JP2010254241A - Bicycle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bicycle equipped with a drive wheel-cum-steering wheel having excellent steering stability. <P>SOLUTION: An intermediate gear 80 is allowed to be rotated around a steering shaft 66 as a rotary shaft. A driving wheel shaft 84 is rotatably supported by the steering shaft 66. A driven gear 82 is fixed to one end of the driving wheel shaft 84. A driving wheel 50 is fixed to the other end of the driving wheel shaft 84. Rotation around the steering shaft 66 as a rotary shaft through the mesh of the intermediate gear 80 and driven gear 82 is changed into rotation around the driving wheel shaft 84 as a rotary shaft. A radius R1 of an effective diameter of the intermediate gear 90, a radius R2 of an effective diameter of the driven gear 82, a rotation radius R3 in which the driving wheel 50 rotates around the steering shaft 66 and a radius R4 of the driving wheel 50 satisfy the relational expression of 0.7≤(R1×R4)/(R2×R3)≤1.3. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a bicycle provided with driving wheels and steering wheels.

  There are bicycles that use the front wheels, which are steering wheels, as drive wheels. The front wheel of the steered wheel can rotate 360 °. As a result, the driving force can be transmitted in an arbitrary direction of 360 °. This bicycle has a large degree of freedom in steering, such as moving backward and obliquely backward.

  FIG. 4 is a front view of a conventional bicycle 2 in which the front wheels, which are steered wheels, are driving wheels. This bicycle 2 is described in JP-A-2002-337781. The bicycle 2 includes a head rack 6 in front of the main frame 4. The head rack 6 holds a steering shaft 8 having a handle so as to be able to rotate 360 °. The head rack 6 includes a drive transmission mechanism 14 that transmits the driving force of the first transmission chain 10 to the second transmission chain 12. A front wheel 16 is rotatably attached to the lower end of the steering shaft 8.

  When the driver strokes the crank 18, the first chain gear 20 rotates. The rotation of the first chain gear 20 is transmitted to the drive transmission mechanism 14 via the first transmission chain 10. The drive transmission mechanism 14 transmits this driving force to the lower side of the head rack 6 by a reciprocating linear motion. This linear motion is converted into rotational motion below the head rack 6 and transmitted to the second transmission chain 12. The driving force is transmitted to the free wheel 22 via the second transmission chain 12. The front wheel 16 is rotated by the driving force transmitted to the free wheel 22.

  The drive transmission mechanism 14 of the bicycle 2 includes a reciprocating linear motion inside the head rack 6. The bicycle 2 is likely to generate vibration of the head rack 6 due to the reciprocating motion. This bicycle 2 is inferior in steering stability because the steering wheel is easily taken on an uneven road surface.

JP 2002-337781 A

  FIG. 5 is a side view showing a partial cross section of a drive transmission mechanism obtained by improving the drive transmission mechanism 14 of the bicycle shown in FIG. In this drive transmission mechanism, the driving force of the first transmission chain 10 is transmitted to the front wheels 24 as a rotational motion. The bicycle 26 includes a mechanism for transmitting a driving force as a rotational movement instead of the reciprocating linear movement portion of the driving transmission mechanism 14. The main frame includes a head pipe 28 at the front. The head pipe 28 holds a steering shaft 30 having a handle so that the steering shaft 30 can rotate 360 °. A front wheel shaft 32 that rotates integrally with the front wheel 24 is rotatably supported at the lower end of the steering shaft 30. The front wheel shaft 32 is supported so as to be rotatable about its axis. When the steering shaft 30 is turned by the steering wheel, the front wheel shaft 32 is turned in that direction and the traveling direction is changed.

  This drive transmission mechanism transmits the driving force of the first transmission chain 10 to the gear 34. The gear 34 is integrated with the bevel gear 36 and is supported so as to be rotatable with respect to the head pipe 28. This driving force is transmitted from a bevel gear 36 that rotates integrally with the gear 34 to a bevel gear 38. The bevel gear 38 is integrated with the bevel gear 40 and the pipe 42. The bevel gear 38, the bevel gear 40, and the pipe 42 are rotatably supported by the steering shaft 30 with the axis of the steering shaft 30 as a rotation axis. The driving force transmitted from the bevel gear 38 to the bevel gear 40 is transmitted to the bevel gear 44. The bevel gear 44 is fixed integrally with the front wheel 24. When the bevel gear 44 rotates, the front wheel 24 is rotated.

