I have some of those old fashioned mag wheels on a fixed-gear bike. The back one seems to wobble about like mad when riding. A random stranger even pointed out that he could see it wobbling about like mad. Depending on what tire I am using, I can feel it moving about like mad. At the minute I am using a 700x28 Tannus tire. Just wondering what this could be? Weak wheel? Buckled? If so how would you adjust it as it doesn't have standard spokes

  • 1
    Could you add a photo of your wheel? Whats under the rim-tape? Not sure from the description what your wheel is made from or how its constructed. The biggest "mag wheel" I've seen was a 20 inch BMX one, but yours is 700c road-wheel sized ?
    – Criggie
    Aug 26, 2017 at 3:04
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    Possible duplicate of My rear bike wheel is wobbling back and forth when I ride Aug 27, 2017 at 13:01
  • The stand-out interesting thing about this question is that its a mag wheel, which (to me) means a single casting of plastic. Not carbon fibre, but plastic. @robert OP please provide more info or accept an answer.
    – Criggie
    Aug 29, 2017 at 8:19

1 Answer 1


There are two possibilities:

1) The wheel is moving at the hub because its bearings are failing or need adjustment. Lift the rear of the bike off the ground, grab the wheel rim and try to move it from side to side. If it can be moved, the bearings need to be looked at.

2) If the rim cannot be moved side to side, spin the rear wheel and look at where the rim passes the brake pads. If the passes closer to one or other of the pads as the wheel spins then the rim is bent.

If the rim is bent then I suspect it cannot be straightened on this type of wheel.

Some wheels have hubs with adjustable bearings. Without knowing what exact wheel you have it's impossible to say if yours can be adjusted. If the bearings have failed then the wheel may be unrepairable.

  • 1
    Another possible explanation for scenario 1 is a broken axle.
    – Adam Rice
    Aug 26, 2017 at 14:09
  • I read that an off-centered axle tunnel through the hub -- a manufacturing error -- with one end of the channel more off-center than the other can result in wobble.
    – compton
    Aug 26, 2017 at 19:53

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