helmets

An interesting article on how helmets work, and some info about the
various standards.

http://www.motorcyclistonline.com/gearbox/motorcycle_helmet_review/index.html

The big question... how do well do the standard tests replicate what's
going to happen to your head if you are silly enough to headbutt the
scenery when you fight the laws of physics and the laws win?

Zebee

 

head will remain intact but neck will snap like a twig.

 

In aus.motorcycles on Thu, 29 Jan 2009 20:10:07 +1100

from the article:

In the case of fatal accidents, there was one more important
discovery in the Hurt Report: There were essentially no deaths to
helmeted riders from head injuries alone.

Some people in the study, those involved in truly awful,
bone-crushing, aorta-popping crashes, did sustain potentially fatal
head injuries even though they were wearing helmets. The problem was
that they also had, on average, three other injuries that would have
killed them if the head injury hadn't.

In other words, a crash violent enough to overwhelm any decent helmet
will usually destroy the rest of the body as well. Newman put this
into perspective. "In most cases, bottoming [compressing a helmet's
EPS completely] is not going to occur except in really violent
accidents. And in these kind of cases, one might legitimately wonder
whether there is anything you could do."

How many people were saved because their helmet was designed to a
"higher" or "higher energy" standard than the DOT standard? As far as
the Hurt researchers could ascertain, none.

[...]

In other words, the latest relevant study, which used state-of-the-art
methods and covered accidents in countries where there are plenty of
10-second, 160-mph superbikes running around, concluded that current
standards - even the relatively soft[1] ECE standards - are allowing
riders' heads to be routinely subjected to forces that can severely
injure or kill them.

[1] "soft" meaning they allow fewer Gs than Snell because they focus
on that rather than on penetration and impact resistance - ZJ

Moral of the story? Rubber side down is better than all the
alternatives.

Zebee

 

Still reading but it's quite thought provoking.

 

In Oz though, providing you are being legal you don't have that many
standards to choose from, do you ? I did like the 'ranty' response from
Snell which really had little humour in it apart from the garlic
reference. I can see how they felt snubbed but the testing and
methodology to me, at least, made a good deal of sense.

 

In aus.motorcycles on Thu, 29 Jan 2009 21:11:29 +1100

You get Snell on some helmets, else you get AS1698.

I'm trying to get info on the G requiremenst for AS1698.

Zebee

 

In aus.motorcycles on 29 Jan 2009 10:24:36 GMT

And straight from the tester (Derek Wainohu who does the testing for
1698)

AS/NZS1698:2006 consists of the following;

Internal projections; no greater than 5mm but any greater than 2mm
require testing
External projections; no greater than 5mm
At least six helmets of the same size shall be submitted for testing
ISO Headforms are required

Testing sequence:
Peripheral vision not less than 105 degrees
Helmet stability (dynamic) not rotate more then 30 degrees
Impact energy attenuation not to exceed 300g
Resistance to penetration no contact of the striker with the
headform
Strength of retention (static) not to exceed 25mm

so 1698 allows the same Gs as Snell (300) and more than DOT (250) or
ECE (slightly higher than DOT but the article doesn't give a number
that I found).

So everything you buy with a 1698 sticker will transmit *less* than
300 to your bonce, but no way to know how much less.

I'm asking Derek for more info, so stay tuned.

Zebee

 

That's 300g in what size area?
e.g. 300g in 0.001sq mm will pierce the skull.

Am I being silly?


=================

Onya bike

Gerry

 

In aus.motorcycles on 30 Jan 2009 00:36:57 GMT

1.8m Flat anvil
1.38m Hemispherical anvil

2 impacts on each test site

Helmets perform better than the 300g

So similar idea to Snell, but 6 foot and 4 foot drops rather than 10
foot and 7 foot.

Zebee

 

In aus.motorcycles on Fri, 30 Jan 2009 11:40:39 +1100

yes

It's either a flat anvil that's bigger than the helmet curvature, or a
round one. Don't know the size, but I bet it's tennis ball or bigger.

Zebee

 

Oh.... Alright...

=================

Onya bike

Gerry

 

Sounds fair enough to me. But now this raises the question (for me,
anyway) What does 'Impact energy attenuation not to exceed 300g'
actually mean?"


=================

Onya bike

Gerry

 

I did read that bit of the standard, and it did use a lower case 'g'.
That said, I agree with your interpretation. (Actually, IIRC, I don't
need to rely on your interpretation. Somewhere near where it said
'300g', it defined 'g' as being a unit of accelleration of 9.8m/s/s)

So yeah, what Big said, AND what Gerry said.


GB

 

I read it as 300G too, but the argument is still valid. 300G over a
small point is more likely to pierce the helmet than a larger impact
area. But as that great bloke Zebee posted, the impact tests due you
larger impact devices.

 

Head cant survive with out a body to support it though, well not for
long anyway. i think any impact strong enough to destroy a helmet, the
rest of the body wont survive anyway.

 

In aus.motorcycles on Mon, 02 Feb 2009 16:12:18 +1100

read the article that I pointed to at the beginning of this thread.
It is explained there.

Zebee