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I cross-threaded my cassette lock-ring on a pair of Fulcrum racing 4 DBs (aluminum threads AFAIK). Upon removing the cassette it looked like the top of the threads were slightly damaged, but I was able to put the lock-ring on correctly and tighten it properly.

Should I consider the fact that the threads were still usable evidence enough that it's fine, or does it need to be replaced?

  • How tight was it before you stopped - torques up all the way or just a bit stiff after threading on a couple of turns so you backed it out? – mattnz Apr 8 at 22:58
  • @mattnz I was going by feel but yeah pretty much torqued to spec – Kevin Klute Apr 8 at 23:10
  • If you cross threadded the lockring, AND torqued it to spec then there would have been a noticeable gap between the lockring and littlest cog. I doubt it sat home completely when inserted at an angle, so the more-innermost threads would be untouched. – Criggie Apr 9 at 11:37
  • When in doubt about safety consider replacing. – Carel Apr 12 at 7:31
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Assuming you refitted the lockring correctly, and the threads are now mated up correctly, then mechanically it should be fine.

You should definitely use a torque wrench to make sure its tight enough but not too tight - a well calibrated elbow just isn't good enough for aluminium where the tolerances have been reduced by munching up a turn of thread.

Long term, don't be swapping cassettes unless you have to. The freehub body might have half the number of refits left that it would have had if undamaged. But it might be a 90% reduction or a 10% reduction too, depending exactly how much is damaged.

Its possible to "chase" threads to help move material out of the valleys, but it won't restore that material into the lands (high bits of the thread) Plus a tap that big is uncommon. Your LBS might have one, but you wouldn't buy one as a home mechanic.

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    Freehub bodies are consumables like cassettes. Especially aluminium ones get wear marks from sprockets. They aren't that expensive to replace. – Carel Apr 11 at 9:15

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