Classic & Vintage - Campagnolo fork races: SR vs. NR Thin vs. Thick

Anyone care to elaborate? Are all thin races SR? Did NR headsets ever come with thin races? Was it a running change for both models?

I have a thin race without <C> marking with "Patent Campagnolo Italy' on the bottom.

SR?

Anyone care to elaborate? Are all thin races SR? Did NR headsets ever come with thin races? Was it a running change for both models?

I have a thin race without <C> marking with "Patent Campagnolo Italy' on the bottom.

SR?

Super Record crown races always have the step just prior to the bottom surface. The "Nuovo Record" head sets did appear to gain some volume over time, I do not know if they machined more out of the lower cup to compensate as the stack height did not appear to grow the same amount. Only problem I had was on an early steel unit that the owner only wished to buy the damaged crown race, he had to take a washer out of the system to still fit his brake yoke after the "thin" for "fat".

Super Record crown races always have the step just prior to the bottom surface. The "Nuovo Record" head sets did appear to gain some volume over time, I do not know if they machined more out of the lower cup to compensate as the stack height did not appear to grow the same amount. Only problem I had was on an early steel unit that the owner only wished to buy the damaged crown race, he had to take a washer out of the system to still fit his brake yoke after the "thin" for "fat".

Thanks for the info. I found a much needed SR race at the LBS!!

I need one of those! I think they are hard as hens teeth to find. My "nago (what eles?) has one that is cracked. I think it came from the factory that way as it is not perceptable when rotating the fork. When I disassebled the head, I found the crack and a lot of original paint under it. Previous posts discuss the common problem of the races breaking and often being replaced with NR ones as they are thicker. I have wondered how it that effects stack height. Another member sent me some extra races out of the kindness of his heart but when comparing the cracked one on the bike with those he sent, the SR was better. I positioned the crack by the down tube thinking that is where the least force on the race would be.
198031

Some former Trek employee discussed having drawer full of them as it common for them to break when assembling new bikes. As it is a force fit, the tolerance is small, .002 interference, IIRC.

here is where everyone with SR equipped bikes runs to check for race cracks...

Yes, Super Record crown races were prone to cracking on installation. The aluminum cups need to be thicker than the steel Record cups, so to keep the stack height reasonable the crown race was made thinner:

http://www.os2.dhs.org/~john/sr-nr-crown.jpg

Don't confuse the Super Record crown race with the Pista crown race; both are thin, but the Pista race is ground for 5/32" balls while the Super Record race is ground for 3/16" balls so they aren't interchangeable.