Disc Brake Alignment After Removing Wheel?

[AndyBSG]

Quick question regarding Disc Brakes and quick release wheels.

Took the wheel off on my new bike last night to fit some new tyres but had a problem when it come to putting the wheel back on. The disc is now rubbing on one side of the brake pads because the wheel is aligned slightly differently leading to two questions.

1 - How do you adjust the alignment of the actual pads on a disk brake?

2 - When you take a wheel off and put it back on is there a tip for getting it to line up in exactly the same way it was before or make sure it is perfectly centered?

[Brucey]

if you have VDOs then it should just come back to the right spot. But even then if the wheel doesn't settle in the VDO as far forwards as it will go when you stand hard on the pedals, you can get a little rub.

So one nifty trick with VDOs is to raise the front wheel so that the bike is at about 45 degrees when you tighten the QR; this way the wheel is more likely to be in the right place. However if the axle is slack in the LH dropout, braking forces may then later pull the left side backwards and this can lead to more rubbing (or if you are lucky, the rubbing disappearing).

Once a frame has seen a fair bit of use, it may develop wear marks that locate the wheel in the same place each time.

With mechanical disc brakes you can vary the fixed pad adjustment and the slack in the caliper to vary the alignment. On some systems the whole caliper moves on an adjuster.

With hydro systems you may need to add/subtract shims from the caliper mount to get the adjustment right. If the adjustment seems erratic, or has changed over time with the same wheel in use, it can indicate that you have a sticky piston.

Generally any alignment problems are worse on frames that don't have VDOs and that do have chainstay mounted (rather than 'overhead') rear calipers.

BTW do be mindful of the possibility that the hub has gone back in the exact same place, but that you knocked the disc when the wheel was out, and bent it slightly. It is also possible to disturb the pads in the caliper to cause a rub. I've even seen a disc setup (with worn pads admittedly) where the owner had managed to reassemble the bike so that both pads were to one side of the disc...

cheers

[stewartpratt]

I find it best to lean (vertically!) on the bike slightly when tightening the QR, then the axle settles into the same place just fine: I've not had an alignment issue when doing that. Of course, it means that if you set up your calipers when the wheel had been fitted without having done that then you might have ended up with the caliper in the wrong place and you'll need to adjust it to the wheel's properly-seated position.

As above, this assumes vertical dropouts, of course.

[Sum]

Modern disc brakes usually have two bolts that screw into a post mount or post mount adapter. You can undo these, squeeze the brake lever to center the caliper and tighten whilst squeezing the lever. If the brake has only IS mounts and doesn't even use a PM adapter, then you have to use shims as Brucey says.

If the wheel is in a VDO then it should have gone back into the right place. Have you try undoing, reseating and redoing the QR? Like Stewart I normally just lean on the handlebars or seat to ensure the wheel is fully in.

[foxyrider]

As you haven't moved the brake or the disc the whole issue is with wheel alignment - i find the best way is to stand the bike upright on the floor then open the relevant QR lever, the wheel will usually align itself correctly in the dropout. Only if that doesn't solve the issue should you consider moving the caliper.

Part of having disc brakes is not having to readjust or disconnect stuff each time you remove the wheels!

[reohn2]

As you haven't moved the brake or the disc the whole issue is with wheel alignment - i find the best way is to stand the bike upright on the floor then open the relevant QR lever, the wheel will usually align itself correctly in the dropout. Only if that doesn't solve the issue should you consider moving the caliper.

Part of having disc brakes is not having to readjust or disconnect stuff each time you remove the wheels!

Spot on.
If the brake wasn't binding/rubbing before the wheel was remove and is when it's taken out and put back in:-
Either the wheel wasn't seated properly in the dropouts before and now is,causing misalignment with the caliper,which will need the caliper realigning.
Or the the wheel is now not seated properly in the dropouts causing misalignment,in which case check dropouts and wheel axle ends if anything is preventing the wheel seating properly.

What brake caliper is fitted?

[bristolmick]

Try just tightening your skewer more. I was advised by my LBS. It has always worked for me. 12 years of hydraulic discs.

Mike O

[tim_f]

Sometimes need to 'sight' disc position whilst doing up quick release. Easiest if bike is leaning up against something. Other technique is to hold brakes on with lever whilst doing up quick release.

If frame is correctly aligned the weight of the bike on the axles in the drop out should align everything, so can be easier to get right with bike restring on wheels than when upside down or in a repair stand. Often find if one inverts bike to take wheel out to fix bike on a ride that need to reset wheel and tighten quick releases again with bike right way up.

Tim.

[reohn2]

Try just tightening your skewer more. I was advised by my LBS. It has always worked for me. 12 years of hydraulic discs.

Mike O

The wheel should be centred in the d/outs against the frame stops/ends,the q/r shouldn't really be tightened any more than it needs two or three fingers pressure to close it.
If all is equal the caliper set up right,no or very little runout on the rotor,and the wheel fitted in the d/outs properly you should be able to fit and remove wheels without any problems or worries.

[reohn2]

Sometimes need to 'sight' disc position whilst doing up quick release. Easiest if bike is leaning up against something. Other technique is to hold brakes on with lever whilst doing up quick release.

I'm struggling to understand the logic in this,see my post above,and in light of:-

If frame is correctly aligned the weight of the bike on the axles in the drop out should align everything, so can be easier to get right with bike resting on wheels than when upside down or in a repair stand.

Agreed.

Often find if one inverts bike to take wheel out to fix bike on a ride that need to reset wheel and tighten quick releases again with bike right way up.

Tim.

Resting on it's wheels,yes agreed.