Originally Posted by
Steel Charlie
I'm not really very adept at phrasing questions.
I was aware of the different shape stuff. I am curious about what the designation signifies. Do C3 and C4 have different shapes or do they differ in tube types and/or wall thickness, or ... ?
That of course presumes that there was a reason for the different designations.
Thanks
They are different in small dimensions - like the butting thickness, alloy and location of the swaging. Just like SL and SP are similar but SP has thicker wall dimensions. In Serotta's case the changes were usually generational, and newer tubes were "better" by being lighter. But they also had lower cost versions of Colorado tubing in some years that might be slightly thicker than the most premium version. Like this 1999 catalog has new versions of C4 and C3 for the CSI and Atlanta models.
These also aren't just simple tubesets - they would use different dimension tubes for a C3 bike for a large rider and someone small. So there is never going to be CC chart like there is for a tubeset like Columbus SL. It is taken on faith that if you buy the most expensive steel bike that year with the highest numbered tubeset that you are getting the highest performing tubes.
I would expect most CC bikes to ride more similarly than different, but the weight will vary.
https://www.retrobike.co.uk/gallery2/d/15544-2/1999.pdf