Bicycle gear shift derailleur

Claim 2

A derailleur mechanism for use with a free wheel of a bicycle for shifting a chain between sprockets of said free wheel, said mechanism comprising: a parallelogram having four pivotally interconnected links including a fixed link, an opposite link and two interlinks; means mounting said fixed link in said parallelogram in fixed position relative to the frame of said bicycle, each of said interlinks being connected to both said fixed link and said opposite link so as to enable said opposite link to move in a plane which is substantially parallel to the axis of the free wheel; guiding and tensioning sprockets supported by said opposite link for movement therewith; means for swinging said opposite link including a cable coupled to said parallelogram for swinging said opposite link in said plane; and guide means stationary with respect to said fixed link and having a curved cable engaging surface positioned adjacent said opposite link for guiding the cable into a path parallel to said opposite link thereby providing a substantially equal relationship between movement of the cable and movement of said opposite link.

Claim 3

The derailleur mechanism of claim 1, said means for swinging said opposite link including a hand lever pivotally mounted to said bicycle frame and a stop plate fixed to said frame, said stop plate having a plurality of stop abutments spaced along an arc concentric to the pivot axis of said hand lever, and detent means on said hand lever engagable with said stop abutments for positioning said cable and thus said guiding and tensioning sprockets relative to said free wheel sprockets.

Claim 4

The derailleur mechanism of claim 2, the number of said stop abutments being equal to the number of free wheel sprockets, and the arcuate distance between the farthest apart of said stop abutments being at least 90°.

Claim 5

The derailleur mechanism of claim 3, the arcuate distance between the farthest apart of said stop abutments being about 180°.

Claim 6

The derailleur mechanism of claim 3 wherein said cable is slack when the detent means of said hand lever engages a first stop abutment at one end of said stop abutments, and wherein the arcuate distance between said first stop abutment and a second stop abutment adjacent said first stop abutment is greater than the arcuate distance between all other stop abutments whereby slack in the cable is taken up during movement of the hand lever between said first and second stops.

Claim 7

The derailleur mechanism of claim 5, said stop abutments including arcuate slots, the arcuate slot of said second stop abutment being greater than all remaining slots whereby a greater range of adjustment is available in said second slot for compensating for cable slack.

Claim 8

The derailleur mechanism of claim 2, said stop abutments including arcuate slots, the arcuate slot of said second stop abutment having an arcuate length greater than all remaining slots whereby a greater range of adjustment if available in said second slot for compensating for cable slack, each of said slots being of a length sufficient to provide slight cable movement within the slot to accurately provide a fine adjustment of the chain on the desired free wheel sprocket.

Claim 9

A derailleur mechanism for use with a free wheel of a bicycle for shifting a chain between sprockets of said free wheel, comprising: a parallelogram having four interconnected links, including a fixed link and an opposite link, means mounting said fixed link in said parallelogram in fixed position relative to the frame of said bicycle, the other links in said parallelogram being pivotally connected to each other and to said fixed link so that said opposite link is movable in a plane which is parallel to the axis of said free wheel; guiding and tensioning sprockets supported by said opposite link for movement therewith; a cable connected to said movable opposite link for actuating said parallelogram for shifting said guiding and tensioning sprockets laterally; and cable guide means having a smooth curved surface approximately tangent to both the cable and the movable opposite link for causing the direction of cable pull on said movable opposite link to be substantially parallel to the axis of said free wheel at said opposite link for converting movement of the cable to approximately 1:1 movement of the guiding and tensioning sprockets relative to the cable movement.

Claim 10

A derailleur mechanism for use with a free wheel of a bicycle for shifting a chain between sprockets of said free wheel, comprising: a parallelogram having four interconnected links, including a fixed link and an opposite link, means mounting said fixed link in said parallelogram in fixed position relative to the frame of said bicycle, the other links in said parallelogram being pivotally connected to each other and to said fixed link so that said opposite link is movable in a plane which is parallel to the axis of said free wheel; guiding and tensioning sprockets supported by said opposite link for movement therewith; a cable connected to said movable opposite link for actuating said parallelogram for shifting said guiding and tensioning sprockets laterally; and cable guide means having a smooth curved surface approximately tangent to both the cable and the movable opposite link for causing the direction of cable pull on said movable opposite link to be substantially parallel to the axis of said free wheel at said opposite link for converting movement of the cable to approximately 1:1 movement of the guiding and tensioning sprockets relative to the cable movement.