Electrically operated transmission gear system for bicycles

An electrically operated transmission gear system for a bicycle, comprising:

• a transmission gear unit including a plurality of transmission gear, an endless chain, and a guide for guiding said endless chain into driving mesh with one of said transmission gears at a time;
• an electrically operated gearshifting mechanism including a reversible motor, a takeup reel actuatable by said reversible motor, and a wire joined to said takeup reel and said guide for displacing the latter in response to rotation of said takeup reel to shift said endless chain into driving mesh with one of said transmission gears;
• means for measuring the speed at which the bicycle is running and/or the speed of rotation of a crank gear of the bicycle with which said endless chain is in mesh;
• means for detecting which transmission gear is in mesh with said endless chain;
• an arithmetic unit for deriving a proper range signal from an output from one of said measuring and detecting means and for comparing said proper range signal with an output from the other means to determine whether the transmission gear with which said endless chain is in mesh is proper or not;
• a gear position display for displaying an output signal from said arithmetic unit to indicate that the transmission gear held in mesh with said endless chain is too low a transmission gear, too high a transmission gear, or in a proper range;
• a gear designation switch;
• means for controlling operation of said reversible motor in response to an output signal from said gear designation switch to bring said endless chain into driving mesh with a designated transmission gear;
• a source of DC electric power for powering said reversible motor and said arithmetic unit;
• and
• a switch for turning on and off said source of DC electric power;
• whereby gearshifting for the bicycle can manually be controlled properly.