JP5612438B2 - Folding bicycle - Google Patents

Description

  The present invention relates to a novel folding bicycle adapted to the current situation in which the rise in awareness of global warming and ecology has permeated people's lifestyles. Specifically, the present invention has a first folding part that connects the seat tube and the chain stay, and a second folding part that is disposed on the front fork, and the rear part is moved forward by the first folding part. Folding bicycle, the front folding part is folded backward by the second folding part, lightweight, rigid, easy to fold and easy to fold, and a highly secure folding bicycle Is to provide.

Conventional folding bicycles include a vertical rotation type. In this type of foldable bicycle, the front and rear body frames in the normal posture have center planes that run vertically along their front and rear directions on the same vertical plane, and each other along the same vertical plane. Although it is configured to be folded by turning up and down, when folding it, the front and rear wheels interfere with each other and cannot be folded, so the folding work or folding mechanism is complicated There is.
In addition, there is a horizontal plane type. This type of foldable bicycle is not on a vertical plane, but is folded so as to rotate horizontally on a horizontal plane and to be arranged side by side. However, in such a foldable bicycle, the pivot between the front and rear body frames is also independently loaded with the weight of the passenger, the weight of the vehicle body, and the vertical load caused by the vertical vibration during travel. If there is no structure to disperse them, there is a drawback of being fragile.

  As an example of a conventional folding bicycle, for example, the vehicle body frame is pivoted forward and backward from a front vehicle body frame with a front wheel and a rear vehicle body frame with a rear wheel, and in its normal posture. The front body frame and the rear body frame are centered vertically along the longitudinal direction of the front body frame and the rear body frame in the same vertical plane, and are pivoted relative to each other while being along the vertical plane from the normal posture by pivoting. In a bicycle that can be in a posture, the pivot is configured so that when the body frame is folded, at least one of the front body frame and the rear body frame is gradually moved away from the vertical plane. A bicycle that can be folded by folding a tube has been proposed (Patent Document 1).

  Further, in a bicycle that can fold the rear wheel in the front wheel direction with the pivot shaft as a fulcrum, the axis direction of the pivot shaft in a plan view of the bicycle before folding is set at least when the folding operation is started. There has been proposed a bicycle in which the rear wheel and the front wheel can be overlapped on the side by folding the vehicle so as to be inclined with respect to the direction, and the folding position is the front end of the rear arm (Patent Document 2). In addition, the rear frame side of the front frame is unlocked in conjunction with the folding of the seat frame. The eccentricity of the seat frame released by the quick bottom lever is released. The support cylinder moves upward along with the folding operation around the shaft, the first lock ring and the second lock ring are separated and the lock is released, and the support cylinder serves as a folding point to the front frame on the rear frame side. There has been proposed a bicycle in which the folding position is made up of the front part of the bottom bracket, which can be folded by overlapping (Patent Document 3).

These folding bicycles have the top tube, the rear arm front end, and the bottom bracket front part from the center of the full length, so the frame design is greatly restricted, and the position of the bottom bracket moves when the seat is folded. There was a problem that the bottom bracket was not fixed to the tube and the down tube and the transmission of driving force was poor.
Furthermore, there is one tube connecting the head tube and the seat tube. Also, since there is only one stay connecting the seat tube and the rear wheel shaft, the rear wheel is supported by a single tube, so the frame rigidity is low, and the fixed strength around the shaft is used. In order to ensure the strength, a strong (heavy) structure is required.

  There is a proposal of a structure that shortens the overall length by bending the top tube halfway and rotating horizontally so that the front and rear wheels are located at substantially the same position. For example, if a single bending mechanism is provided in the top tube at the center of the vehicle body, the handle system is bent in order to solve the problem of widening because the handles bent sideways of the front and rear wheels are arranged. There has been proposed a folding bicycle whose outer shape can be made compact (Patent Document 4). In addition, when the two bending mechanisms are viewed from the side so as to divide the top tube into three, the projection line of the bending central axis can be bent so that the front wheel and the rear wheel are aligned so that the front wheel and the rear wheel are aligned. There has been proposed a folding bicycle that secures a long wheelbase while riding and folds small (Patent Document 5), and the front wheel rotates vertically by a first folding part provided in the chain stay part, and the front wheel is a top tube. There has been proposed a folding bicycle in which front wheels and rear wheels can be arranged side by side by folding backward with a second folding part provided in the vehicle (Patent Document 6). These folding bicycles have one top tube that connects the head tube and seat tube, and by providing one or two bending mechanisms on this, a reduction in rigidity becomes a problem, and the strength of the fixed part during driving is ensured. This requires a strong (heavy) structure.

