Hi CR List Members, Sheldon Brown's website has a couple Gitane models listed the more common one is for the venerable, Gitane "Tour de France", Model year 1973, SEAT POST SIZE: 26.4 mm. My 1969 -1970 GITANE "SUPER CORSA" came with a factory original, CAMPAGNOLO NEUVO RECORD, seat post, SIZE: 26.4 mm. (the stock post for that model & year). My 1971 GITANE INTERCLUB came with a steel seat pin that is "missing in action" I had ordered a lighter seatpost from AMERICAN CLASSIC for the Gitane Interclub and it's still sitting in the seat post parts box it's a 25.0 mm. It's never been installed though..... Your mileage may vary. I guess I'll have to find the old original seat pin for the GITANE INTERCLUB and verify it's size and get that bicycle back on the road.!Good luck with your Gitane project! Yours truly, Marty Walsh in Vienna,Virginia U.S.A.