Wheel not turning properly.

Moreland

Hi.

I am just in the process of building a budget build up for light trail use/general biking.
I have fitted some deore hydraulic discs and they seem to be working fine, problem is thought when I try to spin the wheels or ride the bike.

The wheel turns nearly a full revolution but at one point stops and its pretty hard to move, it's like some one has applied the discs. I can turn the wheels by hand with some force and they it frees up again.

I took the pads out and there is a couple of deep scratches on them (new pads) which leads me to believe something is sticking at somepoint pretty hard.

I had a look last night but lighting was bad and it was freezing so I quickly got pissed off!

Does anyone know what this maybe so I can get it sorted this evening after work?

Thanks

BigAl

Something stuck mto the rotor? Bent rotor?

nicklouse

so have you been out and bedded in the pads yet?

presuming you have set them up correctly and the pads are not moving the rotor.

njee20

Does the wheel actually spin freely without the pads in place? If not any scratches are irrelevant!

Moreland

Pads are not bedded in yet.
I will try removing them this evening and spinning the wheels.
Rotor appears straight and is tight.

It spins freely then STOP, it then it stuck for a small section then free again

njee20

If the rotor is genuinely straight then it's something else - bearings, or something catching.

Take pads out and try again.

jimothy78

If it's stopping that suddenly, it's unlikely to be the rotor rubbing against the pads - you'd need a hell of a kink in the rotor to actually stop the wheel dead - it would be more likely to just slow the wheel, you'd also hear a scraping noise.

If the rotor is somehow not alligned properly radially, there's a chance the edge of the rotor may be fouling the brake calliper itself, though - check for movement vertically, as well as laterally.

I think it's most likely to be the tyre catching on something like the frame/fork (you don't say which wheel) or a cable. check for obstacles the whole way round the wheel's rotation, make sure no cables/hoses are able to form loops or curves that may interfere with the wheel. Could also be a really gritty bearing, or, if it's the rear wheel, something connected with the drivetrain.

Moreland

Thanks for the help guys. Back home now, got a flyer from work.

I have just taken the pads out and think I have found the problem, the rotor is catching on the inside edge of the caliper, its catching all the way around but gets a bit worse at one point.

rotor is tight and visually straight, its new so no reason for it not to be.
It looks like it needs moving about 2/3mm to the right then it would be int he center. Any idea of what this could be?

njee20

The rotor's bent, if it's new new I'd be sending it back, that's seriously warped.

Otherwise could be the hub shell on the piss, but that's much less likely.

Moreland

Bastard! I will send it back.
Is there a way to confirm this, I presume just hold a straight against it and see?

Is this usually heard of, a brand new rotor which is bent? It still has the sticker on it.

njee20

Not unheard of, but not great - as you're finding even 1mm can be a lot with most brakes. Just lay the rotor on a flat surface, by the sounds of it it should be very obvious.

jimothy78

Moreland wrote:

It looks like it needs moving about 2/3mm to the right then it would be int he center. Any idea of what this could be?

If it's out by 2-3mm (which is HUGE in disc-brake terms), then the calliper's been mounted without the wheel in place. Slacken off the mounting bolts and move the calliper so the rotor is dead centre between the pads, with a hair's-bredth gap on each side, then tighten the bolts again, being careful to hold the calliper steady as you do so.

If you can't move the calliper far enough to get the rotor central, then the hub may have been incorectly assembled, shifting the rotor too far in one direction with respect to the locknuts.