, the distance between the saddle and the handle becomes shorter than the conventional one, For example, the handle can be arranged at a position where it can be easily operated while leaning on the backrest portion of the saddle. Therefore, the present invention can improve operability.

1 is a perspective view showing a bicycle to which the present invention is applied. It is the side view which showed the bicycle to which this invention is applied. It is the longitudinal cross-sectional view which showed the head tube and the operation part. It is the longitudinal cross-sectional view which showed the operation part and the front wheel. 1 is a plan view showing a bicycle to which the present invention is applied. It is the longitudinal cross-sectional view which showed the keyway and key between a front wheel shaft and a front wheel, (A) is an Example which provided the keyway and the key in the rectangular shape, (B) is a keyway and a key made circular. It is another Example provided with two or more. 1 is a front view showing a bicycle to which the present invention is applied. It is the figure which showed an example of the relationship between a handle | steering-wheel angle and a handle | steering-wheel load. It is the side view which showed the operation part, the front wheel, and the front wheel brake. It is the figure which showed the human body dimension of elderly person, (A) is a side view, (B) is a front view, (C) is a principal part expanded side view. It is the figure which showed a mode that the bicycle to which this invention was applied was parked in a bicycle parking lot, (A) is a top view, (B) is a side view. It is the front view which showed the human body dimension of the elderly person. It is the side view which showed the use condition which the user got on the bicycle to which this invention is applied. FIG. 6 is a front view showing a modified example of a bicycle in which a front fork includes a first front fork that rotatably supports one front wheel and a second front fork that rotatably supports the other front wheel. is there. It is the front view which showed the modification of the bicycle comprised so that a front fork may have two braid | blades which rotatably support a pair of front wheel.

  Hereinafter, a bicycle to which the present invention is applied will be described in detail with reference to the drawings. In addition, this invention is not limited to the following examples, In the range which does not deviate from the summary of this invention, it can change arbitrarily.

  As shown in FIGS. 1 and 2, the bicycle 1 to which the present invention is applied has, for example, four wheels to improve stability when starting and stopping, which is particularly unstable in a two-wheeled bicycle. The bicycle has stability that is difficult for an elderly person to fall down and has operability that can be easily operated.

  Specifically, as shown in FIGS. 1 and 2, the bicycle 1 to which the present invention is applied includes a main frame 10, twin front wheels 20, 20 provided on the lower front side of the main frame 10, and the main frame 10. Two rear wheels 30 and 30 provided at the rear of the main frame 10, an operation unit 40 for operating the front wheels 20 provided at the front of the main frame 10, and a lower side of the main frame 10 for rear wheels 30 and 30. And a drive unit 50 for driving.

  The main frame 10 includes a head tube 11 disposed vertically at the front end, a down tube 12 extending rearward from the head tube 11 with a gentle downward slope, and a rear end from the rear end of the down tube 12. A back tube 13 extending to the back, a pair of first reinforcing tubes 14 and 14 provided in an inverted V shape from the back tube 13 to the rear, and an inner side at the end of the first reinforcing tube 14 Rear tubes 15, 15 projecting toward the rear, a seat tube 16 standing upright from the vicinity of the rear end of the down tube 12, and a first tube provided between the seat tube 16 and the back tube 13. 2 reinforcing tubes 17 and a loading platform mounting tube 18 provided between the second reinforcing tube 17 and the rear tube 15 to which the rear loading platform 60 is attached. It has been.

The head tube 11 is inclined with respect to the vertical so as to have a predetermined caster angle θ. Here, the caster angle θ of the head tube 11 is provided so as to be, for example, 12 degrees to 26 degrees, preferably 15 degrees to 20 degrees with respect to the vertical. Further, a front loading platform 61 is attached to the outer peripheral portion of the head tube 11 toward the front. Further, an operation unit 40 is rotatably mounted in the head tube 11. By setting the front wheel as a double wheel and providing a caster angle θ, the handle 42 is cut from the straight traveling state, and when a predetermined angle is reached, one of the wheels 20 floats, the operation load on the handle 42 is reduced, and the inner ring difference is also eliminated. . When the steering wheel turning angle is small (the turning radius is large), the difference between the inner wheels is not a problem. However, when the steering wheel turning angle is large (the rotation radius is small), a pair of left and right front wheels (wheels) 20, 20 There is a risk that a resistance will be generated and the vehicle will deviate from the intended travel line. In this vehicle, when the front wheel 20 has a tire diameter of 12 inches to 16 inches, the steering angle is about 30 degrees, and the difference between the inner wheels is not negligible. The caster angle at which one front wheel 20 floats at a 30-degree steering angle is 12 degrees. More angles are needed. Also, by providing a caster angle, when the handle 42 is turned from a straight traveling state, the direction of the tire changes and the vehicle body rises according to the angle. The operating force applied to the operation of the steering wheel lifts the vehicle body in the direction that changes the direction of the tire. Distributed in the direction (vertical direction). By providing a caster angle when the vehicle stops due to this action, the steering wheel works to stabilize in a straight-ahead position. The larger the caster angle θ, the greater the float of the vehicle body and the higher the stability. Considering the use of elderly people whose muscle strength has declined, it is preferable that the component force in the vertical direction is 50% or less of the force used to change the direction of the original tire by the operating force of the handle 42. From tan ⁻¹ (0.5) = 26.6 °, the caster angle is preferably 26 degrees or less.

