Can an out of true wheel cause disc rub?

Had a binding piston on the front brake so I bled it and replaced the pads. Looks like the wheel is out of true now, but worse, the rotor is rubbing.

I reset the pistons before the bleed so it *should* have been fine. The rub is miniscule, so I can live with it, but what on Earth caused it? Could the wheel being out of true cause a rotor to rub? Doesn’t logically seem possible because the rotor attaches at the hub, so the hub would have to be bent to cause rotor rub.

Could try swapping front and back rotors to be 100% sure it’s not a bent rotor, but life’s too short! Reckon trueing the wheel will sort it?

Could the wheel being out of true cause a rotor to rub?.

No

Three possibilities only, I’m afraid:

1. Mis-positioned wheel – try removing and re-seating (but I guess you’ve done this)
2. Rotor bolts have come loose and the rotor has moved. Remove rotor and re-fit (don’t forget threadlock!).
3. Bent rotor (by far the most likely)

As IHN said, a warped rim can’t affect the brake rotor.

Any point trying to get the rotor straight or is it a replacement rotor?

How often do people replace their rotors anyway? I reckon I’ve done it 3-4 times in 5 years but that was just the usual upgrades/sizing up/sizing down thing.

I’ve only done it once or twice, tbh, but each time has been because of vibration rather than overt caliper rubbing. If it was me, I’d take it off and have a go at straightening it – nothing to lose 🙂

I straighten mine out quite frequently, use the caliper as a guide, get hold of the disk with an adjustable spanner set to about 2mm and straighten it up! (Far easier on the bike than off it, unless you have a wheel truing stand).

Wonder if it will stop rubbing once the pad is not as new. Maybe it will be ok with a bit more clearance? IDK.

Could be an excuse to buy another tool, but at £20ish for a new rotor is it even worth bothering?

@wildc4rd does it periodically require re-aligning, or is it a one and done operation?

@curiousyellow, its periodic, whenever a rotor takes a whack (or gets accidentally lent on something in the garage)

Had a binding piston on the front brake so I bled it and replaced the pads.

I’d not necessarily expect that to fix a stiff piston, maybe it’s still stuck? Not had one since I switched to Shimano, but with my old Avids the pistons regularly seized. The proper fix was piston overall haul, i.e. new piston and seal. You could temporarily unseize them by working them in and out with a drop of fluid on the edges.

@dmorts lubed the piston, bled it and it was good. Maybe I need an overhaul. Never had to do one before and this was running 3 pairs of Avids!

Do you use the caliper alignment method recommended by Avid? I.e. put the bolts in, but loose enough so the caliper can move side to side. Then apply the brake to centre the caliper and tighten bolts? I found this method can fail if one piston is sticky, as the caliper ends up misaligned.

Seriously though if you have older Avids bin them and get Shimano. Although I reckon Avids may have better control/modulation, they never worked properly for long enough, so it’s a moot point 😀

Before you start bending the discs, worth checking for any lateral play in the wheel bearings. This would make the whole wheel move slightly from side to side as you’re riding and cause the disc to rub against the caliper.

I had this once on a Shimano cup and cone rear bearing. Initially I tried to cure the disc rubbing by realigning the caliper (many times to no avail) and even tried bending the disc, before I realised the problem was caused by play in the wheel bearing.

What type of axle is it? QR or bolt thru? Cup and cone or cartridge? A (really, really) remote possibility is a bent QR axle, which might make everything a bit wonky.

You say the wheel seems to have gone out of true but in what way? Oscillating, or off-centre and steady? What do you suspect may have caused the wheel issue? Taken a big hit, or just removing and refitting the wheel? They don’t just pop out of true (unless they’re seriously over-tensioned, which is rare).

A bent rotor is easy enough to spot. Get the bike in a stand and get your eyeball in line with the rotor, looking through the caliper. Spin the wheel and any wonkiness should be evident. Bending it back is best done with a large adjustable spanner IME, unless you have the proper tool.

Short answer: no, a wheel out of true won’t affect the rotor. But make sure what you’re looking for isn’t one non-obvious thing that’s causing both of the issues that you’re seeing.

Cheers Bez

Through axle, oscillating, and it looks like it’s the rotor out of true. No idea when it happened. I’ve not had any noteworthy offs. Looking at the rear rotor, it too is slightly out of true. But it is not rubbing! I’m hoping there’ll be enough clearance for it to not rub once the pads are bedded in.

Failing that, I’ll see how best I can cope before ordering a new pair. Delicate flowers these things. I checked my Shimanos and they’re straight as an arrow. Have had a lot more offs on that bike. Make of it what you will!

Yeah, have a bash at straightening it. Put it in the stand, turn it upside down or just hold it up by the stem. find where tyre/rim logo, valve stem, patch of mud is when the noise happens, the see whether its bent inwards or outwards (some squinting required here to see the gaps between the pads and the rotor),. then have a go bending with your fingers holding a clean rag or kitchen roll, or an adjustable spanner.

It’s the kind of thing that can happen now and again, like straightening your bars. Binning them and getting new is a little OTT unless they’re well worn already.

How often do people replace their rotors anyway?

like you said often swapping wheels and rotors around and don’t keep a check on rotors but was surprised to see a post on a commuting thread on one of the Oz cycling forums where people mic’d up thier discs and got some pretty way too thin to be safe numbers – went and checked mine and found one set that had used extensively and taken off and put in spares box that were thinner than recommended 🙁 reckon if i was commuting with discs I’d be checking them or if I’m putting in some heavy mtb mileage then replacing disks probably should be routine (Aldi digital vernier)

as said above I’d be resetting the caliper if not already done Edit forget that see rotor is def’ warped – I’d replace straightening looks a faff – I’d guess easy if you’ve done lots but not something average Joe does everyday

In my case, never!