published helmet research - not troll

On Fri, 18 Jun 2004 22:21:32 -0400, Steven Bornfeld
wrote:


You want to believe this is a helmet manufacturer conspiracy, go right
ahead.

I have no intention of wasting time proving that the earth isn't
flat.


You're a master of building straw men. Did I say anything about a
helmet manufacturer conspiracy. I've simpley asked repeatedly for
evidence that bicycle helmets are important safety devices and
suggested that given a lack of evidence proving that that helmet
proponents should be more honest and say they "hope" or "speculate"
that helmets are important. If that suggestion of honesty threatens
you so much that you have to build straw men to argue against it,
perhaps you should sit back and ask yourself why you feel threatened.

JT

John Forrest Tomlinson wrote:

On Fri, 18 Jun 2004 22:21:32 -0400, Steven Bornfeld
wrote:



You want to believe this is a helmet manufacturer conspiracy, go right
ahead.


I have no intention of wasting time proving that the earth isn't
flat.



You're a master of building straw men. Did I say anything about a
helmet manufacturer conspiracy. I've simpley asked repeatedly for
evidence that bicycle helmets are important safety devices and
suggested that given a lack of evidence proving that that helmet
proponents should be more honest and say they "hope" or "speculate"
that helmets are important. If that suggestion of honesty threatens
you so much that you have to build straw men to argue against it,
perhaps you should sit back and ask yourself why you feel threatened.

JT


JT, I'm really flattered that you consider me a master of
anything--that's high praise indeed!
I am not an epidemiologist, nor am I an actuary. It is possible that
some of these very smart people in fact have large equity positions in
helmet manufacturing companies. I posted the link of a review of
previously published clinical studies. I am not prepared to read them
and critique the design of each. If you have the time to review all of
these studies and find them flawed, more power to you.
I only raced one season--1986. You may recall that was the year that
the USOC lost its liability policy, and the USCF suspended racing until
a policy could be written. I remember the hue and cry that went up when
the hard shell helmet rule went into effect.
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.
Of course, some folks are in favor of allowing performance-enhancing
drugs as well--after all, if they're administered correctly they can be
safe and effective, and it's the racers' bodies after all, isn't it?
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?

Steve

--
Mark & Steven Bornfeld DDS
http://www.dentaltwins.com
Brooklyn, NY

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?

Joe Riel

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.

On Sat, 19 Jun 2004 10:59:23 -0400, 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?
Given that cycling is a fundemantally healthy activity, the only
safety thing that should be mandated are that riders generally follow
the rules of the road. And we already have laws about that everywhere
I have ever lived.

If you or anyone really care about cycling safety, I think that
teaching drivers to give other road users more respect would be
important. And better road design.

I wear a helmet most of the time when I ride both becasue I'm in a
sport where it's use is mandated (racing) and it makes sense to get
used to wearing a helmet. And I imagine that riding with a helmet is
probably a tiny bit safer than riding without one (I don't really know
that -- it's speculation).

JT

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.

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). 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.

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.

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. 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.

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.

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 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.



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. 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.

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

"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

--

A: Top-posters.
Q: What is the most annoying thing on Usenet?

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. In common terms, they're designed to protect against an ideal
"Laugh-In" fall.

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.

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.


Well said.

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.