I've got a bent QR rear axle and am looking for a replacement. Seems that these come in 9.5 and 10 mm sizes with a couple of different threadings. When I measure the OD of the threads I get around 9.8 mm – can I assume that that means I've got a 10 mm axle?

Is the right way to measure to pull the axle and measure an unthreaded section? Or does the size even matter if I'm replacing the cones and nuts with it?

  • 1
    No, if you're buying a whole new axle+cones the things that matter are length and bearing size. The weird sized bearings are so rare now that it's vanishingly unlikely you have them. If you are concerned many bike shops have an axle/nut sample board like this one (that they call a gauge, even though it isn't)
    – Móż
    Feb 14, 2016 at 0:49
  • MTB? Road Bike? Photos? Wheel set brand & model? More information will make it easier to help you. :)
    – zenbike
    May 13, 2016 at 20:48
  • The size of the unthreaded portion is irrelevant, so long as it's not so large as to prevent the axle from fitting into the hub (and that would be incredibly unusual). The two critical factors are the overall length and the threading. The threading can be determined by matching a nut from the axle to an axle of known size/thread. May 14, 2016 at 12:00

1 Answer 1


That sounds like 3/8 inch.

Take the hub to a bike shop, they'll be able to pick out a compatible axle for you.

  • No need to take the hub, to match axle size. All you need is a nut. May 13, 2016 at 21:30
  • Most shops only stock axles with the cones and locknuts on them. Take the hub so they can match the cone to the hub.
    – Emyr
    May 13, 2016 at 21:42

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