Disc Rub After Heavy Braking

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mogwaiboi
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Joined: Fri Feb 08, 2013 10:09 am
Location: Melbourne, Australia

by 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!
Canyon Ultimate - Ultegra Di2 R8050 - HED Belgium +
Focus Cayo - Ultegra 6800 - DT Swiss PR 1600 Spline
Giant TCX Advanced Pro 2 - 105 5800 - Hunt 4 Season Gravel Disc

jfranci3
Posts: 354
Joined: Tue Jul 26, 2016 5:21 pm

by 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...

by Weenie


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ms6073
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Location: Houston, Texas

by ms6073

So for the Hunt 4 Season Gravel Disc, that is centerlock rotors, but which calipers? Assuming mechanical, which calipers (TRP, Shimano, etc)?
Michael - The Anaerobic Threshold is neither...

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mogwaiboi
Posts: 87
Joined: Fri Feb 08, 2013 10:09 am
Location: Melbourne, Australia

by 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...
Canyon Ultimate - Ultegra Di2 R8050 - HED Belgium +
Focus Cayo - Ultegra 6800 - DT Swiss PR 1600 Spline
Giant TCX Advanced Pro 2 - 105 5800 - Hunt 4 Season Gravel Disc

jlok
Posts: 713
Joined: Tue Jun 30, 2015 3:30 am

by jlok

I thought it's the heat that bent the rotor...
Giant Propel Advanced SL Disc 1 / BMC TM02 < Propel Adv < TCR Adv SL Disc < KTM Revelator Sky < CAAD 12 Disc < Domane S Disc < Alize < CAAD 10

menkar
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Joined: Tue Aug 10, 2010 5:23 am

by 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.

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LeDuke
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Location: Front Range, CO

by LeDuke

menkar wrote: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
Posts: 87
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Location: Melbourne, Australia

by 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 :D
Canyon Ultimate - Ultegra Di2 R8050 - HED Belgium +
Focus Cayo - Ultegra 6800 - DT Swiss PR 1600 Spline
Giant TCX Advanced Pro 2 - 105 5800 - Hunt 4 Season Gravel Disc

Squashednuts
Posts: 368
Joined: Tue Apr 25, 2017 11:12 am
Location: Christchurch New Zealand

by 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
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Location: The Grim North.

by mattr

LeDuke wrote:
Sat Aug 18, 2018 5:41 am
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.........

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Lelandjt
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by Lelandjt

jlok wrote:
Tue Aug 07, 2018 3:20 am
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.

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mogwaiboi
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Location: Melbourne, Australia

by mogwaiboi

Lelandjt wrote:
Sat Aug 18, 2018 4:15 pm
jlok wrote:
Tue Aug 07, 2018 3:20 am
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 :)
Canyon Ultimate - Ultegra Di2 R8050 - HED Belgium +
Focus Cayo - Ultegra 6800 - DT Swiss PR 1600 Spline
Giant TCX Advanced Pro 2 - 105 5800 - Hunt 4 Season Gravel Disc

by Weenie


moyboy
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Joined: Thu Aug 18, 2016 12:19 am

by moyboy

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

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