Originally Posted by
fietsbob
got money to throw at it .. ceramic- carbon fiber discs with their own special pads are out there.
at a more modest cost the aluminum cores are a heat-sink for the steel disc rather than cooking your hydraulic fluid.
I don't think heat is an issue. Are there materials that have better friction capabilities, which allow manufacturers to be more creative with the design? I have a pair of XT rotors that have have the aluminum spider. I can't say I've ever seen a marked improvement in performance. Although they work really well, and are easy to true. Again, overheating is rarely an issue. Of course, some other added benefits are that they look pretty cool, and are noticeable lighter.