Originally Posted by
sced
I think a lot of derailleurs will work so long as the FD fits the bike's down tube diameter and, if it doesn't used a hanger, the RD is compatible with the rear drop out.
^This
If you don't care to keep it original, most derailleurs of that era will work, and often work better than the Simplex bits. When I broke my Simplex SX610 RD on my 1985 Peugeot, I swapped in a SunTour V-GT until I could find the proper replacement part, which I wanted because the rest of the bike was original spec.
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● 1971 Grandis SL ● 1972 Lambert Grand Prix frankenbike ● 1972 Raleigh Super Course fixie ● 1973 Nishiki Semi-Pro ● 1979 Motobecane Grand Jubile ●1980 Apollo "Legnano" ● 1984 Peugeot Vagabond ● 1985 Shogun Prairie Breaker ● 1986 Merckx Super Corsa ● 1987 Schwinn Tempo ● 1988 Schwinn Voyageur ● 1989 Bottechia Team ADR replica ● 1990 Cannondale ST600 ● 1993 Technium RT600 ● 1996 Kona Lava Dome ●