Cyclist dies after crash during Tour of Colombia

[Tony Raven]

http://sports.yahoo.com/sc/news?slug=ap-cyclistdies&prov=ap&type=lgns
Cyclist dies after crash during Tour of Colombia

June 11, 2004
BOGOTA, Colombia (AP) -- A cyclist was killed Friday when he crashed during
the fifth stage of the Tour of Colombia.
Juan Barrero, a 31-year-old Colombian, suffered serious head injuries after he
got tangled up with other cyclists and fell while negotiating a fast downhill
curve.
He had a cardiac arrest and died while being transported from a small hospital
to a larger one, said Orlando Cardona, director of the San Vicente de Paul
Hospital, located about 100 miles west of Bogota.
Two other cyclists were also injured in the crash, Cardona said.
``The fall was massive and Juan took the brunt of it,'' said his brother,
Manuel Barrero, also riding in the tour.

[Marc Brett]

On Sat, 12 Jun 2004 19:31:20 +0100, "Tony Raven"
> wrote:

>http://sports.yahoo.com/sc/news?slug=ap-cyclistdies&prov=ap&type=lgns
>Cyclist dies after crash during Tour of Colombia
>
>June 11, 2004
>BOGOTA, Colombia (AP) -- A cyclist was killed Friday when he crashed during
>the fifth stage of the Tour of Colombia.
>Juan Barrero, a 31-year-old Colombian, suffered serious head injuries after he
>got tangled up with other cyclists and fell while negotiating a fast downhill
>curve.
>He had a cardiac arrest and died while being transported from a small hospital
>to a larger one, said Orlando Cardona, director of the San Vicente de Paul
>Hospital, located about 100 miles west of Bogota.
>Two other cyclists were also injured in the crash, Cardona said.
>``The fall was massive and Juan took the brunt of it,'' said his brother,
>Manuel Barrero, also riding in the tour.
>

And yes, he was wearing a helmet:

<http://www.dailypeloton.com/displayarticle.asp?pk=6391>

What should have been a day of epic cycling, with the main contenders
battling it out on the first real mountain stage of the 54th Vuelta a
Colombia, from Santa Rosa de Cabral to Jericó over 171 km. turned a
day of sadness and tragedy as the 31-year-old cyclist Juan Barrero of
the Alcaldía de Fusagasugá-Juegos Nacionales 2004 team lost his life
after falling heavily on a descent, less than nine minutes into the
stage.

Riding at a speed of about 80 km., the man got tangled up with other
cyclists and fell while negotiating a fast downhill curve. He hit a
rock and, despite wearing a helmet, reportedly suffered serious head
and thorax injuries, and later had a cardiac arrest; Barrero died
while being transported from the Hospital de Santa Rosa de Cabal to
the larger "San Jorge de Pereira", located about 100 miles west of
Bogotá, said Hospital director Orlando Cardona.

Two other riders, Barrero's teammate Victor Hugo González, who
fractured his wrist and collarbone, and Óscar Santo Álvarez, that had
some bruises on his left arm and thigh, were also involved and injured
in the pile-up, Cardona said. González was the only one that briefly
commented "We were on the descent between Santa Rosa and Chinchiná,
everything was going fine, but the road was wet, and all of sudden we
found ourselves on the ground". "The fall was massive and Juan took
the brunt of it," Juan's brother Manuel Barrero, also riding in the
tour, added.

Born in Facatativá on May 9, 1973, Juan Antonio Barrero had been a
professional rider for eight years, most of which in the ranks of his
current team. Barrero took part in several editions of the Vuelta a
Colombia as well as other races like Clásico RCN, Vuelta a Chiriquí
and the Tour of Costarica, and more local events in his home country.
He was Cundinamarca Provincial Champion both in 1998 and the past
season, and this year notched up a stage victory at Clásica de
Fusagasugá.

[Howard]

From the cyclingnew.com site


'Death in Tour of Colombia

....The fall occurred some five minutes after the start, but due to the
descent the peloton was already descending at high speed. Other riders
said the turn was slick with some type of liquid on the surface.
Barrero suffered injuries to the head, cervical area, and the thorax
area. Ambulance attention was immediate and all resuscitation measures
were given at the hospital. All three riders were wearing appropriate
helmets.'


Look out for all the 'cycle helmet again fails to save cyclist in
crash' headlines...

