alto's carbon clincher shootout test

Discuss light weight issues concerning road bikes & parts.
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spartan
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by spartan

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2017 Giant TCR Advanced SL 0 DI2 9150

by Weenie


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wheelbuilder
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by wheelbuilder

No doubt. Disappointing Aeolus results. I have Aeolus 3's and love them. Can't see ever putting them through that kind of braking scenario, but still..........

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

by MichaelB

The test is flawed in all sorts of ways, but still shows how much difference there can be in performance.

As mentioned in the test/writeup, two things stand out for me (1) why is it still an issue (albeit decreasing incidence) and (2) what the hell is the right testing/real world test anyway ?


Anyway, I'm a disc convert, so its something I don't worry about, just other potential failures :thumbup:

TobinHatesYou
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by TobinHatesYou

I think the biggest issue is their own rim had the worst actual braking performance so less heat overall was being put into the rim. Also the resins they use may very well be more thermally conductive, but Raoul Luescher says the resins that can transfer heat better also tend to be more brittle. So maybe the Alto rims can survive >3min of brake drag at 7lbs brake force at a constant 21mph, but it's possible they're more likely to get damaged by potholes... That's for another test though.

There is correlation between what I saw happen to a pair of Knight wheels at Phil's Fondo though. In the Alto test, the Knight wheels only lasted 2 minutes...

Anyway, if the rims do perform better for heat dissipation, that's definitely a better end result than what happened to the Roval, Boyd and Knight rims. This could all be avoided by switching to disc brakes however.

Shrike
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by Shrike

Tubulars are stronger/more heat resistant? They're lighter usually so I thought maybe they'd be more fragile. Is it the complex shape of the clincher rim that makes them weaker?

Slack
Posts: 114
Joined: Fri Dec 27, 2013 11:37 pm

by Slack

More bulls**t from Alto, their arrogance astounds me. Here's a test using pads that aren't specified by the manufacturer, look how our competitors fail.

Shrike
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by Shrike

Though using different pads invalidates the test even more as you're removing a control.

But yes, they should really have repeated the test - one test with a control pad and the other with manufacturer's recommended pads.

Then we can learn something from the comparison.

Slack
Posts: 114
Joined: Fri Dec 27, 2013 11:37 pm

by Slack

It makes the test completely invalid not using the recommended pad. If the rim isn't designed to be used with that pad, when it fails using that pad is irrelevant. If the a rim fails after 30's of braking with a Black Prince but lasts 45 minutes with the recommended pad would it still be a bad rim? It's just a bullsh**t made up marketing show to make their wheels look better. For all we know they could have built a rim specifically for this video just to make it look like it has a better performance than others.

Shrike
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by Shrike

Yes a different pad would/could delay how long it takes for the resin to heat up to that degree, but the test does have validity as it's just finding a way to heat the rim. No-one spends any real time braking for that long with that much force.

Again, we really would need both tests. As if you did it with just manufacturer's pads, then you have a less valid test protocol. You would have no way of reading any information from the test as there is no control. You can simply say 'cork pad' was best in test, and have no discernible way of making any conclusion. You couldn't even say 'x combination of pad and rim' was best, unless you cross tested every pad v every rim.

If you had to do just one test, the one with the most controls has the most validity.

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corky
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by corky

Good review of the test on cycling tips .com

fogman
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by fogman

Here is a link to the Cycling Tips article @corky mentioned:
https://cyclingtips.com/2017/12/carbon-clincher-safety/


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nickf
Posts: 538
Joined: Sat Mar 06, 2010 10:34 pm

by nickf

I'm in the camp of use the recommended pads. I can see they just want to heat up the rim to get a result but using the correct pad will delay or even avoid overheating all together. But in the end another reason why i'll never buy carbon clinchers.

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Calnago
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by Calnago

Shrike wrote:Tubulars are stronger/more heat resistant? They're lighter usually so I thought maybe they'd be more fragile. Is it the complex shape of the clincher rim that makes them weaker?

Clincher tires are constantly forcing pressure against the sidewalls of the rim, like a mechanical “spreader”. If the resins soften up enough the pressure from the clincher tire can deform the rim, and voila... the carbon clincher issue becomes a problem. With tubulars, the pressure is entirely contained within the tire, the only real force on the rim is being applied against the rim bed itself, where you want it. The braking surface can still heat up mind you, and the resins can soften but you don’t have this constant force from the clincher wanting to spread apart the rim.

I agree with others that the test is pretty lame however, raising more questions of protocol than answering anything definitively.

spud
Posts: 611
Joined: Sat Feb 07, 2009 5:52 am

by spud

I can see the following problems right off the bat-
1) Use of pad unauthorized by rim mfg
2) prolonged heat may cause pad glazing, which reduces brake torque and energy dissipation
3) pad will have different coefficient of friction against different rims, leading to different energy dissipation

Just don't see the value in this test unless they
1) use manufacturers recommended pads
2) run them at a constant wheel torque and wheel speed to ensure they are actually producing the same stopping power. If I cover my brake track in Crisco, I can squeeze that brake as hard as I want for as long as I want, and the rim won't fail.

Of course, there's also the question of what's necessary in terms of total heat/braking capacity, work rate, and the tradeoff of heat resistance to mechanical toughness due to epoxy used.

stormur
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by stormur

TobinHatesYou wrote:I think the biggest issue is their own rim had the worst actual braking performance so less heat overall was being put into the rim.


That was my 1st thought.... suprisingly low temperatures and fast cooling like for such "friction" applied.

IMO they glazed own rim. no friction, no heat, no fail. But no braking ...
Go to Heaven for the climate, Hell for the company.
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I can be wrong, and have plenty of examples for that ;)

by Weenie


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