  As shown in FIG. 3, the operation unit 40 includes a control tube 41 rotatably supported by the head tube 11, a handle 42 attached to the upper end portion of the control tube 41 via a stem 42a, and the control tube. And a front fork 43 connected to the lower end of 41.

  The control tube 41 is inserted into the head tube 11 and is rotatably supported by bearing portions (not shown) provided at the upper and lower ends of the head tube 11, for example. Furthermore, one front fork 43 disposed below the head tube 11 is connected to the lower end of the control tube 41. The front fork 43 has mechanical strength reinforced by a reinforcing member 44. For example, a cylindrical reinforcing member 44 is provided in a region corresponding to the vicinity of the lower end of the head tube 11 in the front fork 43, and the front fork 43 is reinforced by increasing the thickness. Accordingly, the front fork 43 is exposed from the lower end portion of the head tube 11 to become a stepped portion, and the strength of this region of the front fork 43 where stress concentration tends to occur is reinforced. It is possible to prevent a failure or the like from occurring.

  Further, as shown in FIG. 4, a horizontal cylindrical front wheel bearing box 45 is provided at the lower end portion of the front fork 43. In the front wheel bearing box 45, one front wheel shaft having a pair of front wheels 20 and 20 attached to both ends via bearings 45a and 45a provided on both left and right ends of the front wheel bearing box 45. 46 is rotatably supported. Accordingly, the front wheel 20 is rotated in conjunction with the rotation of the control tube 41. Furthermore, since only one front fork 43 is provided between the pair of front wheels 20, the user can easily grasp the position of the front wheel 20.

  Moreover, the handle | steering-wheel 42 is attached to the upper end part of the control pipe 41 via the stem 42a, as shown in FIG. Such a handle 42 is, for example, an up handle or the like, and is formed to be substantially U-shaped. Furthermore, the grip part 42b which a user hold | grips is provided in the both ends of the handle | steering-wheel 42. FIG. Further, a front wheel brake lever 74 for braking the front wheel 20 with the front wheel brake 70 is attached to one end of the handle 42. Further, a rear wheel brake lever 110 for braking the rear wheel 30 with a rear wheel brake (not shown) is attached to the other end portion of the handle 42. The rear wheel brake lever 110 may be attached to one end portion of the handle 42 and the front wheel brake lever 74 may be attached to the other end portion of the handle 42. Further, as shown in FIG. 5, the handle width W1 of the handle 42 is substantially the same as the vehicle width W2 of the rear wheels 30, 30, or is wider than the vehicle width W2 of the rear wheels 30, 30. It is provided as follows. That is, the handle width W1 of the handle 42 is at least the maximum vehicle width W4 of the bicycle 1. With such a configuration, it can be seen that if the handle 42 is wide enough to pass, the rear wheels 30, 30 are also wide enough to pass, and the rear wheel 30 inadvertently collides with the road shoulder in a narrow alley or the like. Can be prevented.

