This is the earliest Boizot advert that I have been able to find. I think it features the 1910 3 speed Boizot Tri-direct and the 1911 2 speed Boizot Bi-direct. I believe that the 1911 Boizot Bi-direct was a different beast from the Boizot 2 speed derailleur of 1908, and could be fitted to any bicycle.

I believe that the 6 speed option mentioned in the advert is a 3 speed Boizot Tri-direct used with a double chainwheel.

(Source gallica.bnf.fr/ Bibliothèque nationale de France)

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• Publisher: T.C.F. Revue Mensuelle
• Country: France
• Date: June 1911
• Derailleur brands: Boizot
• Derailleurs: Boizot Bi-direct, Boizot Tri-direct