[Gawnsoft]

On 12 Jun 2004 14:50:54 -0700, (Howard)
wrote (more or less):

>From the cyclingnew.com site
>
>
>'Death in Tour of Colombia
>
>...The fall occurred some five minutes after the start, but due to the
>descent the peloton was already descending at high speed. Other riders
>said the turn was slick with some type of liquid on the surface.
>Barrero suffered injuries to the head, cervical area, and the thorax
>area. Ambulance attention was immediate and all resuscitation measures
>were given at the hospital. All three riders were wearing appropriate
>helmets.'

I doubt /any/ of them were wearing helmets appropriate for cycling at
80Km/h down steep roads covered in a slippy fluid.

They were probably wearing bicycle helmets, which are appropriate for
up to about 12mph (about 19Km/h)

An appropriate helmet would have been a heavy-duty motorbike helmet.
then again, that'd just have resulted in a spate of 'cyclists die from
heat prostration' stories.

>Look out for all the 'cycle helmet again fails to save cyclist in
>crash' headlines...


--
Cheers,
Euan
Gawnsoft: http://www.gawnsoft.co.sr
Symbian/Epoc wiki: http://html.dnsalias.net:1122
Smalltalk links (harvested from comp.lang.smalltalk) http://html.dnsalias.net/gawnsoft/smalltalk

[anonymous coward]

> They were probably wearing bicycle helmets, which are appropriate for
> up to about 12mph (about 19Km/h)

I'm not quite sure where this 12mph figure comes from? In the Snell
standards (http://www.smf.org/stds.html) helmets are tested by simulating
a 2.2 metre fall onto a flat anvil or 1.3 metres onto other surfaces. It's
a long time since I did any physics so this may be incorrect:

S=0.5at^2 = 2.2=0.5*10*t^2
t = sqrt(2.2/(0.5*10))
V = at = 6.6 m/s

which corresponds to about 23kmh ~= 15mph which is in the right ball park?

also a 1.3m drop ~= 11.4mph impact

I'm left wondering how well this simulates being thrown over the
handlebars, where you have your whole body weight behind your head - the
tests just use a 5kg dummy head.

If you go ice skating and aren't better than me, you'll find that it
doesn't hurt much more if you fall over at speed compared to if you fall
over whilst standing still - unless you slide into something.

On the same principle, presumably a 12mph helmet might give some useful
protection if you fall off at high speed but scrape to a halt on the
road without hitting anything else. Or else fall off, scrape
almost-but-not-quite to a halt, then hit something?

> An appropriate helmet would have been a heavy-duty motorbike helmet.

Interestingly, motorcycle helmet drop distances are 3m and 2.2m
respectively - not as large a difference as I expected. Though I guess
there's more to their differences than impact absorbtion

> then again, that'd just have resulted in a spate of 'cyclists die from
> heat prostration' stories.

On a related topic, I wonder how big a drop in cycling we would see if
helmets were made compulsory in the uk? I can see how wearing a cycle
helmet might be onerous in Australia because it's hot. I imagine
that's less of a problem here (so far).

Incidentally (to state my position), I currently wear a helmet about 50%
of the time. I'm opposed to helmet compulsion but undecided whether to
wear one myself. I am interested in the theory that helmets increase
torsional injuries, and I accept they're far from the panacea they're made
out to be.

AC

[Howard]

There are a number of differing standards for helmets, the highest one
give a 15 MPH rating, the others 12 MPH or so. In reality many helmets
when independenty tested fail to even meet these standards and when
incorrectly worn quite possibly no protection at all.

The main point about the impact absorbtion abilities of helmets is
that the sort of impacts they can absorb, be they sustained in a low
or a high speed fall, are unlikely to be life threatening in any case.
In an impact high enough to be life threatening a helmet has such a
low ability to absorb impacts it will make little or no difference and
may well just fail catastrophically.

As the energy that has to be dissipated in a crash rises with the
square of the speed a rough estimate of the forces involved can be
calculated as follows:

At 12 MPH the force would be 12 squared x mass. Lets give the mass, a
standard value of 1 so we can compare the effects of speed. This gives
a value of 144 at 12 MPH.

At 42 mph the force would be 42 squared x 1 = 1764. Substracting the
tested ability of a helmet to absorb energy from this this leaves
1620, which still equates to 40.2 MPH, still very likely to result in
a fatality.

When it comes to 'road safety' helmets are a serious distraction away
from the real issues: reducing the number of collisions that occur and
reducing vehicle speeds to a low enough level that colisions are
survivable when they do occur.

