Japanese Patent # S52-137836 - Sanyo

Japanese Patent S52-137836 - Sanyo main image

This is one of seven Japanese Patents and Utility Models, held by Sanyo, which describe various stages in the development of the Maruishi PC system. This was a 1970s electro-mechanical device that takes an electrical signal from a special gear electrical gear lever and then interprets it to pull the appropriate amount of bowden cable to move the rear derailleur to the correct position.

This enabled the rider to shift gears with both a very light touch - a Japanese obsession throughout the 1970s and 1980s. This provided a fantastically complex and sophisticated solution to a vanishingly small problem.

  • Publisher: Japan Patent Office
  • Inventor: Hironori Matsumoto and Yasuyuki Tsuchida
  • Country: Japan
  • Date: Priority date May 1976
  • Derailleur brands: Maruishi
  • Derailleurs: Maruishi PC electro-mechanical system