I've heard there are a couple of good frame builders around Brisy. One of them can probably repair the dropout.
You have a 55cm 1984 Gitane Criterium. That year, Gitane offered their 4 top models with the same geometry: Criterium, Tour de France, Super Corsa and Team Replica. I have a full house, one each in 55cm. The 55cm frames have 73° head and seat tubes. they are all superb riding and handling bikes.
The Criterium was spec'd out with Super Vitus 983 main tubes similar to Columbus Nivachrome and Vitus 181 which is 4130 chrome-moly tubing. So it's not a slouch. My Criterium has 983 main tubes and Super Vitus 980 forks and stays. The Super Vitus bikes are smoother riding and the Team Replica made of Columbus SL tubing.
Getting back to the OP's problem, those are Vitus dropouts which are designed with more chain clearance for shift up off of the small cogs than standard Campy style dropouts. Something like to old Suntour dropouts from the early 70's. I've never heard of those Vitus dropouts breaking???
I got a frame on eBay and began getting it ready to assemble when I saw what looked like a scratch in the paint on the drive side dropout. I scraped away some of the paint and found a crack developing . It was a Shimano UF vertical dropout and they had a reputation for cracking.
I took it to a frame builder friend and had him run a TIG weld bead around the whole area that was failing. It's probably stronger now than when new.
The problem with the OP broken dropout is that it's right in the brazed area of the chain stay end. Trying to TIG weld an area that has been previously brazed creates a can of worms.
One solution is to use something like Allstate 11 with is a high strength nickel brazing alloy with a medium melting temperature of ~1650° F. The same alloy is available from suppliers around the world.
When TIG welding or butt brazing a crack like that, the ends need to be beveled 30° and then it's easier to build up a strong filet.
Finding a replacement Vitus drive side dropout could be difficult. just replacing the dropout with a Campy style dropout will be a problem too because the seat stays attach to the dropouts further back and are shorter and wider. Another problem is it the seat stays happen to be Super Vitus 980 like on my Criterium, the wall thickness is only 0.6mm thick and de-brazing could be fatal to the tube end.
So for those reasons I'd be reluctant to replace the dropout. Been there - Done that.... (the NSW motto)
verktyg