For one I would accept the compulsory wearing of helmets to give
protection from minor injuries, and the odd rare serious injury, at
speeds below 15 MPH if vehicle speeds were restricted to 15 MPH to
prevent all those serious injuries that occur above 15 MPH. (Given
current police guidelines 15 MPH would be enforced at almost 20 MPH
but with ISA systems that guarantee motor vehicles could not exceed 20
MPh I might support a universal 20 MPH limit in towns and on country
lanes).

[Just zis Guy, you know?]

anonymous coward wrote:

> I'm not quite sure where this 12mph figure comes from? In the Snell
> standards (http://www.smf.org/stds.html) helmets are tested by
> simulating a 2.2 metre fall onto a flat anvil or 1.3 metres onto
> other surfaces.

Pop into your LBS some time and try to find a Snell certified helmet. The
helmet makers pushed through a much lower set of standards to allow them to
produce something which was (a) cheaper to make for the same sale price and
(b) more acceptable to users who don't like having their heads boiled when
the ambient temperature is above freezing.

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

Victory is ours! Down with Eric the Half A Brain!

[Simon Brooke]

in message >, anonymous
coward ') wrote:

>> They were probably wearing bicycle helmets, which are appropriate for
>> up to about 12mph (about 19Km/h)
>
> I'm not quite sure where this 12mph figure comes from? In the Snell
> standards (http://www.smf.org/stds.html) helmets are tested by
> simulating a 2.2 metre fall onto a flat anvil or 1.3 metres onto other
> surfaces. It's a long time since I did any physics so this may be
> incorrect:
>
> S=0.5at^2 = 2.2=0.5*10*t^2
> t = sqrt(2.2/(0.5*10))
> V = at = 6.6 m/s
>
> which corresponds to about 23kmh ~= 15mph which is in the right ball
> park?
>
> also a 1.3m drop ~= 11.4mph impact

Yup. When I calculated it out I rounded that up to 12mph which is
probably where the 12mph figure comes from.

> I'm left wondering how well this simulates being thrown over the
> handlebars, where you have your whole body weight behind your head -
> the tests just use a 5kg dummy head.

It's a joke, isn't it?

I mean, if you topple over sideways with your bike stationary that
almost gives the 15mph impact since your head started about 2m up. But
if (as has never yet happened to me) you go over the handlebars, you
must have considerable forward momentum - you cannot conceivably go
over the handlebars with the bike stationary - and that forward
momentum must add to the speed of impact. So an 'over the bars' fall
with no other vehicle involved onto a flat road must in most cases
exceed the design parameters of a helmet. If the surface you fall on
isn't flat...

It's crazy!

--
(Simon Brooke) http://www.jasmine.org.uk/~simon/

Tony Blair's epitaph, #1: Here lies Tony Blair.
Tony Blair's epitaph, #2: Trust me.

[anonymous coward]

On Mon, 14 Jun 2004 00:31:30 -0700, Howard wrote:

> There are a number of differing standards for helmets, the highest one
> give a 15 MPH rating, the others 12 MPH or so. In reality many helmets
> when independenty tested fail to even meet these standards and when
> incorrectly worn quite possibly no protection at all.
>
> The main point about the impact absorbtion abilities of helmets is
> that the sort of impacts they can absorb, be they sustained in a low
> or a high speed fall, are unlikely to be life threatening in any case.

I've read a few newspaper articles to the effect that someone has been
punched, fallen and hit their head against a kerbstone and died.
I wonder whether low-speed impacts generally _are_ innocuous, or whether
we're so good at protecting our noggins that they _seem_ innocuous because
we manage to avoid or mitigate most of them?

> In an impact high enough to be life threatening a helmet has such a
> low ability to absorb impacts it will make little or no difference and
> may well just fail catastrophically.
>
> As the energy that has to be dissipated in a crash rises with the
> square of the speed a rough estimate of the forces involved can be
> calculated as follows:
>
> At 12 MPH the force would be 12 squared x mass. Lets give the mass, a
> standard value of 1 so we can compare the effects of speed. This gives
> a value of 144 at 12 MPH.
>
> At 42 mph the force would be 42 squared x 1 = 1764. Substracting the
> tested ability of a helmet to absorb energy from this this leaves
> 1620, which still equates to 40.2 MPH, still very likely to result in
> a fatality.

