So what brand and model of wheels are they? If they have aluminum braking surfaces, even braking and minimal heat build up isn't surprising. If they are Zipp Firecrest 202 wheels, not surprising either. They are billed as climbing wheels, and you are billed a medium fortune to buy them. Older and less expensive carbon wheels have overheating and braking problems, but they're constantly improving designs.

I have a pair of older Reynolds Attacks on my Parlee, and I wouldn't go on a big climbing ride with them.

Article on braking safety from last year: http://www.bikeradar.com/gear/articl...rs-safe-34521/

Also last year, a fairly comprehensive article on utility of carbon wheels : http://cyclingtips.com.au/2012/08/wh...rbon-wheelset/

The article points out that a growing number of mass participation rides do not allow carbon wheels due to increase rate of failure over more traditional wheel sets. And note embedded article from Red Kite Prayer.