Helmet redux

Well the extant helmet thread is getting quite long and the "debate'
remains quite heated. I've raised a point (in favor of voluntary
helmet use) a number of times and it has never had a direct response.
So I thought I'd try it again in a new thread.

For a moment let us put aside all of the published research - both pro
& con. My issue is the personally witnessed events where a helmet is
percieved to have prevented or reduced an injury. aI think that this
type of data is improtant in individual decsions on helmet use.

In my own case I have seen many crashes over the years but only two in
which I am completely convinced that a helmet prevented injury. In one
instance I was the rider. I came off my bike on a single track and my
head smashed into a large boulder alongside the trail. The helmet
worked as designed. The hard shell shattered and the foam inner had a
large dent. I had no injury to my head whatsoever.

I witnessed a similar case in which a companion came off his bike and
his head impacted the curb. This was long ago and the helmet was the
type with the styrofoam core with a nylon cover. In this instance the
helmet also performed as designed and the foam broke up absorbing the
shock of the strike but there was no injury.

So, my thought is that modern, light weight helmets can, in some cases
prevent head injuries. And modern light weight helmets now are so light
and have so much air flow that the "discomfort factor" is very low.
Thus, I don't see much of a down side.

All this argument over study methodolgies, compulsion causing less
cycling, and the idea that there are more head injuries in motor
vehicles seem to me to be simply changing the subject. Bicycle helemts
do add some measure of observable benefit. Now the debate of just how
much that benefit might be is valid. But as I and others have witnessed
events with such benefit and the citations of helmets causng accidents
are extremely rare or invole unsupervised childrren (another separate
issue) it goes against all intuiton that there is NO benefit.

On 2 Jun 2005 10:37:28 -0700, "gds" wrote:

So, my thought is that modern, light weight helmets can, in some cases
prevent head injuries. And modern light weight helmets now are so light
and have so much air flow that the "discomfort factor" is very low.
Thus, I don't see much of a down side.

I think there's a small amount of merit to the argument that people tend to
ride a little bit more daringly when they know they have a helmet on.
Whether this 'little bit more' crosses the axis with the 14mph crash rating
is hard to know. There's also the feeling that in some slow speed sideways
falls the width of the helmet actually causes the contact with the ground.
This is probably true, but though you might not strike the head, the
whiplash to the neck might be a bit stronger.

The problem with these 'might prevent some' arguments is that they're too
often used to give legislaters the idea that helmets should be mandated,
and they might give the legal community a 'reason' to mitigate damages
because, for whatever reason the person hit by the car might not have had a
helmet on.

These things are not good - choices should remain and we should not be
willing to penalize a person for not wearing a device that is much less
useful in preventing injury on the road than most non-cyclists, and perhaps
beginning cyclists believe.

So what if your POV is taken as the right one. What would you do if, now,
having a nationally mandated bicycle helmet law, the legislators suddenly
realize the made a law based on the idea that this helmet is just for low
speed fall-overs - 'hey, we need bigger and heavier foam and more padding
and, well, let's just make the buggers wear a full face motorcycle helmet,
b/c that -will- prevent those head injuries'. Haha.

I joke, but durn, it wouldn't surprise me.

jj

You are switching this over to the "compulsion" arguement again. First
we have to understand the value of the helmet before compulsion can
ever be broached. I'm no where near arguing for compulsion.

On 2 Jun 2005 10:37:28 -0700, "gds" wrote:

For a moment let us put aside all of the published research - both pro
& con. My issue is the personally witnessed events where a helmet is
percieved to have prevented or reduced an injury. aI think that this
type of data is improtant in individual decsions on helmet use.

Summary: let's abandon any attempt at scientific rigour and fall back
on anecdote ;-)

Every bicycle crash is a statistical fluke. Any inference drawn form
individual flukes is going to have less meaning than one drawn form
large numbers of such flukes collected together. A lot of flukes
collected together is called "statistics" and is how people understand
the rules which govern flukes.

Why abandon science? Is it not telling you what you want to hear?

So, my thought is that modern, light weight helmets can, in some cases
prevent head injuries. And modern light weight helmets now are so light
and have so much air flow that the "discomfort factor" is very low.
Thus, I don't see much of a down side.

Fine, so wear one. I can see a downside, so I often don't. One
downside is called risk compensation - people (including me, and I
know that helmets do very little!) ride less carefully with a helmet
on. Not much, but crashes are generally caused by the taking of
relatively small risks very large numbers of times.

