Thick Paint?

[Sequoia]

I'm building up a CAAD5 frame at the moment. I'm transferring components from a Schwinn frame. Both frames have a 31.8mm seat tube diameter. BUT... when I try to put the front derailleur on the cannondale, it seems as if the clamp is the wrong size. The clamp seems round enough and it IS the right size.

So what gives?

Could it be that the paint is thicker on the cannondale?  Should I simply close my eyes and tighten the sucker up to spec? I've taken the derailleur straight off the other frame, and there is no visible damage to the frame. 

Obviously I don't want to damage the frame.Sequoia2007-12-10 04:32:03

[controlc]

Have you measured the diameter of both seat tubes yourself? or did you take the 31.8 from the frame specs?

[Sequoia]

The diameter is stamped inside the clamp as 31.8mm. The frame is supposed to be 31.8 according to cannondale's dealer book. It measures out as roughly 31.8. Roughly, because I don't have accurate calipers at home and had to resort to a bit of pi*diameter. Everything is supposed to work - that is why I'm wondering if it isn't just a thick paint layer. The next size up is a 34.x and even the most inept home mechanic should be able to spot a 2+ mm difference.

[Speed Devil]

I doubt it is the paint, unless they painted it on with a brush to get it super thick. i suggest you first get the frame to your LBS and check the tube diameter with a vernier.

[Windbreaker]

Clamp the sucker!

[GreyOwl]

PM Johan Bornman...this is right up his alley!!

[Eugene]

I'm not 100% sure, but don't Cannondale seat tubes get progressively wider as they get closer to the bb? It's possible that the specs quoted by Cannondale refer to the top part where the seat post is mounted.