Mountain Biking - Quickie on Disc Brake Sizing & Upgrade

Quick question... I have a 2008 Bianchi Sok (Easton Ultralite Tubing) and I'm looking to upgrade the rotors and braking system. New to mountain bikes, have done road for a while...

Currently has Avid BB7 Mechanical 160mm rotors

From what I can tell all disc brakes have the same 6-bolt pattern... So what's the biggest downside to upgrading to 185mm or 203mm rotors? I'm sure I stop faster and with more torque on the frame, but are there any other downsides?

That being said, I was looking at the Avid Elixir R (or just Code R) at the 185mm rotors. I'm not that familiar with the Elixir line, is it a relatively good bang for the buck? Would those rotors be overkill on my SS 29er? Any help is appreciated...

Quick question... I have a 2008 Bianchi Sok (Easton Ultralite Tubing) and I'm looking to upgrade the rotors and braking system. New to mountain bikes, have done road for a while...

Currently has Avid BB7 Mechanical 160mm rotors

From what I can tell all disc brakes have the same 6-bolt pattern... So what's the biggest downside to upgrading to 185mm or 203mm rotors? I'm sure I stop faster and with more torque on the frame, but are there any other downsides?

That being said, I was looking at the Avid Elixir Code R (or just plain Elixir R) at the 185mm rotors. I'm not that familiar with the Elixir line, is it a relatively good bang for the buck? Would those rotors be overkill on my SS 29er? Any help is appreciated...

Its very common for 29ers to come with a 185 front rotor and 160 rear. The larger rotor in the front provides better stopping power, as you aluded to. Many people (like myself) will run 160 front and rear, even for a 29er, for a cross country set up. But 185 is completely acceptable if you want more torque on the front brake.

You start to see larger rotors on bikes built for All Mountain, Downhill, Freeride, etc because the faster speeds make a higher need for increased stopping power. The major downside to large rotors is they are more prone to damage from crashes, etc. since they are larger. I wouldn't go with a 203mm personally, it is unecessarily big for your purposes (at least from what it seems, I assume you are riding mostly cross country seeing as your are running a SS 29er). My suggestion would be 185 front, 160 rear.

The Elixir brakes are really good, IMO, especially for the price. I have the Elixir 5 (nothing special) and like the lever feel, especially after it has been rebled. The higher end elixir's are even nicer with more adjustable features.

Awesome, thanks!

+1 for running 160F/160R and Elixir's.

I'm 190# and have plenty of stopping power with this setup. If you are in the same weight range or less: only time I consider 185 (or even 180 if you like Ashima rotors) is for rides with long descents (20 minutes or more). Very few like that in the US East coast mid Atlantic region.

You can pop for hydro discs if you want (it's your bike), but the BB7's with 185 are sweet, and XTR brake cables make them feel like silk! Lot less investment.

It's what I use on my FS/AM/daily rider......

+1 for running 160F/160R and Elixir's.

I'm 190# and have plenty of stopping power with this setup. If you are in the same weight range or less: only time I consider 185 (or even 180 if you like Ashima rotors) is for rides with long descents (20 minutes or more). Very few like that in the US East coast mid Atlantic region.

Agreed, 160 front and rear is totally doable for most riders in cross country single-track. Lots of stock bikes come set up 185F/160R for more versatility, like the Giant XTC 29er, Gary Fisher 29ers, etc. But not a necessity if you aren't doing lots of descending and heavy braking.

As a counter point, I wouldn't want less than 180mm on the front. 160mm is fine on the back. Really, I prefer 200mm/180mm, then I know I'm good to go. I live on the east coast with not a lot of long descents but still have lots of fading problems. I'm 185 lbs or so and ride heavish bikes down any stupid mountain I can find. Getting good advice here, just wanted to put my personal experience in there. Not too much drawback to having bigger rotors, unless your a weight weenie, racer type. I'm talking good quality brakes, meaning good modulation. Not on/off lowest grade cable wally world brakes.

Cool, thanks for all the great info everyone.

Any idea why the 160mm set of the Elixir R's are more expensive than the 185mm or 203mm?