This advert from November 1937 mentions 'changement de vitesse' - in this case derailleurs. It is notable that a later, rather similar, advert from October 1938 does not do so.

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

• Publisher: La Pédale Touristique
• Country: France
• Date: November 1937
• Derailleur brands: Idéal
• Derailleurs: It's hard to say!