Originally Posted by
Poguemahone
I believe Surly measures their frames from the center of the bottom bracket to the top of seat tube, which sticks up a bit. Many older makers measured from the center of the bottom bracket to the join between seat and top tubes. A vintage 25"/62 or 63cm may thus be bigger. Check on this. One other thing... bigger frames sizes are pretty cheap in general. Get used to the pricing on vintage frames before you buy, and expect to spend less than you might for a comparable 55cm frame.
These bikes are all the same "size". The Somec and Serotta look bigger, because of differences in how they're measured.
Having an eye for such things, I also find it interesting that the only one of the three that doesn't appear to have a too-steep seat angle is also the least-highly regarded: the Surly. But then most frame designers don't have a clue when it comes to big frames. Just something I've discovered riding for 50+ years and fitting a 63-66cm.
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