  As shown in FIG. 4, the front wheel 20 is configured by attaching a tire 20b to a wheel 20a. Further, as the front wheel 20, for example, a tire 20b (wheel 20a) having a size of about 12 inches to 16 inches is used. The front wheel 20 is attached to both end portions of one front wheel shaft 46. 6A, the front wheel shaft 46 is fitted into the center mounting hole 20c of the wheel 20a, and the key 20e is inserted into the key groove 20d provided across the wheel 20a and the front wheel shaft 46. By being driven, the front wheel 20 rotates integrally with the front wheel shaft 46. At this time, as shown in FIG. 5, the distance W3 between the approximate center in the width direction of one of the front wheels 20 and the approximate center in the width direction of the other front wheel 20 depends on the stability at the time of start and stop and the cutting of the handle 42. In consideration of easiness, it is provided to be 70 mm to 150 mm. The key 20e is not limited to a rectangular cross section, and as shown in FIG. 6B, the front wheel 20 rotates in conjunction with the front wheel shaft 46, such as a circular shape or a plurality of the key 20e. Anything is acceptable as long as it is.

  The front wheel 20 having the above-described configuration is provided to be inclined with respect to the vertical so that the head tube 11 has a predetermined caster angle θ, and the pair of front wheels 20 and 20 rotate below the head tube 11. Since it is provided on both sides of one front wheel shaft 46 that is freely supported, as shown in FIG. 7, when the handle 42 is cut (rotated) to a certain angle, one wheel of the pair of front wheels 20, 20 Can float. Therefore, the front wheel 20 can reduce the operation load of the handle 42 when the handle 42 is cut. Further, since the front wheels 20 and 20 are provided on both sides of a single front wheel shaft 46 that is rotatably supported below the head tube 11, the pair of front wheels 20 and 20 are independent shafts. The structure can be simplified as compared with the case where the pair of front wheels 20 and 20 is lifted, and when the one wheel of the pair of front wheels 20 and 20 floats, the rotation of the ground wheel 20 and the floating front wheel 20 rotates. It is possible to prevent the number of the front wheels 20 from floating and becoming a brake when the floating front wheels 20 are grounded.

  As described above, the caster angle θ of the head tube 11 is set to be 12 degrees to 26 degrees with respect to the vertical. When the angle is smaller than 12 degrees, for example, an elderly person or the like continues a heavy load operation of the handle 42 when turning the handle 42, and when the angle is larger than 26 degrees, the floating amount of the front wheel 20 increases. , The impact will be greater and the ride will be worse.

  Further, as shown in FIGS. 6 (A) and 6 (B), the key groove 20d has a predetermined width from the width of the key 20e so that the front wheel 20 has a predetermined backlash in the rotational direction with respect to the front wheel shaft 46. Is formed wide in the rotational direction by the amount of backlash. The backlash amount is set to be at least larger than the dimensional tolerance and small enough not to deteriorate the riding comfort. Further, the backlash amount is set to such an extent that the other front wheel 20 can be idled for a predetermined time from when the handle 42 is turned to when one of the front wheels 20 floats or after it floats. Therefore, the front wheel 20 can idle the other front wheel 20 until the front wheel 20 floats after the handle 42 is turned off or for a predetermined time after the front wheel 20 floats. The operation load of the handle 42 until the valve floats can be reduced.

  FIG. 8 shows an example of the relationship between the handle angle when the handle 42 is cut and the handle load on the handle 42. A line L1 in FIG. 8 shows a graph when the front wheel 20 is attached to the front wheel shaft 46 so as to have backlash. A line L2 in FIG. 8 shows a graph when the front wheel 20 is attached to the front wheel shaft 46 so as not to have backlash. Note that the bicycles of the lines L1 and L2 are bicycles having the same shape, size, and the like except that the front wheel 20 has / does not have backlash with respect to the front wheel shaft 46. Further, a vertical line L3 in FIG. 8 indicates a handle angle when one of the front wheels 20 is lifted by cutting the handle 42. Here, as described above, the front wheel 20 is between the time when the front wheel 20 is lifted after the handle 42 is turned off, or until a predetermined time after the front wheel 20 is lifted, that is, until the handle angle is around 22 degrees. Is provided so that it can idle. As is apparent from FIG. 8, when the front wheel 20 is attached to the front wheel shaft 46 with backlash (L1), the front wheel 20 is attached to the front wheel shaft 46 without backlash ( It has been found that the handle load can be reduced overall as compared with L2).

  Furthermore, it was found from FIG. 8 that the maximum value of the handle load (P1 in FIG. 8) is reached between the line L1 after turning the handle 42 and when one of the front wheels 20 floats. Accordingly, at least the front wheel 20 can idle the other front wheel 20 from turning the handle 42 to the maximum handle load value P1 in order to avoid the maximum handle load value P1. good. That is, in FIG. 8, the front wheel 20 may be allowed to idle the other front wheel 20 until the handle angle is 10 degrees after the handle 42 is turned. Furthermore, the front wheel 20 may be configured to allow the other front wheel 20 to idle up to another appropriate handle angle such as 20 degrees, 15 degrees, and 5 degrees.

