published helmet research - not troll

"Joe Riel" wrote in message

Frank Krygowski wrote:

Only in a very marginal way. They're designed to prevent a body-less
magnesium headform from exceeding 300 gees of linear acceleration in
a 2 meter drop, IIRC. That's the standard - nothing more than a 14
mph impact, and no provision for fighting rotational acceleration of
the brain.

Any idea what standard (max g's from some speed) motorcycle helmets
are designed to meet?

http://www.smf.org/articles/mcomp1.html

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On Sat, 19 Jun 2004 02:37:40 -0400, Frank Krygowski
wrote in message :

When the standard was first proposed, back in the mid-1970s, there were
serious reservations from the safety community. They felt the standard
was far too weak. But Snell, etc said it was all that was possible -
otherwise nobody would wear the helmet.

Now we're told this weak protection will save people from severe
injuries and trauma - 90+% of which is caused by crashes with cars. And
when data appears saying they don't work, people are surprised.

Er, up to a point. "This" standard is now replaced by new standards
which are substantially lower. Helmets certified to Snell B90 and B95
are very hard to find.

Guy
--
May contain traces of irony. Contents liable to settle after posting.
http://www.chapmancentral.co.uk

88% of helmet statistics are made up, 65% of them at Washington University

"Shayne Wissler" wrote in message news:TQJAc.135474$Ly.96010@attbi_s01...

I have an idea for an experiment. Go outside and have someone hold a brick
about 2 feet over your bare head and have him drop it. Observe the pain and
damage (assuming you're still conscious). Then try the same experiment on
your friend, but have him wear a cycling helmet. If he laughs at you, you
may be able to infer from this, experimentally, that he thought it was not
necessary to run the experiment to know that you would end up with a damaged
head and he wouldn't.

The description of the experiment provides insufficient information
for us to draw the conclusion you wish us to draw. The result we are
supposed to infer is by no means assured.

I speculate that in your example the brick is supposed to impact the
head "square on" resulting in (a direct) linear acceleration. These
are the type upon which helmet certification test procedures are
based. However bicycle accidents are not so simple and if your subject
was bending over with his head in a horizontal position and the brick
hits at a tangent to the surface of the head - mimicking more closely
a cycling accident - then it is likely to be subject to rotational
forces. Certification procedures do not address rotational forces even
though the latter are responsible for diffuse injuries, the most
deadly type. Three out of four brain injuries are of the diffuse type.
Since a helmet makes the "target" on top of a cyclist's shoulders
larger and heavier rotational effects may well be increased in other
than a "square on" impact. Tests with monkeys have shown that
rotational accelerations have much more serious consequences than
linear accelerations at the same level. In some cases linear
accelerations resulted in no injury where the same acceleration of a
rotational nature caused brain injury to the monkey.

Not everything is what it seems to be. A helmet may indeed not be so
good for your health.

DRS wrote:
"Joe Riel" wrote in message


Frank Krygowski wrote:


Only in a very marginal way. They're designed to prevent a body-less
magnesium headform from exceeding 300 gees of linear acceleration in
a 2 meter drop, IIRC. That's the standard - nothing more than a 14
mph impact, and no provision for fighting rotational acceleration of
the brain.

Any idea what standard (max g's from some speed) motorcycle helmets
are designed to meet?


http://www.smf.org/articles/mcomp1.html


Motorcycle helmets are actually about equivalent to bike helmets in
shock absorption. The bike helmet standard uses a 5 kg headform (that's
about 11 pounds) dropped from 2 meters. If the drop is completely
frictionless, that's 98 Joules.

Motorcycle helmets are much more resistant to penetration and abrasion,
and their smooth hard outer shell may be more slippery on the road,
leading to less rotational acceleration of the brain. But this last
point is speculation.

--
--------------------+
Frank Krygowski [To reply, remove rodent and vegetable dot com,
replace with cc.ysu dot edu]

Frank Krygowski wrote:
CowPunk wrote:


I'll bet you put globs of sunscreen on before you go out... don't you.


Well, not me. I seldom use the stuff.

Are we changing the subject??


No, just making the point that the guys not wearing helmets,
are probably smearing their bald heads with sunscreen.
Making them some of the biggest hypocrits around.

Mark & Steven Bornfeld DDS (both of them???) wrote:

Frank Krygowski wrote:


Do you understand that we're talking about multiple papers?

And do you understand that if the confounding factors all would tend
to decrease cyclist injuries, it's disingenuous to attribute all
reduced injuries to just one factor, the helmets?


I think it is disingenuous to say that all the other factors would
decrease cyclist injuries EXCEPT for the helmets!

The point is: If multiple measures are enacted simultaneously, the
proponents of one measure should not take credit for all the benefit.
Unless, that is, they prove conclusively that the other measures are
useless.

To my knowledge, nobody has proven that it's useless to enforce speed
limits and drunk driving laws.

Incidentally, the word "antihelmet" is rather imprecise.
"Anticompulsion" would be more accurate for many.
"Anti-over-promotion" would fit others. "Anti-fearmongering" still
others. But I must say, I can't recall anyone ever wanting to make
helmets illegal.

Of course, it may be that the Church of the Helmet requires absolute
belief in _all_ pro-helmet dogma. If so, then there really are lots
of anti-helmet people.

