This SunTour patent from 1981 describes a parallelogram-free derailleur design that uses cog wheels to keep the pulley cage aligned to the chainline. SunTour never used this system on a production model - but 30 years later it was replicated in surprising detail in the FSA K-Force WE.

• Publisher: Japan Patent Office
• Inventor: Nobuo Ozaki
• Country: Japan
• Date: Priority date October 1981
• Derailleur brands: SunTour with inspiration for FSA
• Derailleurs: none - but is curiously simliar to the FSA K-Force WE