MTB rotors to replace Ultegra 8000?
Moderator: robbosmans
I’m sitting here confused about 1 component choice on my new Emonda ALR build and unsure if i should make an objection to the builders at my local shop.
On the build list i chose ultegra disc. I go in yesterday as the bike is getting partly built (waiting on groupset) but they already have rotors on? I was confused. They explain.
My LBS boys decided i needed heavier duty braking than the Ultegra discs so they’ve opted for Shimano XT rt-81 rotors AKA MtB rotors??? does this sound right?
These guys have serviced my mtb’s for years and my gravel/commuter for the last year, and have been out riding with me here and there over the years. Needless to say, they definitely know my riding style. So, I want to believe them but I was looking very forward to the style of those Ultegra disc brake rotors AND everything I read says the Ultegra has better heat dissipation.
Basically, am I right to want what I had agreed (especially b/c they are so pretty ) on or are the MtB discs actually offering superior stopping power?
On the build list i chose ultegra disc. I go in yesterday as the bike is getting partly built (waiting on groupset) but they already have rotors on? I was confused. They explain.
My LBS boys decided i needed heavier duty braking than the Ultegra discs so they’ve opted for Shimano XT rt-81 rotors AKA MtB rotors??? does this sound right?
These guys have serviced my mtb’s for years and my gravel/commuter for the last year, and have been out riding with me here and there over the years. Needless to say, they definitely know my riding style. So, I want to believe them but I was looking very forward to the style of those Ultegra disc brake rotors AND everything I read says the Ultegra has better heat dissipation.
Basically, am I right to want what I had agreed (especially b/c they are so pretty ) on or are the MtB discs actually offering superior stopping power?
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No, MTB rotor is not better at breaking for the same size.
Their Ice tech XTR rotor weight a tiny bit less than Dura-ace rotor (both still weight more than Sram CenterlineX) . So you could be able to run bigger rotor size for less of extra weight. And bigger rotor= better breaking.
Basically, A solid road 140mm maybe able to shred heat like mtb 160mm rotor because of their more efficient heat sink design, and being more aero since it is a smaller disc. But in term of breaking performance, 160mm rotor still win a 140mm. Nothing except few grams of weight stop you from running road 160mm rotor though.
Another note is road rotor size stop at 160mm as the biggest size. If you really need 180mm or larger on road (i doubt it) then yeah, you need MTB rotor.
Also, if front rotor and rear rotor are the same size, it's either front is too small or rear is too big. They don't face the same force or heat, which dictate rotor size.
If anything else is better on MTB, it maybe default brake pad. Road disc likes to use organic pad because it is quieter. But many MTB shipped with Metalic pads which brake better but noisier. Again, nothing stop you from changing disc brake pad.
Their Ice tech XTR rotor weight a tiny bit less than Dura-ace rotor (both still weight more than Sram CenterlineX) . So you could be able to run bigger rotor size for less of extra weight. And bigger rotor= better breaking.
Basically, A solid road 140mm maybe able to shred heat like mtb 160mm rotor because of their more efficient heat sink design, and being more aero since it is a smaller disc. But in term of breaking performance, 160mm rotor still win a 140mm. Nothing except few grams of weight stop you from running road 160mm rotor though.
Another note is road rotor size stop at 160mm as the biggest size. If you really need 180mm or larger on road (i doubt it) then yeah, you need MTB rotor.
Also, if front rotor and rear rotor are the same size, it's either front is too small or rear is too big. They don't face the same force or heat, which dictate rotor size.
If anything else is better on MTB, it maybe default brake pad. Road disc likes to use organic pad because it is quieter. But many MTB shipped with Metalic pads which brake better but noisier. Again, nothing stop you from changing disc brake pad.
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Resin pads will have more initial bite and better modulation, but sintered pads are going to have more overall stopping power, are less likely to fade and will last a lot longer for people who do a lot of elevation.
Last edited by TobinHatesYou on Tue Aug 07, 2018 9:34 pm, edited 1 time in total.
I was about to post this. I've been running metallic pads for several seasons on my CX bike, and the pads still have quite a bit of life left in them. I use the same pads for gravel riding, too, so it gets a fair bit of use.TobinHatesYou wrote: ↑Tue Aug 07, 2018 9:20 pmResin pads will have more initial bite and better modulation, but sintered pads are going to have more stopping overall stopping power, are less likely to fade and will last a lot longer for people who do a lot of elevation.
Madone 9 - https://bit.ly/2Nqedbn
Emonda SLR - https://bit.ly/2UK5FP8
Crockett - https://bit.ly/2Xem4sk
Emonda SLR - https://bit.ly/2UK5FP8
Crockett - https://bit.ly/2Xem4sk
At that weight, instead of 160mm set. Do 160mm front and 140mm rear. 160mm in the back is way overkill for your weight and it will locked up easily.
Using bigger front than rear so you don't have to be very deliberate about pressing rear brake significantly more gently with less force than front brake. It is actually easier to use than using same size rotor.
Flat mount brake can use either size with different adapter configuration anyway.
Using bigger front than rear so you don't have to be very deliberate about pressing rear brake significantly more gently with less force than front brake. It is actually easier to use than using same size rotor.
Flat mount brake can use either size with different adapter configuration anyway.
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Locking up disc brake rotors is pretty damn hard. If you do it frequently, the solution isn't smaller rotors...it's replacing your ham-fists with fingers and improving your braking technique.
thanks tobin! yeah i have been on equal-sized front and back disc rotors on my MtB and gravelcross commuter, and have never experienced this insanely easy locking up of the rear wheel I always read so much about. If i experience otherwise, I will definitely let you know you were right, Hexsense!
I appreciate everyone’s input!
I appreciate everyone’s input!
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I wish I got along with the very sleek looking RT-900 rotors. I've have basically decided that SRAM Centerline X rotors are objectively better overall than the Shimano RT-900 or Campy H11. It's just that they are the ugliest of the three...