Here are some downsides for you:
o cost, calculated as exceeding the average benefit in injuries saved
o discomfort, which exists (based on the same standard of evidence you
apply)
o bulk - about 1/5 the volume of my folded bike
o sends the message that cycling is dangerous, which it is not

See why we need statistics and data, not anecdote? Anecdote is too
skewed by the perceptions of the person telling the story. I could
tell you about the time I was knocked off by a car and my knitted
acrylic balaclava saved my life if you like, but it wouldn't advance
the debate much.

All this argument over study methodolgies, compulsion causing less
cycling, and the idea that there are more head injuries in motor
vehicles seem to me to be simply changing the subject. Bicycle helemts
do add some measure of observable benefit.

If that's the case, how come there is no known case where cyclist
safety has improved with increasing helmet use? How come cost-benefit
analysis shows that they cost more than they save in injury
treatments? Sorry, but you are glossing over inconvenient facts to
promote your beliefs, which is fine for you but of strictly limited
value to the wider community. If you want validation for your choice,
look no further: Gary, if you want to wear a helmet, that's fine, it;s
an appropriate choice for you. And if you chose not to wear a helmet?
Well, that would be fine too. The problem comes when you try to
assert that only one choice is valid.

Discussing study methodologies is vitally important: it allows us to
understand how two sets of data (small-scale studies and time-series)
can disagree so consistently. And there are two main reasons: one is
that the small-scale studies compare different types of cyclist, and
the other is that they typically count mainly trivial injuries because
serious ones are too rare, whereas whole-population stats count mainly
serious injuries because recording of trivial ones is too inaccurate
(and because, at a policy level, nobody really cares about trivial
injuries).

So the correct response is that helmets prevent many *trivial*
injuries, and (according to the evidence) too few *serious* injuries
to be measurable (or they cause as many as they prevent).

At that point everyone can make up their own mind as to whether the
downsides of wearing a helmet outweigh the benefit to them.

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 CHS, Puget Sound

"gds" wrote in message
oups.com...
Well the extant helmet thread is getting quite long and the "debate'
remains quite heated. I've raised a point (in favor of voluntary
helmet use) a number of times and it has never had a direct response.
So I thought I'd try it again in a new thread.

If a helmet makes you more comfortable, wear one. You are, in the end,
responsible only for yourself.

For me, I perceive the risk as vanishingly small. I am a skilled, well
trained cyclist with decades of experience. I am (mostly) a
transportational/utility cyclist who does not engage in competitive or
"extreme" cycling. I ride as a vehicle, following the rules of the road. No
single track, no curb jumping.

I have fallen on occasion, but never was my head in danger.

I want more people to ride bikes in our cities and suburbs, and fewer of
them to drive cars

People wearing helmets are proclaiming to the world: "I'm doing something
dangerous." There is no evidence I'm aware of to make such a statement any
more true of cycling than it is of driving.

I do not wish to make such a statement, especially to the urban and suburban
drivers who surround me when I ride.

RichC

On 2 Jun 2005 11:12:12 -0700, "gds" wrote:

You are switching this over to the "compulsion" arguement again. First
we have to understand the value of the helmet before compulsion can
ever be broached. I'm no where near arguing for compulsion.

Gary, I'm not saying 'you' are arguing for compulsion. I'm arguing for
choice and offering that if people start believing a 'fiction' about
helmets that it could lead to compulsion and then additional dumbass things
like requiring heavy non-breathable helmets.

There's really no argument that it's nice to have a choice and it's good
that people realize that the current helmets do not help you in collisions
with cars?

My helmet saved me once on a low speed slip on a muddy trail, but I still
want to shout at the dumbasses on TV who say 'WEAR A helmet' - because
they're not aware of the limitations of the helmet. Don't you have this
feeling too when you see those spots?

The truth is, only a tiny, tiny fraction of the accidents people have on
the bike are mitigated by wearing a helmet - most are not head-related, and
most head-related are not slow speed fall-overs.

How about we agree that if they have a spot, they also talk about what the
rating of the helmet is, and give examples of what types of falls are
helped, and include statistics that are accurate?

