I have this bike in a 50. Love it. A solid workhorse through 6 seasons of training, racing duathlons and a few centruy rides. It is an aluminimum frame - I will only know the difference when I get my Trek on the road (carbon). I have had absolutely no issues with it.

Now, my Trek which has not even seen the road yet is curiously dropping pieces of paint or is damaged..LBS is helping me figure out this sad story.