Originally Posted by coupster

Helmet makers use different shape molds, kind of like shoe lasts. Some are round, some are oval. I have a somewhat large head 23" (58cm) but its more oval than round. Giro's are the only helmets that I have found that comfortably fit. Others manufacturers were just too round; tight front to back, loose side to side. Go to a couple of LBS and try different mfg's., eventually you'll find one that just feels right.