Automatic transmission shifter for velocipedes

摘要

An automatic speed range shifter for bicycles is disclosed which produces a downshift when a predetermined pedal force is exceeded and which produces an upshift when a predetermined pedal rotational speed is exceeded. A pedal force sensor comprises a strain gage element on an arm supporting an idler sprocket for the chain. A pedal rotational speed sensor comprises a magnet/coil coacting with the pedal crank. A microcomputer receives inputs from the force and speed sensors and produces control signals for the automatic shifter. The automatic shifter comprises a front shifter actuator including a reversible electrical servo motor which is coupled by a cable with the front derailleur. It also comprises a rear shifter actuator with a reversible servo motor which is coupled by a cable with the rear derailleur.