You can buy a helmet almost anywhere. As a result, many of us have a shelf full of helmets to show off our bad choices.
Motorcycle helmets are generally subject to the Federal Motor Vehicle Safety Standard (49 CFR 571.218) commonly referred to as the DOT standard. In addition, some helmets may be certified by the Snell Memorial Foundation. The fact that a helmet is certified by both Snell and DOT does not necessarily mean that it is superior, but the absence of a DOT certification is an invitation for a ticket from your local highway patrolman if you happen to be pulled over for any other violation. In addition to the DOT and Snell standards, some helmets are rated under the U.N. Economic Commission for Europe standard (ECU 22.05) or the new SHARP Five Star Motorcycle Helmet Safety Standard Rating System used in the U.K.
The full-face helmet is unquestionably the best option if your purpose is to minimize your chance of death or catastrophic brain injury in the event of a crash. According to one German study, almost half of all motorcycle helmet strikes are in the front left or right chin or face shield areas. 35% of all strikes are in the chin area alone.
Open-face ¾ Helmet
An open-face helmet covers the side of the head (ears), but offers no protection for the impact areas in the front of the face. As such the slang term "three quarter" helmet is somewhat misleading, because to the degree that it covers roughly three quarters of the head, it only covers about half of the expected impact points based upon documented strike frequency.
Modular helmets combine the convenience of an open-face helmet with some of the protection of a full-face helmet. Closed, the modular helmet looks the same as a full-face helmet. However, the front half is hinged, and can be flipped up in its entirety. Due to the hinge factor, one would have to assume that it is not as durable in a crash as it would be if the chin bar was solid with the rest of the helmet. Nevertheless, it provides a viable compromise alternative with improved safety over the open-face design.
The half-shell helmet screams out: "I'm only wearing this because the law says I have to." It provides minimal coverage and protection, but in a crash it may be much better than no helmet at all. Besides, there are just some days when we want the wind in our face and a feeling of freedom during the ride. My assessment is that it feels great when I'm riding the backroads with minimal traffic. Since most collisions occur in town, I sometimes question my own judgment if I end up with only a half helmet in heavy traffic.