You haven't addressed my main point at all, which is that in real-life
collisions the energy of any individual impact does not have to be
equal to the total energy theoretically available in a collision occuring
at that speed.

For example, imagine a van pulls out of a side junction, and I hit it
sideways on (90 degrees) at 12mph. Let's assume for the sake of
argument that it does what the label says and can prevent me from
suffering brain damage under these circumstances.

Now imagine that a car pulls over to park on my side of the road, and I
have a head-on collision with it with a closing speed of 24mph. If the
windscreen is at an angle of 30 degrees my head will impact it at only
12mph (24 x sin(30)) so I may still be OK. As you've pointed out, a 24mph
collision has to burn off 4x the energy of a 12mph collision so I'll still
be moving, but if I'm lucky I may get away with it.

This is all horribly artificial, but I have hit a van at maybe 8mph
without hitting my head at all. So presumably a helmet might help in
scenario 1 even if the impact speed is a bit higher than 12 mph.

> When it comes to 'road safety' helmets are a serious distraction away
> from the real issues: reducing the number of collisions that occur and
> reducing vehicle speeds to a low enough level that collisions are
> survivable when they do occur.

I too would put helmets third. But I genuinely haven't yet made up my own
mind whether I think helmets are a 'might as well' option or 'useless and
possibly dangerous'.

> For one I would accept the compulsory wearing of helmets to give
> protection from minor injuries, and the odd rare serious injury, at
> speeds below 15 MPH if vehicle speeds were restricted to 15 MPH to
> prevent all those serious injuries that occur above 15 MPH. (Given
> current police guidelines 15 MPH would be enforced at almost 20 MPH but
> with ISA systems that guarantee motor vehicles could not exceed 20 MPh I
> might support a universal 20 MPH limit in towns and on country lanes).

Shouldn't your limit be 7.5mph - so that no collision can have a closing
speed of more than 15mph?

AC

[Peter Clinch]

anonymous coward wrote:

> I've read a few newspaper articles to the effect that someone has been
> punched, fallen and hit their head against a kerbstone and died.
> I wonder whether low-speed impacts generally _are_ innocuous, or whether
> we're so good at protecting our noggins that they _seem_ innocuous because
> we manage to avoid or mitigate most of them?

Quite probably a bit of both. I'd guess /most/ are innocuous (but can
still be painful) but you can get really unlucky and catch a sensitive
spot at the wrong angle. I've heard of a case of a death slipping
getting out of the bath, when the victim would presumably not have been
in a Big Hurry and probably fairly with it. Plus it is a natural
reaction to protect one's head.

> Now imagine that a car pulls over to park on my side of the road, and I
> have a head-on collision with it with a closing speed of 24mph. If the
> windscreen is at an angle of 30 degrees my head will impact it at only
> 12mph (24 x sin(30))

No, it will impact it at 24 mph. There may well be a deflection effect
so you don't soak up as much energy, but it'll still be travelling at 24
mph. And the deflection effect may or may not be a good thing, if you
remember all that stuff about rotational effects etc.

> This is all horribly artificial

Isn't it just. So that's why whole population studies tend to be
treated as more useful than individual what-ifs. They don't show any
recognisable aid from lids in KSIs.

> I too would put helmets third. But I genuinely haven't yet made up my own
> mind whether I think helmets are a 'might as well' option or 'useless and
> possibly dangerous'.

I personally think neither of the above. "Might as well" assumes there
are no downsides, but if you find that a snugly fitting shell of
non-breathable material (vents can only do so much) with a snug
chinstrap has zero comfort difference then your head is very different
to mine.
I think they are potentially useful in reducing the effects of painful
but minor accidents, but they give a level of discomfort 100% of the
time, so it's a case of "you choose, you lose". I'm not in the habit of
falling off when I'm on the roads, so these days I tend not to bother.
I am in the habit of falling off the MTB if I'm Going For It, and
comfort is a minor issue in those cases anyway, so I will wear it there.

So I regard them for most of the cycling I do as "not useful enough to
overcome the downside of being relatively uncomfortable all the time",
which isn't the same as either of your options above.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net http://www.dundee.ac.uk/~pjclinch/

[Ambrose Nankivell]

In ,
Peter Clinch > typed:
> anonymous coward wrote:
>> Now imagine that a car pulls over to park on my side of the road,
>> and I have a head-on collision with it with a closing speed of
>> 24mph. If the windscreen is at an angle of 30 degrees my head will
>> impact it at only 12mph (24 x sin(30))
>
> No, it will impact it at 24 mph. There may well be a deflection
> effect so you don't soak up as much energy, but it'll still be
> travelling at 24 mph. And the deflection effect may or may not be a
> good thing, if you remember all that stuff about rotational effects
> etc.
>
And you'll probably want something to lubricate the deflection to avoid the
rotational effect. If you're lucky, then you've got a nice head of hair to
do it with.

