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My road bike currently has a nagging wobble in its rear wheel that I've been unable to determine the source of. I probably would not have noticed this had it not been for an unusual (and annoying) sound that appears when the wheel rotates.

The sound is hard to describe, but I'd have to say it has to sound like a low-pitch popping noise - quick, with sudden boundaries. It appears probably every 5 or 10 degrees of rotation and causes noticeable vibration in the frame. It is also worth noting that this is not an issue that gradually built up over time - it appeared after the last ride, so it is almost as if something wasn't squared properly when I reassembled the bike afterwards.

In attempting to find the source of this, I checked to see if the wheel was rubbing up against the brake caliper or if the magnet was making contact with the speed/cadence sensor - both negative. The lateral deviation of the wheel is really too small to be of concern (other than the sound), and the noise seems to be coming from the rear axle/freehub area.

What I most fear is that the wheel may be out of true - the bike, around its last ride, took a few not-so-nice rides to a local park in the trunk of my compact car. While none of the suggested questions really seem to be describing my issue, it seems like a common culprit of rear hub noises is the cone parts.

Given all that, I suppose my question is twofold:

  1. Is there a way to either confirm or rule out the wheel true as the source of this issue?
  2. If it is not the wheel true, what is this problem likely to be caused by and how do I go about fixing it?
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  • Have you checked for wheel eccentricity (vertical deviation). Also check wheels is properly seated in dropouts. I turn bike upside down and push wheel into drop outs to avoid misalignment.
    – Kim Ryan
    Commented Feb 5, 2019 at 21:51
  • @KimRyan There doesn't appear to be any vertical deviation, or at least, enough for me to tell. As far as having it properly seated within the dropouts, I've removed the wheel a couple of occasions since posting this and inspected the hub, replaced skewer and then wheel so I don't believe that is the root cause.
    – ecfedele
    Commented Feb 5, 2019 at 22:44
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    Sounds like a bad bearing. Though could be spokes rubbing against each other, chain "climbing" the cog, et al.
    – Daniel R Hicks
    Commented Feb 5, 2019 at 23:44

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If you are getting multiple clicks per revolution wheel trueness (relating to even spoke tension) is not the issue here. A bumpy ride in a car will not damage a wheel - spoked bicycle wheels are actually pretty strong.

Wheel trueness is easy to check though. With wheel held off the ground spin the wheel and watch the rim relative to a convenient point such as the brake caliper pads. If you have disc brakes s piece of tape or a zip tie on a chain stay works well. Some wheels will have a little lateral or radial deviation, but if the rim isn’t hitting anything it’s not causing this problem.

A loose spoke would create a click once per wheel revolution so that’s not the problem either.

I strongly suspect you have a problem with a bearing. Hold the wheel off the ground, grab the tire/rim and rotate the wheel. If you feel resistance, grinding or 'notchiness' there is a problem. Also try to push the rim back and forth laterally, there should not be any lateral movement or play. You can also take the wheel out and turn the axle by hand to feel for resistance, grinding, notchiness, or play

Next step is to determine what kind of hub you have and how to disassemble it to find out what broke.

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    Could also be broken axle.
    – mattnz
    Commented Feb 5, 2019 at 23:11
  • @mattnz - Which is basically a bad bearing squared.
    – Daniel R Hicks
    Commented Feb 5, 2019 at 23:45
  • @mattnz yep, def could be. Same next steps though.
    – Argenti Apparatus
    Commented Feb 5, 2019 at 23:46
  • Keep in mind that once one spoke is loose it can induce others to become loose in turn... How do I know this? I've built my own wheels and it's happened to me. In the case here, after checking for trueness I'd take the wheel off and spin it while holding on to the axle, you should feel if the internals are affected.
    – Lamar Latrell
    Commented Feb 7, 2019 at 7:21
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This sounds similar to the symptoms I experienced with a broken rear axle. (I see @mattnz has already suggested this in a comment to the previous answer.)

If that is the case, it could quickly become a safety issue. For me, my rear wheel suddenly angled enough to bind against the frame. Don't put off fixing it.

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    +1 for pointing out safety issue
    – Argenti Apparatus
    Commented Feb 8, 2019 at 16:13

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