Sep 29, 2009

Snell Loyalty

People are loyal to the oddest things. For a couple of decades scientists and testing engineers have questioned the Snell standards. A key part of Snell's standards is the dual impact (same location) test and the 300g internal impact allowance. Those two bits mean that the helmet must be harder (less able to spread impact) both on the shell and in the internal impact liner. A while back, Motorcyclist magazine did some of their own testing and cast some aspersions on the Snell standard. More recently, the New York Times published a piece called Sorting Out Differences in Helmet Standards.

I'm not here to argue the standards. I read the Motorcyclist article and was impressed with the authors' thoroughness. At the time, I'd traded my comfortable old (highly damaged) Shoei X11 (a Snell helmet) for a brand new non-Snell HJC CL-15. The new HJC was the first non-Shoei, non-Snell helmet I'd owned since the early 1980s. That first HJC was the first of three HJC helmets that I've owned since. While my Shoei's have saved my bean from several scrapes, nothing about the crashes I've experienced have tested Snell's extreme standards. I'm, apparently, inclined to get off at 20-50mph, on dirt trails and deep gravel or sand, and I have yet to land on top of my head. I have scraped the paint off of the side of my full-face helmets and gouged the snot out of the faceshields.

On a MN motorcycle chat site, the responses to the NYT article went like this:
  • "The advantage in my eyes to a Snell rating is that I know the helmet's been validated to the guideline. "
  • "Until the standards are re-written its just a holy war and I'll continue to wear my RF1000 helmet replete with 05 Snell standards. "
  • "My helemts [sic] (full face always) have always been snell rated, but I am an Arai loyalist and they don't make anything less than snell rated--and honestly--I wouldnt want it any other way."
  • "Usually the NYT limits its coverage to political and scientific thingsthat they don't understand. Now they've added international standards setting to the stew."
I think it's interesting that a testing lab can generate so much customer loyalty, even with other testing labs, scientists, and engineers disagree with those results. No, I don't know what that means. Yes, I'd love to hear your opinions.

2 comments:

  1. I remember that back when Steve Anderson was working in accident reconstruction, he told me about a type of minivan accident. When a stream of cars suddenly had to stop, the front of the minivan hitting the car ahead would trigger the bomb ballon just as a car hitting the rear caused all the rear door pins to pop out and the door to open as the colliding vehicles recoiled. The bomb balloon would then blow any babies or toddlers in right-hand front seat position out the back of the vehicle to their deaths. He had seen documentation on 17 such "baby-cannon" accidents in the US.

    I take this as an example of how even the most-carefully-thought-out safety standard can result in unforeseen difficulties. The perfect-safety nuts expect their immortality and that of their offspring to be legislated by Congress but it cannot be so.

    Right now they are hard at work on staggered-ignition bomb balloons for the sides of driver and passenger - a soft delayed upper and a firmer, prompt lower. Jist tell us what you wants, boss - we'm put 800 engineers on it right away!

    KC

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  2. To me it seems pretty obvious that a "softer" shell would absorb more impact force without transmitting that force to the skull below. The Snell standard requires helmets to resist point-source impacts better, but those are apparently rather rare in real-world crashes. It's why modern cars are designed to crumple up like beer cans in a crash--they absorb the impact instead of transmitting it to the occupants. What I'd like to see are tests indicating if weight is a factor--it seems that lighter helmets would help reduce the overall impact force. I wonder if we'd actually be safer wearing bicycle helmets!

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