Retro Bob said:If a headset fork race is spec'ed at 26.4, is the fork itself supposed
to be 26.4 or a little oversize ? That is, if both the fork and race
are exactly 26.4, it will sit loose, so either the fork should be over
a little or the race, correct ? What's the tradition ?
Same question for the crown race ? If the spec is 30.2, is the cup
itself a little oversize ? Or is the head tube a little undersize ?Did the Italians have their own standard for headset dimensions 20
or so years ago ?As you might guess, I am trying to diagnose why a headset that
should fit is loose. Something is wrong, but I'm not sure which
part should be at which spec.
The races are always an interference fit on the frame and fork, i.e. the
crown race is a little smaller than the fork crown and the cups are a
little larger than the head tube. This means that things are stretched
slightly when fitted, which keeps them in place.
The sizes are here, and the 1" ISO size is "Campagnolo" standard:
http://www.sheldonbrown.com/gloss_h.html#headset
The Japanese used to have their own JIS sizes but modern bikes use the
ISO standard.