Oh, a libertarian. Never mind--this explains it.

Not even close.

Really, you ought to work on overcoming the simplistic labeling of others.





Oh, a dentist.

IOW, you know something about teeth. You know relatively little about
head trauma. I should have guessed.

Ad hominem. You have no idea what I know about head trauma.

I know that your residency didn't have you specializing in brain
injuries, and that you don't specialize in them now. From your
previous allusion to your residency, I thought otherwise. It's good to
clear that up.


You probably realize that nationally, cyclists are less than 1% of
that problem, right?

If it's you, you're 100% dead.

... and, apparently, you know relatively little about evaluating
relative risk.

I personally know several people (including myself) who have
suffered head injury of various degrees while cycling. In most of
these, there was no automobile involved.

That's not unlikely. You're corresponding with a guy who suffered a
head injury just a few years ago. In my case, it was related to boating.

Specifically, our canoe was hanging from our garage ceiling, and I
bumped my head on it. It hurt for several days any time I combed my
hair at that spot. And that illustrates some of the distortion that
creeps into these discussions. What, exactly, should we call a "head
injury"?

Remember that in their (in)famous 1989 paper, Thompson & Rivara
considered cut ears as "head injuries." Ditto for scratches on the
chin. Of course, a minor bruise on the scalp would qualify too -
although none of these comes close to being serious.

I hope you are lucky enough to have escaped serious injury, and that
your loved ones do the same.

Like the vast, overwhelming majority of cyclists throughout history,
I've escaped serious injury perfectly, both as an adult (30+ years) or
as a kid (about 20 years). The same is true of my wife, and our
now-grown kids.

And until helmets became a commercial item, this was known to be normal.
Now we're faced with fear mongering.


--
--------------------+
Frank Krygowski [To reply, remove rodent and vegetable dot com,
replace with cc.ysu dot edu]

Mark & Steven Bornfeld DDS wrote:


Krygowski (and perhaps you) can probably name some safety measures
that you would acknowledge will decrease death and morbidity from
bicycle accidents. Are there any that you would mandate? Or is this
more about personal freedom than safety?

Personally, I heartily agree with many already-mandated safety measures.
Examples are obedience to traffic signs and signals. Respecting right
of way, and other similar traffic laws. Use of lights at night.

There are some I disagree with. For example, many states require a
bicycle bell. To me, this is senseless - it adds nothing practical to
safety.

IOW, it's a mistake to paint me as a libertarian, as you did in another
post.

Having said that, I _do_ think personal freedom is very important. If
you disagree, post your diet for the past month, and we'll get started
on what, and how much, you should be allowed to eat!


--
--------------------+
Frank Krygowski [To reply, remove rodent and vegetable dot com,
replace with cc.ysu dot edu]

On Fri, 18 Jun 2004 22:16:19 GMT, "Shayne Wissler"
wrote in message
TQJAc.135474$Ly.96010@attbi_s01:

I have an idea for an experiment. Go outside and have someone hold a brick
about 2 feet over your bare head and have him drop it. Observe the pain and
damage (assuming you're still conscious). Then try the same experiment on
your friend, but have him wear a cycling helmet.

Why would I do that? Helmeted cyclists are more likely to hit their
heads than non-helmeted cyclists, so the proper experiment would be to
drop the brick on the helmeted head (hoping it gets the helemt and not
the face), but not to drop a brick at all on the unhelmeted.

Guy
--
May contain traces of irony. Contents liable to settle after posting.
http://www.chapmancentral.co.uk

88% of helmet statistics are made up, 65% of them at Washington University

On Sat, 19 Jun 2004 13:37:49 -0600, Abe Oogerfart
wrote in message
:

No, just making the point that the guys not wearing helmets,
are probably smearing their bald heads with sunscreen.
Making them some of the biggest hypocrits around.

I guess we're lucky in the UK; we can get cotton hats which are light
and comfortable, don't boil your brain like a plastic prophylactic,
and keep the sun off.

And I'm doubly lucky, what with not being bald and all.

Guy
--
May contain traces of irony. Contents liable to settle after posting.
http://www.chapmancentral.co.uk

88% of helmet statistics are made up, 65% of them at Washington University

Frank Krygowski wrote:
DRS wrote:

"Joe Riel" wrote in message


Frank Krygowski wrote:
Only in a very marginal way. They're designed to prevent a body-less
magnesium headform from exceeding 300 gees of linear acceleration in
a 2 meter drop, IIRC. That's the standard - nothing more than a 14
mph impact, and no provision for fighting rotational acceleration of
the brain.


Any idea what standard (max g's from some speed) motorcycle helmets
are designed to meet?



http://www.smf.org/articles/mcomp1.html


Motorcycle helmets are actually about equivalent to bike helmets in
shock absorption. The bike helmet standard uses a 5 kg headform (that's
about 11 pounds) dropped from 2 meters. If the drop is completely
frictionless, that's 98 Joules.

I assumed that they would be close, given that their thickness of foam
is comparable. The above site looks like it has a misprint; the
DOT FMVSS 218 drop onto a flat anvil gives a nominal fall of 1.83
meters, while the drop onto a hemispherical anvil gives the drop at
1.38meters. It seems likely that one of these (probably the second)
has digits transposed.

Joe Riel