US 4,938,733 AGranted

Bicycle gear shifting method and apparatus

AssigneeSram, LLC

InventorSam H. Patterson

Life of this patent

Estimating the term…

Loading patent…

Abstract

A bicycle derailleur gear shifting system having a rotatable handgrip actuator cam which is coupled with the derailleur shifting mechanism through a control cable system so as to control the derailleur mechanism. Separate actuator cams are associated with the front and rear derailleurs. For the down-shifting direction, at least the rear derailleur cam is configured so as to substantially compensate for increasing force of the derailleur return spring; so as to substantially compensate for numerous cumulative lost motions in the derailleur shifting mechanism and cable system, and for chain gap variations; and so as to overshift the chain a sufficient amount beyond the destination freewheel sprocket so that the chain will approach the destination sprocket in the same direction as it would in the up-shift direction, but not sufficient to cause a double shift, or derailling from the #1 sprocket. A front derailleur cam is configured to provide fine-tuning for "cross-over" riding. In one form of the invention a secondary overshift boost cam is added axially in tandem with the primary cam, and is adaptable to both the front and rear derailleur shift actuators.

A bicycle derailleur gear shifting system, which comprises:

derailleur shifting means having return spring means operatively associated with the rear wheel of the bicycle;
primary shift actuator cam means rotatably mounted on the bicycle handlebar generally coaxially of the handlebar;
control cable means having one end operatively associated with said primary cam means and the other end operatively connected to said derailleur shifting means, said cable means being biased toward said derailleur shifting means by said return spring means;
said primary cam means being configured so that rotational movement thereof in one direction will cause said cam means to pull said cable means against the biasing force of said spring means so as to cause down-shifting of said shifting means, and rotation thereof in the opposite direction will release said cable means in the direction of the biasing force of said spring means so as to cause up-shifting of said shifting means;
and
secondary handgrip slip cam means rotatably mounted on the bicycle handlebar coaxially in tandem with said primary cam means for actuating said primary cam means, said slip cam means being axially located so that said primary cam means is biased against said secondary slip cam means by the force of said spring means;
said slip cam means having a cam face engaged against said primary cam means whereby preliminary rotational movement of said slip cam means in the down-shift direction moves said primary cam means against the biasing force of said spring means to apply an overshift increment of cable pull against the biasing force of said spring means, further down-shifting movement of said slip cam means causing said down-shifting;
and preliminary rotational movement of said slip cam means in the up-shift direction releases said primary cam means in the direction of said biasing force so as to release at least a portion of said overshift increment of cable pull, further up-shifting movement of said slip cam means causing said up-shifting.

5 more elements

Facts

Application

07/456,155Filed 21 Dec 1989 · continuation in part

Priority

6 Jan 1988

Granted

3 Jul 1990

Term ends

Not estimatedThe source records don’t support an estimate.

Classification19 codes

B62M 9/1248
Mechanisms for shifting laterally: characterised by the use of biasing means, e.g. springs; Arrangements thereof
B62K 23/04
Hand actuated: twist grips
B62M 9/127
Rear derailleurs: mounting or guiding of cables
B62M 9/131
The chain, belt, or the like being laterally shiftable , e.g. using a rear derailleur: front derailleurs

Family

Serial141,625Parent of this continuation · filed 6 Jan 1988

Serial291,359Parent of this continuation-in-part · filed 29 Dec 1988

Serial293,521Parent of this continuation-in-part · filed 5 Jan 1989

US 4,900,291 AParent of this continuation-in-part

US 4,938,733 AThis patent

From the US filing history. Foreign family members aren’t listed.

Abstract

Claims41