SHIMANORt-Mt800 Centerlock Disc Rotor Grey, Internal Serration Lockring, 160Mm

I replaced my Shimano ultegra rotor with this and I saw an amazing performance improvement

I ditched the stock rotors in favor of these, and ... WOW!First, they are quiet even when braking hard.Second, make sure you test their 'stopability'. Tested before taking a serious ride at various speeds and conditions. On high-speed emergency stop, I almost launched myself over handlebars.Very happy.

Several years back, Shimano began to offer their ICE-TECH rotors which they promise will lower temps greatly, last longer than regular rotors, and possibly get you laid three times a week.Instead of the standard steel rotor offered by almost every other company, ICE-TECH sandwiches an aluminum core between two thin layers of steel for the outer ring of the rotor. Using an infrared heat gun to measure temps, I found that when comparing the same size rotors (say, 180 mm ICE-TECH versus 180 mm full steel), the temps are indeed lower but only by about 35 to 40 deg F. So, ... the rotors do work as long as you don't hold unrealistic expectations. According to Shimano, this means the entire rotor lasts significantly longer. IMHO though, these rotors last only about 1.2 to 1.3 times as long as a standard full steel rotor, ... which in turn lasts longer than the typical Kardashian marriage. That may sound good but you also have to factor in that they cost 1.4 times to twice as much as a standard all-steel rotor.I weigh 181 lbs and am slightly over six feet and use two 180 mm ICE-TECH rotors on my 24 lb carbon fiber full-suspension race bike and on my 28.3 lb back-up full-suspension trail bike. On both, these rotors (when used with organic pads) typically last me about three years of riding (but my riding is done almost entirely in sunny, warm, and dry California). When the rotors are brand new, they are 1.82 mm thick and Shimano recommends replacement when they reach 1.5 mm in thickness. After my first year of use, I am only at 1.71 mm and have about two years left before I will need new rotors.Another great feature of these rotors is that they are Centerlock. Instead of using the six-bolt pattern common to all cheaper steel rotors, you simply slide these onto a compatible Centerlock hub and tighten the lockring. Far, far nicer in my opinion and greatly preferred over six-bolt. Centerlock is also better at dissipating heat.Something else to consider, several of these ICE-TECH rotors just look nicer than the competition. Shimano's design team has done a good job with the 3D modeling of the rotors and their overall appearance. From the photo, you can see a shot of my son's bike which includes the super cool looking SM-RT99 rotor. The only other company that makes rotors that come close in appearance is Hope.Bottom line, ... Are these rotors essential? ... No, but they are fairly nice, although for a relatively high price as well. I would recommend them for lighter to medium weight riders in drier conditions. If you are a big boy (more than 210lbs) or riding in the wet forests of British Columbia, regular steel rotors will be cheaper. YMMV, ... four stars for me.

Q/a section and description implies the internal spline lockring, not external. Result, some very nicely gouged paint in my fork.