Hopefully, also, your head will be retracting away from the impact site to
mitigate the collision as well.

Like Pete says, these are reasons why it's pretty complicated to try and do
it by imagining what happens in the case of a collision and instead look at
the data.

A

[anonymous coward]

On Mon, 14 Jun 2004 11:22:00 +0100, Peter Clinch wrote:

> anonymous coward wrote:
>
>> I've read a few newspaper articles to the effect that someone has been
>> punched, fallen and hit their head against a kerbstone and died.
>> I wonder whether low-speed impacts generally _are_ innocuous, or whether
>> we're so good at protecting our noggins that they _seem_ innocuous because
>> we manage to avoid or mitigate most of them?
>
> Quite probably a bit of both. I'd guess /most/ are innocuous (but can
> still be painful) but you can get really unlucky and catch a sensitive
> spot at the wrong angle. I've heard of a case of a death slipping
> getting out of the bath, when the victim would presumably not have been
> in a Big Hurry and probably fairly with it. Plus it is a natural
> reaction to protect one's head.
>
>> Now imagine that a car pulls over to park on my side of the road, and I
>> have a head-on collision with it with a closing speed of 24mph. If the
>> windscreen is at an angle of 30 degrees my head will impact it at only
>> 12mph (24 x sin(30))
>
> No, it will impact it at 24 mph. There may well be a deflection effect
> so you don't soak up as much energy, but it'll still be travelling at 24
> mph.

You make it sound as if it's almost the same thing, but of course it isn't.

A few people on this list have fallen off on the flat at speeds of 24mph+
and are here to tell the tale; I'd wager that none of us have ridden
directly into a brick wall at 24mph (unless they flew over the top of it
or were riding a recumbent). Hitting a sloped surface has got to be
somewhere in between.

> And the deflection effect may or may not be a good thing, if you
> remember all that stuff about rotational effects etc.

Point taken.

>> This is all horribly artificial
>
> Isn't it just. So that's why whole population studies tend to be
> treated as more useful than individual what-ifs. They don't show any
> recognisable aid from lids in KSIs.

I tend to think the population studies are so fraught with uncertainties
and confounding factors that it's difficult to draw any firm conclusions
from them. Do bike helmets help? Is autism linked to MMR? Do whisky or
olive oil drinkers make you live longer? What about drinking whisky and
olive oil together?

Take the seatbelt paradox - seatbelts may not make the roads safer, but if
I get into a car as a passenger I'm probably well advised to wear one.
It's a while since I read John Adam's book, but IIRC the population
statistics would have suggested I shouldn't bother.

I seem to be very argumentative today. Maybe some fresh air will help
(lunchtime bike ride),

AC

[Just zis Guy, you know?]

anonymous coward wrote:

> I tend to think the population studies are so fraught with
> uncertainties and confounding factors that it's difficult to draw any
> firm conclusions from them.

A criticism which applies to a very much greater degree to the small-scale
prospective studies which suggest benefit. If you're going to discount the
evidence, then you need to discount /all/ of it :-)

> Do bike helmets help? Is autism linked to
> MMR? Do whisky or olive oil drinkers make you live longer? What about
> drinking whisky and olive oil together?

These things show correlations between things. The population level studies
on bike helmets show /no/ correlation - that's the point. You can argue for
ever about whether autosm is caused MMR or just happens to manifest at
around the time the MMR is administered; in the case of helmets what you
have is no discernible effect (see Tony's "spot the year" charts posted
earlier).

> Take the seatbelt paradox - seatbelts may not make the roads safer,
> but if I get into a car as a passenger I'm probably well advised to
> wear one. It's a while since I read John Adam's book, but IIRC the
> population statistics would have suggested I shouldn't bother.

Invalid comparison: Adams' population statistics show that for optimum
safety everybody except the driver should wear one :-) As a passenger you
will probably not materially affect the outcome of the journey.

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

Victory is ours! Down with Eric the Half A Brain!

[Peter Clinch]

anonymous coward wrote:

> You make it sound as if it's almost the same thing, but of course it isn't.

