Holy Grail: Road disc brakes that don't rub

Discuss light weight issues concerning road bikes & parts.
Digger90
Posts: 103
Joined: Sun Jun 21, 2015 9:34 pm

by Digger90

I’m fed up with my SRAM Force Hydro-R calipers rubbing on the disc rotors, it’s driving me nuts.

I’m experienced mechanically, and have bled the systems (front & rear) several times. I’ve also stripped, cleaned, lubed and rebuilt the Master Cylinders per PSImet’s great vid on YouTube. I’ve advanced, cleaned and lubed the caliper pistons multiple times – far more often than with each pad change.

But they still rub – the pistons just don’t retract far enough.

And yes, the rotors are perfectly straight.

Rding in UK winter conditions, whenever I ride through puddles or on sh*tty roads, the brakes produce that horrible grating, gritty, rubbing noise for far too long. Dabbing the levers several times does nothing to stop this… it’s down to inadequate pad retraction.

Next step is a full caliper and piston strip and rebuild with fresh seals.

I’m otherwise happy with SRAM Force Hydro-R brake performance, but the inadequate pad retraction issues are ruining it for me.

Googling around, it seems that Shimano hydraulic road brakes also suffer this problem. There aren’t many (any?) reports I can find about Campagnolo hydraulics.
There are reports that Hope RX4’s have better pad retraction, but others have had problems with those too.

Are there ANY road disc brake systems that don’t rub?

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corky
Posts: 1395
Joined: Thu Jul 06, 2006 5:53 pm
Location: The Surrey Hills

by corky

Bike Disc brakes rely on the deformed plastic square edged seals to retract the pads when the lever is release, which is a very simple and light but totally inadequate mechanism as it means the pad rotor gap has to be very small...hence all the rubbing issues that the mfgrs never talk about(or bike sellers either). It's ok for my mtbs as there is so much other noise going on.

Rumour is that the new Dura Ace groupset design team are targeting the disc brakes for the new version......lets hope they can come up with a better design.

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wheelbuilder
Posts: 763
Joined: Wed Feb 08, 2017 2:10 am

by wheelbuilder

Cue Nefarious or someone like him to come in and say his brakes never rub, and his pistons always retract. Must be a set up issue for OP.
Never cheer before you know who is winning

ChiZ01
Posts: 345
Joined: Wed Jan 01, 2014 6:20 pm

by ChiZ01

sounds like the caliper is defective and should be replaced. I had to replace my shimano caliper a few times due to oil leaking.

Digger90
Posts: 103
Joined: Sun Jun 21, 2015 9:34 pm

by Digger90

ChiZ01 wrote:
Sun Feb 09, 2020 3:54 pm
sounds like the caliper is defective and should be replaced. I had to replace my shimano caliper a few times due to oil leaking.
The caliper is not defective - the same noises occur on my wife's Gravel bike and 4 out of 5 of my mates' bikes all with SRAM Hydro-R.

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Miller
Posts: 1697
Joined: Thu Sep 21, 2006 8:54 pm
Location: Reading, UK

by Miller

I ride with Campag disc. if I go along a wet road or through a puddle, and god knows there's been plenty of that this winter, then yes I get the grating noises as wet grit clears off the disc rotors. I tolerate it, seems to me that if you ride in shitty conditions then your bike is going to complain somehow no matter what technology you're riding.

The latest Campag disc pads come with springs to aid pad retraction. As this is what other brands use anyway I doubt it will make a huge difference to this issue but I haven't tried them.

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synchronicity
Posts: 1566
Joined: Sun Sep 17, 2006 11:41 pm
Location: Sydney, Australia
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by synchronicity

:lol: :lol: :lol:
Go back to rim brakes? :lol:

I love disc brakes on MTBs, but I will *never* put discs on a road bike. Sacriledge! :lol:
(sorry I couldn't resist :P )

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wheelsONfire
Posts: 3108
Joined: Mon Jul 07, 2014 8:15 am
Location: NorthEU

by wheelsONfire

I noted myself that the rotors themselves, easily gets uneven. Disc brakes are great stoppers, but anyone could wish for more distance between pads and rotors.
Or way better retraction.
Bikes:

Ax Lightness Vial EVO Race (2018.12.21)
viewtopic.php?f=10&t=156137
Paduano Racing Fidia (kind of shelved)
Open *UP* (2016.04.14)


Ex bike; Vial EVO D

bbee
Posts: 3
Joined: Thu Feb 09, 2017 3:36 pm

by bbee

You might want to double check that your calipers are installed perfectly parallel and perpendicular to the rotors. I used to have a lot of issues with rubbing and it was due to a misaligned caliper.

