Seating fork crown races
 

What ID pipe is needed to drive the crown races on different size forks?

1”? 1 1/8” threadless?

Thank you.

1" races are either 26.4 or 27.0 in ID, 1 1/8" are 30mm. So a pipe with slightly larger ID would be what I would look for, but I won't be doing that research for you.

The trick is to either have the end of the pipe a rather close fit and square ended so it contacts the very top of the race, above the ball track or bevel. or to be loose a fit enough to slide down onto the ball track or bevel but then have a rounded corner between the pipe's ID and its face. Some people have used PVC pipes for this which would have less chance to mar surfaces when driving the race down. Andy (who has used bench vise jaws or a huge adjustable wrench jaws for this when in a pinch)

And take care to ensure that the race is not tilted before you drive it down. If you drive the race on crooked, there is a risk of it cracking. This is particularly true when the race is thin, like the vintage Campagnolo Super Record crown races.

Maybe I shouldn't even say this, but I've installed 3 or 4 races by tapping then into place very carefully and evenly and slowly and carefully and did I say carefully and evenly? using a ~pencil sized, squared off piece of hardwood and a hammer. I did say carefully, the careful part is to keep the race even at every step, little taps at a time, patience. They usually go on pretty easily that way and it's not all that difficult doing it right. Next time I'll see if I'm patient enough to go to the store and get a correct ID piece of pipe because, yes that's simple, but sometimes I'm not patient enough to spend an hour going to the store at the moment I want to do the job. And I don't think of it again until, typically, a few years later when I have to set one again. But I'm also thinking you'd have to be careful to keep it going on evenly even with a pipe.

I have used a section of a floor lamp by putting the fork in upside down and slaming it on the ground. Can't recommend it for all situations, but it worked when I was a broke high school kid.

I try to keep this up-to-date for my own reference:

Outer diameter of the fork crown (and fork crown race inner diameter) table

Relja Write-Down-Everything Novović

Your question answers itself if you stop to think.

Headsets are sized by the OD of the fork's steerer. So the pipe ID would have to be slightly larger than the headset's nominal size.

No, that's way too simple! :)