All I'm saying is that the impact velocity is not reduced according to a
simple bit of trigonometry, and I said that because that is the case.

> I tend to think the population studies are so fraught with uncertainties
> and confounding factors that it's difficult to draw any firm conclusions
> from them.

The point about whole population studies is you have a very big sample
base so that fact alone tends to round off a lot of the awkward corners.
In a single case /that/ is where you are so fraught with uncertainties
you can't usefully deduce much except for very specific cases.

> Do bike helmets help? Is autism linked to MMR? Do whisky or
> olive oil drinkers make you live longer? What about drinking whisky and
> olive oil together?

In the first case, very probably not as far as KSIs are concerned. In
the other cases you're not asking such simple questions and there are
plenty of other variables that may influence your results. For example,
olive oil is just one thing in a diet so you can't really isolate it.
For MMR, there were autistic folk before there was MMR and the causes
weren't well understood to start with so it could be all sorts of other
things. But with helmets we knew what the rates were before everyone
was wearing them and after everyone was wearing them where compulsion
was introduced. If they have a significant effect you'd expect to see
it when the figures come in, and we don't. There will be other
variables, but nothing like as many, or of such significance, as the
rest of a diet aside from olive oil.

The only way to recreate accidents and their effects properly for study
is... well, actually you can't do it. There are far more things you
have to account for in a single incident than you have to account for at
a population level, because the population level accounts for all the
accidents people really had.

> Take the seatbelt paradox - seatbelts may not make the roads safer, but if
> I get into a car as a passenger I'm probably well advised to wear one.
> It's a while since I read John Adam's book, but IIRC the population
> statistics would have suggested I shouldn't bother.

If you get into a car as a passenger then you have no control over the
vehicle, so effectively all else is equal. And if all else is equal
then you're better off wearing a seatbelt. Where the seatbelt safety
argument breaks down is where all things aren't equal: a driver may
drive faster and brake later because they feel safer with their seatbelt
on, for example, but that's irrelevant to a passenger.

Whole population studies here show no effect for the passenger but OTOH
the nullifying effect is mainly produced by the driver's actions.
Stokers aside, on a cycle you're in charge.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net http://www.dundee.ac.uk/~pjclinch/

[Mark Tranchant]

Peter Clinch wrote:

> If you get into a car as a passenger then you have no control over the
> vehicle, so effectively all else is equal. And if all else is equal
> then you're better off wearing a seatbelt. Where the seatbelt safety
> argument breaks down is where all things aren't equal: a driver may
> drive faster and brake later because they feel safer with their seatbelt
> on, for example, but that's irrelevant to a passenger.

There are undoubtably situations where both seat belts and bicycle
helmets reduce one's survival chances. Take for example this accident:

http://www.topgear.com/content/my_topgear/prangs/05/03/

From the pictures, it's astonishing the driver survived. I'd suggest
that wearing a seatbelt would have given rise to a less fortunate outcome.

There are hints that bike helmets *may* increase the risk of rotational
injury in certain circumstances, although I'm not aware of any direct
case studies on this.

As you say, the key difference is that we have good, statistically sound
data that wearing a seat belt increases one's chances of surviving a car
journey. We do not have such data for the wearing of bike helmets, and
if there were a significant advantage, this evidence should be jumping
off the pages at us.

I wonder if the driver of the car linked to above wears a seatbelt now?

--
Mark.

[Peter Clinch]

Mark Tranchant wrote:

> There are undoubtably situations where both seat belts and bicycle
> helmets reduce one's survival chances. Take for example this accident:
>
> http://www.topgear.com/content/my_topgear/prangs/05/03/
>
> From the pictures, it's astonishing the driver survived. I'd suggest
> that wearing a seatbelt would have given rise to a less fortunate outcome.

This is indeed the case, but since you can't predict the sort of
accident you'll have before it's too late, knowing that such cases exist
isn't of much use. You've got to go with the overall probabilities
every time for the best chance, though that doesn't guarantee you won't
be caught in one of the uncommon accidents where your precautions work
against you.

> There are hints that bike helmets *may* increase the risk of rotational
> injury in certain circumstances, although I'm not aware of any direct
> case studies on this.

I think any such thing would be affectively impossible. You need
reliably controlled data to do useful studies, and you aren't going to
get Ethics Committee approval for the sort of experiment that provides
reliably controlled data for brain injuries!
Just taking victims off the streets, you won't really know enough about
enough accidents to pin down the hows and whys well enough unless
there's an epidemic of people with their necks screwed off, but AFAICT
there isn't.

