protect differently? I bought a snowboarding helmet last season to protect my head against any hard blows on the snow/ice. I am getting back into casual biking this year and was wondering if I could use that helmet (http://www.redprotection.com/Default.aspx ) while biking, or if a bike helmet protects against different possible head blows. I've noticed that multipurpose helmets look very similar, so wanted to check before going out and dropping money on a bike helmet.