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I bought a new bike and was wondering why my rear wheel starts to vibrate at higher speeds. I also have high carbon rims (50mm) for the first time and thought it must be the rims. But I mounted the bike in my bike stand and then I realised that when I move the rear wheel it has an effect on the whole bike. Is that normal? I find it very unnatural. What could be the reason for this?

Note: They are 28 mm wide tyres with an inner tube.

Video: https://streamable.com/9o0a8i

rims unbalance road bike

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    To me it looks like there's a really heavy spot (or I suppose a really light spot) at the rim. With the wheel out, will it balance on the hub end cap on a flat surface? Does it consistently go one way? What about the front as the rims appear to match. The video stops a bit soon but it looks like the magnitude is increasing as the wheel slows (as you get nearer a mechanical resonance, probably in the stand. With a clear mark at one spot and a slowly spinning wheel it might be possible to check whether the biggest movement of the whole bike is in time with the wheel.
    – Chris H
    Commented Jul 8 at 14:37
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    Balancing vs truing: bicycles.stackexchange.com/q/85022/48599 What does it look like at lower RPMs? What does it look like seen from the back?
    – Sam7919
    Commented Jul 8 at 14:42
  • Can you feel that while riding? The bike weighs about 6 kg and the rider outmasses that by at least 10-fold.
    – Criggie
    Commented Jul 9 at 2:26
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    @Criggie While your comment and Weiwen's answer are probably pragmatically ok, the wheel should not behave like that, should it? Commented Jul 9 at 14:58
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    @Peter-ReinstateMonica no it shouldn't bounce like that. But also notice the wheel is turning ridiculously fast. I can't even guess how many RPM its doing in the video, definitely above 15 RPS or 31 metres/sec or 100 km/h. Plus the bike is suspended in a workstand providing unsupported length and that promotes an oscillation, a harmonic resonance. If OP were to clamp or just hold the front wheel, I suspect it would change significantly. Hence my question "can you feel that while riding?"
    – Criggie
    Commented Jul 9 at 22:28

2 Answers 2

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As said in comments, when you spin the rear wheel, that wobble is caused by the wheel being out of balance. I appreciate that the wobble may seem scary on the stand, but when you're sitting on the bike, you have quite a bit of weight on that rear wheel. That said, the imbalance doesn't usually cause the bike to shake on the stand.

I think that if the imbalance causes problems, they might occur at higher speeds, maybe in corners. You could first verify by trying a long straight descent, and maybe take some corners you know well.

If you are interested in actually balancing the wheel, Flo Cycling has a YouTube video where they apply golf weights - small, adhesive-backed lead weights that can be cut by scissors - to a wheel to balance it.

Otherwise, that looks like a new bike judging from the stickers still on the crank. If warranty applies, a wheel manufacturer in the West seems likely to warranty the rear. Of course, if you bought them overseas, the manufacturer may or may not be willing to accommodate you. You could certainly try anyway.

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    I would be checking the rim was true (vertically) before balancing. Also, if it is a tubeless setup, as it is a new bike, it is possible sealant has pooled and dried.
    – mattnz
    Commented Jul 9 at 2:22
  • Additionally - the extra weight could be in the tyre or the rim, or both. It would be interesting to move the tyre 180 degrees around the rim and see what effect that has. Then try and balance the rim without the tyre then again with the tyre installed, and finally add sealant if tubeless.
    – Criggie
    Commented Jul 9 at 2:25
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I've seen bikes bounce like that in the workstand. Many bikes wheels are out of balance. If it's in the stand and you get it going silly fast it will bounce.

But, at riding speeds with a person on-board the rider doesn't feel it. Go for a ride, try different speeds. If you feel it check Weiwen's sources for balancing.

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