tomPietrowskiThey are not just for keeping you warm but wicking moisture when you sweet. They will be so much better to wear then say a tshirt.
I bought an armada waterwicking base layer with a microbacterial wash. Well worth the money. Tuck this into your pants. I learned this the hard way from landing on my back after a rail or something. This lifted up my jacket and gave me serious snow burn as I was sliding down.