Hello,

I have a 24" 1971 Schwinn Super Sport that I was looking to upgrade. But, I was also tossing up the idea of buying a Surly Cross Check Frame, or an All-City Space Horse Frame. I like the Schwinn due to the fact that it is old, and would like to see how long it will last. Just wondering if anyone knew if frame geometry is significantly different where it wouldn't be worth upgrading/modifying the super sport.

Thanks in advance for your advice

I have no direct knowledge of the details of the SSS, other than riding one a little 40+ yrs ago, but I would carefully check the diameters and threadings of the head tube and BB
to be sure they were compatible with "universal standards". Schwinn had a tendency to go its own way on some of these, though I would expect a '71 to not be a problem..
Also seat tube size and a look see down the tubings for internal rust, always possible in a 40+ year old frame. The two frames you mention are well made and designed for urban use
or long distance touring. With your other bikes as listed I would leave the Schwinn alone. For a laugh, put your SSS side by side with the Domane and the Fuji for a estimate of
frame geometry.