French Patent # 723,162 - Idéal

French Patent 723,162 - Ideal main image

This rather sophisticated design shows a twin pulley touring derailleur in which the pulley cage slides along two slanted rails, in an attempt to maintain a reasonably constant chain gap. As such it anticipates some of the benefits of SunTour’s game-changing sloping parallelogram design. It certainly shares a lot with White Industries’ 1996 LMDS concept.

Claudius Jacquemard marketed this design under his Idéal brand.

In 1938 he developed his ideas further in French Patent # 848,964, which also led to a commercial Idéal product.