I agree with jperryss. Although having said that I wear an Arai helmet. You MUST try each one on. Different manufactures make helmets for different sized heads. While a helmet can be expensive piece of equipment, it is a no-brainer to use one. Otherwise, you may be left with no brains!jperryss said:Paying $300 for a helmet will not necessarily make it safer than a cheaper helmet. Once you get into the high-dollar helmets (Shoei, Aria, etc) I think you're mostly paying for convenience and features, such as quick-change visors, more vents, changable pads, etc. I would trust a $60 Snell approved helmet over a $400 non-Snell approved model.
I'd also recommend trying some helmets on at a local shop. Every manufacturer seems to size their helmets differently.