DISRAELI DOCUMENTS
see also L'Officiel A.C.M. 27/09/1931 - Un nouveau changement de vitesses pour cycles: le Radios-Vario
see also L'Officiel A.C.M. 27/09/1931 - Un nouveau changement de vitesses pour cycles: le Radios-Vario
see also L'Officiel A.C.M. 18/10/1931 - Radios ad
see also L'Officiel A.C.M. 18/10/1931 - Radios ad
Établissement Radios was based in Bellegarde, in France but on the Swiss border near Geneva. It's main line of business, in the 1920s and 1930s, was manufacturing, what were then high-tech, electrical dynamo lighting systems. As a cycling technology leader it was natural that Radios should be interested in the newly developing field of derailleur gearing.
In 1931 they appear to have launched a derailleur called the Radios-Vario. This was a twin pulley model that clamps onto the chsainstay. How it operated is not exactly clear to me.