  In this drive transmission mechanism, the driving force is transmitted to the front wheels 24 by a vertical rotating body comprising a bevel gear 38, a bevel gear 40 and a pipe 42 instead of the reciprocating linear movement portion of the drive transmission mechanism 14 shown in the prior art. It has been. This drive transmission mechanism does not include a portion that reciprocates linearly. The head pipe 28 is not vibrated. The bicycle 26 provided with this drive transmission device is excellent in handling stability. The structure of the drive transmission mechanism is simple, and the bicycle 26 can be reduced in weight.

  In this drive transmission mechanism, the bevel gear 38, the bevel gear 40, and the pipe 42 rotate about the axis of the steering shaft 30 as a rotation axis. The steering shaft 30 rotates about its axis as a rotation axis by steering the steering wheel, and the traveling direction is changed. In the bicycle 26, the driving force is transmitted from the bevel gear 40 to the bevel gear 44, and thus the force that causes the front wheel shaft 32 to rotate the steering shaft 30 works. In particular, when power is applied from a stationary state, the force for rotating the steering shaft 30 is likely to work. For this reason, when the crank is pulled out in a state where the handle is not firmly grasped, a phenomenon occurs in which the handle is taken in the rotational direction of the bevel gear 40. This drive transmission mechanism has room for improvement in handling stability at start-up.

  An object of the present invention is to provide a bicycle provided with driving wheels and steering wheels having excellent steering stability.

The bicycle according to the present invention includes a main frame, a steering shaft, an intermediate gear, a drive wheel shaft, a driven gear, and a drive wheel. The steering shaft is supported on the main frame so as to be rotatable about the axis thereof. The intermediate gear is rotatable about a steering shaft as a rotation shaft. The drive wheel shaft is supported by the steering shaft. The drive wheel shaft is rotatable about an axis that intersects perpendicularly with the axis of the steering shaft. The driven gear is fixed to one end of the drive wheel shaft so as to rotate together with the drive wheel shaft. The drive wheel is fixed to the other end of the drive wheel shaft so as to rotate together with the drive wheel shaft. The intermediate gear and the driven gear mesh with each other to convert rotation about the steering shaft into rotation of the drive wheel shaft. The radius R1 of the effective diameter of the intermediate gear, the radius R2 of the effective diameter of the driven gear, the rotation radius R3 where the driving wheel rotates about the steering shaft, and the radius R4 of the driving wheel satisfy the following relational expression. Yes.
0.7 ≦ ((R1) · (R4)) / ((R2) · (R3)) ≦ 1.3

  Preferably, the bicycle includes a driven wheel. The driven wheel is attached to one end of the drive wheel shaft. The driven wheel is rotatable with respect to the drive wheel shaft. The vertical position of the ground plane of the driven wheel and the vertical position of the ground plane of the drive wheel are matched. Preferably, in the self-propelled vehicle, the driving wheel is a front wheel.

  In the bicycle according to the present invention, the rotation of the steering shaft due to the driving force is suppressed. The rotation of the drive transmission mechanism prevents the steering shaft from rotating. This bicycle has excellent handling stability.

FIG. 1 is a front view showing a bicycle according to an embodiment of the present invention. FIG. 2 is a side view showing a front wheel of the bicycle shown in FIG. 1 and a partial cross section of the steering unit and the driving device. 3A is a schematic view taken along the line III (a) of FIG. 2, and FIG. 3B is a schematic view taken along the line III (b) of FIG. FIG. 4 is a front view showing a conventional bicycle provided with steering and driving wheels. FIG. 5 is a side view showing a partial cross section of a drive transmission mechanism obtained by improving the drive transmission mechanism of the bicycle shown in FIG.

  Hereinafter, the present invention will be described in detail based on preferred embodiments with appropriate reference to the drawings.

  FIG. 1 is a front view of a bicycle 46 according to an embodiment of the present invention. The rightward direction in FIG. 1 is the forward direction of the bicycle 46. The leftward direction in FIG. 1 is the rearward direction of the bicycle 46. The direction perpendicular to the paper surface of FIG. 1 is the left-right direction of the bicycle 46. The vertical direction in FIG. 1 is the vertical direction of the bicycle 46. The bicycle 46 includes a main frame 48, a front wheel 50 as a driving wheel, a front wheel 52 as a driven wheel, a pair of rear wheels 54, a steering unit 56, and a driving device 58. The front wheel 50 and the front wheel 52 are steering wheels.

