Friday, February 5, 2010

Beanies And Bullshit: Just One Of The Things The Anti-Helmet Guys Don't Want You To Know

It’s my own fault, really, for signing up for all those Google news alerts. A couple of the ones I get regularly are about helmets, and this evening I made the mistake of following a link to a site full of misinformation, half-truths, unsubstantiated claims, and just plain muddled thinking about helmets and why no one should be forced to wear one. And then I got my rant on.

If pinned down for an unequivocal yes or no on the issue, I'd have to say that if you don’t want to wear a helmet, you shouldn’t have to. I take that position for purely selfish reasons; a few of my hobbies are, shall we say, potentially hazardous to my continued health and well-being, and I don’t want them to be outlawed by politicians and/or insurance companies citing the social-burden argument, which says the societal costs of an inherently dangerous activity like motorcycling (or shooting, or rock climbing, or skiing) outweigh the right of people to indulge in them.

But anti-helmet-law advocates too often take their argument a crucial step beyond the rights issue, and insist that helmets don’t increase your chances of surviving a crash—in short, that they don’t work. And that's where it goes off the rails.

The statistic these guys are most fond of bleating about is one that even the staunchest helmet advocates don't dispute: a motorcycle helmet isn’t designed to protect you from an impact at speeds much above 13 mph. The problem with that argument is it assumes the 13 mph figure applies to the speed the bike is going when you fall off. It doesn’t.

Some years ago I spoke to Dave Thom, who worked alongside the late, great Harry Hurt on the Hurt Report, which is to date still the most comprehensive, credible, and scientifically valid peer-reviewed study of the causes of motorcycle accidents (summary of the Hurt Report here). Thom knows his stuff. He's been a motorcycle-accident research assistant and associate (1977-1981), a research associate and later the laboratory director of University of Southern California’s Head Protection Research Laboratory (1981-1998), and the general and senior program manager of the Head Protection Research Laboratory of Southern California (1998-2003). He’s currently a senior consultant specializing in protective headgear, safety, and research at Collision and Injury Dynamics, Inc.

In short, Thom knows a lot more about helmets and motorcycle accidents than some guy from ABATE named Road Dog or Spider or Poochy.

First, I asked Thom about the 13 mph figure.

“It’s an important and often misunderstood point,” he said. He explained that 13 mph—13.4 mph, to be precise—was 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.”

But what about the speed the bike is traveling? I asked. What effect does that have on the speed at which the rider’s head hits the ground?

“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 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.”

If you need further proof that the bike’s forward, or horizontal, velocity is far less important than the vertical velocity of the rider’s head, said Thom, go to a motorcycle 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, which is what we test helmets at.”

Once you understand the bike’s forward velocity is nowhere near as important as the speed at which the rider’s head hits the ground, the argument that helmets don’t work because they aren’t designed to protect you at speeds higher than 13 mph loses virtually all of its weight.

And yet you’ll see that argument put forward in most anti-helmet-law rants. The actual information is there for anyone to find, if they just look for it. But the anti-helmet faction doesn’t want to look for it, and they don’t want you hear about it, because it leaves them with one less bullet in their ammo belt in their fight against helmet laws.

As I said above, if you don’t want to wear a helmet, don’t. If you’re above the age of consent, it’s up to you. But there’s a difference between consent and informed consent. Some people don’t know the facts; others don’t want to know them. And that’s the difference between ignorance and stupidity.

1 comment:

ProCycle said...

I read a quote the other day. "If you think you shouldn't wear a helmet you probably don't need one".