The Huret Allvit was, for 1958, a ground-breaking design. It featured an 'upside down' parallelogram that maintained a reasonably even chain gap - much like SunTour's more famous, slant parallelogram design.
Most importantly, Huret, with its main customer Schwinn of the USA, decided to position the Huret Allvit as a mass-market derailleur for regular cyclists, rather than as a luxury item for competitive racers (like a Campagnolo). Frank Berto claims that 5 million Huret Allvits had been sold by 1965.
This is the patent that kicked it all off.
In previous patents Roger Huret was named as Roger-Henri Huret. Here he has become Roger-Marius Huret. What's this all about?
Browse associated derailleurs.