Raleigh Twenty: Starting to wish I’d left it standard!

Another day, another issue!

I got the new fork over the weekend, so I started putting things back together.  I got the old lower headset race off, put on the new one, and then attempted to fit the new crown race to the new fork.

  • I tried hammering it using the old headset cup and a screwdriver.  It wouldn’t budge.
  • I tried hammering a piece of plastic pipe, to even out the force.  It wouldn’t budge.
  • I filed down the fork crown a bit, then tried hammering it via the pipe.  It wouldn’t budge.
  • I tried using a hammer again.  It budged!  Then it got stuck.
  • I hammered more and more and more…

JIS vs. ISO

So, it turns out that there are different measurements of fork crown.  Just because a fork is 1″ diameter, and you have a 1″ headset, it doesn’t mean they’ll fit together.  In my case, the fork had a JIS crown, which is 27mm in diameter, whereas the headset had an ISO crown, which is 26.4mm.  ISO has been the standard for years, with JIS only being adopted in any kind of number in Asian countries.

The fork I bought has a German-sounding brand name, so it surprised me to find that it had a non-standard crown. My theory is that it makes more sense to make the larger diameter, and let bike shops face it down to 26.4mm if needed.  That way it can fit anything! That’s probably why it also has such an enormous steerer – let someone else cut it, rather than limit the appeal.

Anyway, this lesson in crown diameters has now cost me a crown race, and judging by the stuff available on the interweb, and what I’ve got at home, I might have to buy another headset.  For £10.  I guess I should’ve taken this job to the bike shop.  😐

ooh, and while I’m here – I forgot that the locknuts from the old fork won’t work on the new fork, because the old fork has Raleigh threading.  It never bloomin ends!

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