Japanese Patent No. 3951522 JP-A-10-194179 JP 2000-128055 A Japanese Patent Laid-Open No. 11-20766 JP 2001-146188 A JP 2007-8418 A

Currently, the domestic bicycle market has a domestic sales volume of 11.5 million units (of which 91 million units are imported) and a market size of 103.4 billion (average unit price of 9,400 yen). Among them, sports cars (MTB, roads, etc.) account for about 9%, 990,000 units. Among them, there are 300,000 brand-name sports cars and a market size of 10.5 billion (average unit price 35,000 yen). High-end motorcycles (over 100,000) are estimated to be about 60,000, 20%. The recent trend in the domestic bicycle market is that domestic production (2 million units) continues to decrease every year due to the rapid increase in imports of inexpensive products from China, but the market scale has expanded (over 10 million units over the past five years). )doing. However, the average purchase unit price is low and the ownership rate (1.5 people / vehicle) is high.
Future trends include a growing awareness of environmental conservation and a high-grade orientation that has been reconsidered as a means of transportation such as commuting, which has led to a growing tendency to expand the number of new users of sports cycle vehicles, and has become established as a lifestyle for people. It is expected to continue. New product targets are high-grade, fashion-oriented, and lifestyle-oriented groups, and it is necessary to work to stimulate and develop this group. In Japan, the bicycle population and market size are still smaller than in Europe and the United States, but due to the above-mentioned background, the expansion of the user base and the new demand layer such as baby boomers generation is expected, and the small-diameter car market has further expanded. In Asia, our target high-value-added bicycle market is expected to expand steadily.

Under such circumstances, the development of high-quality folding bikes (Folding Bikes) has become an urgent need from Japan and Korea against the backdrop of growing needs for small-diameter bicycles due to increased use of commuting bicycles. Utilizing the accumulated knowledge and know-how related to the development of small-diameter bicycles, we have started research and development of new functional folding bicycles. The product targets are as follows.
(1) Develop the world's lightest folding bike.
While the weight of existing products is approximately 10 kg or more, the product of the present invention can reduce the weight of the 8 kg range, and can provide the world's lightest bicycle among 20-inch wheel folding small-diameter bicycles.
(2) Achieve high driving performance and compact performance.
A frame design that does not sacrifice running performance, has a wheel base similar to that of a bicycle without an existing folding function, and is designed to be compact so that it can be stored about 80 cm square by its original folding mechanism.
(3) Realize “a novel folding mechanism and high-rigidity frame design”.
Maintains the shape of the original slant design and folds without losing strength. Develop a folding mechanism that has two pivot links (movable parts) and can be stored in a short time of about 30 seconds. By increasing the strength of the pivot link, the rigidity of the entire frame is improved and the running performance is improved.

  Thus, an object of the present invention is to provide a bicycle that retains superiority in three points of “weight”, “running performance”, and “designability” over conventional products. In terms of weight, it is about 3kg lighter than conventional products, and in terms of running performance, it aims to make a bicycle that participates in small diameter bicycle competitions and events and whose performance is highly evaluated. In terms of design, a frame shape that is characteristic of the design is adopted. The present invention aims to develop a new lightweight folding small-diameter vehicle to which a “folding function” is added, utilizing the know-how and achievements of small-diameter bicycle development.

