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
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.
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.
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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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.
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.
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 ...
I can be wrong, and have plenty of examples for that
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