US Patent # 3,364,762 - SunTour

US Patent 3,364,762 - SunTour Gran-Prix main image

This is one of the most famous patents in the history of the derailleur - covering SunTour’s invention of the slant parallelogram - and giving them the opportunity to control the derailleur market until this patent ran out in 1984.

There is much else here - including coverage of SunTour’s single spring system.

Finally the patent is in the name of Tetsuo Maeda, the owner of SunTour, although the design of the slant parallelogram is usually attributed to Nobuo Ozaki, SunTour’s chief designer at the time.

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SunTour Gran-Prix derailleur thumbnail