The present invention for solving the above-described problems comprises the following technical means.
( 1 ) The front frame is composed of a head tube, a top tube, a down tube and a seat tube, the rear frame is composed of a seat stay and a chain stay, and the rear frame is on the same plane with respect to the front frame; In a folding bicycle that can be converted into a state in which the front frame and the rear frame are folded so as to overlap each other, a first folding portion is disposed at a connecting portion between the front frame and the rear frame, and a second fork is disposed on the front fork. The folding part is arranged, the rear wheel part is folded forward by the first folding part, the front wheel part is folded backward by the second folding part , and the front frame and the rear frame are The first folding part provided in the connecting part is a shim for connecting the rear end part of the chain stay and the seat tube. Tosute is provided, the seat stay is removable at the junction between the seat tube, folding, characterized in that has a rotatable connection portion of the chain stay bicycle.
( 2 ) The folding bicycle according to ( 1 ) above, wherein the seat stay is fixed to the chain stay.
( 3 ) The connecting portion between the seat stay and the seat tube is provided with a safety pin as a locking mechanism, and the same safety pin is used for fixing the rear wheel portion after unlocking, as described in (1) or (2) above Folding bike.
( 4 ) The folding bicycle according to any one of (1) to ( 3 ), wherein the seat stay, the chain stay, and the rear wheel portion are rotated forward in parallel with the frame with the first folding portion as a fulcrum.
( 5 ) From the above (1), the second folding portion provided on the front fork is formed such that the upper connecting portion and the lower connecting portion are foldably connected, and the front wheel portion is bent to the rear of the bicycle together with the lower connecting portion. The folding bicycle described in ( 4 ).
( 6 ) The upper connecting part and the lower connecting part of the second folding part are provided with a safety pin as a lock mechanism, and the same safety pin is used for fixing the front wheel part after being bent after the lock is released ( 5 ) Folding bicycle as described.
( 7 ) Folding as described in said ( 5 ) or ( 6 ) by which a concave groove is provided in each of the surface of an upper connection part and a lower connection part, and both connection parts are fixed by the fixing member fitted to both grooves bicycle.
( 8 ) The folding bicycle according to any one of (1) to ( 7 ), wherein the handlebar includes a handle rotation mechanism that can be adjusted to a position substantially parallel to the top tube.

The following effects are exhibited by the present invention.
(1) It is not a structure that folds the center part of the frame, but is based on the idea of a new innovation. By adopting a mechanism that folds the rear wheels (seat stays / chain stays) and front wheels (front forks), it is light, strong and has high running performance Can provide folding rotation.
(2) Since it is not a structure that bends the center of the frame, the degree of freedom in designing the frame is increased, a design different from that of a conventional folding bicycle can be achieved, and an appearance that cannot be seen from a folding bicycle is born.
(3) The main frame does not have a folding part, and the main frame can be constituted by several tubes. Therefore, a highly secure, strong and strong folding bicycle can be made. At the same time, the frame does not have the large joining parts found in conventional products, making a lightweight frame.
(4) It is possible to provide a lightweight folding bicycle having a weight of 10 kg or less, which is a weak point of the conventional product, and further improved in weight reduction, running performance and safety.
(5) A bicycle that can be folded compactly to about 80 cm without shortening the distance between the wheel bases can be provided.
(6) By adopting a folding structure that does not reduce the strength of the frame, a folding bicycle that does not require a mechanism for improving rigidity that contributes to an increase in weight can be provided.
(7) A relatively free frame structure with few restrictions on the design due to the folding structure can be adopted.
(8) The bicycle can be folded and restored in a short time.

The driving | running | working state of the folding bicycle of this invention is shown. However, the chain is not shown. The state where the seat stay is released from the connection with the seat tube and folded on the chain stay is shown. The state which folded the rear-wheel part is shown. The figure which looked at the state which folded the rear-wheel part from upper direction is shown. The state which folded the rear-wheel part and the front-wheel part is shown. The state which folded the rear-wheel part and the front-wheel part and was seen from upper direction is shown. The frame structure of a folding bicycle is shown. The structure of a chain stay and a 1st folding part is shown. The structure of the seat stay is shown. The structure of the seat stay joint is shown. The state where the seat stay is released from the seat stay joint is shown. A state in which the first folding portion is offset outward from the fulcrum just before the rear wheel portion is folded is shown. A state in which the rear wheel portion is rotated forward with the first fold portion as a fulcrum together with the chain stay and the seat stay is shown. The solid view of the upper connection part which comprises a 2nd folding part is shown. The three-dimensional structure of the lower connection part which comprises a 2nd folding part is shown. The top view and side view of the lower connection part which comprise a 2nd folding part are shown. The top view in which the upper connection part and lower connection part which comprise a 2nd folding part are connected, the side view, and the side view of the folded state are shown. The side view before the connection of the upper connection part and lower connection part which comprise a 2nd folding part is shown. The procedure for folding the bicycle of the present invention will be described.

  The present invention relates to a folding bicycle that can be converted into a traveling state in which the rear frame is on the same plane with respect to the front frame and a state in which the front frame and the rear frame are folded so as to overlap each other. The first folding part is disposed at a position where the two are connected to each other, the second folding part is disposed on the front fork, the rear wheel part is folded forward by the first folding part, and the second folding part It relates to a folding bicycle that is configured so that the front wheel part is folded rearward by the part, the rear wheel part is folded in the vertical rotation direction, and the front wheel part is bent rearward in parallel with the frame. The type of folding bike is provided.