  Further, as shown in FIG. 9, the front wheel 20 is provided with a front wheel brake 70 for braking the front wheel 20. The front wheel brake 70 is, for example, a disc brake, and is provided between a pair of front wheels 20 and 20, as shown in FIG. Specifically, as shown in FIG. 9, the front wheel brake 70 is provided with a single disk-like brake rotor 71 on the front wheel shaft 46 between the pair of front wheels 20, 20, and the front fork 43. One disc caliper 72 is mounted on the rear wheel 30 side or the like to clamp and brake the brake rotor 71. Further, a front wheel brake lever 74 connected to the disc caliper 72 via a wire rope 73 is provided at one end of the handle 42 as shown in FIG.

  Accordingly, the front wheels 20 and 20 are braked by one front wheel brake 70 when the front wheel brake lever 74 is operated by being gripped by the user. Further, since the front wheel brake 70 brakes the two front wheels 20 and 20 by one front wheel brake 70, it is possible to apply a braking force evenly to the two front wheels 20 and 20. Furthermore, since the pair of front wheels 20 and 20 is braked by one front wheel brake 70, the braking adjustment between the front wheels 20 and 20 required when the front wheel brake 70 is provided on each front wheel 20 is unnecessary, and maintenance is good. Moreover, it is inexpensive. Furthermore, since the front wheel brake 70 is provided between the pair of front wheels 20, 20, there is a low possibility that a user's hand or foot will touch, and safety is high. Further, since the disc caliper 72 is provided on the rear wheel 30 side or the like of the front fork 43, the front wheel brake 70 receives the rotational load on the disc caliper 72 when the front wheels 20, 20 are braked by the front fork 43. Can do.

  As shown in FIG. 2, the saddle 80 is attached to the upper end portion of the seat tube 16 by inserting a saddle column tube 80 a into the seat tube 16. The saddle 80 is provided with a backrest 81 at the rear. Therefore, the user can drive in an easy posture while leaning on the backrest 81 when driving.

  Further, the distance between the saddle 80 and the handle 42 is set shorter than that of the conventional bicycle. Specifically, as shown in FIGS. 2 and 5, the distance L1 from the rear end of the saddle 80 to the center of the grip part 42b of the handle 42 is preferably 380 mm to 530 mm so as to be 300 mm to 600 mm. It is provided as follows.

  As shown in FIG. 10 and Table 1 below, the human body dimensions of 50 boys and 50 girls of the elderly (60 to 88 years old) are disclosed (AIST Human Body Dimension Database 1991-92). reference.). According to this, the distance from the back of the elderly to the fist (E2 / ÷ C12 in FIG. 10) averaged 415 mm, 380.7 mm for the 10 percent tile, and in a comfortable posture when drowning on the saddle If the upper body is bent backward by 5 degrees, the 90 percent tile is 526.5 mm. Therefore, by setting the distance L1 from the rear end of the saddle 80 to the center of the grip portion 42b of the handle 42 to be 380 mm to 530 mm, most people can easily hold the handle 42 in a comfortable riding posture. Thus, the bicycle 1 has improved operability, and the user can easily drive.

  Further, as shown in FIG. 2, the head tube 11, the down tube 12, and the seat tube 16 are provided so that these three parts form a substantially U shape. Furthermore, the down tube 12 has the inclination part 12a and the linear part 12b. The straight portion 12b is provided at a low height so that even an elderly person can easily get on and off without having to raise his / her foot for example. For example, here, the straight portion 12b is provided so that the height from the ground is 270 mm, which is the same as that of the non-step bath. Further, as shown in FIG. 1, the linear portion 12 b is provided with a foot placement member 90 for placing a foot when the user gets on and off. The footrest member 90 is formed of, for example, a plate-like member, and is integrally provided on the upper side (upper surface) of the straight portion 12b of the down tube 12 by welding or the like. Therefore, the user can easily get on and off even a person who is difficult to raise his / her foot such as an elderly person by placing his / her foot on the footrest member 90 when getting on and off. In addition, the height from the ground of the linear part 12b of the down tube 12 is not limited to 270 mm, and if it is provided low so that even an elderly person can get on and off easily, it can change suitably.

