Join Date: Nov 2004
Sorting Out Differences in Helmet Standards
THE surest way for motorcycle riders to avoid joining the rapidly growing ranks of fatality statistics — up 144 percent since 1997, according to the National Highway Traffic Safety Administration — is to wear proper head protection. A helmet increases the chances of survival in an accident by 37 percent, the safety agency says.
Picking the helmet that provides ideal protection is not easy, however. While all helmets sold for road use in the United States are required to carry the stamp of a federal safety standard established by the Transportation Department, riders may also find an independent certification label, from the Snell Memorial Foundation, on many helmets they are considering.
The certification by Snell, a nonprofit research and testing organization financed by helmet makers, is not mandatory for road use but it is for some racing series, which can lead consumers to assume that a Snell-compliant helmet is safer — an assumption that is not agreed upon by researchers.
Even knowing the differences between the standards is not enough: on Oct. 1, helmets meeting a new Snell test, M2010, with revised force limits, can go on sale, probably adding to the confusion among helmet shoppers.
The debate in the helmet industry and the scientific community about just what constitute the best design criteria for a motorcycle helmet — especially for riders with smaller heads — has been going on for years.
The conflict is between scientists and helmet designers who prefer the government-mandated helmet standards of the United States and Europe, up against the current Snell standard, called M2005, which Snell says provides “premium levels of protective performance.”
Many head-injury scientists, motorcycle-accident researchers and helmet makers say they are concerned that the “premium protection" proffered by current Snell-certified helmets may not be better after all. They argue that current Snell-rated helmets are too rigid and unyielding to properly absorb impact energy in the great majority of motorcycle crashes, subjecting riders to preventable brain injuries.
Why is this a concern, considering that the new M2010 standard — a major revision that addresses some of the objections scientists and helmet makers have raised for decades — is coming next week? It stems from the fact that the Snell Foundation will continue to certify helmets made under the Snell M2005 standard until March 31, 2012. There are now hundreds of thousands of pre-M2010 Snell helmets on rider’s heads, in garages and on retailer’s shelves, and hundreds of thousands more that will be made in coming years — which means that riders, especially those with smaller heads, will have to pay close attention when buying a helmet.
In one test the Snell M2005 standard requires each helmet to withstand two successive impacts against an orange-sized steel hemisphere without subjecting the aluminum “headform” inside to more than 300 times the force of gravity, or 300 g’s.
Hugh H. Hurt, a researcher who developed the Head Protection Research Laboratory at the University of Southern California, and author of the Hurt Report, a seminal study of motorcycle crashes, calls the current Snell M2005 standard “a little bit excessive.”
“What should the limit on helmets be?” Mr. Hurt asks, referring the g-force levels. “They should be softer, softer, softer. Because people are wearing these so-called high performance helmets and are getting diffuse brain injuries — well, they’re screwed up for life. Taking 300 g’s is not a safe thing.”
James A. Newman, a former director of the Snell Memorial Foundation, considers the Snell tests obsolete. “If you want to create a realistic helmet standard, you don’t go bashing helmets onto hemispherical steel balls. And you certainly don’t do it twice,” he said.
Mr. Newman has estimated an impact of 200 to 250 g’s to the head corresponds to a severe brain injury, that a 250 to 300g impact corresponds to a critical injury, and that a hit over 300 g’s is often not survivable.
“Over the last 30 years,” Mr. Newman said, “we’ve come to the realization that people falling off motorcycles hardly ever, ever hit their head in the same place twice. So we have helmets that are designed to withstand two hits at the same site. But in doing so, we have severely, severely compromised their ability to take one hit and absorb energy properly.”
Scientists and helmet makers have also objected to the Snell M2005 standard’s requirement for impact-testing all helmets with a headform of the same weight, regardless of the helmet’s size. Even Ed Becker, executive director of the Snell Foundation and its most outspoken defender, agrees that the weight of a wearer’s head is of great significance in helmet design. “These headform issues of mass and geometry are crucial. The mass determines the total momentum that must be exchanged in an impact.” The mandatory Transportation Department, or D.O.T., standard has dictated graduated-weight headforms since 1988, forcing makers to tailor the impact-absorption qualities of a smaller helmet to the lower levels of inertia produced by a smaller head. The European standard, mandatory in Europe, Britain and a total of over 50 countries, has required graduated-weight headforms since 1983.
David R. Thom, a respected helmet-testing scientist who operates Collision and Injury Dynamics in El Segundo, Calif., said of Snell’s one-weight-fits-all approach: “They are not in touch with reality.”
The standards disagreement has prompted some riders and racers to choose helmets that do not carry the Snell certification label — even though the most expensive and respected helmet brands available in the United States are predominantly Snell-certified. It has also inspired some helmet manufacturers, especially European makers, to forgo Snell, preferring to build their helmets to what they consider the more-appropriate American and United Nations ECE 22-05 standards.
In one comprehensive study of real-world impact performance based on research done for Motorcyclist Magazine, presented by Mr. Thom to the Motorcycle Safety Foundation, a $79.95 helmet certified to Transportation Department standards performed the best of the 32 tested, withstanding the most violent hits while transmitting as much as 67 g’s less impact force to the headform than a $400 Snell-certified helmet.
The M2010 Snell standard will drop its maximum allowable g’s from 300 to 275. It will also adopt graduated-weight headforms.
According to Mr. Becker, the M2010 standard was designed in consultation with helmet manufacturers, to allow a single helmet design to pass all the world’s major standards. As it stands now, a Snell M2005-certified helmet may also pass the D.O.T. standard, but is unlikely to pass the ECE 22-05 standard used in European countries. Manufacturers must re-engineer their Snell M2005-rated helmets, making them “softer” in order to sell them in Europe.
So Snell M2010 helmets will, according to Snell, fall in line with both the D.O.T. and ECE 22-05 standards. As of now, no manufacturer has announced to market helmets that meet both Snell M2010 and the European standard.
It’s difficult to tell a Snell M2010 helmet from the outside; the label on the back of most helmets simply says Snell. But deep inside, stuck somewhere on the inner foam liner, should be a detailed Snell sticker that will reveal the specific Snell rating.
Of course, a rider can also do what some outspoken scientists have recommended for years: simply choose a non-Snell-rated helmet.