I hope you are not referring to me, because even though you may not know it, alot of what you state is uncomfortably close to the truth. But, in my defense, I did not have 203s or XTRs at that time, and unknown to me, my brakes had been swapped back to the standard front on left and rear on right from the moto (reverse) setup I'm used to by my LBS the day before when they did some handlebar/stem changes for me. There's no denying the extreme stopping power of my current setup, but I'm learning to modulate the brakes and use them effectively. I primarily ride the Santa Ana mountains and that means a lot of continuous downhill to end the ride, and these brakes just don't fade, and stop just as strongly after 10 miles of dragging them continuously downhill as they do when cold. You've just got to learn to use them to your advantage....respect them too!
I wasn't referring to you SXP. We were typing at the same time and between work and my chicken peck typing, you posted. Although, your post did agree + disagree equally to what i had typed. Ironic.
I see both sides of the issue as having their merits, and can't convincingly come down firmly on on one side or the other. I'm just sharing my experience, trying to temper it with a little humor, fully aware that there will come a day when I grab too much brake and execute a very ungraceful OTB human dart maneuver. I just hope it doesn't entail a helo ride to the ER (again)!
Basically, if you feel like you need more stopping power, it's cheaper to upsize your rotors and get the appropriate adapter, than to buy a more powerful brake. Beware that many forks and frames only allow certain size rotors. Don't let the trends influence you too much; trends often come and go and the tried and true doesn't go away, unless the trends actually are that much better. In this case, it's not that bigger rotors are better (they can actually be worse), it's more about bigger rotors being more suitable for some setups. Generally 29ers will need more stopping power than a comparable 26" bike; if spec'd with the same brakeset as a comparable 26" bike, the 29er would need a bigger rotor to better match the braking performance and feel of the 26" setup. From my experience, here's some info that might help you make your decision: At the last Yeti demo, I rode a SB-95 with 180 F and 160 R rotors, the latest XT brakes, with Ardent 2.4 up front and Ikon 2.2 rear, the bike weighing 28 lbs and me weighing under 150, but pushing my speed on everything and found that this setup felt strong and well suited for the bike. On the other hand, I rode a ASR5c with the same brake and tire setup, except 26" instead of 29er tires, and the brakes were outright dangerous and hard to modulate and I felt that going as fast as I would normally was risky. It was a combination of not being able to slow smoothly, as just trying to feather the brakes resulted in a very responsive loss of speed, with a jerky start that kind of makes you nervous, which was made even worse when I was decided to pump the brakes to make up for the lack of modulation, and the tires felt like they couldn't cope with it on the dusty hardpack (Ardent 2.4 is def not the wisest choice for Sycamore Canyon in Riverside, esp in 26"). The morale of the story is, choose brakes suited to you bike, your weight, and trails. I went from stock Elixir CR 160 F/R to 185 F (not really anything wrong with them, except a bit noisy at times, some minor rubbing, and I was in an upgrading mood), then very briefly to Formula R1 180 F and 160 R, and finally to Avid XX 185 F and 160 R on my Superfly 100. The XX is not nearly as powerful as the R1s, but feels perfect for my bike and my riding style. It took a few rides on a specific trail to get accustomed to the touchy feeling from the R1s; once accustomed, I began to appreciate what stronger brakes could do for me. On the other hand, the feel and power of the Avid XXs felt really natural, and I was riding the trails without any want for a different brake. I could stop extremely fast without skidding; I once thought that other brakes had good modulation, but after experiencing these brakes, my idea of modulation totally changed and now I think a majority of other brakes have shitty modulation. Modulation is a trendy word, IMO. What has good modulation on one setup, may be too weak or too powerful on another; it's probably more like that the brakeset has the ideal stopping power for your setup, as the XTs on the SB-95s could be modulated well and the XTs on the lighter weight ASR5c couldn't. The XX brakes are the smoothest brakes I've ridden and, much to my surprise, I was blown away when they became even smoother, when I thought they were already at the pinnacle of smoothness, when I bled them. I wouldn't go back to 160 front, as I found the extra braking power actually enables me to go even faster. Sounds contradictory at first, but you can't go fast without the ability to safely and effectively slow yourself down. Basically, the heavier and beefier your bike, the heavier the rider, the beefier the tire, and how fast you like to go, the bigger the rotor and stronger the brake you need. If you bought a bike from a company with a big racing heritage and it's one of the race models, and you're a weekend warrior as opposed to a young and fit athlete, the stock spec might not be optimal for you. That is where aftermarket customization comes in. I've become more trusting of mfg stock specs lately, but that might be more because I'm turning out to be more like their target customer, with an athletic build, and also because I've been looking at bikes that match my preferred style of riding well, rather than looking to turn a lightweight racy bike into a do-it-all trail bike. Trivia: did you know that Avid brakes have their strength and modulation tuned per model, with models such as the Juicy 3 offering more stopping power, than maybe a Elixir CR, due to Juicy 3s being spec'd on heavier entry level bikes? Due to this, the Juicy 3 also finds its way onto the stock spec of some bigger bikes and even cost effective DH bikes. Hard to pin rotor sizes to a certain group, but it would go something like this: - If you have a XC or trail hardtail with about 110mm (~4") or less of travel that weighs under 25 lbs, you weigh under 150 lbs, and/or ride with fast low profile tires like the Racing Ralph, Rocket Ron, Ikon, Aspen, Driver, Race King, Small Block 8, etc. 160 rotors may likely suit you best. - If you have a 120-150mm (~5-6") bike that weighs more than 25 lbs, you weigh under 185 lbs, and/or ride with moderately knobby tires like the Nobby Nic, Fat Albert, CG 4X/AM, High Roller, Ardent, Trail King/Rubber Queen, etc. 180/185 rotors may likely suit you best. - If you have a FS bike with more than 160mm travel (6"+) that weighs more than 28 lbs, you weigh over 200 lbs, have a 35/36/40mm fork, and/or ride with a bit more aggressive tires like the Nevegal, ExCavator, Rampage, Purgatory, Bronson, Hans Dampf, Muddy Mary, etc., you probably should be considering the biggest rotors you can fit. - FR/DH bike riders should be considering stronger calipers to go with their bigger rotors, such as the Formula The One or the quad piston ones like the Saint and Code. I might suggest the Stroker Ace or M4, but I don't think they're even comparable to the top 3 in braking performance. The lightest weight weenie bike, with a weenie rider to match, and practically bald tires, might like 140mm rotors (at least in the rear, as I don't think there's many forks that allow 140). Having bigger wheels (29er or 650b) or being a heavier rider with a beefier setup might give you a hint that you'd be better off with a rotor that is a size up from the basic guide above.