[Outline of folding mechanism]
An example of a bicycle before folding according to the present invention is shown in FIG. However, the chain is not shown. The frame configuration is such that the other ends of the top tube 2 and the down tube 3 coupled to the head tube 1 are connected to the seat tube 4 to form a triangular shape, and the lower end of the seat tube 3 is connected via the first folding portion 101. It is connected to the chain stay 5. A bottom bracket shell 6 is fixed to the frame in the vicinity of the chain stay 5, the down tube 3 and the seat tube 4. One end of the seat stay 7 is detachably connected to the seat tube 4, and the other end is rotatably connected to the chain stay 5 near the rear wheel axle. A second folding portion 102 is disposed on the front fork 8 near the lower end of the top tube 2. The handle bar 9 is connected to the front fork 8 via the handle stem 10 and is rotatable within a range of about 90 degrees. Preferably, in order to strengthen the frame, a reinforcing tube 11 that connects the head tube 1 and the seat tube 4 is provided.

  The seat stay 7 is detachably connected to the seat tube 4 at the upper end portion, is opened when folded, is rotated about the lower end portion, and is placed on the chain stay 5 (FIG. 2). The rear wheel portion rotates in parallel (vertical rotation direction) to the frame around the first folding portion 101 and is folded forward to have the shape shown in FIG. At this time, the rear wheel portion can be folded without being interfered with the frame by being offset. FIG. 4 shows a state in which the rear wheel is folded and viewed from above. The second folding portion 102 provided on the front fork 8 has a structure in which the front fork 8 is folded rearward, and the front wheel portion is folded rearward on the side opposite to the frame side where the rear wheel portion is folded (FIG. 5). ). At this time, the handlebar 9 is folded in a slightly rotated state so that the front wheel portion and the rear wheel portion do not overlap. FIG. 6 shows a state in which the front wheel portion and the rear wheel portion are folded and viewed from above. Thereafter, the handlebar 9 is rotated so as to be substantially parallel to the top tube 2 to be compact, and the folding of the bicycle is finished.

[Frame structure and seat stay]
An example of the frame structure of the folding bicycle of the present invention is shown in FIG. The head tube 1, the top tube 2, the down tube 3, the seat tube 4, the reinforcing tube 11, and the bottom bracket 6 are firmly coupled to each other by welding or the like to constitute a front frame. The rear frame is composed of a chain stay 5 and a seat stay 7, and the tip of the chain stay 5 is rotatable near the connecting portion between the front frame and the rear frame, for example, near the lower portion of the seat tube 4 and the bottom bracket 6. Are connected to each other to form a first folding portion 101, and a rear end portion thereof receives a rear wheel axle and is rotatably connected to a rear end of the seat stay 7. The first folding part 101 at the front end of the chain stay 5 is a mechanism that does not cause interference between the rear wheel part and the frame when the rear wheel part is folded forward, and the rear wheel part rotates eccentrically. It has an offset mechanism located outside the frame (FIG. 8). A plan view of the seat stay 7 is shown in FIG. The seat stay 7 is detachable by locking the tip of the seat stay 7 to a rod-like body attached to the seat stay joint 201 at the top of the seat tube 4.

  The seat stay 7 and the seat stay joint 201 are connected by a lever 204 that can be fastened to the seat stay joint 201 and a bar-like safety pin 203, and a quick attachment / detachment mechanism and a safe lock mechanism are provided. (FIG. 10). In order to release the connection between the seat stay 7 and the seat stay joint 201, first, the rod-shaped safety pin 203 inserted in the seat stay joint hole 202 is removed, and the lever 204 is loosened. Next, the seat stay 7 is tilted forward and coupled to the seat stay 7 and the chain stay 5. (Fig. 11)

