Angus Bohanonwrote a review of Kask K.50 EVO Team Helmet - Men's on May 20, 2013
So the sizing chart splits at 23 inches, and when I measured my head it was exactly 23. I ordered the medium first, and it was definitely too small, but the large came a few days ago and I love it. It ventilates perfectly when I ride, fits snugly, and is light and comfortable not to notice on 20+ mile rides. Would recommend to a friend.