Établissements F. Charvin was owned by Francis Charvin and was based in St-Étienne.

Francis Charvin held a number of derailleur patents dating from the 1930s and 1940s and developed a range of derailleur designs. Unfortunately he also contracted the French disease, rampant at the time, of naming his derailleurs in an extremely random and confusing way. His story might go like this:

• In 1930 (see French patent # 694,417) he developed a twin pulley, pull-chain derailleur called ‘Le Lautaret’ (named after a pass in the Alps that has been on the route of the Tour de France on 40 occasions). This derailleur had a distinctive, symmetrical pulley cage.
• In 1935 he improved his original pull-chain design by using an asymmetric pulley cage, with the tension pulley considerably further from the pivot than the guide pulley. This device was also called Le Lautaret.
• In 1935 he patented an interesting fork type derailleur with a built in tension arm (see French patent # 799,054). This was known as the GRI-GRI Course. Frank Berto suggests that this was produced in 1936.
• In 1936 he introduced a touring derailleur called GRI-GRI Route. This has a pulley cage much like the 1935 asymmetric Le Lautaret, but was a direct-pull design. I believe this derailleur used a curved tube to route the cable.
• In 1937 he patented a pure fork-type derailleur with a separate tension arm (see French patent # 822,652). This derailleur was sold as the name of 'L'As des As'.
• In 1937, just to make things as confusing as possible, he renamed the GRI-GRI Route with the name Le Lautaret. I think that it still has a curved tube routing the cable.
• In 1942 he patented a twin pulley long arm derailleur which was, you guessed it, called ‘Le Lautaret’ (see French patent # 889,673). This was an improved version of the 1937 Le Lautaret, slimmer, lighter and, I believe, it used a roller to route the cable, rather than a curved tube.

Wikipedia tells us that a Gris-Gris or grigri is a voodoo amulet from Africa that is believed to protect the wearer from evil. Gris-gris is also, of course, the name of the 1968 debut album by Dr John, although it is not recorded whether the bespectacled physician was thinking of the amulet or the derailleur when he christened it... kon kon, the kiddy kon kon, walk on guilded splinters...