As late as 1952 Le Chemineau was promoting itself as 'pioneer of the derailleur' and gives dates - 1911 - 1952.

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

• Publisher: L'Officiel A.C.M.
• Country: France
• Date: September 1952
• Derailleur brands: Chemineau
• Derailleurs: nothing specific