The RAS brand is often shown as capitals, with full-stops between the letters - 'R.A.S.' - which could lead you to think that it was an acronym. However it appears to be the eponymous brand of Jean Ras of Levallois, a suburb of Paris.

In the early 1940s, Jean Ras received three patents for rather eccentric derailleur designs using a leaf spring. The later two of these designs do seem to have been real products:

• I have an advert from April 1944 claiming that his derailleurs placed 8th in the 'Polymultipliée' and a pungent second in the 'Grand Prix de Camembert'.

• Daniel Rebour, writing in the October 1946 edition of Le Cycle notes that he first saw the RAS derailleur two years earlier (1944), but now saw an improved version which had the ability to perfectly align its pulley wheel with the chain. He claimed that this improved version had been launched onto the market and was being produced in some volume.

Daniel Rebour also commented that RAS produced a system hub that allowed the rear wheel to be removed, while the chain, derailleur and, crucially, sprockets stayed, in place, attached to the bike. This is somewhat similar to a device produced by Nivex. Daniel Rebour claims that René Herse, the renowned Parisian frame builder, had adopted this RAS system hub on some of his 1946 models.