  Further, as shown in FIG. 1, the rear wheel 30 is configured by attaching a tire 30b to a wheel 30a. Further, as with the front wheel 20, for example, a tire 30 b (wheel 30 a) having a size of about 12 inches to 16 inches is used for the rear wheel 30. Further, the rear wheel 30 is composed of two wheels, and is supported by a bearing portion (not shown) provided in each rear tube 15 so as to be independently rotatable. Further, as shown in FIG. 5, one rear wheel 30 is connected to the first rear wheel drive shaft 100a, and the other rear wheel 30 is connected to the second rear wheel drive shaft 100b. The first rear wheel drive shaft 100a and the second rear wheel drive shaft 100b are connected via a differential gear 100c. Therefore, when turning left and right, the rotational speed of the rear wheel 30 on the outside of the turn increases, so that it can run smoothly without slipping and stably support loads including centrifugal force during turning. While driving safely. Therefore, it is possible to make a U-turn while riding even if the road is narrow, for example, even if the road is narrow. The distance W2 between the one rear wheel 30 and the other rear wheel 30 is provided to be 500 mm to 600 mm.

  As shown in FIG. 2, the drive unit 50 includes a crankshaft 51 that is pivotally supported at the rear end of the down tube 12, and a disk-shaped chain ring 52 that is fixed to the crankshaft 51. . Further, a pair of cranks 53 and 53 for turning the chain ring 52 are attached to the left and right ends of the crankshaft 51 in opposite directions. At the tip of the crank 53, a pedal 54 is attached as a step board on which a user puts his / her foot and transmits force to the bicycle 1.

  An endless chain 55 is bridged between a rear wheel sprocket (not shown) provided on the rear wheel drive shafts 100 a and 100 b of the rear wheel 30 and the chain ring 52. The endless chain 55 transmits the rotation of the chain ring 52 to the rear wheel 30. The endless chain 55 may be prevented from loosening by an auxiliary sprocket 56 provided below the down tube 12 or the like. Moreover, it is not limited to the endless chain 55, You may make it use an endless toothed belt.

  Furthermore, the drive unit 50 is set so that the GD value, which is the distance (m) that the bicycle travels with one rotation of the pedal, is 1.5. For example, since the GD value of the general bicycle is around 5.5, the GD value of the bicycle 1 is set lower than that of the general bicycle. The standard number of pedals per minute (cadence) is 60 times / minute, and the speed at this time is expressed in km / h: (GD value) x (cadence) x (60 minutes) ÷ 1000 Become. Therefore, in a general bicycle, 5.5 × 60 × 60 ÷ 1000 = 19.8 km / h. On the other hand, in the bicycle 1, 1.5 × 60 × 60 ÷ 1000 = 5.4 km / h. That is, the bicycle 1 is set so that it does not go too fast, and is substantially equivalent to the walking speed, for example. The walking speed varies depending on the person, but is generally 3 to 7 km / h, and the GD value is preferably 0.8 to 2.0.

  The rear wheel 30 is provided with a rear wheel brake (not shown) for braking the rear wheel 30. The rear wheel brakes are provided for each of the rear wheels 30, and a total of two rear wheel brakes are provided. The rear wheel brake is, for example, a band brake that brakes by tightening the outer periphery of a brake drum provided on the hub of the rear wheel 30 with a band-shaped band. Further, a rear wheel brake lever 110 connected to a band drive lever connected to the band via a rear wheel wire rope (not shown) is provided at the other end of the handle 42. Accordingly, the rear wheel 30 is braked by the rear wheel brake when the rear wheel brake lever 110 is operated by being gripped by the user.

  In addition, as shown in FIG. 5, the bicycle 1 having the above-described configuration is provided such that the total length L2 is 1000 mm to 1500 mm, for example. Furthermore, the bicycle 1 is provided so that the vehicle width (maximum vehicle width) W4 is 800 mm or less. Therefore, this bicycle 1 has excellent stability.

  Here, as shown in FIG. 11, bicycle parking racks 121 that support general two-wheel bicycles 120 in bicycle parking lots such as stations and apartments are generally arranged at intervals of 400 mm. Therefore, the bicycle 1 can be parked in the parking space 122 between the parking racks 121 and 121 by providing the maximum vehicle width W4 to be 800 mm or less.

