From the GWRRA Texas Chapter M-2 Education Corner

New Insights into Helmet Safety

Turns out there’s way more to helmet safety than I thought. We’ve been riding for over 30 years, and have been with GWRRA for ten, so I figured I was pretty well up to speed on the ins and outs of helmet safety. You know, DoT standards (the government specs) the Snell Foundation (private testing and stricter standards), replace your helmet if you drop it hard, get a new one after five (or was it seven?) years, yada yada.

Then I read an article from Motorcyclist On Line. (Thanks to Jackie Vaughan for forwarding.) Twenty seven pages later, I had a whole new perspective on helmet standards. Originally published in Motorcyclist in 2005 and written by Dexter Ford, the article describes a year’s worth of research and testing performed by Ford and his colleagues. Happily for you, dear reader, I’m not transcribing all 27 pages in our newsletter. I am going to attempt to digest Ford’s work and his conclusions in two articles, this month and next. This month: how helmets work and how standards are established. Next month: the results of Ford’s testing.

How good is your helmet anyway? This most important piece of safety equipment is certified by government and private test standards to protect our heads (and thus, our brains) from injury in a crash. What do those standards mean, anyway? And just how strong does a helmet need to be? A helmet must not stop your head abruptly, allowing your brain to slam to a stop inside your skull. An effective helmet has a cushioning effect, which absorbs energy and slows your head to a stop, thus protecting your brain. That’s why the insides are made of polystyrene (think Styrofoam) which is designed to collapse in an accident, acting as a cushion. Quoting Ford, “the perfect helmet would have 6 inches or more of soft, fluffy material cradling your precious head like a mint on a pillow.” Perfect if you want to look like the guy in the Jack in the Box commercial. Instead, helmets are designed to balance form and function and it turns out to be an inexact science.

The Department of Transportation and the Snell Foundation use G forces to measure helmet performance. That is, how many times the force of gravity the helmet transmits to your head. Two G’s are a force equal to double the force of gravity.

In testing, helmets are weighted with a form inside them, and then dropped onto test anvils, or struck with a round steel object. Snell uses the most aggressive test: a double-strike to the same place on the helmet. Lower scores are better – you want your helmet transmitting the fewest number of G’s possible. Tough tests like these have driven helmet development over the years.

The medical community has some standards around how many G’s your head will tolerate, but there is not universal agreement. One scale says under 200 G’s transmitted results in little to no long term injury to the rider’s brain; 200 to 250 G’s results in “diffuse brain injury” and 250 to 300 G’s results in serious injuries. Others take a “threshold” approach, and believe that under 300 G’s does not result in serious injury. (These are very general guides since size and shape and health of the victims play a big role – your mileage may vary.) One thing that everyone agrees on: fewer transmitted G’s are better.

It’s these head injury standards versus the test design that’s caused the recent debate. The very aggressive test methods used by Snell have caused helmets to be designed more rigidly, in order to obtain the coveted Snell certification. (The conventional wisdom declaring that the more aggressive testing produces a better helmet.) But the aggressive double-strike test permits a helmet to transmit up to 300 G’s.

Do you need a helmet that survives an aggressive double-strike test? The Hurt report, published in the early 1980’s assessed causes and results of motorcycle accidents. So did subsequent testing in Europe. They suggest that the double-strike test is not a good measure of a typical accident. Two categories of accidents make up the majority: first, relatively low speed collisions with cars, and second, higher speed single-bike accidents where bike and rider leave the road (as in a curve.) The high-speed, high impact crash is more rare.

One one side of the debate: those who believe the “softer” DoT certified helmets are more effective in “normal” crashes. On the other side: those who believe the Snell standard is important in protecting against a very high energy impact, such as a direct head impact at high speed.

Nancy Kwiecien
GWRRA Spring, Texas Chapter M-2 Chapter Educator

Next month: results of Ford’s own independent testing.