A guy who once told me motorcycle helmets are tested to a maximum speed of 13 mph, so how can you expect them to protect you at highway speeds? Is this true?
YES......But, it’s not the whole story. For that I turned to Dave Thom, who worked with the late, great Harry Hurt on the first comprehensive study of motorcycle safety ever conducted in the U.S., Motorcycle Accident Cause Factors and Identification of Countermeasures, often appropriately called the Hurt Report.
Thom’s CV is impressive: motorcycle-accident research assistant and associate (1977-1981); research associate and later the laboratory director of the University of Southern California’s Head Protection Research Laboratory (1981-1998); general and senior program manager of the Head Protection Research Laboratory of Southern California (1998-2003); and currently a senior consultant specializing in protective headgear, safety, and research at Collision and Injury Dynamics, Inc. So, yeah, he knows something about helmets.
I once asked Thom about that 13 mph figure. “It’s an important and often misunderstood point,” he said. It turns out that 13 mph—13.4 mph, if you want to get picky about it––is the terminal velocity of an object dropped from six feet, or about the maximum height of the head of a rider seated on a motorcycle. “If you pick something up and drop it from six feet, it’ll hit the ground going 13.4 mph.”
OK, but what if I’m going 60 mph when I crash?
“The speed on your speedometer is very seldom any indication of how hard you’re going to hit your head,” Thom said. “The only situation where it is an indication is if you hit a vertical object, like a bridge abutment. Then your speedometer speed is very important.” But in most motorcycle accidents, the rider’s head falls more or less straight down and hits the ground at 13.4 mph or less. “We found way back in the Hurt studies that the typical impact on a head at the 90th percentile was less than the DOT impact speed of 13.4 mph.”
In other words, the vertical speed at which your head hits the pavement matters far more than the horizontal speed you’re moving when it happens. If you want a demonstration of this, Thom said, just turn on your TV and watch a motorcycle road race. “If you’ve ever seen a guy fall off at 120, they almost always get up even though their forward speed was huge. They fall off, and they very likely hit their head at least once, but they have that six-foot fall––“ much less in the case of many road racers whose elbows are practically skimming the track when they bail “––which is what we test helmets at.”
No safety device works 100 percent of the time––not helmets, air bags, seat belts, parachutes, or condoms––but using them increases the odds in your favor. If you disagree, fine. It’s that sort of keen analytical thinking that keep Las Vegas casinos open, and EMTs working double shifts on sunny weekends. Just don’t try to convince me or anyone else that head-butting the highway without a helmet is safer than with one.