Escamanaze I think a GOOD mountain bike helmet is plenty safe for mountain riding and I bet they are a LOT cooler with better venting. I am looking at doing the same thing, thanks for the thread. The best snowmo helmets are just as light but they don't have nearly the venting that I have seen. Most of our riding we aren't moving that fast anyway. I will take it a little easier on the trail, 80mph into a 3' diameter tree would test any helmet. BTW, I am a pretty big safety nazi, wear my tether, avy vest, armor, knee braces, mouthguard and take a avy and first aid training.