Hey guys, so I just ordered a set of new XT brakes off blue sky and a matching set of icetech 160mm rotors for front and rear on my nimble 9 ss. I've been noticing that a lot of 29ers are using 180mm front rotors, is there any particular reason for doing so besides a little more stopping power? Should I be using a 180 up front?
You kinda answered your own question...The larger rotor means the caliper grabs the rotor at a point further away from center when compared to a 160mm rotor. It is a matter of leverage. With all things being equal, namely the squeeze of the caliper and the friction between the brake pads and disc, it takes less force to stop the wheel with a 185mm rotor than with a 160mm rotor. I will spare you the force vectors and angular momentum nonsense.
I understand the whole concept of more stopping power and how it may be ideal to stop a 29er wheel with a larger amount of rotating mass, I guess my question is more of is it necessary to run a 180 up front or does it come down to personal preference?
Not necessary, I have been running 160 on my 29'er and it stops me just fine. Do you go really, really fast to warrant a 180? IMO its more of a personal preference.
Depends on what type of trails you ride and how fast. If you do long fast downhills or very steep stuff, my opinion is go with the larger rotor. You will likely never get forearm pump or have to use 2 fingers. They aren't much more $ or much more weight.
180 will have more power and run cooler. They also seem to visually fit proportionally on a 29er like a 160 on a 26". If you run all mountain or long downhills, i wouldn't go smaller than a 180. XC/trail i wouldn't go bigger than 180. If you ever get brake fade with the 160, its time to upsize. You will likely be able to lock up a 160. So, the power will be there. Heat management can be a human factor as well.
I guess I should have done a little more homework first, http://forums.mtbr.com/brake-time/curious-about-rotor-wheel-size-767977.html Has anyone ran a 160 as a front for a 29er and then switched to a 180 and can tell me if there is an actual noticeable difference?
Yes I have. Previous rotor was 160 on the front for Tallboy C. Changing out to a 180 gave it more stopping power & made it easier to brake. There is very little downside & much more upside if you change.
ice tech by design is supposed to be more resistant to fade issues. If you already spent money on the rotors why not just use them? What brakes are you used to using? I recently switched from avid and the new shimano has much more stopping power.
I had 160 front and rear on my Ellsworth Evolve, then switched to 180 for the front. I noticed the improvement in stopping power. My bike weighs about 27lbs so I skipped swapping out the rear to a 180 as well. I am happy with having the 180 in the front.
Well they haven't gotten here yet, just ordered them today. I did change the order to a 180 front, so I guess I'll be answering my own question. I'm swapping out my old Hayes 9s, I have another set of the new XTs on my geared bike, but I'm running those on Hope discs because the wheels have the three bolt pattern.
I use what ever rotor runs without making noise. Harmonic vibrations is what makes some brakes squeal and changing rotor size can get a brake to run quite. Even the smallest rotor have given me excellent braking power. Now modulation and overheating is much better with larger rotors. Dean
All of my bikes are in the 25-29lb range. I weigh 160 (170 w/ camelbak). 203 would be overkill on my Trek HT and my rigid SS and they are fine with the 180's up front. My 1x9 HT is running an old RS Sid (28mm) and the 160 makes it flex. I would guess most quality modern forks will allow a max rotor ~205, but, i think some XC lightweight versions should stay under the 185.
Run 160's on my Tallboy.......never thought I needed more brakes....even towing the BoB Trailer. Run 160's on my 29 SS......never thought I needed more brakes. Had 180's when I built it, but turned out to be too much brake. I am 210 without a pack.
