French Patent # 734,244 - JIC

French Patent 734,244 - JIC main image

This is the first of Charles Jeanmot’s JIC derailleur patents - and I have to say that I don’t quite understand how his cunning device is supposed to work. But this 1932 derailleur design is recognisable as that of a discrete bicycle component that attaches at the rear dropout, is operated by a cable and contains springs and a chain-tensioning pulley wheel.