Is there a consensus on disc brake rotor size for XC 29ers?

Depends on several things- your weight, riding style, & terrain. I normally run 180F/160R on my HT and 160F&R on my rigid ss bikes (205lbs riding in Western NC).

Yes, there is no consensus.

180 front, 140 rear (lighter weight, works just as well as a 160 rear)

i like my 180s front and rear.

mostly it depends on rider weight and tyre choice i would guess...

I ride 203 on all my bikes....then again I am probably much bigger than you

See...I told you!

CommuterBoy said:

Just curious...

I'm building my 29er with 180mm rotors, and I've had 160's on all of my 26" trailbikes. 203mm seems like overkill.... but to me there is some justification for bigger rotors on bigger wheels. Opinions?

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No consensus, but larger rotors can be justified.

For me, I use 185/160 on most of my bikes, 26 and 29.

shiggy said:

No consensus...

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Now, I believe it.

I also like 185F/160R setup on my mountain bikes.

RedGreen said:

180 front, 140 rear (lighter weight, works just as well as a 160 rear)

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Your signature line in a post about brakes is kinda funny! :thumbsup:

160's front and rear.
185lb, purely XC.

I've never felt like my 160's weren't enough on my Kona Dawg (hayes 9's)... and they are certainly enough on my commuter (BB7 mechanicals), but I liked the idea of a larger rotor to go with my larger wheels. 180's seem proportional.
I don't like the idea of a bigger rotor up front and a smaller out out back... it makes all the sense in the world, but it just doesn't sit right with me. I want my brakes to be feel identical. That starts with them actually being identical. To each his own I guess...

CommuterBoy said:

...I don't like the idea of a bigger rotor up front and a smaller out out back... it makes all the sense in the world, but it just doesn't sit right with me. I want my brakes to be feel identical. That starts with them actually being identical. To each his own I guess...

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You would never "sit right" on ANY streetbike then. Hahahah talk about being different when not only are the rotors generally larger but they have two in the front and only one small one in the back. But shoot a motorcycle and a mtb are two different animals and you are right.... I don't think anyone ran XTR v-brakes up front and canti/side pulls in the back.

Bryan d

^^ The Brembo's on my KTM are different sizes, I'll grant you that... but you operate one with your foot and the other with your hand, so they already feel different right there... Apples to oranges. :lol:

I still remember seeing DH bikes w/ disc front, V rear.

CommuterBoy said:

^^ The Brembo's on my KTM are different sizes, I'll grant you that... but you operate one with your foot and the other with your hand, so they already feel different right there... Apples to oranges. :lol:

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There was a special someone from way back when that used his left hand for his rear brake and won GP's.

I'm surprised no one has mentioned heat dissipation in this thread, and how it plays in rotor size?

bryan d

Found a major advantage in stopping power in changing from 185/160 to 203/185mm rotors on a dual suspension play bike. The 29ers is still running a 185/160mm combo and have been really happy with them.

brakes??? we dont need no stinkin badges!!!

160mm front/140mm rear, both 26 and 29 inches