The problem is, if they did that, to get the protection they're imagining
they'd be saying 'wear a motorcycle helmet, a mouthpiece, motorcross armor
and armored gloves, oh and an air-bag vest'. g

jj

gds wrote:

Well the extant helmet thread is getting quite long and the "debate'
remains quite heated. I've raised a point (in favor of voluntary
helmet use) a number of times and it has never had a direct response.
So I thought I'd try it again in a new thread.

For a moment let us put aside all of the published research - both pro
& con. My issue is the personally witnessed events where a helmet is
percieved to have prevented or reduced an injury. aI think that this
type of data is improtant in individual decsions on helmet use.

In my own case I have seen many crashes over the years but only two in
which I am completely convinced that a helmet prevented injury. In one
instance I was the rider. I came off my bike on a single track and my
head smashed into a large boulder alongside the trail. The helmet
worked as designed. The hard shell shattered and the foam inner had a
large dent. I had no injury to my head whatsoever.

I witnessed a similar case in which a companion came off his bike and
his head impacted the curb. This was long ago and the helmet was the
type with the styrofoam core with a nylon cover. In this instance the
helmet also performed as designed and the foam broke up absorbing the
shock of the strike but there was no injury.

So, my thought is that modern, light weight helmets can, in some cases
prevent head injuries. And modern light weight helmets now are so light
and have so much air flow that the "discomfort factor" is very low.
Thus, I don't see much of a down side.

All this argument over study methodolgies, compulsion causing less
cycling, and the idea that there are more head injuries in motor
vehicles seem to me to be simply changing the subject. Bicycle helemts
do add some measure of observable benefit. Now the debate of just how
much that benefit might be is valid. But as I and others have witnessed
events with such benefit and the citations of helmets causng accidents
are extremely rare or invole unsupervised childrren (another separate
issue) it goes against all intuiton that there is NO benefit.



OK. IF you are going to hit your head in a direct blow, it would be
better to do it with a helmet than without. This is simple physics.

However, the broad helmet issue is not that simple.

First, there must be a greater liklihood of hitting your head while
wearing a helmet. It may be very small or even negligible, but a
helmeted head is larger and does weigh something.

Second, the larger size and possibly composition of the helmet may
result in increased rotational injury to the brain, which is the most
damaging mechanism. This is why a glancing blow to the jaw can knockout
boxers.

Third, the wearing of helmets has resulted in greater risk taking,
leading to more crashes and more severe crashes.

Fourth, it may be that motorists are more cautious around an unhelmeted
bicycist. This may be due to perceived increased vulnerability. It is
well known that motorists in general exhibit more caution around
bicyclists than around other motor vehicles. However, it is unlikely
this has reduced crashes, and it certainly is not measureable.

Fifth, clearly many people don't like wearing helmets as evidenced by
drops in cycling where helmet laws have been enacted.

Sixth, there are many helmet zealots who try to shame others into their
pro helmet stance. This is detrimental to bicycling.

I conclude that wearing a helmet may be useful for the individual given
that he will engage in aggressive riding or if there is a substantial
chance of hitting his head. I used to gently promote helmet wearing but
have since decided that the indivdual can make their own decisions and I
will not even mention using one. Helmet promotion does have the negative
effect of making bicycling appear hazardous, and that has a negative
effect on bicycling. It should certainly not be compulsory.

Wayne

Just zis Guy, you know? wrote:


Summary: let's abandon any attempt at scientific rigour and fall back
on anecdote ;-)

It does sound like that but that is not the arguement. From what I
have looked at I don't see any scientific studies that prove anything
(at least to me). From what I've looked at there is a lot of use of
proxy variables without the proof that these proxies are very good.So,
I'm not suggesting we abandon science but rather admit that we don't
have very good science. I have no argument with the proposition that
properly designed studies should be implemented.


Every bicycle crash is a statistical fluke. Any inference drawn form
individual flukes is going to have less meaning than one drawn form
large numbers of such flukes collected together. A lot of flukes
collected together is called "statistics" and is how people understand
the rules which govern flukes.


Not really my point. My point was/is that I have a certain intuitive
"feel" for what the answere should be based on anecdotal evidence. This
is how a null hypothesis for a true scientific is often developed

Why abandon science? Is it not telling you what you want to hear?

No, I want to hear what a study with a proper design discovers.




Here are some downsides for you:
o cost, calculated as exceeding the average benefit in injuries saved

To me the studies are flawed so the calculation prove little or
nothing.

o discomfort, which exists (based on the same standard of evidence you
apply)

Agreed, this is purely personal.

o bulk - about 1/5 the volume of my folded bike

Have no idea why this means anything, I ride outdoors. Is my helmet
taking up too much space in the world?

o sends the message that cycling is dangerous, which it is not

We have different perceptions on this. I don't hink it sends that
message at all.

