Warp/wobble in rear rim and both tyres

Ditlan
Ditlan Posts: 19
edited August 2018 in MTB workshop & tech
Hi,

So when spinning the front and back tyres a 'wobble' can be seen during the rotation, so if spun whilst looking down at the tyre there is a point in the wheel where is moves over to one side a touch.

I took off the wheels today and the tyres to see if it was the rims - the front rim seems perfectly true, so this must have been the tyre causing this wobble - so first question - is this a problem? Do I need a new tyre or tube or just leave it be?

The rear rim however it itself a bit warped, here is a video showing how much, when the camera holds mostly steady you can see it move against the line of the seat post:

https://youtu.be/Pn4nXucYgnM

None of the spokes seem damaged or broken - so whats the best course of action with this? New wheel or can it be fixed?

Cheers!

Comments

  • steve_sordy
    steve_sordy Posts: 2,453
    The rim can be trued by adjusting spoke tension. Advice on how to do it can be gained from YouTube etc. But to be honest, you'll be best leaving it to the local bike shop.

    Tyres are not machined but moulded, so they will never be perfectly true. A little wobble can be expected without a fuss. As long as you can't feel it when riding it'll be fine. However, most wobble can be removed by installing the tyre correctly. Always inflate past 40psi so that you hear some bangs as the tyre bead drops into the correct place around the wheel rim.I confess hear that it is so long since I have inflated a tyre with a tube in it that I cannot remember whether that advice holds true for tyres with tubes. I'm sure others will advise accordingly.

    Whatever, if you inspect the tyre/rim interface, you should see a moulded line on the tyre wall that is about 2-4 mm from the rim. It should be an equal distance from the rim all the way around the rim. If it isn't, or even if it disappears altogether, then the tyre is not installed evenly. To restore the even line spacing, you have two choices: One is to inflate to a high pressure and hope that pushed the tyre into place (maybe with a bang). The alternative is to lower the pressure substantially and to move the tyre physically. This is done by holding the wheel very firmly with two hands close to each other near the part of the tyre where the mould line needs moving away from the rim and waving the tyre up and down. This uses the weight of the wheel to pull the tyre away from the rim. If it doesn't move, reduce the pressure. If all fails, then start again.
  • Ditlan
    Ditlan Posts: 19
    Thanks for the advice, I did look into tuning spokes on youtube - the first video I came across was showing adjustment with an adjustable spanner - I have now learnt that that is a terrible tool to attempt it with.

    I have a spoke wrench on the way but I may just take it for a service, all the spokes are super tight/hard to turn already so I have a feeling one or two of them might be over tight.

    I had the tyres off today, cleaned them and put them back on but no change - I'll have a look to see if they are seated correctly tomorrow, cheers!
  • steve_sordy
    steve_sordy Posts: 2,453
    Ditlan wrote:
    ..............

    I have a spoke wrench on the way but I may just take it for a service, all the spokes are super tight/hard to turn already so I have a feeling one or two of them might be over tight.

    ..............

    A quick check of spoke tension is to work your way around and tap them with an Allen key. The ones on one side should sound the same as each other (that will depend upon your musical ear, mine is poor). The ones on the left may sound different to the other side, but they should sound the same as each other. If you have a noticeably different sound with one or two spokes on one side, then it is worth investigating
  • 02gf74
    02gf74 Posts: 1,171
    steve_sordy wrote:
    . However, most wobble can be removed by installing the tyre correctly. Always inflate past 40psi so that you hear some bangs as the tyre bead drops into the correct place around the wheel rim.in.

    That is usually the case but Ive found that if a tyre is wobbling, either radially or circumferentialy, no amount of ducking around will unwobble it. Not all tyres are created equally.

    It is rare but if it worries you, only solution is different, tyres and it's not related to tyre price.
  • 02gf74
    02gf74 Posts: 1,171
    Oh, altough tyres are not machined, the moulds to make them are. I can't remember the last time I had a wobbly tyre nor brand/model.

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