  Furthermore, the general two-wheeled bicycle 120 supported by the bicycle parking rack 121 often has an overall length X of about 1800 mm. Therefore, the bicycle 1 can be prevented from interfering with the handle 42 of the bicycle 1 and the handle 120a of the bicycle 120 by providing a total length L2 that is at least about 300 mm shorter than that of the bicycle 2. it can. Furthermore, the bicycle 1 is located at substantially the same position as the rear portion of the adjacent two-wheel bicycle 120 adjacent to the rear portion of the rear wheel 30, the rear loading platform 60, etc., and protrudes rearward from the rear portion of the adjacent two-wheel bicycle 120 for general use. Can be prevented.

  Furthermore, in general, a storage passage 123 is provided behind the bicycle parking space 122 of the bicycle parking lot so that bicycles or the like that can park the bicycle can pass therethrough and the bicycles can be taken in and out freely. The road width of the storage passage 123 is standard at 1.8 m for parking lots with many face-to-face traffic, and 1.5 m for other parking lots (Bicycle Parking Lot Maintenance Center / Bicycle Parking Lot Installation Technology) (Refer to the guidance study report). Therefore, by setting the total length L2 of the bicycle 1 within 1500 mm, the bicycle 1 can be drawn straight out from the parking space 122 to the storage passage 123. Furthermore, by setting the total length L2 of the bicycle 1 within 1450 mm, the bicycle 1 can be drawn straight out from the parking space 122 to the storage passage 123 with a margin of about 50 mm with respect to the road width. Therefore, for example, it is not necessary to enter a narrow space between the bicycle 1 and the adjacent two-wheeled bicycle 120 as shown by S1 in FIG. 11 and operate the handle 42 to turn right or left and pull it out. For example, the rear portion of the bicycle 1 may be simply pulled from the rear and pulled straight back, and the bicycle 1 can be easily pulled out from the parking space 122.

  Furthermore, when the bicycle 1 is viewed from the parking lot, the shorter the total length L2, the better. However, even if the total length L2 is too short, the straight running stability is deteriorated, or the wheels are lifted on a steep slope. A malfunction occurs. As shown in FIGS. 12, 13 and Table 2 below, the average value of the inseam height (B18) of the elderly is about 675 mm (National Institute of Advanced Industrial Science and Technology / AIST Human Body Size Database 1991-92). Assuming that the saddle height H1 is 600 mm, the triangle connecting the front and rear wheel ground contact points and the saddle position where the weight is applied can maintain stability by making the bottom side longer than the regular triangle or the other two sides. . When the saddle height H1 is 600 mm as an equilateral triangle, the distance L3 between the wheel shafts is about 692 mm, and the outer diameter of the tire size 12 inches is about 320 mm. Therefore, the total length L2 should be about 1000 mm. It becomes the necessary length.

  As described above, the bicycle 1 to which the present invention is applied is provided with the head tube 11 of the main frame 10 inclined with respect to the vertical so as to have a predetermined caster angle θ, and a pair of front wheels 20, 20. It is provided on both sides of one front wheel shaft 46 that is rotatably supported below the head tube 11. Therefore, the bicycle 1 to which the present invention is applied can float one of the pair of front wheels 20 and 20 when the handle 42 is cut to a predetermined angle. Therefore, the bicycle 1 to which the present invention is applied can reduce the operation load of the handle 42 when the handle 42 is turned, and can improve the operability.

  Further, in the bicycle 1 to which the present invention is applied, the pair of front wheels 20, 20 are attached to the front wheel shaft 46 so as to have a predetermined backlash in the rotational direction with respect to the front wheel shaft 46. Therefore, the bicycle 1 to which the present invention is applied can idle the other front wheel 20 when the handle 42 is turned to a predetermined angle. Therefore, the bicycle 1 to which the present invention is applied can reduce the operation load of the handle 42 when the handle 42 is turned, and can improve the operability.

  Furthermore, the bicycle 1 to which the present invention is applied is provided so as to be inclined with respect to the vertical so that the head tube 11 of the main frame 10 has a caster angle θ of 12 degrees to 26 degrees. Therefore, in the bicycle 1 to which the present invention is applied, the distance between the saddle 80 and the handle 42 is shorter than that of the conventional one, and it is not necessary to take a forward leaning posture as in the conventional case. The handle 42 can be disposed at a position where it can be easily operated while sitting on the saddle 80 in an easy posture. Therefore, the bicycle 1 to which the present invention is applied can improve operability.