Since there isn't any extra room for misalignment or warped rotors, using quality rotors is also important. I don't know much about SRAM, but I have found that Dura-ace rotors warp and bend a lot easier than XTR. I'm now using XTR rotors on all my bikes.

The latest Cycling Tips 'Nerd Alert' podcast talks about all the issues with disc brakes and what manufacturers are doing about them.


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Caadnme
Posts: 8
Joined: Sat Feb 06, 2016 3:03 pm

by Caadnme

I have been through this process of cleaning and lub and repeat over and over again with my first Sram hydro road brakes a few years ago. Thing got better when I finally gave up and left then alone. When pads wear, you get a bit more clearance. That helps.
I also thought that the pistons would be self centering. Forget that. Pistons go where they want, as per the relative friction from the seal, you can't have any control on that. So the only solution is to loosen the mounting screws and center the caliper yourself. Feeler gages, shims or dedicated tools, choose your preferred method. Centering is the key.
I get better results if my disks are straight within +/-.003 inch. I use a dial gage with a large probe foot mounted on my park tools wheel building stand using a standard magnetic base.
I used shims to adjust the disk position relative to the hub on all my wheel sets within .005 inch so I don't have to mess with caliper centering each time I swap wheels.
I have found that with some time and use, the pistons seals get a bit more sticky and you get more retraction. So I leave my pistons alone as much as I can. I commute with this bike 45 km per day thru Canadian winter, so these caliper live their live through a very contaminated environment. I have to re-center my calipers maybe once a month, summer or winter doesn't seem to make a difference. Sometimes a caliper stays perfectly centered for months. The less I touch them, the less brake rub I get.
Hope that helps.

Sockman
Posts: 49
Joined: Mon Jun 17, 2019 1:58 pm

by Sockman

The nerd alert podcast actually mentions that sram has just released an updated calipers design with a new piston that retracts a little further to fix this issue. But also check the frame/caliper interface is square!

rwoofer
Posts: 1
Joined: Wed Dec 11, 2019 9:24 pm

by rwoofer

Been through the same process myself. Rarely have problems with my MTB disc brakes, but road is another matter. Nothing I could do or the local shop could do to stop rubbing when it rains, climbing etc. Eventually got another new rim brake bike for summer riding - quiet, lighter and easier to maintain. Disc brake bike is now winter bike and I leave alone as much as possible and put up with the rubbing.

adilosnave
Posts: 31
Joined: Sat Dec 23, 2017 2:10 pm

by adilosnave

Noise is a really big reason why I'm still reluctant to switch over to road disc. As mentioned above, a little noise is fine for 'cross or mountain but not on the road. Nope!

So my question is why the pads have to be SOOOO close to the rotor to work? Which such small clearance? Is adding some sort of quick-release to the pads not possible? Something to spread the pads apart just like on calipers? Or, gee, I don't know, maybe make the pad travel distance greater so that they retract further? It is mind-boggling how the manufacturers seem to completely turn a blind eye to this.

TobinHatesYou
Posts: 4881
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

I’m continually amused by temporary noise complaints with disc. Sure, sometimes discs will honk like a goose in the wet. Mine don’t with SwissStop RS pads. Yes occasionally grit will scrape on rain rides.

However textured braketracks on carbon rims have that Doppler sound effect. Why are never-disc users okay with that sound? It’s present in all conditions.

adilosnave
Posts: 31
Joined: Sat Dec 23, 2017 2:10 pm

by adilosnave

Because when I'm NOT braking, it's silent and I know I'm not wasting any precious watts either. Sure, carbon rims will sometimes howl like a banshee but at least it's only while actually braking. And I'll still admit to thinking the sound of Exaliths braking is cool. Listening to a disc rotor slightly drag or 'ting ting' while soft pedaling down a quiet country road...that brings out madness not seen since the days of the original Look cleats.

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