That is to say, nonexistent.
Some of us already knew some of the information in this video, but no matter who you are or how long you’ve been riding, this is great information to have. FortNine strikes another one out of the park.
Forewarned is forearmed, as they say, so read through this and watch the video, get curious, and before the next time you go helmet shopping you should know all about the safety certifications on helmets. It’s good to know not just what they mean but where the numbers and testing methods come from and how the regulatory agencies came to settle on those numbers and testing methods (or lack thereof).
Specifically, what do DOT ratings on helmets mean? This video goes into all of the numbers. Just like an “LD50” rating on a potentially toxic substance, many studies found a 50 percent possibility of skull fracture at 290G’s of peak acceleration. Trouble is, though, that the studies the DOT bases their ratings on are between twenty and forty years old, and they have left a helmet’s failure criteria at 400G’s of peak acceleration.
A Snell helmet certification means the helmet fails if it allows the “head” to experience 300G’s of peak acceleration. Further, however, the Snell foundation tests a rotational load on helmets to see if, when properly secured, the helmet is able to roll off the head form. The foundation also tests the retention system (straps) for failure, and also the chin bar to be sure it does not collapse into a rider’s face. The shell of the helmet and the shield (or visor) are both tested for penetration, and the entire helmet is also exposed to a flame resistance test.
I could tell you all about how these tests differ from DOT testing, if DOT tested helmets. That’s the rub, folks: DOT does not do any testing. The Department leaves it up to the manufacturers to do their own testing and certify to the DOT that they have tested up to certain standards and that their helmets pass.
The fox insists the hen house is secure, everyone: he’s tested it.
The real lesson here is, buyer beware. Protect your noggin with a decent helmet made by a respected manufacturer. A cheap helmet, even with a DOT rating, could have a dangerously shatter-prone visor, or weak spots, or a chinbar that will collapse on impact with anything. Yikes.