  Each rear wheel 54 is attached to the rear of the main frame 48. The rear wheel 54 is rotatably attached to the main frame 48. One rear wheel 54 is positioned on the right side surface of the main frame 48. The other rear wheel 54 is positioned on the left side surface of the main frame 48. The main frame 48 includes a saddle 60 on the upper side. A head pipe 62 is provided in front of the main frame 48. The head pipe 62 is hollow and has a cylindrical shape.

  The steering unit 56 includes a handle 64 and a steering shaft 66. The handle 64 has a U shape. A central portion of the handle 64 extends in the left-right direction. Both end portions of the handle 64 stand upward. Grips are formed at both ends of the handle 64. The steering shaft 66 has a round bar shape. A central portion of the handle 64 is fixed to an upper end portion of the steering shaft 66.

  FIG. 2 is a side view showing the front wheels 50 and 52 of the bicycle 46 of FIG. 1 and a partial cross section of the steering unit 56 and the drive device 58. The steering shaft 66 is supported by the head pipe 62 via a bearing (not shown). The steering shaft 66 is rotatable about its axis as a rotation axis. As shown in FIGS. 1 and 2, the driving device 58 includes a driving mechanism 68 and driving force transmitting means 69. The driving force transmission means 69 includes a pair of cranks 70, a driving gear 72, a chain 74, a driven gear 76, and a bevel gear 78 as a driving gear.

  As shown in FIG. 1, one crank 70 is rotatably attached to the right side of the main frame 48. The other crank 70 is rotatably attached to the left side of the main frame 48. A drive gear 72 is rotatably attached to the main frame 48. The rotating shaft of the crank 70 and the rotating shaft of the drive gear 72 are horizontal and coaxial. The chain 74 is spanned between the drive gear 72 and the driven gear 76.

  As shown in FIG. 2, the driven gear 76 and the bevel gear 78 are supported by the head pipe 62. The driven gear 76 and the bevel gear 78 are rotatably supported with the horizontal direction as a rotation axis. The driven gear 76 and the bevel gear 78 are integrated with the center of rotation being coaxial. The rotation shafts of the driven gear 76 and the bevel gear 78 intersect the axis of the steering shaft 66 perpendicularly.

  The drive mechanism 68 includes an intermediate gear 80, a bevel gear 82 as a driven gear, and a drive wheel shaft 84. The intermediate gear 80 includes a bevel gear 86, a pipe 88, and a bevel gear 90. The bevel gear 86, the pipe 88, and the bevel gear 90 are integrated. A bevel gear 86 is fixed above the pipe 88. A bevel gear 90 is fixed below the pipe 88. The bevel gear 86 is located below the bevel gear 78. The bevel gear 86 meshes with the bevel gear 78. A steering shaft 66 is passed through the hollow of the pipe 88. The intermediate gear 80 is supported on the steering shaft 66. The intermediate gear 80 is rotatable about the steering shaft 66 as a rotation axis.

  The drive wheel shaft 84 is supported at the lower end of the steering shaft 66. The steering shaft 66 supports between both ends of the drive wheel shaft 84. The bevel gear 82 is fixed to one end of the drive wheel shaft 84. The bevel gear 82 and the drive wheel shaft 84 are rotatable about the axis of the drive wheel shaft 84 as a rotation axis. The bevel gear 82 meshes with the bevel gear 90.

  As shown in FIG. 1, the front wheel 50 includes a wheel 92 and a tire 94. The wheel 92 is fixed to the other end of the drive wheel shaft 84. The wheel 92 and the tire 94 are rotatable together with the drive wheel shaft 84 about the axis of the drive wheel shaft 84 as a rotation axis.

  As shown in FIG. 2, the bicycle 46 includes a front wheel 52 as a driven wheel, a driven wheel shaft 96, and a bearing case 98. Although not shown, the front wheel 52 includes wheels and tires in the same manner as the front wheel 50. The wheel of the front wheel 52 is fixed to one end of the driven wheel shaft 96. The other end of the driven wheel shaft 96 is attached to the bearing case 98 via a bearing. The bearing case 98 is fixed to one end of the drive wheel shaft 84.

