Disc brake rubbing during cornering

[ADKmike]

So after getting my new bike assembled and taking it out on the trail - what I thought was mis-aligned front caliper, is now becoming really frustrating. No matter how many times I try and adjust and retorque the caliper down, the pads still rub the rotor. I inspected the rotor and from what I can tell visually, it looks true. There also appears to be a slight gap between rotor and pad on each side of rotor, when caliper is at rest, which I was shooting for.

It was doing a ch ch ch ch ch sound during first ride, which I figured would reduce as the pads broke in and seat themselves.

I figured I would try and readjust the caliper after first ride out to really fine tune it.

I managed to get the rub out when the wheel is spinning while the bike is ridden straight but as soon as I pump into a turn, lean in, get the tire rolling over on to its sides, etc I hear the rotor getting worse on rub with the more force that's pumped into the lean. It's making me cringe.

Based on my testing out in the street on asphalt to try and reduce the variables of a rough riding surface, and whatnot, it seems like there must be something flexing in the front end. I've checked for loose things, and even tightened my quick release to make sure that the hub isn't floating around under heavy load.

So I guess my main questions are is this somewhat normal under heavy loads in leaned positions, and what are the best ways to reduce this, if any. Or, what is potentially wrong with my setup.

Bike is a 2015 Diamondback Overdrive Comp. Rockshox XC30 and Shimano Deore are the two main components causing the problem here, if it makes any difference in terms of component levels.



Thanks!

 

[Patrick]

Hub bearing/cone adjustment (is that the right term for a bike?) - under load the hub can deflect in relation to the bike?
put bike in stand, see if wheel can be wobbled on axle.

 

[ADKmike]

Hub bearing/cone adjustment (is that the right term for a bike?) - under load the hub can deflect in relation to the bike?
put bike in stand, see if wheel can be wobbled on axle.

Yeh I thought it might be this - which I also tightened down hub (quick release) more, but everything is tight there.

 

[Johnny Utah]

Quick release does not tighten the Bearings, just the wheel on the axle. When the quick release is tight, pick the bike off the ground and see if you can rock the wheel back and forth.

Sounds like a bearing issue to me.

 

[ADKmike]

Quick release does not tighten the Bearings, just the wheel on the axle. When the quick release is tight, pick the bike off the ground and see if you can rock the wheel back and forth.

Sounds like a bearing issue to me.

Just tried that - feels fine.

Is this a common thing? Is it to be expected to a degree?

 

[alex_k]

QR suspension forks always flex, some more, some less. Get used to it or upgrade to thru axle

 

[qclabrat]

Are the brakes real tight? Maybe can back them out a bit

Don't have Deore brakes so modulation may not allow to loosen

 

[moray42]

Was the caliper aligned by sighting it or by loosening the bolts and fetich tending while holding the brake lever? Normally I'll give the wheel a spin, slowly pull the lever so it aligns to the spinning rotor, and then hold the brake lever down once the brake is fully clamped down and tighten the bolts again. Sometimes exact center between the pads isn't actually the correct position as the Pistons can move at a different rate of one can remain mostly stationary.

Also as mentioned, play in the hub can create a wobble while leaning in to a turn. The cones that would need tightening are the caps at the ends of the hub when the wheel is off.

 

[Johnny Utah]

Rider weight?

 

[greeek32]

i had this issue with my deores. it's no big deal. most likely you're not aligning the caliper correctly.

loosen your caliper just enough so that you can move it side to side but not enough so that it pulls away from the mounting points. take 2 pieces of cardstock (business cards work) and put them between your brake pads and rotor on either side. if they fall out, fold them and put them back in.

now grab your brake lever and squeeze it relatively hard. lightly tighten the bolts back up one by one. go back and forth between the bolts, lightly retightening them one by one until the caliper is tight again. i usually try and make it take at least 4 repetitions.

the problem is that even if you grab the brake lever when you're tightening the caliper, if you tighten the bolts all the way at one time, you will send your caliper out of adjustment and it will sing to you.

if you still have an issue, you probably have loose hubs (like others said) which is common on brand new wheels without sealed bearings as the grease is still settling.

 

[ADKmike]

Rider weight?

170

 

[ADKmike]

i had this issue with my deores. it's no big deal. most likely you're not aligning the caliper correctly.

loosen your caliper just enough so that you can move it side to side but not enough so that it pulls away from the mounting points. take 2 pieces of cardstock (business cards work) and put them between your brake pads and rotor on either side. if they fall out, fold them and put them back in.

now grab your brake lever and squeeze it relatively hard. lightly tighten the bolts back up one by one. go back and forth between the bolts, lightly retightening them one by one until the caliper is tight again. i usually try and make it take at least 4 repetitions.

the problem is that even if you grab the brake lever when you're tightening the caliper, if you tighten the bolts all the way at one time, you will send your caliper out of adjustment and it will sing to you.

if you still have an issue, you probably have loose hubs (like others said) which is common on brand new wheels without sealed bearings as the grease is still settling.

Yes I played with multiple methods - brake squeeze align and tighten, sight it and tighten etc.

