Campagnolo BB thin cups vs. thick cups.
 

Can someone fill me in on the difference please? Campy NR. How does using one over the other affect the spindle length? Thx.

I'd have to pull some to be sure, but somewhere in the 3mm-5mm difference flange to flange measurement. In any case, I know that it's enough that you won't be able to mix thin cup spindle with thick cups. Tried and failed.

These are not Campag NR, but they should give you an idea of the difference:

http://www.jaysmarine.com/thincup_thickcup_1.jpg

http://www.jaysmarine.com/thincup_thickcup_2.jpg

-Kurt

Yes, thin and thick use different spindles.

You'll know you have mismatched axle/cups if the adjustable cup diasappears into the shell, or sticks out past the lockring.

The main difference is between the lands (or bearing surfaces). IIRC, the thick cup spindles are 49mm between them, while the thin cup spindles are 53 or 54mm between them. A thin cup spindle used in thick cups will result in the adjustable cup sticking out way too much.

I believe that all NR doubles were thick cup; Gran Sport and Record were thin. Check Sutherland's for more detail.

Thanks guys. Wish I could justify the cost of a Sutherlands but it isn't in the cards. So, if I understand correctly, a BB that currently uses thin cups and a 68 spindle, would take something like a 64 mm spindle to use a set of thick cups? Or, maybe thick cups are not useable with a 68 BB. Did Campy make a NR spindle that short? If there is a web site that has all this data I'd appreciate a link. Didn't find what I was looking for but my search criteria may have lad me astray. Thx.

The difference in the spindle center distance (B-dimension in Sutherland's, between the outer peaks of bearing surfaces) between thin and thick cup types is 5 mm even. Difference between 68 and 70 mm spindles is 2 mm, pretty obviously. For instance, B-dimension of spindles for 68 mm BB are 49.5 and 54.5 for thick cup use and thin, respectively, while those for 70 mm BB are 51.5 and 56.5. Sugino (similar taper end size) spindles MW-68 were 51.5 and MW-70 were 53.5, and Stronglight was 56, TA 55 -- so you might get one of those to work depending on what you have in hand. The B-dimension doesn't tell everything, since the geometry of the bearing track is a bit different on all of these, I imagine; but it's a fairly good rough indicator of where the bearings are supposed to be in the whole configuration.

Thank you Charles. That's very succinct and helps a lot.

1) Get a Sutherlands. Worth every single penny.

2) You can't really fart around with mismatched stuff like that, to be honest. You have to use compatible parts.

Nuovo Record cups were the first "thick" cups. That's what was 'Nuovo' about them (the rifling, which made them thicker, by design). The ATB cups with the rubber seals are also about the same thickness as Nuovo Record cups. Nuovo Record cups were only used on double-crank bottom brackets, not singles (didn't need the sealing improvements) or on triples (didn't want the additional flex caused by the narrower bearing spacing).

The difference between thick cups and thin cups is 2.5 mm per side (so 5 mm total) in bearing shoulder spacing on the spindle, as has been mentioned.

How is it that a single ring negates the additional benefit of the thick cup's spiral? After all, if flex isn't an issue, I can't see why one wouldn't wish their BB grease to stay where it belongs.

-Kurt

Old thread, I know, but for more current readers doing a bit of research (or like me, trying to refresh my memory ...):

The single-ring cranksets were generally intended for track use, so no weather-sealing (the primary purpose of the helical grooving) was really required since most outdoor tracks are pretty much unrideable in the wet and it was never a consideration on indoor tracks, obviously.

The same distinction is currently made on the Pista BB - there are no external weather seals installed, unlike the road square-taper BBs.

It's also worth noting that the post C-Record road sealed BBs have true ISO tapers wheas the current Pista BB retains the pre-ISO, Campagnolo proprietary taper - and as such, there are frequently problems with the current Pista crankset being mated with a 111mm road BB unit - the taper is not quite long enough on ISO spindles so the back of the LH crank comes up against the scallop where the spindle transitions from cylindrical to square section - this can and does cause radial cracking to develop, away from the corners of the square broaching in the crank.