Bicycle speed change system, bicycle speed change method and bic

Details Bicycle speed change system, bicycle speed change method and bic Bicycle speed change system, bicycle speed change method and bic

1993-07-08

1995-06-06

Luong, Vinh T.

Machine element or mechanism

Control lever and linkage systems

Hand operated

74489, F16C 110, G05G 1100

Patent

active

054212197

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

The present invention relates to a bicycle speed change system, a bicycle speed change method and a bicycle speed change operation assembly, more specifically to those wherein a cylindrical member as a speed change operation member is rotatably supported around each grip end portion of a handlebar so that a speed change operation can be performed substantially without unhanding a handlebar and without erroneously shifting to a lower or higher speed.


BACKGROUND ART

As shown in FIG. 10, a conventional speed change system for a bicycle provided with a front derailleur a and a rear derailleur b comprises a speed change operation assembly d1 for the front derailleur and another speed change operation assembly d2 for the rear derailleur. Each of the speed change operation assemblies is mounted at a suitable portion of a bicycle such as a handlebar and connected to a corresponding one of the derailleurs a, b by means of a corresponding control cable c1, c2. The derailleurs a, b are activated by operating the respective speed change operation assemblies d1, d2.
Each of the conventional speed change operation assemblies d1 , d2 includes a lever having a base portion rotatably supported on a fixed shaft which is mounted on the bicycle frame or handlebar. The control cable c1 , c2 is wound on the base portion of the lever. When the lever is turned in one direction, the control cable c1, c2 is wound further on a cable winding groove of the lever base portion. On the other hand, when the lever is turned in the opposite direction, the control cable c1, c2 is paid out from the winding groove under the tension applied by a return spring of the derailleur. The axial movement of the control cable is transmitted to the derailleur for actuation.
Such a derailler as shown in FIG. 10 (speed shifter of the external mounting type) is commonly used for laterally pressing a chain relative to a sprocket cluster which includes a plurality of diametrically different sprockets arranged side by side at a predetermined spacing, thereby performing a speed change by shifting the chain into engagement with a desired sprocket.
A rear derailleur, which is provided at the rear wheel, includes a chain guide which rotatably supports a guide pulley and a tension pulley, as disclosed in the Japanese Patent Application Laid-Open No. 63-251388 for example. The chain guide is rotatably supported, via a shift linkage mechanism such as a parallelogram pantograph mechanism, on a link base mounted on the bicycle frame while being urged in a chain tensioning direction. The shift linkage mechanism is deformed by operating a speed change lever assembly connected to the linkage mechanism via a control cable, thereby translating the chain guide, which is carried by a movable member of the shift linkage mechanism, axially of the hub shaft to shift the chain into engagement with a desired sprocket of a multiple freewheel for speed change.
On the other hand, a front derailleur includes a pair of inner and outer guide plates facing each other with the chain interposed therebetween. The pair of guide plates is moved laterally relative to a front gear, which includes a plurality of sprockets arranged side by side, for pressing the chain inward or outward into shifted engagement with a desired sprocket.
The conventional speed change operation assemblies described above are provided at a suitable portion of the handlebar or bicycle frame and may necessitate removing the hand from the handlebar at the time of performing a speed change. During the speed change operation, therefore, it becomes impossible to apply brake quickly, and steering of the bicycle is unavoidably instable since the bicycle must be steered by a single hand.
Meanwhile, a speed changes operation is required usually when the road condition change, for instance, from flat to slope or vice versa. In such a case, the running condition tends to become unstable with greater needs for braking.
In order to solve this problem, Japanese Utility Model Laid-Open No. 58-26693 proposes

REFERENCES:
patent: 3218879 (1965-11-01), Reed
patent: 5102372 (1992-04-01), Patterson et al.
patent: 5186071 (1993-02-01), Iwasaki
patent: 5197927 (1993-03-01), Patterson et al.
patent: 5241877 (1993-09-01), Chen
patent: 5315891 (1994-05-01), Tagawa
patent: 5325735 (1994-07-01), Nagano

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