For a bike I'm building, I had my headset crown race press fitted to my fork crown by my LBS, along with my top and bottom cups into the headtube. The crown race was loose such that I could rotate it with my fingers, but there was no discernable lateral play. I was actually able to remove it with my hands, but it's not loose enough to put back on just by hand.

The headset is very good condition English-threaded Shimano 600 HP-6400. The fork is Italian threaded. My understanding is that the fork would expect a 26.5 mm diameter crown race, while the English headset has a 26.4 mm diameter race.

I measured the OD of the fork crown and it is exactly 26.4 mm (digital caliper). The crown race has an ID of 26.42 mm. What are my options? I really would like to use this headset.

(I hope it's clear to all that this is not an ISO vs JIS issue, and neither part is 27.0 mm.)


  • 1
    You could invest in a bottle of Loctite retaining compound. Numbers 635, 680, and 638 are all for loose-fitting components and have varying strengths. I don't know what tolerances they specify for loose or tight-fitting component retainer, but it probably won't make a big difference with the high strength formulas.
    – WTHarper
    Jan 25, 2013 at 4:08

2 Answers 2


I was checking out Sheldon's website again and came across the following line in the article Servicing Bicycle Headsets:

If the crown race is loose, sometimes you can fix it by using a hammer and centerpunch to create a series of "craters" in the side of the surface that locates the crown race. The raised edges of the craters may be just enough to remove the slop.

Although I was skeptical, this actually did the trick! I made punches 1/4" apart around the fork crown. Once I fitted the crown race again, there was no play at all.

  • Great! You didn't happen to get pictures did you?
    – WTHarper
    Jan 26, 2013 at 0:50
  • Argh, I really wish I did now! But I did not take photos of the fork crown after punching.
    – fideli
    Jan 26, 2013 at 4:51
  • Done! Had to wait a day after I posted it. Thanks.
    – fideli
    Jan 29, 2013 at 3:33

A common solution is to use slivers of aluminum can to shim the race into a tighter fit. Be mindful not to get the shims underneath the race to where they sit on the crown- attempt to get them only between the steerer and the race. Having said that, I've seen folks shim races where the shim sat between the steerer and the crown and they had no issue.

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