  Furthermore, the bicycle 1 to which the present invention is applied brakes a pair of front wheels 20, 20 provided on both sides of one front wheel shaft 46 with one front wheel brake 70. Therefore, in the bicycle 1 to which the present invention is applied, an equal braking force acts on the pair of front wheels 20 and 20, and the pair of front wheels 20 and 20 can be evenly braked.

  Furthermore, in the bicycle 1 to which the present invention is applied, the vehicle width (maximum vehicle width W4) is 800 mm or less, so that the bicycle parking space 122 between the bicycle parking racks 121 and 121 of the bicycle parking lot for the general two-wheel bicycle 120 is provided. You can park.

  The bicycle 1 to which the present invention is applied can be any other conventionally known one other than the key groove 20d and the key 20e as long as the front wheel 20 can be attached to the front wheel shaft 46 so as to have a predetermined backlash amount. A method may be used. Furthermore, in the bicycle 1 to which the present invention is applied, the backlash amount of the front wheel 20 with respect to the front wheel shaft 46 may be limited to a dimensional tolerance.

  Further, the bicycle 1 to which the present invention is applied is not limited to braking the pair of front wheels 20, 20 by providing the front wheel shaft 46 with the brake rotor 71 of the front wheel brake 70 and braking the front wheel shaft 46. Alternatively, for example, the brake rotor 71 of the front wheel brake 70 may be provided inside the wheel 20a of the front wheel 20 to directly brake the pair of front wheels 20, 20. Furthermore, the bicycle 1 to which the present invention is applied is limited to providing the brake rotor 71 of the front wheel brake 70 on the inner side of the front wheel shaft 46 and the wheel 20a of the front wheel 20 and between the pair of front wheels 20, 20. Instead, it may be provided outside the pair of front wheels 20 and 20. Further, in the bicycle 1 to which the present invention is applied, the disc caliper 72 of the front wheel brake 70 may be attached to the front or side of the front fork 43.

  In the bicycle 1 to which the present invention is applied, the front wheel shaft 46 may be constituted by a plurality of members such as two members. Further, at this time, the front wheel shaft 46 forms, for example, an engaging convex portion on one shaft member to which one front wheel 20 is attached, and an engaging convex portion on the other shaft member to which the other front wheel 20 is attached. It is also possible to form an engagement concave portion that engages with the engagement convex portion and the engagement concave portion to form a joint portion so that the two shaft members rotate in conjunction with each other. Even in such a case, the pair of front wheels 20 and 20 can be braked by one front wheel brake 70 by providing the brake rotor 71 on any shaft member or any front wheel 20.

  Further, the bicycle 1 to which the present invention is applied is not limited to the handle 42 being an up handle or the like, and is not limited to be formed in a substantially U shape, and the portion of the handle that is raised by the hand rises upward. Retracting cruiser handle, connecting left and right rising parts with a horizontal tube (crossbar), mainly used for BMX (bicycle motocross) bike BMX handle, straight flat handle, butterfly wing outline or glasses as a whole Butterfly handle shaped like a frame, mustache-shaped master shell handle, bullhorn handle that the handle grips forward, and a drop with both ends of the handle protruding forward and down A conventionally known handle such as a handle may be attached. Furthermore, a handle having a circular shape, a semicircular shape, an A shape, or the like may be attached.

  Further, the bicycle 1 to which the present invention is applied is not limited to the front wheel brake 70 being a disc brake and the rear wheel brake being a band brake, and the disc brake, the band brake, and the rim are tightened from both sides for braking. Rim brakes such as cantilever brakes, V brakes and caliper brakes, drum brakes that press a pair of arc-shaped brake shoes against the inner surface of the rotating drum, and a cam in the brake attached to the hub axle is placed around the cam Roller brake that pushes up a plurality of rollers and presses a metal brake shoe against the inside of a metal drum for braking, and the inside of a drum with two semicircular brake shoes attached to the wheel hub by a cam Servo brakes and metal bosses that are pressed against Put because the metal link brakes for braking friction between the metals, may be attached to conventional brakes. Furthermore, the bicycle 1 to which the present invention is applied is not limited to providing the front wheel brake 70 between the pair of front wheels 20, 20, and may be provided outside the pair of front wheels 20, 20.

  Further, the bicycle 1 to which the present invention is applied is not limited to using the front wheels 20 and the rear wheels 30 of 12 inches to 16 inches, but may use the front wheels 20 and the rear wheels 30 of 16 inches or more. good.

