This is one of a series of derailleur patents granted to Eduard Bergles and assigned to Sachs in the mid 1970s. At this point in derailleur history there was a settled 'classic' design (the Campagnolo Nuovo Record) and a settled set of insurgent designs (the SunTour V GT and Shimano Crane). Despite this, or perhaps because of it, Sachs were determined to come up with something radically, or even insanely, different.

This particular absurdity uses a pair of leaf springs to power the sideways movement of the pulley cage. As such it owes something to the 1940s designs of Jean Ras.

• Publisher: Deutsches Patent- und Markenamt
• Inventor: Eduard Bergles of Graz, Austria, assigned to Fichtel & Sachs AG
• Country: Germany
• Date: Priority date March 1973
• Derailleur brands: Sachs, Fichtel & Sachs
• Derailleurs: Sachs prototype