Disc brake performance: etap HRD or Di 9170?

Discuss light weight issues concerning road bikes & parts.
dogrange
Posts: 26
Joined: Mon Sep 10, 2012 3:44 pm

by dogrange

dvq wrote:
TobinHatesYou wrote:
Fri Apr 06, 2018 3:27 am
morrisond wrote:
Fri Apr 06, 2018 2:00 am
By many reports Campy is probably the best right now for disc braking, then probably Shimano then SRAM.
The company with the first-generation product made for them by Magura is the "best?" Citation needed.

I can tell you at least one thing. H11 rotors are designed in a way that give no consideration to noise. The high number of evenly spaced vertical vents turn the brakes into WWII Carter air raid sirens (or Chewbacca.)

Mr. Wizard example with a hilariously dangerous circular saw: https://www.youtube.com/watch?v=Lsfczwy3KOE
Dura-Ace rotors are just as bad.
The Shimano rotors suck. The aluminum core makes them very soft and they go out of True under hard use and are very hard to bend back in a way that will stay. Steel rotors much better.


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by Weenie


jasjas
Posts: 133
Joined: Sun Aug 23, 2009 10:15 am

by jasjas

Would that level of heat discolouration be normal on those disks? are you dragging them alot/badly adjusted?

My Carbon tub or alloy clincher rims do not even get particularly hot on a 10k descent in the Dolomites.

TobinHatesYou
Posts: 1529
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

jasjas wrote:
Sat Apr 07, 2018 9:07 am
Would that level of heat discolouration be normal on those disks? are you dragging them alot/badly adjusted?

My Carbon tub or alloy clincher rims do not even get particularly hot on a 10k descent in the Dolomites.

It's pretty normal. The rotors are reaching the very low end of tempering range...about 200C. DOT 5.1 boils at 260C. The pistons aren't reaching 200C and neither is the fluid. Now if your rotors turn blue, then I'd start to worry.

https://upload.wikimedia.org/wikipedia/ ... ithing.JPG

dvq
Posts: 123
Joined: Mon Sep 25, 2017 1:36 pm

by dvq

morrisond wrote:
Sat Apr 07, 2018 2:50 am
That does look like pretty good coverage on the Rotor - Weird.

You will love RX4's - they provide the power you think you should get from Hydro's.

I'm building another bike with H11's and Campy Rotor's/Calipers so I should be able to compare.

I had two bikes with Shimano Hydro - very nice but I was underwhelmed by the braking power.
Ordered a set of RX4s after reading your post. I haven't been unhappy in the slightest with SRAM eTap HRD, I'm just willing to try something. I've been on the fence for a while just because I have no qualms with it and that it would require me to route new lines internally again.

hkgmatt
Posts: 6
Joined: Sun Apr 08, 2018 9:17 am

by hkgmatt

dogrange wrote:
Sat Apr 07, 2018 5:50 am
The Shimano rotors suck. The aluminum core makes them very soft and they go out of True under hard use and are very hard to bend back in a way that will stay. Steel rotors much better.
This is my experience as well. I'm running Dura Ace R9170 and I'm disappointed with brake performance generally, which I would say is on par with but not better than my rim brakes with aluminium Mavic wheels. The front rotor deformed after one of my first outings and needs replacing. I have not ridden the other disc brake options.

dvq
Posts: 123
Joined: Mon Sep 25, 2017 1:36 pm

by dvq

hkgmatt wrote:
Sun Apr 08, 2018 9:23 am
dogrange wrote:
Sat Apr 07, 2018 5:50 am
The Shimano rotors suck. The aluminum core makes them very soft and they go out of True under hard use and are very hard to bend back in a way that will stay. Steel rotors much better.
This is my experience as well. I'm running Dura Ace R9170 and I'm disappointed with brake performance generally, which I would say is on par with but not better than my rim brakes with aluminium Mavic wheels. The front rotor deformed after one of my first outings and needs replacing. I have not ridden the other disc brake options.
I've been happy with the sram centerline x rotors, make sure you bed them and pads aren't contaminated. Disc has been way more powerful than any alu rim brakes I've ever owned.

RedbullFiXX
Posts: 6
Joined: Sat Aug 05, 2017 6:13 am

by RedbullFiXX

dvq wrote:
Sun Apr 08, 2018 3:08 pm
hkgmatt wrote:
Sun Apr 08, 2018 9:23 am
dogrange wrote:
Sat Apr 07, 2018 5:50 am
The Shimano rotors suck. The aluminum core makes them very soft and they go out of True under hard use and are very hard to bend back in a way that will stay. Steel rotors much better.
This is my experience as well. I'm running Dura Ace R9170 and I'm disappointed with brake performance generally, which I would say is on par with but not better than my rim brakes with aluminium Mavic wheels. The front rotor deformed after one of my first outings and needs replacing. I have not ridden the other disc brake options.
I've been happy with the sram centerline x rotors, make sure you bed them and pads aren't contaminated. Disc has been way more powerful than any alu rim brakes I've ever owned.
+1
Sram centerline x rotors paired with Sram HRD system
Excellent feel, power, and nearly silent

Vermu
Posts: 223
Joined: Wed Dec 22, 2010 6:39 am

by Vermu

TobinHatesYou wrote:
jasjas wrote:
Sat Apr 07, 2018 9:07 am
Would that level of heat discolouration be normal on those disks? are you dragging them alot/badly adjusted?