[First folding part]
The 1st folding part 101 should just be installed in the position which connects a front frame and a rear frame. The first folding part 101 has a rotation axis perpendicular to the frame surface, and the chain stay 7 is disposed on this axis. By rotating the rear wheel portion together with the chain stay 7 from below to the front, the rear wheel portion is disposed on the side surface of the front frame. In the running state, the rear wheel part is in a straight line with the frame and cannot be folded. Therefore, when folding, the main frame and the down tube 3 are connected to the rear wheel part by giving the folding part 101 an angle of about 6 degrees. An offset state is assumed (FIG. 12). In the first folding part, the rear wheel part is folded in an offset state by a mechanism as shown in FIG. In order to lock the rear wheel part after folding the rear wheel part, a joint part B42 and a joint part A41 are provided on the side surface of the chain stay 5 at the lower part of the down tube 3, and these are engaged with each other. Then, in a state of being engaged with each other, the hole A43 provided in the down tube 3 and the hole B44 provided in the chain stay 5 serve as concentric shafts, and the safety pin 203 is inserted into the mutual holes to fix the rear wheel portion. (FIG. 13).
The front end portion of the chain stay 5 is coupled to the lower portion of the seat tube 4 and the vicinity of the bottom bracket 6. For example, the chain stay 5 may be rotatably joined to the bottom bracket 6 at the lower portion of the seat tube 4 via a connecting member. .

[Second folding part]
The second folding part 102 has a structure in which the front fork 8 is divided into two parts and connected. The connection structure of the 2nd folding part 102 consists of the upper connection part 20 shown to FIG. 14 (1)-(4), and the lower connection part 30 shown to FIG. 15 (1)-(4), for example. FIG. 14 shows a three-dimensional view of the upper connecting portion, and FIG. 15 shows a three-dimensional view of the lower connecting portion 30. The concave portion 21 of the upper connecting portion 20 and the convex portion 31 of the lower connecting portion 30 are fitted and connected by bolts passing through the fixed bolt holes 22 and 32 that communicate with each other. FIG. 16 shows a plan view and a side view of the lower connecting portion. Grooves 24 and 34 are respectively provided on the surfaces of the upper connecting portion 20 and the lower connecting portion 30 facing the running direction, and the upper connecting portion 101 is provided by installing a coupling member 35 (FIG. 17) that fits into these grooves. And the lower connecting part 202 can be fixed. The coupling member 35 is attached by a knob 39 using the bolt hole 36 of the lower connecting portion 30. For further safety, safety pin holes 23 and 33 communicating with the upper and lower connecting portions are provided, and an unexpected situation such as accidental release of the connection can be avoided by inserting the safety pin 38 into the hole.
By loosening the knob 39 of the second folding part 102, the coupling member 35 is loosened and released from the groove, and then the safety pin 38 is pulled out to unlock the connecting part and move (FIG. 17 (2)). The safety pin holes 23 and 33 are designed to be located on the concentric shaft when the front wheel part is folded back 90 degrees. By inserting the safety pin 38 extracted from the second folding part 102 into the safety pin holes 23 and 33 again, the front fork is fixed (FIG. 17 (3)). When the first folding part and the second folding part are completed, they can stand on their own without any support in the folded state.

[Connection of upper connection part and lower connection part]
The connection between the upper connecting portion 20 and the lower connecting portion 30 can be rotated by a bolt, and the front fork can be rotated backward together with the front wheel around the bolt to be folded. However, in consideration of safety and easy folding, a structure in which forward rotation is suppressed is adopted. A member that prevents forward rotation is provided at the front portion of the upper connecting portion 20 and the lower connecting portion 30. FIG. 18 shows the side surfaces of the upper connecting portion 20 and the lower connecting portion 30, but the convex portions 27 and 37 are in contact with each other in the running state to prevent the front wheel portion from bending forward. Yes.

Next, the folding procedure of the folding bicycle of the present invention will be described (see FIG. 19).
(1) Folding is started from the seat stay side among the first and second folding parts installed at the two front and rear locations (front fork and seat stay).
(2) Pull out the safety pin of the seat stay joint that connects the seat stay and the seat tube, loosen the lever of the seat stay joint, and remove the seat stay from the seat tube.
(3) Lower the seat stay and fix it on the chain stay.
(4) Hold the saddle and fold the rear wheel to the front wheel side while taking care not to drop the chain by lifting the frame.
(5) Next, remove the safety pin when folding the front fork.
(6) Loosen the knob on the front fork and release the connection by the upper and lower connecting parts. (Make sure the knob is fully closed when returning.)
(7) Fold the front fork back 90 degrees. (Be careful not to interfere with the rear wheels.)
(8) Insert the safety pin 38 of the front fork into the safety pin holes 23 and 33 located on the concentric shaft, and fix the front fork.
(9) Insert the safety pin of the seat stay joint into the hole where the down tube joint and chain stay joint are engaged, and fix the rear wheel completely. By completing the folding of the front fork and rear wheel, you can stand on your own.
(10) Loosen the handle clamping tool installed on the handle stem and rotate the handle bar 90 degrees.
(11) Loosen the quick release and lower the saddle.

