I have been riding the Hi Fi helmet for 3 seasons now. I was hesitant to wear a helmet at first but now I feel naked without one. This helmet is supe light and I really don't even notice it's on. It has plenty of venting. In fact I am bald and I usually need a skullcap under my helmet on colder days cause it gets a little breezy. So those of you with hair should be just fine. My hat size is 7 1/4 and I wear a large in the Hi Fi. It fits perfectly. The detatchable ear covers are a must on warm spring days. This is a great feature. I would reccomend this to anyone. I am giving it only 4 stars though due to it being a bit high profile. It sticks up a bit making me feel somewhat like an astrounaut.