My Carbon tub or alloy clincher rims do not even get particularly hot on a 10k descent in the Dolomites.

It's pretty normal. The rotors are reaching the very low end of tempering range...about 200C. DOT 5.1 boils at 260C. The pistons aren't reaching 200C and neither is the fluid. Now if your rotors turn blue, then I'd start to worry.

https://upload.wikimedia.org/wikipedia/ ... ithing.JPG
It’s exactly same fluid as used in cars, so inherently disc temperature is irrelevant to piston temperature. Discs warm, not the pads.
A lot of braking and dragging would cause colouring, I highly doubt that disc wouldn’t reach temperature of 200 C on long descents. Disc will cool fast so there might be a lot higher temperatures momentarely.

After all on rimbrakes the heat is dispersed on larger area vs discs, so discs will run with higher temperatures.


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dvq
Posts: 123
Joined: Mon Sep 25, 2017 1:36 pm

by dvq

Vermu wrote:
Sun Jun 17, 2018 8:17 am
Discs warm, not the pads.
There's a few types of fade but the interaction between the disc and the pad is is called friction fade. When you experience friction fade, the heat is so great that the organic elements binding the pad material itself are boiling from a solid to a gas (sublimation). The gas buildup is actually pushing back against the pistons pushing the interface together -- that gas is actually what is causing the fade.

This is the reason why they offer pads with less organic material and more metal material -- they resist outgassing more.

While this may or may not be relevant to your other point, I just wanted to point out that pads get warm, really really warm.

dvq
Posts: 123
Joined: Mon Sep 25, 2017 1:36 pm

by dvq

Additionally, a lot of brake pads have copper backing plates to transfer heat, and many pistons are made highly thermally conductive ceramic. The whole point would be to make the whole system a heatsink.

TobinHatesYou
Posts: 1529
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

Pads get so hot, some even come with copper backplates to conduct heat away from the friction material faster. Consequently that heat goes into the system of pistons, fluid, caliper body behind it.

Some pad backplates even come with cooling fins!

e: get out of my damn head, dvq

Hexsense
Posts: 481
Joined: Wed Dec 30, 2015 12:41 am

by Hexsense

Are these experience about Dura-ace rotor not stiff come from older gen or MTB?
I look at the current DA rotors and they are quite chunky. I'm not sure it is as soft as it said to be, unlike the MTB's Icetech rotor.
It looks to be chunkier than Centerline X in my eyes, which also made partly with aluminum.

TobinHatesYou
Posts: 1529
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

Hexsense wrote:
Wed Jun 20, 2018 9:42 pm
Are these experience about Dura-ace rotor not stiff come from older gen or MTB?
I look at the current DA rotors and they are quite chunky. I'm not sure it is as soft as it said to be, unlike the MTB's Icetech rotor.
It looks to be chunkier than Centerline X in my eyes, which also made partly with aluminum.

Only the carrier on a Centerline X rotor is aluminum. The problem with all IceTech rotors is the sandwich steel/alu/steel rotor construction. The layers have different rates of expansion, leading to a little bit more warping. Also the overall stylized design of the rotor makes it less compatibly with other calipers vs something with a really smart design like SRAM's Centerline X shape/vents.

MichaelB
Posts: 453
Joined: Tue Apr 22, 2008 4:31 am

by MichaelB

I've been reading some people saying the IceTec rotors warping really easily and getting out of true.

Meh, not had that issue in many years of using them and being a heavier guy, I work them hard. Their performnace is the best thatI have tried, and have had fade issues with the Cleansweep G3 and Centreline, but the IceTec are fine (same pads and same descent).

by Weenie


pdlpsher1
Posts: 1564
Joined: Thu Jul 19, 2012 6:09 pm
Location: CO

by pdlpsher1

TobinHatesYou wrote: It's pretty normal. The rotors are reaching the very low end of tempering range...about 200C. DOT 5.1 boils at 260C. The pistons aren't reaching 200C and neither is the fluid. Now if your rotors turn blue, then I'd start to worry.

https://upload.wikimedia.org/wikipedia/ ... ithing.JPG
Nice chart. Based on the chart the rotor (254mm) on my tandem reaches 260-280C. I guess that’s why it’s a mechanical disk and not hydraulic.


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