  The bicycle of the present invention folded in this way does not stand on its own and fall down by positioning the crank on the lower side or the lower side and slightly rearward. Can be carried with a top tube. Hold the saddle and move it while pushing forward. The size after folding is, for example, W870 × H798 × D350 mm.

  In recent years, as seen in “LOHAS”, a sustainable lifestyle that considers health and the environment, bicycles have spread to fashion and everyday life, and have begun to spread to young people with a sense of “cool, good-natured”. It is attracting attention as the ultimate ecological product with a small environmental impact powered by human power alone. Bicycles are closely rooted in people's life culture, from those who enjoy themselves as a competitive sport, to the feet of weekend touring, living space movements, and even those who commute to improve their health. It has been reviewed as a means. For example, in Kagawa Prefecture, due to the warm climate and flat topography, two out of three prefectural citizens own bicycles, and the number of vehicles per population is the sixth highest in the country. high. In particular, Takamatsu City's commuting rate (27%) is about twice the national average. The present invention further promotes such a situation, and provides a new folding bicycle as one of effective means for promoting the comprehensive use of bicycles with the goal of bicycle paradise. is there.

1: Head tube 2: Top tube 3: Down tube 4: Seat tube 5: Chain stay 6: Bottom bracket 7: Seat stay 8: Front fork 9: Handle bar 10: Handle stem 11: Reinforcement tube 101: First folding part 102: Second folding part 201: Seat stay joint 202: Seat stay joint safety pin hole 203: Seat stay joint safety pin 204: Lever 20: Upper connection part 21: Connection recess 22: Fixing bolt hole 23: Safety pin hole 24: Connecting groove 27: Forward rotation prevention member 30: Lower connecting part 31: Connecting convex part 32: Fixing bolt hole 33: Safety pin hole 34: Connecting groove 35: Connecting member 36: Connecting member locking bolt Hole 37: Forward rotation prevention member 38: Safety pin 39: Knob 41: Gee installed on chain stay Into parts A
42: Joint part B installed in the down tube
43: Hole in joint part B 44: Hole in joint part A

Claims (8)

The front frame is composed of a head tube, a top tube, a down tube, and a seat tube, and the rear frame is composed of a seat stay and a chain stay. In a folding bicycle that can be converted into a state in which the rear frame is folded so as to overlap, a first folding portion is disposed at a connecting portion between the front frame and the rear frame, and a second folding portion is provided on the front fork. Is arranged, the rear wheel part is folded forward by the first folding part, the front wheel part is folded backward by the second folding part, and the connecting part between the front frame and the rear frame is The first folding portion provided is a seat stay that connects the rear end portion of the chain stay and the seat tube. Bicycle There is arranged, the seat stay is removable at the junction between the seat tube, folding, characterized in that has a rotatable connection portion of the chain stay. The folding bicycle according to claim 1 , wherein the seat stay is fixed to the chain stay. The folding bicycle according to claim 1 or 2 , wherein a safety pin is provided as a locking mechanism at a connecting portion between the seat stay and the seat tube, and the same safety pin is used for fixing the rear wheel portion after unlocking. The folding bicycle according to any one of claims 1 to 3 , wherein the seat stay, the chain stay, and the rear wheel portion are rotated forward in parallel with the frame with the first folding portion as a fulcrum. The second folding portion provided in the front fork is made is foldably connected to the lower connecting portion and the upper connecting portion, one of the front wheel claims 1 to be folded together with the lower coupling portion to the rear of the bicycle 4 Folding bicycle as described in 6. The folding bicycle according to claim 5 , wherein a safety pin is provided as a locking mechanism in the upper connecting portion and the lower connecting portion of the second folding portion, and the same safety pin is used for fixing the front wheel portion after being bent after the lock is released. . The folding bicycle according to claim 5 or 6 , wherein a concave groove is provided on each of the surfaces of the upper connecting portion and the lower connecting portion, and both connecting portions are fixed by a fixing member fitted in both grooves. The folding bicycle according to any one of claims 1 to 7, further comprising a handle rotation mechanism capable of adjusting the handle bar to a position substantially parallel to the top tube.