> As you say, the key difference is that we have good, statistically sound
> data that wearing a seat belt increases one's chances of surviving a car
> journey.

If (and only if) all else is equal we have good evidence that in a
notional road accident a seat belt is more likely to do us favours than
not, and that's not /quite/ the same thing as you've written above.

> I wonder if the driver of the car linked to above wears a seatbelt now?

Interesting question. If she's dopey enough to drive at 100mph on a wet
road who can predict what she "thinks" about safety questions?
Hopefully she learned that doing the ton in the wet is Not a Cunning
Plan and isn't particularly concerned about any seat belt aspect.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net http://www.dundee.ac.uk/~pjclinch/

[Simon Brooke]

in message >, Mark Tranchant
') wrote:

> There are undoubtably situations where both seat belts and bicycle
> helmets reduce one's survival chances. Take for example this accident:
>
> http://www.topgear.com/content/my_topgear/prangs/05/03/

Browsing that site as displacement activity because I have a
particularly heavy workload just now, I came across this:

<URL:http://www.topgear.com/content/jsp/bigpic.html?car=/content/my_topgear/prangs/01/04/bigImages/img01.gif>

Enjoy.















Oh yes, before anyone asks, the frequency of my posting to Usenet _is_
in direct proportion to the size and urgency of my workload. You all
better hope I get some let-up, soon.

--
(Simon Brooke) http://www.jasmine.org.uk/~simon/

' ' <------- this blank intentionally spaced left

[Just zis Guy, you know?]

On Mon, 14 Jun 2004 14:36:48 +0100, Mark Tranchant
> wrote in message
>:

>http://www.topgear.com/content/my_topgear/prangs/05/03/

The pictures in that site are a munument to stupidity, aren't they?
So many of them are clearly the result of physics: 1 testosterone:
nil. And the explanations? Not - ahem - universally plausible.

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

[anonymous coward]

On Mon, 14 Jun 2004 13:44:57 +0100, Peter Clinch wrote:

> anonymous coward wrote:
>
>> You make it sound as if it's almost the same thing, but of course it isn't.
>
> All I'm saying is that the impact velocity is not reduced according to a
> simple bit of trigonometry, and I said that because that is the case.

Velocity is a vector and includes a directional component; speed is a
scalar.

>> I tend to think the population studies are so fraught with
>> uncertainties and confounding factors that it's difficult to draw any
>> firm conclusions from them.
>
> The point about whole population studies is you have a very big sample
> base so that fact alone tends to round off a lot of the awkward corners.
> In a single case /that/ is where you are so fraught with uncertainties
> you can't usefully deduce much except for very specific cases.
>
>> Do bike helmets help? Is autism linked to MMR? Do whisky or olive oil
>> drinkers make you live longer? What about drinking whisky and olive oil
>> together?
>
> In the first case, very probably not as far as KSIs are concerned. In
> the other cases you're not asking such simple questions and there are
> plenty of other variables that may influence your results. For example,
> olive oil is just one thing in a diet so you can't really isolate it.
> For MMR, there were autistic folk before there was MMR and the causes
> weren't well understood to start with so it could be all sorts of other
> things. But with helmets we knew what the rates were before everyone
> was wearing them and after everyone was wearing them where compulsion
> was introduced. If they have a significant effect you'd expect to see
> it when the figures come in, and we don't. There will be other
> variables, but nothing like as many, or of such significance, as the
> rest of a diet aside from olive oil.
>
> The only way to recreate accidents and their effects properly for study
> is... well, actually you can't do it.

You can try - that's what crash-test dummies and the like are for. For
example, I think I'm right in saying that most of the evidence against
bull bars is based on kinematics and the epidemiological data against
them is relatively weak.

> There are far more things you have to account for in a single incident
> than you have to account for at a population level, because the
> population level accounts for all the accidents people really had.
>
>> Take the seatbelt paradox - seatbelts may not make the roads safer, but
>> if I get into a car as a passenger I'm probably well advised to wear
>> one. It's a while since I read John Adam's book, but IIRC the
>> population statistics would have suggested I shouldn't bother.
>
> If you get into a car as a passenger then you have no control over the
> vehicle, so effectively all else is equal. And if all else is equal
> then you're better off wearing a seatbelt.

