Patent ID: 7137314

Claim:
A hydraulic gear shift mechanism for a bicycle having a handlebar, the gear shift mechanism comprising: a control lever; a positioning mechanism actuatable by the control lever, the positioning mechanism having: a bracket; a pivot shaft spaced apart from the handlebar and fixedly secured to the bracket; a rotating member rotatable in a first direction and a second direction about the pivot shaft; a push mechanism comprising a first latch segment and a push pawl biased toward the first latch segment and configured to cooperate with the first latch segment to rotate the rotating member in a first direction; and a return mechanism comprising a second latch segment and a return pawl, the return pawl having a first claw and a second claw which alternately engage the second latch segment when the rotating member is rotating in the second direction; a master cylinder assembly operatively connected to the rotating member of the positioning mechanism, the master cylinder having a piston that is movable in a push direction when the rotating member rotates in a first direction, and is movable in a return direction when the rotating member rotates in a second direction; a slave cylinder assembly; a conduit conveying a fluid between the master cylinder assembly and the slave cylinder assembly; and a derailleur operatively connected to the slave cylinder assembly and movable in response to the actuation of the master cylinder assembly.