Peter,
I think by your timeline - the 1970s through 1980s - many of the older French "cadreurs" had gone out of business/died/retired.
In the 1940s and 1950s, there were dozens in Paris alone, who made only frames, no paint, no decals. They worked for various pros, but also some smaller constructeurs, who then added their braze-ons, racks and other parts.
Examples include
Bianco, from whom Alex Singer learned his craft "Le Barbichet" (Monsieur Huret) who is mentioned in the current VBQ in the article about Goeland Ducheron also seems to have built bikes for various makers, including the famous "yellow" bikes of the Tour de France for those who didn't bring their own.
There were many others. Their names have faded into obscurity because their bikes were anonymous. Even during your timeframe, there were numerous smaller makers, some better than others. Names like Cadiou, and others I don't recall off the top of my head.
I doubt that many pros went to CNC - too big a shop from what I understand. They seem to have specialized in more series-produced bikes for other manufacturers, like Match in the U.S. in the 1990s.
I suspect the only reason CNC is known in the U.S. is because of Konlin/De la Rosa's book "The Custom Bicycle." Unfortunately, the authors only visited the shops that were well-known in the U.S. during the bike boom, which by definition meant larger shops. Especially in France, they seem to have known little about the "local" bike scene - and they missed both Alex Singer and Rene Herse. -- Jan Heine, Seattle Editor/Publisher Vintage Bicycle Quarterly c/o Il Vecchio Bicycles 140 Lakeside Ave, Ste. C Seattle WA 98122 http://www.vintagebicyclepress.com