Run metal pads and i dont now about sram if they have something like ice tech from shimano but those are really good. Hope you have a fun ride sounds awesome. Is ice tech a thing on road bikes or is it only mtb?
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Shimano road rotors are noisy according to several LBS, and in my own experience. At the suggestion of LBS, my 2015 Trek Domane road bike was running (mtb) RT-MT900 rotors and J03A pads (both pads and rotors had Ice Tech).
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Yup, can confirm that the regular āRoadā rotors from Shimano can suffer from enough heat distortion to go from clean & true when cold to a notable ātickā or ādragā when hot. Even at my light 66kg [145lbs] weight, my properly setup R8000 setup would make noise after hard braking. They went back to straight and silent after some clean running so itās a minor but annoying issue. Function is fine and totally safe, just noisy at times.
As a result, Shimano is swapping to using the āMTBā rotors in most cases now. They have a different construction method & materials, that is more dimensionally stable even at higher temps and loads. Iāve been wanting to try a swap, but rotors are one of those items that is rare right now (like chains).
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I donāt feel strongly about many things bike parts related, but will say the Shimano DuraAce and Ultegra road rotors were very disappointing. Let me know if you are interested in new-in-box RT-MT900 lol, still clearing the remaining āgarage always has next maintenance part, its a pandemic after allā but Craigslist is slow going on these and the J03A pads.
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I had the finned Shimano MTB rotors and they still ping after a good brake application. No fade on either the road or MTB rotor, but they still get that momentary warping after hard braking. I am pushing 80kg and my brakes get get steaming hot after any steep descent. Never had them fade, though.
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I have only experienced overheating disc brakes on mountain bikes, and even then only very, very few times. The times I did, I had to drag my brakes for a very long descent, e. g. descending Mount Tremalzo we had oncoming traffic of motor bikes (which is strictly forbidden, but that didnāt stop those morons). Despite that, even though my weight is average (in Europe at least, 75 kg) I always spec the largest brakes that would fit on the frame, 160 mm on my road bikes and 180 mm (at least in the front) on my mountain bikes.
Even on very long descents (think 500ā1,000 m in elevation difference) my road bikeās disc brakes remain well-behaved. I have SRAM Force eTap AXS at the moment. I only heard a few tings at the bottom of a 1,000 m descent, but that disappeared as soon as the brakes had cooled off.
Although the non-IceTech Shimano rotors on my previous road bike were, hmmm, not great. They lacked bite and had more trouble in the wet, too. On my mountain bike, I have only had IceTech XTR rotors for the last 10+ years (mostly a coincidence, I would be fine with XT rotors). They have worked great. My SRAM road bike rotors are also great, no complaints.
I think you can do a lot by changing your braking techniques and your aerodynamics. For example, one thing that Peak Torque hasnāt properly taken into account in his earlier videos on the subject is that aero drag is often a big factor on road bike descents. You can shed off quite a bit of speed by just sitting more upright into the wind, and since this deceleration is gently, it is a great tool to adjust your speed when you are riding with others. So even though road bikes are quicker, I think a larger share of the potential energy is ādissipatedā by aerodynamic drag than if you were on a mountain bike. The second thing is braking technique: you should avoid dragging your brake.
Despite my disagreement with some of Peak Torqueās arguments, I completely agree with his overall conclusion: I think the idea of speccing 140 mm brakes on road bikes is ridiculous, even if you are a light rider. Rather than 140 mm/160 mm, frames should accommodate 180 mm rotors in the front as standard. Iām saying that despite my experience, IMHO you should always overspec your brakes.
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That is my experience as well: my SRAM road disc brakes are much quieter than any of the Shimanoās I have ridden ā (almost) no tinging, much less squealing and yet I vastly prefer the feel (at least on road bikes).
(I was very much surprised how bad the 105-level hydraulic Shimano disc brakes felt compared to the XT brakes I had on my mountain bike. I loved those, they literally never failed me.)
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It really depends on a lot of factors, for me itās about 15m
Iāve never had an issue with rotors permanently warping, despite being a heavy rider who does some reasonable descents (for the UK). I feel like overall the basic steel rotors Ive had on cheaper bikes have been less problematic than higher end Shimano ones.
A much bigger problem that affects cautious riders dragging the brakes on long descents is boiling the brake fluid - Iāve felt that start to happen to me while stuck on a long winding downhill in traffic, and I know people whoāve lost braking while descending on hilly cycling holidays.
See also Richard Branson.
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I canāt recall the article now, and itās 12:30AM, so Iām not looking for it right now, but there was something from one of the brake makers (SRAM, Shimano, Magura, ?) that warned about using rotors that are too big. They donāt get hot enough, and braking performance suffers. If youāre not having issues with fade, your brakes are not too small. You should have some mild discoloration of the rotor once youāve bedded it in, and done some decently hard braking. If youāre not getting that, your brakes arenāt getting hot enough. At least, thatās what I recall at the moment.
-Tim
I have never heard of that. Like someone posted above, there are brakes on race cars that need to be brought to temperature before they bite properly, but I am quite sure that bike brakes are built to function like that.
Bigger brakes have several advantages, including shorter stopping distances. That is because you have more leverage, so when pad and rotor first make contact, you have more braking power sooner.
Also, most of the time you do not need bigger, beefier brakes ā¦ until you do! You might need them only a few times in years, but when you do, you really, really do. Thatās why IMHO brakes should always be overspecced. I see no reason to go for smaller rotors. The weight savings are negligible. The increase in rotational inertia is likewise negligible.
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My disc brakes work fine on first use from cold to stop after descending a hill at 40mph, thereās clearly no need for them to be warm.
That sounds like it was about race car/motorbike brakes, Iāve never heard of (pedal) bike brakes needing to be warm. They rarely are warm during normal use, so that would be odd.
My guess is as time goes on we may start to see more options in bike disc brake pads with special descending pads that can handle more heat. The technology is already there for cars.
FWIW - I took my car to a track day and swapped out the street pads and high temp brake fluid. I had a choice of about a dozen different high performance pads to chose from and that was in addition to all the basic street pads. Contrast that with the couple of choices youād have for a bike. But, while the track pads did great on the track, they sucked for normal driving and I was happy to quickly swap back to my street pads. (Noisy, dusty and they did not stop for shit when cold). Braking systems always involve a trade off.
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