Originally Posted by
FBinNY
Your mechanic was asleep at the switch. The ISO (Campy) crown race nominal dimension is 26.4, not 26.6. The actual size is 26.42-26.45 (.05mm oversize for interference). If you measured correctly the .2mm difference is too much and will often split crown races which are too brittle to expand that much. The right solution is to have the crown seat milled to spec. A job that any decent road shop should be able to do for $25.00 or less.
Thank you FBinNY! So the crown seat should be milled to between 26.42 and 26.45 in order to produce the interference fit with a 26.4 ID race? Or should it be milled to 26.4mm? I ask because I have the cracked race (it didn't split - the flange just broke off) and its ID seems to be 26.37mm. I'll try to find the nearest frame builder 'cause I have yet to find a shop in my city where the mechanics seem competent.
Originally Posted by
FBinNY
While you're at it, have someone confirm that the head tube dimensions are also to spec, though head tubes are relatively ductile and more forgiving of an overly tight fit.
Thanks for the advice although I got the headset parts onto the headtube by hammering them in (with a wooden block). They went into relatively easily.