Okay, there's two bikes, each with different forks but the same hubs. Both exhibit the same promlem. You set them up so the stem is straight and the caliper doesn't rub the rotor. You then remove the wheel, turn the axle 90 degrees and refit. Now the rotor rubs the inside pad. Remove the wheel, turn the axle 180 degrees and refit. Not it rubs the outside pad.
What gives?
I've offered one of the wheels up to a dishing stick and I can't see anything to suggest that the lock nuts are not square to the axle. I can't see anything to suggest that the axle is bent. I'm not over tightening the skewer, the axle fully locates in the drop outs each time and I've tried the QR with the lever on both sides.
Anyone got a theory as to what's going on here? I'm stumped.
Is the axle snapped?
or bent
try a bent test - can you roll it on a mirror ?
This is happening on two brand new bikes. I've not stripped the hub but the axle feels fine. I've had it on a dishing stick and turned the axle, it doesn't appear bent. Those were my first thoughts. I'm now starting to wonder if the ball races are not in line with the axle or something bizare like that.
Sounds like everyone is as stumped as me.
Try a different skewer. Check the dropouts for any flash that's leftover from manufacturing. If the axle threads got stripped or crushed where it rests in the dropouts it might cause the fit problem you describe.If the races are off, say one is cross threaded or something, would the hub still run smooth?
If it's rubbing badly you can always grease the rotor 😉
Warped rotors?
What hubs?
dicky, it's not the rotor, that's either always on the inside pad or always on the outside pad depending on which way the axle is turned. The rotor is very straight indeed.
@axroads, both the same hub from an big bike companies own branded stuff. Cup and cone stuff. I'd rather not say which brand at this point as they're still being helpful (more helpful than the shop).
Mojo K, I'm wondering if the racers might be in line with each other but not square to the hub shell. That way, I'd imagine that the hub would still run smooth.
I'll be trying a different wheel and skewer this weekend. I'll also try the suspect wheel in a fork I know is good. Long drawn out process of elimination. Would be so much easier if I had another front wheel with a 160 rotor. I've got to mess around with swapping rotors as well now!
If the cones are not ground concentric with their own centres, ie:the bearing surface of the cone is off centre with reference to the internal thread, then you could have the problem you describe.
With your description you are talking about 0.2-0.3mm runout at 80mm from the centre (at the caliper), so only a small error at the hub will be multiplied at this distance.
You could check for cone eccentricity by stripping the hub, mounting the axle assembly between live centres, then rotating the axle with a DTI on the cone surface. this would reveal any eccentricity. Of course you should also check the axle for staightness as well, with the same set up. and the DTI reading on the middle of the axle.
I reckon there are a few options...
1. Bent axle? unlikely if new.
2. Damaged dropouts? unlikely if we are getting predicatable results, if they were damaged then rotating the axle would not be the factor that causes the offset.
3. Dodgy cones/axle? I think this is the issue. The bearings are running on the cone on the axle, so if the cones/axle are not maching/cast/forged exactly symetrical then essentially it makes the axle act link an eccentric rather than being concentric (is that the right terminology?). So, to check if this is the case take the wheel out and rotate the axle, watching it to see if it rotates about its centre, with no up/down/roundyround action. If this is the case youll be wanting the shop to fit a new axle (or give you another wheel off a different bike as a quicker fix)
How can you turn the axle round 90 degrees and refit? Very confused. 😕
Axle relative to dropout, not to hub.
Doh! 90 degrees rotationally? Damn I am slow this morning!
Either the axle or the hub body/bearing positions are not straight.
No mystery.
Sounds like dodgy manufacture to me. What make are the hubs?
Cant be a fault in the hub body or its races as it would come and go as the wheel rotated, it must be a fault with the axle or the inner races in order for it to remain constant with wheel rotation. That is, if I'm reading the problem correctly (depending on axle rotation you get permanent displacement of the rotor face).
Yes, refit the wheel with a different axle rotation and get a consistant but altered position for the rotor. It's sounds very much live the centre line of the hub shell (caused by the centre line of the inner races) doesn't match the centre line of the axle.
I'll spend the evening testing and feed back!
Yep, it's the hubs. I've swapped rotors around. Tried good wheels in the new frame and forks and the suspect wheels in a good frame and forks. The problem follows the wheels every time.
Took it back to the shop tonight, explained what was happening and was told that "it was just the end nuts and was within tollerance". I strongly disagreed with this and informed him of such. We'll see what the call to the inporter reveals tomorrow. Not impressed at all so far. I'm appalled at the way this shop thinks it can fob people off. I wonder how many novies are being fed this sort of BS so the shop staff don't have to lift a finger!