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Helmet Technology 101

Snell Foundation

Okay time for a refresher of Helmet Technology 101:

A motorcycle helmet is a Protection System, okay and there's basically three important parts in that system:

1. The Outer Shell - as the first line of defense, the outer shell spreads the impact force over a greater area by flexing and deforming (but does nothing to attenuate the level of impact force), and provides protection to the inner shell from abrasion and puncture.

2. the inner shell - this is the second and most important line of defense, and is a thick layer of Expanded Polystyrene (EPS) Foam (very much like the kiddy surfboards, or two-dollar coolers you can by next to the ice at the supermarket) the job of the EPS foam is to crush, attenuating the impact force by spreading the impact event out over a longer period of time.

No.2 is why, after a crash or fall where the helmet gets a good clout, the helmet should be replaced, because one the EPS crushes it's used up. No.2 is ALSO why novely helmets are no protection at all, because they are comprised of the shell, and, at most, soft upholstery foam and a liner. novelty lids have no ability to attenuate the accelerations involved in inpacts, and those accelerations are what cause injuries to the brain.

if you are wearing a novelty, lid, and fall off, your risk of traumatic head injury is completely dependant on the physics of the fall. The BEST a novelty can do is protect your scalp from abrasion. Whatever impact force your head receives in the fall will be directly transmitted to your skull, and then your brain, full force with no attenuation whatsoever.

3. the attachement straps: helemts can't protect if they fall off.

I respectfully submit that 3/4s and full coverage lids don't limit hearing as much as many
(who've never or seldom worn them) claim that they do. I own 5 lids: 2 fulls, 1 3/4, ad 2 halfsies, and by FAR the loudest are the halfsies - due to wind roar - once you're up above 35 mph. I won't wear them on the highway. The fulls and 3/4 attenutate the wind roar enough that other sounds are more easily heard.

I have heard many state here, and on other discussion boards that "Helemets are only tested to 12 MPH, so they're not going to protect you above that speed anyway." this is wrong. UNLESS your accident involves directly centerpunching some hard object horizontally (bridge abutment, culvert, other and bigger vehicle) without any slowing down at all due to sliding bouncing rolling etc (uinder which circumstnaces you are at far higher risk of greivous internal injuries far beyond a simple head trauma) you're going to hit the ground, and the force of that impact is dependant how high you fall from, regardless of what your forward speed may be. (we're talkin' High School physics here folks)

At this point, I'm direct you to the Snell Foundation online site, where they have an excellent explanation of accident modelling, testing methods and the physics of impacts and resultant impact acceleration. Their explanations are beter than I could do here. GO read it. Suffice to say, novelties are good for two things;

1. giving yourself an excellent case of Helmet Hair and,

2. ummm, not much else.

BTW I have read the "Motorcycle Helmets are NOT safe!" essay by Steve "Red" Barron from ABATE of Californa... hmmm. He's right about the physics, but wrong about the methodology, and his logic is faulty. For those who would continue to NOT wear a decent lid, all I can say is, "Remember CHEECH". Cheech was a member of the Original Intruder Alert Cafe, who was SERIOUSLY Injured & NOT wearing a helmet

RC23 was a Member of the Cafe


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