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Rotor diameters
NB: Originally posted elsewhere on the Global Riders Network and appears via syndication.
I've just picked up a set of 2014 XT brakes from Pushy's in the ACT for a good price ($100 an end, sans rotors and brackets) and need to pick your brains on appropriate rotor sizes.
Currently the Scalpel 29r has 180F/160R with the Elixir 9s.
Will 180 be too much on the front with the XTs?
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I have 2012 xt front and rear, and am running 180f/160r on a trek rumblefish with no worries at all!
I'm running a 180 on the front on my Mach 5.7 with XT's and haven't had any issues, so I'd say you'll be fine. People run 203s for even greater stopping power without issues.
If anything you'll be better off on a larger rotor since they should stay cooler and be less prone to fade from excess heat.
I guess the main concern was the 2014 XTs are supposed to have a lot of power and with low tread height XC rubber on front and rear I didn't want to overpower the available grip on the front. Collarbones suck when you break 'em.
Previous experience with a 180mm rotor on the front and 160 on the back was with 26er wheels and the old 2006 Hayes Nines. That was scary sudden on the front and I was glad to get rid of that bike.
On the other side of the ledger I am running bigger wheels now (29er), wider rims and tubeless 2.25 rubber, and the brake modulation these days is so much better.
I was just wanting to check in with what people thought. Hard to know where the balance lies!
I''m about 90kg kitted up & have run XT 180/160 on my 29er HT since new. The XT pads initially were pretty "bitey" but now seen less so.
I personally think that this combo feels balanced as to the amount of actual pressure you can apply /useable braking force & wouldn't like less power up front especially with the additional leverage imposed by the big wheels.
I'm actually not that impressed with the XTs. Sure they're good vfm but the SLX & Deore are better & the power has been a bit inconsistent, the modulation isn't great & the pads noticeably move in the caliper giving a slight initial knock.
Maybe having Hope's on my other bikes show these traits up.
T
The XT brakes will work better on XT rotors, but they will work fine on non-XT rotors. I have experimented using XT brakes on Avid rotors and Magura rotors, and I can tell the difference.
There are 2 types of rotors from what I understand: Ice-Tech and non Ice-Tech.
I am currently using 180mm (ice-tech) on front and 160mm(ice-tech) rear on my Epic and it's fine, you just have to get used to the braking prowess of the XT.
The pads that I use are the metal ones F03C is the part number I believe, and they last a long time.
http://www.mbaction.com/Main/News/Product-Test-S...
John,
I'm running 160mm Ice Tech rotors front and back on the Epic with 2012 XTs and I have plenty of stopping power.
For what its worth I'm running 160 front and changed to 140 rotor on rear on my epic XC 29r. BUT I'm 70kg. I found that it is too easy to lock up the rear with a 160 on the rear so changed to a 140. I can still lock it up if needed and modulation is easier (I can also deliberately lock the front). As the front does most of the braking and the rear I use for stability and turning, the smaller diameter is more manageable for me. But thats me and my style on my terrain with the level of grip our WA pea gravel provides.
Are many XC MTBs over braked on the rear, especially for lighter riders? Why would you need a rear brake with close to the power of the front? The rear does far less work and the number of people locking up the rear, well seems most tend to do it. Unless you are doing a long downhill with lots of braking or are dragging the brakes, is rear brake heat build up an issue?
FWIW.
PS: For the weight weenies out there it saves a few grams of unsprung rotational weight
i've got the 2013 XT brakes (785's) on my stumpjumper 26er and run a 203mm (avid) rotor on the front and a 185 on the rear. didnt go the full combo (rotor / caliper etc) as was swapping out some Avid CRSL's. stopping certainly isnt an issue, neither is modulation for descents.
also have the slx version of same (675's) on my 29er stumpy evo (as lbs had no xt's in stock) and run a 200 / 180 rotor combo on that. i am 6'2 ish, 80-85 kg depending on the week i'm having and the amount of rubbish in the backpack, and both are xl frames.
now that i am used to the grunt both sets of brakes have on their respective bikes, i wouldn't go any smaller....
guess thats the opposite end of the scale to oldernslower above, but my riding style (or more likely lack thereof) may be a contributing factor to liking big brakes...