Another year, another patent for the ever eager Oscar Egg. This patent appears to cover a design incorporating a detensioning device - so that you can reduce the chain tension when you want to change gear. I believe that Super Champion introduced just such a thing on the 1937 Super Champion Tour de France.

Note also that the chain tensioning arm attaches to the chainstay. This was typical of earlier Super Champion models - later models had the tensioning arm mounted on the down tube.

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• Publisher: L’Institut national de la propriété industrielle
• Inventor: Oscar Egg
• Country: France
• Date: French application December 1934
• Derailleur brands: Super Champion
• Derailleurs: Super Champion, Super Champion Tour de France