This Utility Model appears to feature a proposal to use a, very large, 21T tension pulley - much in the modern fashion. It is shown fitted to both a two pivot and a three pivot mechanism.

This patent was held by Kawamura Cycles, not by SunTour, but the derailleur design is clearly derived from SunTour models of the time.

• Publisher: Japan Patent Office
• Inventor: Shizuo Nakamura
• Country: Japan
• Date: Priority date February 1984
• Derailleur brands: SunTour
• Derailleurs: a wild alternative to the SunTour 3 Pulley System - that looks disturbingly modern