Kommisar89

Yes, the theory of bike fit has changed. Taller frames were the norm back in the day which worked out well with the normal "7" shaped stems of the time to give an appropriate amount of drop from seat to bars. If you could clear the top tube while standing over the bike you should have about "fist" full of seatpost showing and a 2-3" drop from seat to bars. Modern frames, even those with horizontal top tubes, are generally sized a couple of centimeters smaller. Modern threadless stems have rise that evens out the seat to bar drop. Six or one, half dozen of the other. However, that doesn't necessarily corrolate directly to geometry. I have a 2002 Bianchi Veloce. The geometry is quite similar to my 1972 Bottecchia and they feel very similar on the road. What is different is that the Bianchi, which was fitted according to modern fit, is a 55cm C-C frame while the Bottecchia is a 58.5. The Bottecchia has a 1cm longer top tube while the Bianchi has a 1cm longer stem so the riding position is the same. I suppose that could have some affect on weight distribution but I can't tell any differance. Depending on the particular older bike you are considering, many came in 2 inch increments so you might find that if you get a frame sized according to the modern theory that the top tube is a bit short. But I have short legs and a very long torso. YMMV. For the 72 Bottecchia I went with the same size (23") I rode back then. I plan someday to get a late 80's - early 90's Bottecchia frame and build it up with modern kit. For that bike I'll probably go a little smaller like 56cm.