See why we need statistics and data, not anecdote?

Agred, but we need valid statistics. As I said anecdote only helps
construct the null hypothesis.

how come there is no known case where cyclist
safety has improved with increasing helmet use? How come cost-benefit
analysis shows that they cost more than they save in injury
treatments?

Well, I don't know the real answer. And when a proper study is executed
you may well turn out to be correct. But right now I don't see any such
rigorous studies so there is nothing out there provign anything.

Gary, if you want to wear a helmet, that's fine, it;s
an appropriate choice for you. And if you chose not to wear a helmet?
Well, that would be fine too. The problem comes when you try to
assert that only one choice is valid.

I've never done that. I keep suggesting that a proper study needs to be
done.

Discussing study methodologies is vitally important: it allows us to
understand how two sets of data (small-scale studies and time-series)
can disagree so consistently. And there are two main reasons: one is
that the small-scale studies compare different types of cyclist, and
the other is that they typically count mainly trivial injuries because
serious ones are too rare, whereas whole-population stats count mainly
serious injuries because recording of trivial ones is too inaccurate
(and because, at a policy level, nobody really cares about trivial
injuries).


Agreed! And that is precisely why a properly designed study is needed.
My problem with the time series studies I looked at is that they appear
to not have been designed with the specific null hypothesis we are
discussing but rahter to be the result of culling extant data sets to
see what comes out. This type of data mining is often usefull (like
anecdotes) for forming null hypethesis for furhter study but seldom for
proving anything.




So the correct response is that helmets prevent many *trivial*
injuries, and (according to the evidence) too few *serious* injuries
to be measurable (or they cause as many as they prevent).

I don't think we know what the corret response might be.

At that point everyone can make up their own mind as to whether the
downsides of wearing a helmet outweigh the benefit to them.


Agreed, but I would like better data.

Guy, I appreciate that you feel strongly about this and do not question
your motivation. And my guess is that you have spent far more time on
the issue than I have. I respect all of this. But I find the
"scientific" data lacking on both sides of the issue.

2 Jun 2005 10:37:28 -0700,
.com,
"gds" concluded:
\szip

Bicycle helemts
do add some measure of observable benefit. Now the debate of just how
much that benefit might be is valid. But as I and others have witnessed
events with such benefit and the citations of helmets causng accidents
are extremely rare or invole unsupervised childrren (another separate
issue) it goes against all intuiton that there is NO benefit.

Based on empirical evidence, cooked data and sloppy methodology, I'll
have to believe my helmet has saved me from more broken legs than a
millipede has legs to break. I'll also attest its ability to chase
bears and keep me safe from cougar attacks. It's deflected a few more
bugs than it's trapped and ISTR the odd pebble having struck its
shell.
Once I was glad to have it on when my head was trapped between a team
mate's pedal and the ground. I finished out the game with a cut ear
rather than a cut ear and scalp wound.
--
zk

On 2 Jun 2005 11:47:45 -0700, "gds" wrote:

Summary: let's abandon any attempt at scientific rigour and fall back
on anecdote ;-)

It does sound like that but that is not the arguement.

Sure sounds like it to me.

From what I
have looked at I don't see any scientific studies that prove anything
(at least to me).

Maybe you need to ask yourself what it is you are looking for in a
study, and what would constitute the type of data you are after. If
you are saying that the balance of evidence does not back your
perceptions, then perhaps that's an indication your perceptions are
wrong. If you are saying the data does not consist of double-blind
trials - well, no, and it never will for ethical and practical
reasons, so we just have to make the best of what we have.

What we do have is some pretty reliable data saying that cycling is
not especially dangerous, some convincing if flawed data saying that
helmets might be good at preventing minor injuries, some other good
data saying they don't affect serious injuries, and some standards
which specify that they should work well for minor injuries but not
major ones, which fits the observed facts quite neatly.

As far as I'm concerned that's a reasonably convincing result, and an
acceptable standard of proof given that we can't have proper
randomised blind trials.

My point was/is that I have a certain intuitive
"feel" for what the answere should be based on anecdotal evidence. This
is how a null hypothesis for a true scientific is often developed

Sorry, but your proposed mechanism for overcoming the deficiencies in
the science is markedly worse than the imperfect science that we
currently have. If you are honest with yourself you will admit this.