  Moreover, the bicycle 1 to which the present invention is applied is not limited to providing the distance between one front wheel 20 and the other front wheel 20 to be 70 mm to 150 mm, but 70 mm or less, or 150 mm or more. You may make it provide so that it may become. Furthermore, the bicycle 1 to which the present invention is applied is not limited to be provided so that the distance between the one rear wheel 30 and the other rear wheel 30 is 500 mm to 600 mm, and is 500 mm or less, or You may make it provide so that it may become 600 mm or more.

  Moreover, the bicycle 1 to which the present invention is applied is not limited to being provided so that the total length L2 is 1000 mm to 1500 mm, but may be provided so that it is 1000 mm or less, or 1500 mm or more. Furthermore, the bicycle 1 to which the present invention is applied is not limited to providing the maximum vehicle width W4 to be 800 mm or less, and may be provided to be 800 mm or more.

  In the bicycle 1 to which the present invention is applied, as shown in FIG. 14, the front fork 43 has two blades 43c and 43c, and supports one front wheel 20 through the first front wheel shaft 46a. A first front fork 43a having two blades 43d and 43d, and a second front fork 43b that rotatably supports the other front wheel 20 via a second front wheel shaft 46b. The pair of front wheels 20 and 20 may be rotatably supported by the first front fork 43a and the second front fork 43b.

  Further, in the bicycle 1 to which the present invention is applied, as shown in FIG. 15, the front fork 43 has two blades 43 e and 43 e, and a pair of them is provided near both ends by the two blades 43 e and 43 e. You may make it support the edge part of the front-wheel axis | shaft 46 to which these front wheels 20 and 20 were attached so that rotation is possible.

  Further, the bicycle 1 to which the present invention is applied is not limited to the so-called rear wheel drive in which the drive unit 50 drives the rear wheels 30, 30, and the drive unit 50 drives the front wheels 20, 20. So-called front wheel drive may be used.

  Further, in the bicycle 1 to which the present invention is applied, the rear wheel 30 may be formed by one wheel or three or more wheels.

  The bicycle 1 to which the present invention is applied includes an electric motor that outputs auxiliary power for assisting pedaling force, a battery for supplying electric power to the electric motor, a motor controller that controls the operation of the electric motor, and the like. An electric assist unit may be provided.

1 Bicycle, 10 Main frame, 11 Head tube, 12 Down tube, 12a Inclined portion, 12b Straight portion, 13 Back tube, 14 First reinforcing tube, 15 Rear tube, 16 Seat tube, 17 Second reinforcing tube, 18 Loading platform mounting tube, 20 front wheel, 20a wheel, 20b tire, 20c mounting hole, 20d keyway, 20e key, 30 rear wheel, 30a wheel, 30b tire, 40 operation unit, 41 control tube, 42 handle, 42a stem, 42b Grip part, 43 Front fork, 44 Reinforcement member, 45 Front wheel bearing box, 45a Bearing part, 46 Front wheel shaft, 50 Drive part, 51 Crankshaft, 52 Chain ring, 53 Crank, 54 Pedal, 55 Endless chain, 56 Auxiliary sprocket , 60 rear loading platform, 61 front loading platform, 70 front wheel brake, 71 brake rotor, 72 disc caliper, 73 wire rope, 74 front wheel brake lever, 80 saddle, 80a saddle strut tube, 81 backrest, 90 footrest member, 100a first Rear wheel drive shaft, 100b Second rear wheel drive shaft, 100c Differential gear, 110 Rear wheel brake lever, 120 Two-wheel bicycle for general use, 120a Handle, 121 Parking rack, 122 Parking space, 123 Storage passage

Claims (5)

An operation unit, and a head tube that supports the operation unit;
A front wheel shaft provided below the head tube and rotatably supported;
A plurality of front wheels provided on both sides of the front wheel shaft,
The head tube has a predetermined caster angle with respect to the vertical direction,
A bicycle having a caster angle of 12 degrees to 26 degrees. The bicycle
The bicycle according to claim 1, wherein the distance from the rear end of the saddle to the grip center of the operation portion is 300 mm to 600 mm. The bicycle
The bicycle according to claim 1 or 2, wherein a footrest member for placing a foot when the user gets on and off the frame is provided on the down tube of the frame.   4. A front fork for rotatably supporting the front wheel shaft is provided below the head tube, and a reinforcing portion for reinforcing the front fork is provided. The bicycle according to any one of the above.   The bicycle according to any one of claims 1 to 4, wherein the bicycle has a GD value of 0.8 to 2.0.

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