GB2293145A

GB2293145A - Cycle rear suspension

Info

Publication number: GB2293145A
Application number: GB9417869A
Authority: GB
Inventors: Fu-Hsiung Lin
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-09-06
Filing date: 1994-09-06
Publication date: 1996-03-20
Also published as: GB9417869D0

Abstract

A bicycle B has a frame F which includes a five-way joint 11 mounted at a lower end of a seat tube 10, a down tube 30 connected to the five-way joint 11, and a crossbar 20. A lower rear fork 50 has a shank 60a pivoted to the five-way joint 11 and a pair of prongs 61 located on the sides of the rear wheel 100. Each prong 61 fixedly locates on a shaft 100a of a rear wheel 100. An upper rear fork 50 has a shank 50a fixed to the seat tube 10, in the region of the cross bar 20, and a pair of prongs 51 extending rearwardly and downwardly from the shank 50a, and located at the sides of the rear wheel 100. A shock absorbing device R includes a pair of connecting units R1, interconnecting resiliently the rear end 611 of the prongs 61 of the lower rear fork 60 and the rear end 51a of the prongs 51 of the upper rear fork (50). <IMAGE>

Description

BICYCLE WITH A SHOCK ABSORBING DEVICE This invention relates to a bicycle, more particularly to an improved bicycle with a shock absorbing device.

Figure 1 shows a conventional shock absorbing device 4 of a bicycle. The conventional shock absorbing device 4 is mounted on a seat tube assembly 1 to support a saddle 5 thereon in order to absorb vibration of the bicycle's frame when the bicycle encounters impact so as to minimize vibrational forces acting on the saddle 5.

Referring to Figure 2, a conventional bicycle (b) has a front wheel, a rear wheel and a frame (f). The frame (f) includes a seat tube 6 which has an upper end for supporting a saddle and a lower end that is mounted with a crank mounting member (c). A rear chain stay 9 has a front end pivoted to the crank mounting member (c) and a rear end fixed to a shaft of the rear wheel.

A curved lever member 7 has a rear end connected fixedly to the rear end of the chain stay 9, a front end and an intermediate portion pivoted to the seat tube 6 above the crank mounting member (c). A compression spring 8 is mounted between the front end of the lever member 7 and the crank mounting member (c). When the rear wheel moves upwards due to impact, the chain stay 9 turns upwards about the crank mounting member (c) to cause the front end of the lever member 7 to turn downwards about the seat tube 6 so as to compress the spring 8. With the provision of the spring 8, the rear wheel's vibration can be absorbed so as to reduce discomfort of the rider.

With the provision of either the conventional shock absorbing device 4 or the compression spring 8, the bicycle's vibration is transmitted primarily from the rear wheel to the bicycle's frame and is then absorbed.

Since the vibration is transmitted to the frame, the rider still feels the vibrational forces. Thus, the shock absorbing effects in the above-mentioned devices are not good.

Therefore, the objective of this invention is to provide an improved bicycle with a shock absorbing device in order to absorb completely the bicycle's vibration so as to minimize the rider's discomfort due to vibrational forces.

A bicycle according to this invention has a front wheel, a rear wheel with a shaft, and a frame. The frame includes a substantially upright head tube connected to the front wheel, a seat tube having an upper end for supporting a saddle and a lower end, a five-way joint mounted at the lower end of the seat tube, a down tube connected to the head tube and the five-way joint, and a crossbar connected to the head tube and the seat tube above the down tube.

The frame further includes a lower rear fork which has a shank pivoted to the five-way joint and a pair of prongs located on two sides of the rear wheel. Each of the prongs has a rear end mounted fixedly on the shaft of the rear wheel. An upper rear fork has a shank which is fixed to the seat tube, and a pair of prongs which extend rearwardly and downwardly from the shank of the upper rear fork to the rear wheel and which are located at two sides of the rear wheel. Each of the prongs of the upper rear fork has a rear end. In addition, the upper rear fork and the crossbar may lie in a same plane.

