Bottom bracket mounted bicycle derailleur gear chain shifter - has cylinders with sloping contact faces to adjust chain shifter

摘要

The forward derailleur gear for bicycles has the chain shifter (10) attached near the bottom bracket carrying the cranks. The shifter is carried by a parallelogram linkage mounted on a lug (9) projecting from the tube (1a) supporting the bracket. The parallelogram linkage includes two links and a bracket attached to the chain guide (10). An arm with a cable retainer is rigidly fastened to one link. Thus the control cable can produce combined sine and vertical motion of the chain guide (10). The unit is carried on the bicycle frame (1a) by a tightening band (18) carrying the lug (9). The bracket (14) has an integral tube (11) through which passes a screw (26) which holds the bracket (14) to the lug (9) using a nut (28) and allowing adjustment. A return spring is provided for the cable, motion is limited by screws (30) in conjunction with the bracket integral with the outer link (15).