Obviously, the paramount consideration in chooosing a motorcycle helmet is how it performs in crash tests. If you’re going to be cruising on the highways without any sort of bodily protection, you need to go to great lengths to protect your head and brain.
Does the helmet stay on your head? A simple test to gauge how well the helmet will stay on your head in a crash is to fasten the strap around your chin and grab the back of the helmet, trying to lift it up and off your head. Even when you’re pulling hard enough to hurt yourself, you shouldn’t be able to get the helmet off. Different helmets will perform more or less well on this test based on your head shape. The right fit for your friend might not be hte right one for you.
Which leads us to the next consideration: how well does the thing actually fit? The basic rule is that a helment should fit so snugly that when you shake your head from side to side, up and down, or front to back, the helmet doesn’t move. You don’t want to be out on the road when you discover that the helmet does not fit properly and keeps blocking your vision when you turn to look for traffic. It ought to be so snug that the skin on your face moves with it as you move the helmet.
From a safety perspective, more coverage is better coverage. A study in the January 2003 Annals of Emergency Medicine found that bikers with facial injuries are 3.5 times more likely to suffer a brain injury than those without facial injuries. In addition, those that suffered facial fractures are 6.5 times more likely to suffer a brain injury. A full-coverage facial helmet is more likely to prevent these types of injuries.