This is curious - it appears to describe a system using a helical groove and peg that is extremely similar to that that had been used by Cyclo for many years before 1938. I am also unaware of Simplex ever using anything like this system.

Perhaps it was a spoiling patent, designed to mess with Cyclo’s business - or perhaps there is some devilishly clever and original detail here that I am missing.

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• Publisher: L’Institut national de la propriété industrielle
• Inventor: Lucien Juy
• Country: France
• Date: French application December 1938
• Derailleur brands: Simplex
• Derailleurs: unknown