Disc Rub After Heavy Braking

[mogwaiboi]

Hi All

I upgraded the rotors to the Icetech type on my Giant TCX recently. I centred the pads as per usual and the back rotor isn't rubbing when I spin the wheel, but after heavy braking there is a loud sound for at least 5-10 seconds that I assume is the rotor rubbing against the pads. Has anyone else come across this before?
By the way, I did sand the pads back to remove any glaze and to level them out, but is it normally recommended to replace pads as well when changing rotors?

Thank you!

[jfranci3]

On things to check, the cables. Make sure the housing is seated all the way in the endcaps and the cable is firmly seated down to the fork/dropout. It seems bad seating can cause some resonance. Also recheck the tq on the disc - to tight or too loose shouldn't cause a shimmy, but there may be a shimmy sweet spot in there. Same with the calipers...

[ms6073]

So for the Hunt 4 Season Gravel Disc, that is centerlock rotors, but which calipers? Assuming mechanical, which calipers (TRP, Shimano, etc)?

[mogwaiboi]

Thank you, I'll recheck the disc torque, maybe pull pads out as well to start again.
It's Shimano RS505 hydraulic.
There was initially a shimmy on the back disc which I gently corrected but maybe this is being exacerbated under heavy load...

[jlok]

I thought it's the heat that bent the rotor...

[menkar]

Same thing happens with my Icetech rotors on steep descents under heavy breaking and I agree that heat temporarily seems to warp the rotors and they straighten out upon cooling.

[LeDuke]

Same thing happens with my Icetech rotors on steep descents under heavy breaking and I agree that heat temporarily seems to warp the rotors and they straighten out upon cooling.

I’m guessing it’s thermal expansion, then contraction, at which time the sound goes away.


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[mogwaiboi]

Thanks all, yes it seems that this must be the case. Someone on another forum said the exact thing happens with his Dura Ace set up as well. I just wanted to make sure there wasn't an issue to be resolved

[Squashednuts]

It may be that the pistons aren't retracting quickly or smoothly

Here's a Park Tool vid on how to clean the calipers....may help with piston retraction

https://www.youtube.com/watch?v=vQXFFgRButo

[mattr]

I’m guessing it’s thermal expansion, then contraction, at which time the sound goes away.

Maybe time for a few more manufacturers to get on with some proper floating discs, rather than the two piece we have now.........

[Lelandjt]

I thought it's the heat that bent the rotor...

Yes, the 180mm Shimano rotors on my enduro bikes do this after prolonged heavy braking. When they're cold they're straight but when they're really hot they get a little wobble that goes away again once they cool off (maybe something about the aluminum/steel sandwich). Ah, the vagaries of disc brakes. Worth it on an enduro bike, not so much for how I ride my road bike.

[mogwaiboi]

I thought it's the heat that bent the rotor...

Yes, the 180mm Shimano rotors on my enduro bikes do this after prolonged heavy braking. When they're cold they're straight but when they're really hot they get a little wobble that goes away again once they cool off (maybe something about the aluminum/steel sandwich). Ah, the vagaries of disc brakes. Worth it on an enduro bike, not so much for how I ride my road bike.

Yes I think it has to be the case. I upgraded the rotors from the steel generic versions that came on the bike. The improved braking and quieter operation is worth the trade off of a little noise after braking

[moyboy]

Try cleaning your pistons, one might be lazy and not retracting as fast as the other one.