French Patent # 408,173 - Terrot

French Patent 408,173 - Terrot main image

This patent covers Terrot’s notion that the shifting of the chain by a derailleur system (such as the Terrot Numéro 1) would be helped if some of the teeth on larger cogs were bevelled one way (to aid the up-shift) and other teeth were bevelled the opposite way (to aid the down-shift). It’s a fine notion, that was revived by SunTour many moons later.