Originally Posted by chaadster

I dunno...most of the pro downhill bikes weigh north of 40lbs irrespective of material, so I don't think weight is really a factor. There are also just a ton of carbon fiber pro downhill bikes, so maybe to say "most bikes" are aluminum is not accurate, either, but I don't know. Notably, Trek's pro team was all Al this year, and Specialized only offer Al bikes, but some pros were riding very trick hybrid Al/CF bikes. Hattie Harnden also has a very cool looking Al bike that uses CF inserts for stiffness tuning. Surely cost is an issue for privateer racers; Canyon's Torque, for example, is $1k less in the Al frame compared to the CF frame. Again, I don't follow the sport closely enough to say which material is most in use, but there's a lot of CF in the elite ranks.