Bounce/Vibration from the back of the bike

Mattiuslh
Mattiuslh Posts: 3
edited May 2013 in Road general
I've just come back from a 24 mile ride (making the most of the sunshine) but noticed that even on flat surfaces I was getting an unusual vibration through the back end of the back which I primarily felt through the seat post.

The bounce/vibration was consistent with the rotation of the back wheel, so if i sped up, the vibration intervals would increase with each rotation of the wheel.

I've given the wheel a quick looking over and cannot find anything unusual.

Any advice on other things I could be looking for here?

Thank all.

Comments

  • navrig
    navrig Posts: 1,352
    I've had that twice.

    First time came after I dunted the rear wheel in a large pothole. The rim was bent inwards (not a buckle) and hence the bounce.

    The 2nd time was on a set of newish handbuilt wheels which were due a service but I hadn't arranged. The wheel had loosened and as a result dished. The pulse was one part of the tyre rubbling on the inside of the chainstay. It rubbed somuch that the friction softened the tyre wall and eventually it exploded (I should have stopped before then :oops: )

    The first one couldn't be fixed so the wheel is now my turbo wheel.

    The 2nd just required the LBS to true and tighten the wheel - £10, which was less than the fuel to take the wheel back to the builder for the "free" service.

    The way to check is to either put the bike in a worktand or upside down on the garage floor and spin the back wheel. Look at it from a few different angles to say where the lateral movement occurs. You can also, carefully hold a piece of chalk such that the wheel mostly misses it but the "buckled bit marks it".
  • slowbike
    slowbike Posts: 8,498
    you can also mount a wheel in a turbo and spin it on there ... actually I built a wheel using a turbo as a stand ... :)
  • Mattiuslh
    Mattiuslh Posts: 3
    Thanks both.

    I've turned it upside down and spun the wheel round whilst looking down the gap of the seat post. You're right, there's actually a dip in the tire about two inches wide. Not sure how the tire/tube have dipped' (maybe a pothole).. I'll have to replace those.

    Thanks again :)

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