French Patent # 992,495 - As

French Patent 992,495 - As main image

Claudius Bouillier, aged 62 at the time, maintains his position as one of the most innovative of the early derailleur designers with this patent. It is for a chainstay mounted, sliding rod type, twin pulley, derailleur with the pulley cage pivot concentric with the guide pulley - all very conventional for the time. However, in this case, the sliding rod is mounted at an angle in order to maintain a more equal chain gap.

I don’t think that this device ever made it onto the market.