The bicycle further has a shock absorbing device that includes a pair of connecting units, each of which interconnects resiliently the rear end of one of the prongs of the lower rear fork and the rear end of a respective one of the prongs of the upper rear fork in order to bias the two rear ends to move away from each other. Each of the connecting units may include a telescopic rod member which is connected to the rear end of the respective one of the prongs of the lower rear fork and the rear end of the respective one of the prongs of the upper rear fork, and a compression spring which is mounted on the telescopic rod member between the two rear ends. The telescopic rod member may be inclined relative to a vertical line by an angle of between 140 and 170.

The telescopic rod member of each of the connecting units may include an elongated housing which has an upper end connected to the rear end of the respective one of the prongs of the upper rear fork and a lower end with an opening, and an elongated rod which has an enlarged upper end retained slidably in the housing via the opening and a lower end connected to the rear end of the respective one of the prongs of the lower rear fork. The compression spring is sleeved around the elongated housing and the elongated rod between the upper end of the elongated housing and the lower end of the elongated rod to bias the upper and lower ends away from each other.

Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment, with reference to the accompanying drawings, in which: Figure 1 is a schematic view of a conventional shock absorbing device of a bicycle.

Figure 2 is a schematic view of a conventional bicycle which has a frame provided with a compression spring for absorbing vibration.

Figure 3 is a schematic view of a bicycle of this invention.

Figure 4 is a perspective view of a shock absorbing device of the bicycle of this invention.

Figure 5 is a schematic view of the bicycle of this invention when the bicycle encounters impact to cause upward movement of the rear wheel.

Referring to Figures 3 and 4, a bicycle (B) according to this invention has a front wheel 200, a rear wheel 100 with a shaft (100a), and a frame (F). The frame (F) includes a substantially upright head tube 40 connected to the front wheel 200, a seat tube 10 having an upper end for supporting a saddle (s) and a lower end, a five-way joint 11 mounted at the lower end of the seat tube 10, a down tube 30 connected to the head tube 40 and the five-way joint 11, and a crossbar 20 connected to the head tube 40 and the seat tube 10 above the down tube 30.

The frame (F) further includes a lower rear fork 60 which has a shank (60a) pivoted to the five-way joint 11 and a pair of prongs 61 located on two sides of the rear wheel 100. Each of the prongs 61 has a rear end 611 with a hook member 63 fixed to the shaft (100a) of the rear wheel 100. An upper rear fork 50 has a shank (50a) fixed to the seat tube 10 and a pair of prongs 51 extending rearwardly and downwardly from the shank (50a) to the rear wheel 100 and located at two sides of the rear wheel 100. Each of the prongs 51 has a rear end (5lea). It is noted that the upper rear fork 50 and the crossbar 20 lie in a same plane.

A shock absorbing device (R) has a pair of connecting units (R1), each of which interconnects resiliently the rear end 611 of one of the prongs 61 of the lower rear fork 60 and the rear end (51a) of a respective one of the prongs 51 of the upper rear fork 50 in order to bias the two rear ends 611, (5la) away from each other.

Each of the connecting units (R1) has a telescopic rod member (R2) which includes an elongated housing 83.

The housing 83 has an upper end mounted with a plate member 81 and a lug 82 projecting upwardly from the plate member 81 and pivoted to the rear end (51a) of the respective prong 51 by means of a pin 52. The housing 83 further has a lower end with an opening 832.

The telescopic rod member (R2) further includes an elongated rod 73. The elongated rod 73 has an enlarged upper end 731 retained slidably in the housing 83 via the opening 832, a lower end mounted with a plate member 71, and a lug 72 projecting downwardly from the plate member 71 and pivoted to the rear end 611 of the respective prong 61 by means of a pin 62. Each of the connecting units (R1) further includes a compress ion spring 90 sleeved around the housing 83 and the rod 73 between the plate member 81 and the plate member 71 in order to bias the plate members 81, 71 away from each other. Referring to Figure 4, the telescopic rod member (R2) is inclined relative to a vertical line (L) by an angle of between 140 and 170.

