Cycles Bertin
André Bertin (1912-1994) started making and distributing road bikes and components circa 1945 in Saint-Laurent-Blangy, France 1) after a successful career as a pro rider for France-Sport in the 1930's.
For over 20 years Bertin sponsored a pro-tour team which saw some moderate success. In 1970, Cycles Bertin became the sole distributor for Shimano in France, resulting in many made-in-France bicycles wearing Japanese components. Cycles Bertin also supplied bicycles to Go Sport, Nickel, Nakamura and Specialized. Cibo Participations bought out Bertin in 1993 and production was halted a couple of years later 2). The brand has been resurrected a few times since then, most recently in 2016 and still sells today.
Resources:
1970's etsy
André Bertin, 1933. bertinclassiccycles
Is that an air-brushed single dimple (scar?)? It doesn't appear on later images.
1985
Shimano A105 golden arrow derailleur (1983-86). Sturmey Archer Elite hubs w/coaster brakes (March 1985 date code,) lugged steel frame with Suntour dropouts.
1985
retrobike
1987
Cantilevers front, u-brakes rear. Probably Shimano Deore MT60 derailleurs (1987-88). The article states that this is Shimano Exage, which isn't in the 1987 catalog, nor does it look like this. This is likely the prior year's model announcing the coming year's model. From the magazine Le Cycle de Novembre 1987.
1987
tontonvelo
1988
Full Shimano XT, possibly M730 (1986-88).
1988
tontonvelo
1990
Shimano XT M733 u-brakes rear (1989-92), Shimano Exage 400EX rear (1990-92), Tange tubing.
1990
velobi
1991
“Badge engineered” == Asian import. Shimano Exage LX (1990-92), Tange Prestige MTB tubing (1985-), SR stem.
1991
bertinclassiccycles