Originally Posted by
dddd
Schwinn and their proprietary tire sizes could have been to increase sales of it's tires, but was also an assurance that only tires of a certain quality standard would be fitted.
And their 28TPI crank threading was superior to the competition's 24TPI threading, because it made for greater resolution i.e. adjustment accuracy.
It also was better at resisting loosening, and I've noticed that all of Schwinn's fitting were of much higher quality than found on other brands having Ashtabula cranks.
The bottom bracket shell ID and width on Schwinns was the same as Huffy or Murray or even Japanese Vista for that matter. I believe Schwinn's head tube ID on the Supersport and other Fillet-brazed models at was proprietary, as was the seat tube diameter (but which was a standard size for chrome-moly tubing outside of the bike industry).
Huffy and Schwinn's "gas-pipe" models use different seatpost diameters for some reason as I recall, and the super-narrow post top was I believe exclusive to Schwinn.
Schwinn wasn't the only maker to offer welded-on kickstand housings, but theirs definitely stood above others in terms of quality and function.
Schwinn was the first to use some tire sizes, such as the 2.125 balloon. There are some interesting histories that describe how Schwinn in the 1930s broke the back of the US monopolies that stuck the American public with horrible "single-tube tires" which had a lot to do with dampening adult interest in cycling in the early part of the 20th century. I'm not sure why the rest of the industry went with different standards than Schwinn for middleweight and lightweight 26" tire sizes, where Schwinn was also the trendsetter. The Schwinn sizes were the most logical, and were based on established European sizes. I think their mistake was in selecting the 26 x 1 1/4 EA1 as their lightweight size (popular in GB for club racers) and then calling it 26 x 1 3/8, which was in fact the EA3 size which was coming on all the rebranded Raleighs that the other US manufacturers were importing as their "lightweight" 3-speed models. Schwinn also had their whole "Schwinn Approved" schtick, which often was just rebranding, but sometimes included modifications that made the components a better fit for their careless and clumsy US customers.