Hi all, I would have thought regardless of how good the framebuilder is, that some distortion/shrinkage would occur, and that any framebuilder would run a reamer down the headtube and seatube after the frame being painted, otherwise anyone buying a new frame would have the frame prepped by a LBS or themselves depending on tooling. Both my #17 & #18 Campagnolo catalogs list 27.4 as a standard option, nothing special about them........regards wayne davidson Invers NZ........