  The axes of the drive wheel shaft 84 and the driven wheel shaft 96 are positioned on a straight line. The front wheel 52 and the driven wheel shaft 96 are rotatable about the axis of the driven wheel shaft 96 as a rotation axis. In this bicycle 46, the outer diameter of the front wheel 50 and the outer diameter of the front wheel 52 are made equal. The vertical position of the ground contact surface of the driven wheel coincides with the vertical position of the ground contact surface of the drive wheel. In the left-right direction, the steering shaft 66 is located at the center between the front wheel 50 and the front wheel 52.

  A double arrow R <b> 1 in FIG. 2 is the radius of the pitch circle of the bevel gear 90. A double-headed arrow R2 is the radius of the pitch circle of the bevel gear 82. In the bicycle 46, the tooth that is actually engaged between the teeth of the bevel gear 90 and the teeth of the gear 82, that is, the effective tooth bamboo is determined. A point P2 in FIG. 2 shows the midpoint of the effective tooth bamboo in the tooth bamboo direction. The effective diameter of the bevel gear 90 is obtained as a radius from the middle point P2 to the rotation center of the bevel gear 90, that is, a diameter having R1 as a radius. Similarly, the effective diameter of the bevel gear 82 is obtained as a radius from the midpoint P2 to the rotation center of the bevel gear 82, that is, a radius having R2 as a radius. In the bevel gear 90 and the bevel gear 82, the diameter of the pitch circle is the effective diameter of the gear.

  Point P <b> 1 indicates the ground point of the front wheel 50. This double-headed arrow R3 represents the distance from the axis of the steering shaft 66 to the point P1. A double-headed arrow R3 is a radius at which the front wheel 50 rotates about the steering shaft 66. A double-headed arrow R4 represents the distance from the axis of the steering shaft 66 to the point P1. A double-headed arrow R4 represents the distance from the center of rotation of the front wheel 50 to the point P1. This double-headed arrow R4 is the radius of the front wheel 50. When the front wheel 50 is grounded with a width in the left-right direction, the midpoint of the width in the left-right direction to be grounded is a point P1. When the front wheel 50 is grounded with a width in the front-rear direction, the midpoint of the width in the front-rear direction to be grounded is the point P1.

In this bicycle 46, the pitch circle radius R1 of the bevel gear 90, the pitch circle radius R2 of the bevel gear 82, the rotation radius R3 about the steering shaft 66 of the front wheel 50, and the radius R4 of the front wheel 50 are as follows. It is comprised so that a formula may be satisfied.
(R1) · (R4) = (R2) · (R3)

  In this bicycle 46, the turning radius of the front wheel 52 around the steering shaft 66 is equal to the turning radius R3 of the front wheel 50 around the steering shaft 66. The outer diameter of the front wheel 52 is the same as the radius R4 of the front wheel 50. In the bicycle 46, the midpoint between the front-rear position of the ground contact surface of the front wheel 52 and the front-rear position of the front contact surface of the front wheel 50 is located on the axis of the steering shaft 66.

    In the bicycle 46 of FIG. 1, the crank 70 is wound by the driver. The crank 70 is rotated. The drive gear 72 is rotated by the rotation of the crank 70. The rotation of the drive gear 72 is transmitted to the driven gear 76 by the chain 74. As shown in FIG. 2, the driven gear 76 includes a free wheel 100. The freewheel 100 has a ratchet structure. By this free wheel 100, the rotation of the driven gear 76 is transmitted to the bevel gear 78 only in one rotational direction. The other rotational direction is not transmitted to the bevel gear 78.

  When the driven gear 76 is rotated in one rotational direction, the bevel gear 78 is rotated about the horizontal direction as the rotation axis. By the rotation of the bevel gear 78, the bevel gear 86 is rotated. As the bevel gear 86 rotates, the integral pipe 88 and bevel gear 90 are rotated. The intermediate gear 80 including the bevel gear 86, the pipe 88, and the bevel gear 90 is rotated with the steering shaft 66 as a rotation axis.

Fig.3 (a) is a schematic diagram of the III (a) arrow of FIG. A point Q <b> 1 in FIG. 3A indicates the rotation center of the steering shaft 66. The bevel gear 90 rotates around the point Q1. Arrow F1 indicates the rotational tangential force transmitted by the bevel gear 90 to the bevel gear 82. The moment M1 generated by the rotation of the gear 90 is expressed by the following equation.
(M1) = (F1) ・ (R1)

FIG.3 (b) is a schematic diagram of the III (b) arrow view of FIG. A point Q2 in FIG. 3B indicates the rotation center of the drive wheel shaft 84. A rotational moment M2 generated in the drive wheel shaft 84 by being rotated by the force F1 from the bevel gear 90 is expressed by the following equation.
(M2) = (F1) ・ (R2)
The driving wheel shaft 84 and the front wheel 50 are rotated by the rotational moment M2 of the bevel gear 82.

