published helmet research - not troll

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

"R15757" wrote

I think the CPSC which runs the tests and provides the stickers also drops
the
headform onto a sharp curb-like edge to simulate a fall at 11 mph. 300g!
Ouch.

Actually, the manufacturers and importers run *their own* tests. And print
and apply *their own* labels.

From the CPSC regulation:
http://www.bhsi.org/cpscfinl.htm and
http://www.cpsc.gov/businfo/regsumbicyclehelmets.pdf (plain English summary)

"Sec. 1203.33 Certification testing.

(a) General. Manufacturers, as defined in Sec. 1203.32(b) to
include importers, shall conduct a reasonable testing program to
demonstrate that their bicycle helmets comply with the requirements of
the standard.

(1) Within the requirements set forth in this paragraph (b),
manufacturers and importers may define their own reasonable testing
programs. Reasonable testing programs may, at the option of
manufacturers and importers, be conducted by an independent third party
qualified to perform such testing programs. However, manufacturers and
importers are responsible for ensuring compliance with all requirements
of the standard in subpart A of this part.

-----------------

Sec. 1203.34 Product certification and labeling by manufacturers
(including importers).

(a) Form of permanent label of certification. Manufacturers, as
defined in Sec. 1203.32(a), shall issue certificates of compliance for
bicycle helmets manufactured after March 11, 1999, in the form of a
durable, legible, and readily visible label meeting the requirements of
this section. This label is the helmet's certificate of compliance, as
that term is used in section 14 of the CPSA, 15 U.S.C. 2063."

The CPSC defines the test standard, it is up to the manufacturer or importer
to conducts the test, and certify a particular model and lot.
I believe the CPSC can check their testing procedures, but it does not
appear that they are required to do so.

And we all know how scrupulous corporations are about complying with
government regulations.

Pete

S o r n i wrote:
Mark & Steven Bornfeld DDS wrote:

JT, I'm really flattered that you consider me a master of

anything--that's high praise indeed!


Hard to consider your positions when you can't even fix your user name.

Bill "multiple personalities? OK then" S.

Name's Steve Bornfeld. I sometimes post from my home computer, and
sometimes at the office.

Steve

Just zis Guy, you know? wrote:
On Sat, 19 Jun 2004 10:59:23 -0400, Mark & Steven Bornfeld DDS
wrote in message
:


I posted the link of a review of
previously published clinical studies.


That'll be where you went wrong, then. Epidemiological studies based
on whole population data (including series where there are substantial
step-changes in helmet use over very short periods, like in Australia)
show no discernible benefit. Small-scale prospective studies show
benefit, but often fall apart under investigation due to basic errors.
Injury Prevention has just published a critique of one such paper by
Cook & Sheikh; they mistook percentages for percentage points (a
fairly basic statistical error) - if you correct this they are saying
that helmets are 186% effective, with every helmet protecting not only
its wearer but somebody else as well - this clearly demonstrates that
there are major confounding factors in the data for which they have
not accounted.

Let me see if I get this straight. All the studies showing a benefit
have fatal flaws; all the studies that show no benefit are well-designed.
The studies I saw cited are all retrospective studies. I believe it is
possible that somewhere a paper may have been published that confuses
percentages for percentage points. It is hard to believe this happened
multiple times in referreed journals.
Let me be clear--I am not an expert in safety data nor in epidemiology.
But I am up to my eyeballs in newsgroup pundits (in unrelated fields)
making patently ridiculous claims about the body of evidence in fields
in which I do have expertise. It is impossible for me to evaluate
helmet data for myself, nor have I found it prudent to believe folks
such as yourself who may very well have that expertise.
One hopes that people in position of authority choose carefully in whom
they listen to when policy is made.


Many of the clinical papers are actually just literature reviews, with
remarkably few actual studies, of which the best-known is Thompson,
Rivara and Thompson's 1989 paper in the New England Journal of
Medicine. The flaws in that study are well-documented (it arrives at
a figure of 85% effectiveness by comparing poor solo urban street
cyclists with middle-class families on bike paths and attributes the
entire difference in injury rates to differences in helmet use).

See, I'm going to have to look up that paper. It is very, very
difficult for me to believe that NEJM would publish a paper with a flaw
that blatant.

It
is still quoted as gospel by almost every "new" paper and literature
review, and I have only once or twice seen any explicit mention of the
known flaws in the study. In fact, if you replace the "control" group
with Rivara's own street counts from the previous year, the supposed
benefit vanishes. BHSI still quote it, despite knowing that it is
wrong, because the figure is "so ingrained in the injury prevention
community" that to use another figure would be "unhelpful". Unhelpful
to whom? Those seeking to make the case for compulsion? Or those
seeking to form a balanced judgement based on theevidence?

By the way, according to BHSI this thread is not happening ;-)


The fact that head injury rates have risen by 40% in the USA in a
period when helmet use rose from 18% to 50% surely tells us something.


Are we talking about cycling head injuries, or total head injuries?


As does the fact that the pro-helmet British government has admitted
that it knows of no case where cyclist safety has improved with
increasing helmet use.


I'd love to hear some context.



