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I'd like to replace the fork of my bike (basic SR Suntour NEX-25), and have ordered a replacement. The transfer of the crown race from the old fork to the new one seems however problematic, as it may require a specific tool, and this part seems quite fragile. I consider buying a new crown race instead of buying a tool that is more expensive than a crown race (and certainly an entry level one, that seems very hard to remove without damaging it), and that I'll use only once.

According to this question:

In the current era there is broad interchangeability among IS headset crown races of a given lower steerer diameter and bearing crown race contact angle, to the point where there are almost never issues mixing and matching.

Reading from that post, I understood that the important metrics are the two diameters (inner - 30mm and outer - 41.1mm), and the angles of the chamfer, that should match the one of the bearing (in that case 45° - cartridge bearings). However, when I'm looking for alternatives, I don't find crown races that are similar to the one fitted on the current/previous fork.

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Considering the 3 specifications, I mostly find crown races that look like this (example from Ritchey).

enter image description here

The "plane sequence" is however different on the current one "chamfer-vertical-horizontal", while the replacement candidate is "chamfer-horizontal-vertical". I also noticed that the thickness of the bearings is different from what Ritchey indicates in their technical drawings (mine: 6.5mm, Ritchey's: 8mm)

So the questions are:

  • does these differences really matter? (it looks like the second design will allow a smaller opening for dust ingress)
  • is the thickness of combination bearing/race standardised? (in this case, I may be better off replacing the bearing and the crown race)
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  • I've personally had the best luck with a foreign crown race working if the headset has cartridge bearings. Matching the angle of the crown race to the inner bearing race (36 or 45°) and a cartridge bearing works. However, loose bearings in retainers have given me problems from the size of the bearing balls, to the thickness of the base of the crown race, even plastic seals that seem to fit can end up interfering when preload becomes adequate. My point being if you're dealing with cartridge bearings, there's a much better chance of avoiding problems.
    – Jeff
    May 22, 2023 at 21:40
  • The bearings are cartridge bearings, question updated to reflect that, I also noticed a difference in thickness in bearings when comparing Ritchey's technical drawings and what I have on the bike (that matches IS41/30)
    – Rеnаud
    May 23, 2023 at 4:19
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    Fancy shop tools for crown race removal aren't strictly necessary, especially if you can tolerate the old fork getting some cosmetic dings. Use a knife blade you don't care about and gently tap it into the gap with a hammer, alternating 90 degrees as you work around. Wear eye protection. May 23, 2023 at 7:02

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