I've noted that the early 70's the Schwinn catalogs listed the Super Sport and Sports Tourer as available in 22", 24", and 26" for men's frames in most years (the Superior does not appear in the catalogs in the early 70's). In another forum someone commented that he had what appeared to be a 20 1/2" Super Sport, which appeared to contradict the catalog. I think I have discovered the answer. My circa 1973 Sports Tourer measures 22" from the center of the crank to the TOP of the SEATTUBE. But these models had an extended seatube to accomodate a seat collar. The distance from the center of the toptube to the top of the extended seattube is about 1 3/4". So a 22" frame in the catalog is about 20 1/4" ctc and a 24" in the catalog is about 22 1/4" ctc.
Now owning a Superior and a Sports Tourer, I've been looking for a good clean Super Sport. The nominal 22" is probably best, but I thought about buying a nominal 24" (22 1/4" ctc) and converting to 650B wheels as I recently did with a 23" World Voyageur. However, today I measured my Sport Tourer BB height. It is 265 mm with 27 1 1/4 tires. 650B wheels would lower this almost 20 mm, even allowing for slightly fatter tires, so you're looking at as little as 245 mm BB height, probably not a good idea. For comparison, the Sports Tourer BB height with original 27" wheels is nearly identical to the World Voyageur AFTER the 650B conversion. So assuming all the early 70's fillet-brazed Schwinns have a BB height similar to my Sports Tourer, they would appear not to be good candidates for a 650B conversion.
Regards,
Jerry Moos
Big Spring, Texas, USA