It is certainly understandable to me that racers who'd become
accustomed to the wind in their hair would object to the "intrusion" of
the insurance companies. Certainly there had been no studies back then
demonstrating the uselessness of helmets in preventing serious injuries,
but those I spoke to (some of whom you undoubtedly know personally) were
just as opposed to mandated helmets as you are now.


That was not, in my opinion, an actuarial judgement; there was not
enough data to go on at the time. Quite why a device designed for a
crash at around 12mph should be mandated for racing is an interesting
philosophical question.

Actually in this area you have a point. It was a decision made for the
USCF by whichever insurance carrier was willing to write the liability
policy. Far be it from me to tell you their decisions are made on the
basis of good, rational data. ;-)


HPV races now have helmets mandated. I have
never seen an HPV racer sustain a head injury in a crash. Several
helmeted wedgie racers have died and been brain injured in recent
times, though.


Krygowski (and perhaps you) can probably name some safety measures that
you would acknowledge will decrease death and morbidity from bicycle
accidents.


Only about 10% of cyclist injuries are to the area covered by the
helmet and many (possibly most) cyclists who die of head injury also
have other mortal injuries. Most fatal cyclist injuries are of course
sustained in crashes involving motor vehicles: it is motor traffic,
not cycling, which is dangerous.


Statistically you are right of course. But we are talking about
cycling; we might have much more to talk about were this a political or
automotive ng. But I know of several folks who have suffered head
injury, a couple of which were life-threatening (prolonged coma and
permanent neurological damage) without the benefit of motor vehicles.


Any "safety programme" which ignores these fundamental facts is
necessarily going to be of limited effect.


The first, best thing that can be done to improve cyclist safety is to
promote cycling. There is robust evidence from around the world that
risk falls as participation increases, for a variety of reasons.

The best thing a cyclist can do to ensure their own safety is to ride
confidently and in a vehiclular style, as per Effective Cycling (and
the equivalents in other countries such as Cyclecraft).

If you look at detailed returns on crashes you find recurrent themes:
cyclist injured by turning goods vehicle after the cyclist has gone up
the inside at a junction; cyclist hit by car emerging from junction
(which can be reduced by riding further out so you are where the
driver is looking); cyclist hit by overtaking car which turns across
their path (which can be reduced by riding further out, as the
overtaking manoeuvre is then more deliberate and reminds the driver
that you are there, rather than simply cruising by).

And of course a cyclist should ensure that their bike is well
maintained, with brakes and steering in good order.



The biggest problem with helmet promotion is that it reinforces the
perception of cycling as dangeorus without teaching any of the
techniques which reduce the danger. In doing so, it actively deters
cycling, which paradoxically /increases/ risk.


Clarification please: are you talking about relative risk to the rider,
or total risk to the population?


Now, I would not normally care too much about people who decide to
promote helmet use, if it weren't for the studies which show that it
deters cycling - but these days the only thing stopping some
jurisdictions from passing a helmet law is low levels of helmet use.
More than one Government has said that compulsion will be introduced
when voluntary wearing rates are high enough (at least they've learned
that much from Australia, where cycling was decimated by compulsion).

So the Liddites


I must complement you on this usage!

have persuaded Gvernments that every person who wears
a helmet is voting for compulsion. That is unacceptable.

My objections to helmet compulsion are not libertarian, but
evidence-based. We have the experience of laws in Australia, New
Zealand and Canada to draw on. In no case did injury rates reduce.
In every case cycling was deterred.


As long as this is not libertarian, and allowing that proper bicycle
maintenance and effective cycling are more important to cyclist safety,
what would your feelings be about:
1) Mandatory licensing of cyclists (as per motor vehicles)
2) Mandatory minimum age for cyclists on public streets and roads
3) Mandatory registration of bicycles and periodic bicycle inspections




But of course, these are unwelcome messages. When you compare child
head injury rates for road crashes you find that pedestrians and
cyclists have around the same proportion of head injuries, and
pedestrian injuries are much more numerous (the risk levels in
off-road cycling for children are an order of magnitude lower). Any
justification of cycle helmet promotion applies to a much greater
extent to walking helmets. And even more so for car occupants, whose
fatality rate from head injuries is much greater.

Another clarification please: The head injury rates for cyclists vs.
pedestrians vs. auto passengers are for 1) Mile traveled
2)total number in population 3) hour spent in activity

What to do?
Clearly the answer is to reduce the danger which cars pose to other
road users, but that is politically unacceptable. Cycle helmets give
the impression of "doing something" without the need to offend the
motor lobby, which is politically very attractive.

I think that making the auto industry the focus in this discussion in
very much the same way makes it too easy to absolve ourselves of
responsibility in this issue. I certainly agree with you about the
relative danger of autos. I also agree that doing anything meaningful
in this area will be difficult (although the increase in the price of
crude oil is doing more than the political will would allow--if a
sustained rise in gasoline prices leads to diminished sale of SUVs, I
would be very happy). But if we wish to appear to be "doing something",
it is not enough to fault those who think helmet laws will save us; we
must have the courage (and the political clout) to do something that
WILL be meaningful.

Best,
Steve


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