The relationship of the following expression is established between the magnitude of the rotational moment M1 and the magnitude of the rotational moment M2.
(M1) = ((R1) / (R2)). (M2)

An arrow F2 in FIG. 3A indicates the force in the rotational tangential direction around the point Q1. This force F2 is a force that the front wheel 50 receives from the ground as the front wheel 50 rotates. At the point P1, this rotational moment M2 is expressed by the following equation.
(M2) = (F2) ・ (R4)
At this time, the rotational moment M3 acting in the direction in which the front wheel 50 rotates the drive wheel shaft 84 is expressed by the following equation.
(M3) = (F2) ・ (R3)
The relationship of the following expression is established between the magnitude of the rotational moment M3 and the magnitude of the rotational moment M2.
(M3) = ((R3) / (R4)). (M2)

As described above, the bicycle 46 satisfies the following expression.
(R1) · (R4) = (R2) · (R3)
This formula is expressed by the following formula.
(R1) / (R2) = (R3) / (R4)
That is, the magnitude of the rotational moment M1 is equal to the magnitude of the rotational moment M3.

  A bevel gear 82 is fixed to one end of the drive wheel shaft 84, and the front wheel 50 is fixed to the other end of the drive wheel shaft 84. The drive wheel shaft 84 is supported by the steering shaft 66 at a portion between the bevel gear 82 and the front wheel 50. As a result, the rotational direction of the rotational moment M1 is opposite to the rotational direction of the rotational moment M3. In this bicycle 46, the rotational moment M1 and the rotational moment M3 are balanced. In the bicycle 46, the rotational moments M1 and M3 acting on the steering shaft 66 cancel each other.

Thereby, it is suppressed that the drive wheel shaft 84 is rotated. When the driving force is transmitted from the stationary state, the driving wheel shaft 84 is prevented from rotating. Thereby, it is suppressed that the steering shaft 66 is rotated due to the driving force. By satisfying the following expression, an effect of suppressing the rotation of the steering shaft 66 due to the driving force can be obtained.
0.7 ≦ ((R1) · (R4)) / ((R2) · (R3)) ≦ 1.3
From the viewpoint of suppressing the rotation of the steering shaft 66, it is preferable to satisfy the following expression.
0.8 ≦ ((R1) · (R4)) / ((R2) · (R3)) ≦ 1.2
Furthermore, it is more preferable to satisfy the following formula.
0.9 ≦ ((R1) · (R4)) / ((R2) · (R3)) ≦ 1.1

  The handle 64 of FIG. 1 is released by the driver. As the handle 64 rotates, the steering shaft 66 rotates. As the steering shaft 66 rotates, the traveling direction of the front wheels 50 and the front wheels 52 is changed. Thereby, the traveling direction of the bicycle 46 is changed. In the bicycle 46, the rotation of the steering shaft 66 when a driving force is applied is suppressed. Even if the force to grip the handle 64 is weak, the handle 64 is prevented from being taken. The bicycle 46 has a reduced force for gripping the handle 64.

  In this bicycle 46, the front wheels 50 are drive wheels and steering wheels. When the traveling direction of the front wheel 50 and the front wheel 52 is changed from the straight traveling direction to the diagonally forward direction by turning the handle 64, the bicycle 46 is turned while moving forward. When the traveling direction of the front wheel 50 and the front wheel 52 is changed from the straight traveling direction to the diagonally rearward direction, the bicycle 46 is turned while moving backward. When the traveling direction of the front wheel 50 and the front wheel 52 is changed by 180 ° from the straight traveling direction, the bicycle 46 is moved backward. In this way, the bicycle 46 is suitable for small turns. The steering and driving configuration of the bicycle 46 is also suitable for wheelchairs for the disabled and elderly. The bicycle according to the present invention includes a wheelchair.

  The free wheel 100 transmits only the rotation of the driven gear 76 in one rotational direction to the bevel gear 78. The rotation in the other rotational direction of the driven gear 76 is configured not to be transmitted to the bevel gear 78 by the free wheel 100. As a result, the bicycle 46 is run with the gear 72 and the crank 70 stationary while the front wheel 50 is rotating.

