Brake Disc Questions
 

Hi all!


Getting new wheels soon, and as my old wheels are 6-bolt and the new wheels are center lock, I'm looking to zero in on new brake rotors. I don't think I saw any threads on this in my casual search, so here goes:


- Have 160mm rotors now, Ultegra calipers. Will any 160mm rotor work?


- Are Shimano IceTechs still considered the best with regards to heat dissipation? I already get rotor-zing after hard descents, wouldn't mind minimizing that.


Thanks for the help! And because pictures supposedly help, a pic of my new wheels:

https://cimg2.ibsrv.net/gimg/bikefor...d27bbf2483.jpg

As long as the rotors are CenterLock and 160, they'll work. Or, they should. There are some oddballs like the Hope floating rotors that may or may not have clearance issues. Anything Shimano will be fine. You may need to re-align your calipers, though, which is a pretty simple operation.

When I built my bike ~6 months ago (maybe still the case?) using MT800/900 rotors was the thing. Lighter, cheaper, and more readily available than the roadie equivalents. Something to look into....

Any 160 center lock rotor for the 'narrow' brake pad should work well

some will mix the wide brake pads with the rotors designed for the narrow pads - but Shimano does not recommend this

What is "rotor-zing"?

When rotors expand and warp after hard braking, and lightly scrape the brake calipers even after the brake levers are released, causing a metallic zing.

The new brake calipers that come with the Shimano 12 speed groupsets allegedly have more pads to rotor clearance to avoid this phenomenon.

I think I read your thread when I was looking for information on this. I'll keep the MT rotors in mind, but I think I actually like how the road ones look a little bit better. Still have a little time to decide - the wheels are still on the slow boat across the Pacific...

How do I know which brake pads I have? I haven't changed out my brake pads yet, so that much is new to me.

Clearance has always seemed to be a hydraulic brake issue - even the Magura rim brakes on my mountain bike back in the late 90s had trouble dealing with a wheel that was even slightly out of true. I'll keep a look out for long term reviews of Shimano 12 speed - if the new brakes can really eliminate zing as an annoyance, that would be great!

I don't care much for carbon wheels but those are pretty sexy

I would also pick parts based on cosmetics, provided they were a functional equivalent. I lucked out because I liked the look of the Mt800 better but that's just my opinion. FWIW I looked and couldn't find any hard data that said either was better than the other, also the only difference between the Mt800 and MT900 seems to be the aluminum layer is painted black. On paper that would help them dissipate heat better but I question if there is any real world difference - and at the time they were 2x as much! My point being, I thing any of the higher tier Shimano offering, regardless of Rxxx or MTxxx, should work equally well. I'd base my decision on price, availability, and cosmetics. It's all good.

the Ultegra calipers use brake pads for the 'narrow' track rotors

basically - the majority of the low end Shimano hydraulic disc brake systems use the 'wide' track rotors and corresponding /compatible calipers and pads ; relatively cheap/stamped steel rotors and organic / resin pads (only) ...

the upper level Shimano systems use the 'narrow' track rotors and corresponding/compatible calipers and pads ; rotor choices include the top available Shimano models including machined steel and Ice-Tech 3 layer rotors and metal / sintered pads or organic / resin pads (including finned pads)

As far as I can tell, the Shimano Road and Mountain disc rotors are functionally close enough that I wouldn't be able to feel a difference - so between the two, I'd likely pick based on aesthetics or availability, provided the cost were similar.

But part of me had been wondering if Shimano IceTech really was the best, and if there were any other rotors (cool looking or not) that would offer measurably better braking performance or resistance to warping, that were in the same price range. SRAM Centerlines have a cool aesthetic, and Hope rotors have the option for anodized carriers, but not switching if their performance is worse with Ultegra calipers.

Based on the duration of the zing-zing-zing after hard braking, the Ice Tech do seem to shed heat quickly.

The other thing that I like about them is that they're easy to true - with the all steel rotors, you sometimes have to overshoot when trueing so that they spring back to the desired line.

I really love the bling of the Hope rotors, but they're expensive, hard to come by, and of questionable compatibility (I've heard that the rivets may interfere with some calipers). I'd love to try them, but that's about an $180 roll of the dice.

I have XT (MT-800) rotors on one wheelset and cheaper Shimano RT-56 rotors on another. Both are used with GRX brakes - the only difference I notice is that the XT rotors are louder and have a bit more "bite", and make more of a loud "zing zing" after hard stops (which goes away after a few seconds).

I've been running the Ultegra IceTech rotors on one of my bikes for about 11k miles, and no issues even under prolonged braking on long steep descents. I managed to locate a pair of them a few months ago just for my parts inventory.

same type of pads on both bikes ? (should be resin on the bike with the RT56 rotors)

if the bike with the XT / MT800 rotors has metal / sintered pads - this could account for the additional sound (?)

I have prev gen XT (RT81) rotors on one bike and RT56 rotors on another bike - both with resin pads - and the XT / RT81 combo is quieter (and has much better feel / power )

Both wheelsets are used on the same bike, resin pads. I should add that the XT rotors are on a carbon wheelset whereas the RT56 are on alloy wheels. The carbon wheels might just amplify the sound a bit.

interesting

and curious - why RT56 rotors on a GRX bike ? - I believe you can use the better rotors (RT6x etc)

(for my one bike - RT56 rotors are installed due to the calipers ... low end M396 or something like that)

The RT56 rotors came with the bike. The groupset is GRX800, though I'm pretty sure the brake calipers are actually GRX400. Shimano's GRX product page does say that RT64 rotors are recommended for the GRX400 caliper. They recommend MT-800 (XT) for the GRX800 caliper. The pad recommendations for both are the same (L03A-Resin or K03S-Resin) so I'm not sure what difference it would make. I'm running the L30A Resin pads (the ones with the fins).