On the racing bikes the geometry has definitely changed. I raced back in the early to mid 70's and we preferred the more stretched out feeling. I know when tri-racing came along the tri riders moved the saddles way up to give them more of a "running on the pedals" posture. I could never get comfortable on that style of bike. By today's standards most of my racing bikes from the 70's have fairly slack angles and the saddle is set too far back. One thing I cannot get used to is the "compact" geometry of today's bikes with the sloping top tube. Also depending on the model of your Gitane it may have been more of a sport geometry rather than a racing geometry.
Aaron