Referring to Figures 3 and 4, when the bicycle (B) is in use on an even surface, the compression spring 90 biases the plate members 81, 71 to move the rear ends 611, (51a) away from each other so as to keep the bicycle (B) in a balanced condition. Under such a condition, the enlarged upper end 731 of the rod 73 is located adjacent to the opening 832 of the housing 83.

Referring to Figure 5, when the bicycle (B) encounters an uneven surface to cause the rear wheel 100 to move upwards, as shown by the phantom lines, the prongs 61 of the lower rear fork 60 turn upwards about the fiveway joint 11 relative to the upper rear fork 50. The compression spring 90 is compressed and the rod 73 slides upwards in the housing 80 so as to absorb vibration induced upon the rear wheel 100. As shown in this Figure, the distance between the rear end (51a) of the prong 51 and the rear end 611 of the prong 61 becomes smaller than that in Figures 3 and 4. Due to the provision of the compression spring 90, the rear end 611 of each of the prongs 61 can turn downwards to a normal position as shown in Figures 3 and 4 relative to the rear end (51a) of a respective one of the prongs 51 when the effect of the rear wheel's impact is obviated.

In the present invention, since the wheel's vibration is absorbed immediately by the compression spring 90 and is not transmitted to other portions of the frame (F), the discomfort of the rider due to vibrational forces can be minimized. Thus, the bicycle (B) according to this invention has a better shock absorbing effect than that of a conventional bicycle.

Claims

CLAIMS:

1. A bicycle having a front wheel, a rear wheel with a shaft and a frame which includes a substantially upright head tube connected to said front wheel, a seat tube having an upper end for supporting a saddle and a lower end, a five-way joint mounted at said lower end of said seat tube, a down tube connected to said head tube and said five-way joint, and a crossbar connected to said head tube and said seat tube above said down tube; the improvement comprising: said frame further including a lower rear fork which has a shank pivoted to said five-way joint and a pair of prongs located on two sides of said rear wheel, each of said prongs having a rear end mounted fixedly on said shaft of said rear wheel, and an upper rear fork which has a shank fixed to said seat tube and a pair of prongs extending rearwardly and downwardly from said shank of said upper rear fork to said rear wheel and located at said two sides of said rear wheel, each of said prongs of said upper rear fork having a rear end; and a shock absorbing device having a pair of connecting units, each of which interconnecting resiliently said rear end of a respective one of said prongs of said lower rear fork and said rear end of a respective one of said prongs of said upper rear fork in order to bias said two rear ends to move away from each other.

2. A bicycle as claimed in Claim 1, wherein each of said connecting units includes a telescopic rod member connected to said rear end of said respective one of said prongs of said lower rear fork and said rear end of said respective one of said prongs of said upper rear fork, and a compression spring mounted on said telescopic rod member between said two rear ends.

3. A bicycle as claimed in Claim 2, wherein said telescopic rod member of each of said connecting units includes an elongated housing which has an upper end connected to said rear end of said respective one of said prongs of said upper rear fork and a lower end with an opening, and an elongated rod which has an enlarged upper end retained slidably in said housing via said opening and a lower end connected to said rear end of said respective one of said prongs of said lower rear fork, said compression spring being sleeved around said elongated housing and said elongated rod between said upper end of said elongated housing and said lower end of said elongated rod to bias said upper and lower ends away from each other.

4. A bicycle as claimed in Claim 3, wherein said upper rear fork and said crossbar lie in a same plane.

5. A bicycle as claimed in Claim 2, wherein said telescopic rod member is inclined relative to a vertical line by an angle of between 140 and 170.

6. A bicycle substantially as hereinbefore described with reference to and as illustrated in Figures 3, 4, and 5.