Problem also is that when you do the final torquing down, the caliper moves a bit out of alignment. Almost need a second person to try and hold it in opposite direction of torque of the bolts.

I'll have to check the hubs now - maybe I can tighten them. Any special size tool needed for that or is it just two 14 or 15mm nuts or something.

 

[Patrick]

if the caliper is moving, that is the problem - something is boogered, probably from overtorque (?) or an incorrect part - is there a spacer? - they really don't need to be too tight, as long as they don't work loose. maybe some locktite,
and go with a nice easy install. i'm poking here, so hopefully the last post will get the local wrenches to tell you the trick they use.

 

[Johnny Utah]

Well it is not weight. I suggest watching several youtube videos on setting bearings, it is usually something that someone does not get the first time out. As for alighing the caliper, that comes with practice. My guess after reading everything is that the caliper is not lined up properly. Hub bearings can play a part in the issue, but if you rocked the wheel (firmly) back and forth (not rolling it, shacking in against the plan of the axle) and felt no play, it is a caliper alignment issue.

If none of this makes sense, find a friend who is handy with bike mechanics to walk you through the process or stop by your local shop.

 

[ADKmike]

if the caliper is moving, that is the problem - something is boogered, probably from overtorque (?) or an incorrect part - is there a spacer? - they really don't need to be too tight, as long as they don't work loose. maybe some locktite,
and go with a nice easy install. i'm poking here, so hopefully the last post will get the local wrenches to tell you the trick they use.

the caliper is not moving - i actually used a torque wrench to set it at 7 nM per spec (6-8nM) to make sure it was right.
This is pretty much only happening when I put torsional/lateral flex to the bike...picture standing up of the seat and peddling really hard so that you are like waving the whole bike side to side as you pedal hard. This is what is making it really flex and rotor contact pads un-intentionally.....

I'm a mechanic by hobby - so technical skill is not lacking...something is physically wrong with the adjustment, loose hub, or at worst, rotor is bent slightly.

Gonna have to get deeper into troubleshooting this.

 

[jShort]

How is the clearance between the spokes and the caliper?

 

[Patrick]

Yes I played with multiple methods - brake squeeze align and tighten, sight it and tighten etc.

Problem also is that when you do the final torquing down, the caliper moves a bit out of alignment. Almost need a second person to try and hold it in opposite direction of torque of the bolts.

I'll have to check the hubs now - maybe I can tighten them. Any special size tool needed for that or is it just two 14 or 15mm nuts or something.

the caliper is not moving - i actually used a torque wrench to set it at 7 nM per spec (6-8nM) to make sure it was right.
This is pretty much only happening when I put torsional/lateral flex to the bike...picture standing up of the seat and peddling really hard so that you are like waving the whole bike side to side as you pedal hard. This is what is making it really flex and rotor contact pads un-intentionally.....

I'm a mechanic by hobby - so technical skill is not lacking...something is physically wrong with the adjustment, loose hub, or at worst, rotor is bent slightly.

Gonna have to get deeper into troubleshooting this.

Wasn't calling out your skills, just quoting you. I'm also a general wrench, but the peeps in the business have their tricks, like adding a star washer, or some of that gritty paste that keeps carbon parts from slipping.
could be a manufacturing thing too - is there a spacer for the front caliper to correct for rotor size?

 

[ADKmike]

Wasn't calling out your skills, just quoting you. I'm also a general wrench, but the peeps in the business have their tricks, like adding a star washer, or some of that gritty paste that keeps carbon parts from slipping.
could be a manufacturing thing too - is there a spacer for the front caliper to correct for rotor size?

Yeh, I know you weren't calling out my skills - just wanted to mention so that any responses aren't based on the thought that maybe the person asking the question lacks the skills to tune the bike...so no worries.

You mean a spacer to bring caliper out and in for different rotor diameters?

 

[icolquhoun]

just how tight are you making the quick release and what do the mating surfaces of the hubs/fork look like?
If the quick release isn't "damn friggin tight, like holy s$eet" tight, the hub can and will rock in the dropouts. I've seen cheesy cheap QR's that don't really work so well. If you have a decent QR from another bike swap it out and see (shimano, Mavic, etc.) Tighten it so taking it off is pretty impossible unless you summon deep dark inner rage energy, take it for a spin and I'd bet it (rotor scrub) is gone
The interface between the hub and fork, if buggered a little can also cause this, usually in conjunction with said QR issues.

 

[ADKmike]

just how tight are you making the quick release and what do the mating surfaces of the hubs/fork look like?
If the quick release isn't "damn friggin tight, like holy s$eet" tight, the hub can and will rock in the dropouts. I've seen cheesy cheap QR's that don't really work so well. If you have a decent QR from another bike swap it out and see (shimano, Mavic, etc.) Tighten it so taking it off is pretty impossible unless you summon deep dark inner rage energy, take it for a spin and I'd bet it (rotor scrub) is gone
The interface between the hub and fork, if buggered a little can also cause this, usually in conjunction with said QR issues.

I stepped up the tightness of the QR twice now - I am worried I'm going to snap it - but prob not.
I should make it SUPER tight and go in for a third try....this would be the easiest fix if that works.