Why abandon science? Is it not telling you what you want to hear?
No, I want to hear what a study with a proper design discovers.

Can't be done. And in the absence of this, abandoning science for
anecdote is a step in the wrong direction.

Here are some downsides for you:
o cost, calculated as exceeding the average benefit in injuries saved

To me the studies are flawed so the calculation prove little or
nothing.

You have better data? No.

o discomfort, which exists (based on the same standard of evidence you
apply)

Agreed, this is purely personal.

Quite :-)

o bulk - about 1/5 the volume of my folded bike

Have no idea why this means anything, I ride outdoors. Is my helmet
taking up too much space in the world?

I ride a folding bike (which I take on the train). The helmet adds
significantly to the volume of stuff I have to find a home for at the
other end. You need to remember that mountain biking is not all
biking :-)

o sends the message that cycling is dangerous, which it is not

We have different perceptions on this. I don't hink it sends that
message at all.

OK, so do you wear one when walking on roads with motor traffic? Or
when travelling in the car? Or around the house? These activities
have comparable risks of head injury. By wearing a helmet for only
one of them, we give the impression that it is uniquely dangerous -
which it isn't.

See why we need statistics and data, not anecdote?

Agred, but we need valid statistics. As I said anecdote only helps
construct the null hypothesis.

No, anecdote further obfuscates the situation. There is no way I ca
think of that bad science is made better by adding non-science!

how come there is no known case where cyclist
safety has improved with increasing helmet use? How come cost-benefit
analysis shows that they cost more than they save in injury
treatments?

Well, I don't know the real answer. And when a proper study is executed
you may well turn out to be correct. But right now I don't see any such
rigorous studies so there is nothing out there provign anything.

Once again, you need to ask yourself what standard you are setting for
a "proper" study. The studies which show, at the population level, no
measurable benefit, are adequate to prove that smoking causes cancer
or that obesity causes type II diabetes - cancer varies with levels of
smoking, type II diabetes varies with levels of obesity. Logically,
if head injury rates don't very with helmet use (and they don't) that
tells you something important.

Gary, if you want to wear a helmet, that's fine, it;s
an appropriate choice for you. And if you chose not to wear a helmet?
Well, that would be fine too. The problem comes when you try to
assert that only one choice is valid.

I've never done that. I keep suggesting that a proper study needs to be
done.

But then you suggest that in the absence of a "proper" study we revert
to something markedly worse than the "improper" studies. That makes
no sense!

My problem with the time series studies I looked at is that they appear
to not have been designed with the specific null hypothesis we are
discussing but rahter to be the result of culling extant data sets to
see what comes out. This type of data mining is often usefull (like
anecdotes) for forming null hypethesis for furhter study but seldom for
proving anything.

You surely cannot be under any illusion that anecdote has a validity
comparable with whole population and times series data? I refuse to
believe that anyone is that naive!

So the correct response is that helmets prevent many *trivial*
injuries, and (according to the evidence) too few *serious* injuries
to be measurable (or they cause as many as they prevent).

I don't think we know what the corret response might be.

I think we have a pretty good idea by now, we have after all around
thirty years of data to go on.

At that point everyone can make up their own mind as to whether the
downsides of wearing a helmet outweigh the benefit to them.

Agreed, but I would like better data.

Wouldn't we all. But we also have to recognise that such data may
never become available due to irreconcilable practical and ethical
difficulties.

Guy, I appreciate that you feel strongly about this and do not question
your motivation. And my guess is that you have spent far more time on
the issue than I have. I respect all of this. But I find the
"scientific" data lacking on both sides of the issue.

You're right that it's important to me: I ride a bike for daily
transport - cycle safety is of immediate and vital interest to me.

We all find the data lacking. Everybody is looking for that one study
that finally settles the issue one way or the other. Unfortunately
the people who keep claiming that they have done so are helmet
promoters, and in every case thus far all they have done is trotted
out another case-control study or (worse) meta-analysis of
case-control studies which ignores the inescapable fact that the
predictions made by such studies are never borne out in real
populations.

That is one of the many reasons I have changed from being strongly
pro-helmet to being sceptical. This, too, could change, if convincing
new data comes along. But anecdote is neither new nor convincing.

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 CHS, Puget Sound