  In the bicycle 46, bevel gears are used as transmission means for rotations whose rotation axes are orthogonal to each other. As long as the rotation transmission means are orthogonal to each other, the bevel gear is not limited. Spur gears may be used. The bevel gear may be any of a bevel gear, a bevel gear, a spiral bevel gear, and a hypoid gear. Spiral bevel gears are preferable because they are capable of quiet rotational movement at high speed.

  In this bicycle 46, the front wheel 50 and the front wheel 52 are grounded. Since the steering shaft 66 is located at the center of the front wheel 50 and the front wheel 52 in the left-right direction, the bicycle 46 is excellent in steering stability. In the bicycle 46 in FIG. 1, the front wheels 50 are drive wheels and steering wheels. The rear wheel 54 may be a driving wheel and steering wheel. A bicycle having the rear wheel 54 as a steering wheel is provided with a steering force transmission mechanism that transmits the steering of the front handle 64 to the rear steering wheel.

  The bicycle 46 in FIG. 1 is driven by a crank 70. This crank 70 is rotated by a foot. The crank may be a manual crank installed above the main frame 48. The crank may be driven by a motor instead of driving by human power. The motor gives a driving force to the driving force transmission means 69. A gear attached to the shaft of the motor may mesh with the intermediate gear 80 to transmit the driving force. Further, this motor may directly drive the intermediate gear 80 to rotate.

  Although not shown in the drawing, casters may be provided at four positions on the front left and right and rear left and right of the main frame of the bicycle, and the driving and steering wheels may be provided. The caster is a wheel whose traveling direction can be freely changed. For example, driving and steering wheels may be provided between the front left and right casters and the rear left and right casters of the main frame. This bicycle can move in any direction regardless of the front-rear direction of the main frame. In a bicycle in which driving wheels and steering wheels are provided at the center between the front left and right casters and the rear left and right casters, linear movement is possible in any direction of 360 ° in the traveling direction of the driving wheels and steering wheels. This bicycle is more suitable for wheelchairs because it is more effective in turning.

  As shown in this embodiment, the bicycle according to the present invention is superior in steering stability as compared with the bicycle provided with the drive transmission mechanism of FIG.

  The driving wheel and steering wheel described above can be applied to a bicycle including a wheelchair.

46 ... Bicycle 48 ... Main frame 50 ... Front wheel 52 ... Front wheel 54 ... Rear wheel 56 ... Steering part 58 ... Drive device 60 ... Saddle 62 ... Head pipe 64: Handle 66 ... Steering shaft 68 ... Drive mechanism 69 ... Driving force transmission means 70 ... Crank 72 ... Drive gear 74 ... Chain 76 ... Driven gear 78 ... -Bevel gear 80 ... Intermediate gear 82 ... Bevel gear 84 ... Drive wheel shaft 86 ... Bevel gear 88 ... Pipe 90 ... Bevel gear 92 ... Wheel 94 ... Tire 96 ..Driven wheel shaft 98 ... Bearing case 100 ... Free wheel

Claims (3)

It has a main frame, steering shaft, intermediate gear, drive wheel shaft, driven gear and drive wheel,
This steering shaft is supported by the main frame so as to be rotatable about its axis.
This intermediate gear is made rotatable with the steering shaft as the rotation axis,
This drive wheel shaft is supported by the steering shaft and is rotatable about an axis that intersects perpendicularly with the axis of the steering shaft.
This driven gear is fixed to the drive wheel shaft so as to rotate together with the drive wheel shaft,
This drive wheel is fixed to the drive wheel shaft so as to rotate together with the drive wheel shaft,
This drive wheel shaft is supported on the steering shaft between the driven gear and the drive wheel,
The intermediate gear and the driven gear mesh with each other to convert rotation about the steering shaft into rotation of the drive wheel shaft,
The radius R1 of the effective diameter of the intermediate gear, the radius R2 of the effective diameter of the driven gear, the rotation radius R3 where the driving wheel rotates about the steering shaft, and the radius R4 of the driving wheel satisfy the following relational expression. bicycle.
0.7 ≦ ((R1) · (R4)) / ((R2) · (R3)) ≦ 1.3 It has a driven wheel,
The driven wheel is attached to one end of the drive wheel shaft and is rotatable with respect to the drive wheel shaft.
The bicycle according to claim 1, wherein the vertical position of the grounding surface of the driven wheel is matched with the vertical position of the grounding surface of the driving wheel.   The bicycle according to claim 1 or 2, wherein the driving wheel is a front wheel.

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