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My front wheel has got a visible wobble on it and the brake rotor catches on the pads in sync with wobble... thunk, thunk, thunk even when off the brakes.
I've had if at 2 different bike shops and they've just checked my wheel on their balancer, told me it's running true and sent me on my merry way.
Even without a tyre on it you can see the wobble and hear the rotor catching on the disk so it's not just a warped tyre.
So what on earth is causing the wobble? Bent or misaligned forks?
The forks look straight enough with no signs of damage (secondhand bike) and I would have thought if the forks were in any way damaged and skewed it would cause the wheel to just be constantly misaligned in one direction or other rather than having a wobble?
My front wheel has got a visible wobble on it and the brake rotor catches on the pads in sync with wobble
Where is the wobble visible? e.g. at the rim, hub, tyre
Warped / bent rotor?
Bent axle, possibly?
Sounds like 2 separate issues in many ways...
1. wheel/rim
2. rotor
Truing a rotor is easy, simply flip the bike and spin slowly, looking where it's rubbing and then bend it back a little the opposite way after rotating 90deg back to you.
Worn bearings/cups, although you'd only feel that with the bike un-weighted. Other issue is bent axel.
If you hold the rim, and push side to side are you getting a thunk from the hub ?
You could re-centre the caliper and check the disc for catching. Is the rim moving side to side - a couple of mm is OK. Is the tyre seated centrally.
As youve said, a bent fork wouldnt cause a wobble. It would just spin off true.
On a rear wheel you can get this with a bent axel, but not sure how this would happen on a front, as its related to the freehub mechanism in that scenario
It has to be at the bearing. One of the bearing races or seating surfaces is out of alignment?
Surely thats all it can be?
What hub is it?
Is it a rattle too, or just a wobble?
I would strip the bearings out. Roll the axel along a known flat surface like a stone kitchen work top, and check it for bends, and check the bearing races in the hub are seated/assembled correctly (depending on what hub it is).
Also check the axel mating surfaces on the fork?
Is the axel done up tight enough? i suppose a loose axel could rotate "epicyclically" and that would cause a wobble, but it would also rapidly wreck your fork and axel so you would notice it.
Wow thank you for all the speedy replies, I'm just relieved if appears to be a wheel/rotor issue rather than damaged forks.
I have noticed that the middle ring of the rotor (well away from the braking surface) has obviously been fouling the caliper as all the anodising has been worn away but there's also an obvious visible wobble on the rim as well... and just for good measure I've spotted that three of the Allen heads on the rotor have been snapped off by the previous owner presumably through overtightening!
and just for good measure I’ve spotted that three of the Allen heads on the rotor have been snapped off by the previous owner presumably through overtightening!
What? As in heads completely missing? That being the case, I'd get yourself a different bike shop(s)! I'd also check that the hub rotor mounts aren't cracked. Is the rotor the right size? Not a 183mm rotor and a 180mm mount?
It's possible that due to the bolts being missing, the rotor has deformed and is now fouling the caliper/fork mount and it's this contact which is wobbling the rim.
Remove the rotor and see if the wheel runs true - this will confirm if it's just the disc causing all the problems. Assuming it is, you're going to need to find a way of extracting the leftover bits of bolts and installing a new rotor. If you can't extract the bits, you may need a new hub/wheel.
Thanks again, yes the heads are completely missing! It was the previous owner that must have done that, not the bike shops I've been to, all they did was stick it on their balancing frame thing, tell me the wheel was running true and end me on my way.
I'm not sure I'd be able to drill out the broken screw threads to get the rotor off, I imagine it would need some very precision equipment, but it dies make sense that a warped rotor is throwing the whole wheel out of balance, looks like it might be easier to just get a new wheel.
If you remove the other 3 rotor bolts, is there enough of the broken bolts present to get some mole grips on them? I suppose they're going to be in there pretty tight for the heads to have been sheared off.
Can't believe someone would sell a bike in such a dangerous condition.
Thought a bike shop mechanic might have spotted the bolts.
But yes. If it was me I'd just get a new wheel.
They are not sounding like very good shops...If I had paid someone to check issues with a wheel, I would have expected such a serious safety fault to be picked up. That is aside from the fact that a wheel can be true but with a wonky rotor, or a wonky tyre, or a wonky axle or a dodgy bearing. A wheel in a trueing stand spinning and a couple of minutes looking could advise or rule out on some of that...
My partner has a Superstar V6 hub on her front wheel and the 15mm end caps have play in them no matter how tight the through-axle is tightened, which results in side-to-side play in the wheel, a bit of rotor rub when out the saddle and a slight knocking when rocking the bike back and forward with the front brake on. Been like that on two forks, so it is the hub, so worth checking that (assuming you can sort the sheared rotor bolts...)?