I think that you probably mean that the wheel is in the drop-outs crooked. I agree that the axle is very unlikely to bend - far more likely to break and only a small chance of that. But depending on the bike it could be crooked in the drop outs. I was riding behind a Cannondale the other day and the vertical dropouts in that bike were offset. If that were a disk bike i would always drag in the same spot.
There is a small possibility that there is a piece of metal embedded in the mounting surface that causes a misalignment of the entire disk. That is easy enough to fix by either poking it out with a knife or hitting it with a file to make the surface level in the event that there was a damaged mounting surface..
No I do not mean that.
I think you misunderstand the question. He had a disk dragging in one spot which I assume he knows because of the tire label or the Presta valve. When he replaced the DISK it dragged in the same location. So while I agree with you that changing wheels usually requires resetting the position, I don't think that was his point. It was the same wheel.
Exactly, it drags on the same spot on both discs I used. Its not a brake adjustment issue.
Centerlock, all is good with the disc and mating surfaces.
Yep, tried both discs on the front wheel and they are perfectly true. Thats why I'm suspicious its a problem somehwere in the rear hub assembly.
The wheel rotates on the axle so a bent axle would interfere with that though I can't see how you would bend the axle on the bike. The area that would have to bend is well inside of the outer spacers which support the wheel in the dropouts. And axles are hardened steel that would probably crack rather than bend.
It is my understanding that he means that the disk is dragging as if the wheel were off-center in the dropouts. But all bikes today have vertical dropouts and if there were enough free play in the drop out to do this it would change when he changed the disk and reinserted the wheel. I would be more willing to believe that his frame is slightly misaligned but you can compensate for that with the play in the actuator. I would expect that his front wheel is a quick release which is why he would be talking about a bent axle. There is almost zero chance of a 12 or 15 mm through axle bending. I tend more to Duriel's explanation that the disk surface was never machined flat. But it would probably be cheaper to get some Fulcrum disk wheels rather than have a machine shop work them over because it would change the position of the disk. If he has insufficient play in the actuators to correct for the present misalignment, machining them would make it far worse.
Yes, I put the same disc on a different wheel and it is perfectly true...no rubbing whatsoever. The problem is definitely with the hub assembly. When I stare at the hub from the rear it appears to be wobbling on it axis ever so slightly. I can also see the same action when I stare at it from the side, looking into the gap between the axle and the hub body. From that angle it looks like the hub wobbling up and down over the axle.
Although I am leery of blaming it on a bent axle which I have never seen. THAT statement of yours pretty much proves it to be a bent axle. If it were a bearing failure it wouldn't scrub in the same place every rotation. You can take it to a dealer that has a wheel truing stand and if there is a bent axle it would show on that. This bent axle would have to be very slight if you are questioning whether you can see it wobble. It the RIM is not true it would also look like a wobble. Another means would be to carefully hold a pencil on the off-side chain stay and see it it marks the disk in the same place every rotation. Axles are pretty strong steel since they are hollow but stranger things have happened.
I'm not sure about that. When the wheel is installed in the frame, the axle is locked into a fixed position and the wheel bearings, hub, and rotor all rotate around that axis. If the axle were bent, that axis wouldn't be perpendicular to the plane of the bike's frame and the hub/rotor would spin in that off-axis plane - BUT that would not cause the wobble that you see because the axis is fixed.
