You've just got to keep trying on different helmets until you find one that fits the best because you have to remember that you are going to be wearing that bad boy for a few hours at a time. Peoples heads are generally 1 of 2 shapes, Oval and more Round. Different manufactures make different medels to fit different shapes of heads. I have more of a round head and have a RED Skycap. I believe Giro fits more of an oval head but don't quote me on that. I haven't researched helmets for quite a while.