This is my reasoning too - taken from JA.

> Where the seatbelt safety
> argument breaks down is where all things aren't equal: a driver may
> drive faster and brake later because they feel safer with their seatbelt
> on, for example, but that's irrelevant to a passenger.

IIRC John Adams argued that the population statistics showed no reduction
in road deaths after seatbelt wearing became mandatory - if you take
drink-driving and similar factors into account.

This could be because:

1) All else stayed equal, but on average seat belts confer no benefit.

2) Seat belts are effective, but drivers became more reckless nullifying
their advantages.

3) Car performance increased to match the rate of seatbelt-wearing, rate
so collision speeds became higher.

4..) Other explanations.

In:

http://www.adamsmith.org.uk/policy/publications/pdf-files/risky-business.pdf

John Adams argues case (2) convincingly. He draws heavily on
whole-population studies and I'm not arguing that he's wrong to do so.
However, he also draws on small-scale interviews, case-control studies and
crash test data to make his case.

> Whole population studies here show no effect for the passenger but OTOH
> the nullifying effect is mainly produced by the driver's actions.

Did JA have enough population data that he could make this claim without
recourse to other types of study? Not in the link I've given above. But
perhaps he has enough data to do so (reading "Risk" is on my todo list).

AC

[anonymous coward]

On Mon, 14 Jun 2004 13:33:36 +0100, Just zis Guy, you know? wrote:

> anonymous coward wrote:
>
>> I tend to think the population studies are so fraught with
>> uncertainties and confounding factors that it's difficult to draw any
>> firm conclusions from them.
>
> A criticism which applies to a very much greater degree to the small-scale
> prospective studies which suggest benefit. If you're going to discount the
> evidence, then you need to discount /all/ of it :-)
>
>> Do bike helmets help? Is autism linked to
>> MMR? Do whisky or olive oil drinkers make you live longer? What about
>> drinking whisky and olive oil together?
>
> These things show correlations between things. The population level studies
> on bike helmets show /no/ correlation - that's the point. You can argue for
> ever about whether autosm is caused MMR or just happens to manifest at
> around the time the MMR is administered; in the case of helmets what you
> have is no discernible effect (see Tony's "spot the year" charts posted
> earlier).

Would even a large protective effect necessarily show up? Especially given
that minor and major head injuries are grouped together (i.e. all the
population studies use a blunt tool).

Suppose helmets were 60% effective at preventing head injuries. If c. 30%
of admissions include a head injury, if 40% more cyclists wore a helmet,
we might only expect to see a reduction of 100x(0.6*0.4*0.3) = 7.2% in the
total number of injuries that resulted in a head injury, or a 25% decrease
in the number of head injuries.

By eyeball, the amount of year-to-year variation in Tony's graphs is
pretty high compared to 25%. And we know this data is affected by a
decrease in cycling and other confounding factors.

>
>> Take the seatbelt paradox - seatbelts may not make the roads safer,
>> but if I get into a car as a passenger I'm probably well advised to
>> wear one. It's a while since I read John Adam's book, but IIRC the
>> population statistics would have suggested I shouldn't bother.
>
> Invalid comparison: Adams' population statistics show that for optimum
> safety everybody except the driver should wear one :-) As a passenger you
> will probably not materially affect the outcome of the journey.

There could be a similar argument for cycle-helmets. Assume that
due to helmet compulsion, there are fewer cyclists and the balance of
leisure v. transportational cyclists changes. Perhaps drivers will be less
cyclist-aware and may believe that cyclists are now invulnerable - causing
them to drive more dangerously and increase the proportion of accidents
that result in a head injury. Perhaps cyclists who were less likely to
have the sort of accident resulting in a head injury will stop cycling.
Even if helmets are quite effective they may not be good enough to counter
the increased risk, and the proportion of head injuries will go up.

If this scenario were accurate I would draw two conclusions:

Cycle-helmet compulsion is wrong and dangerous

As a cyclist, I should wear a helmet

It wouldn't be inconsistent with a level / increasing trend in the
proportion of injuries that include head injuries (though there may
be data that I'm not aware of to counter it).

AC

[Jon Senior]

Simon Brooke opined the following...
> in message >, Mark Tranchant
> Browsing that site as displacement activity because I have a
> particularly heavy workload just now, I came across this:
>
> <URL:http://www.topgear.com/content/jsp/bigpic.html?car=/content/my_topgear/prangs/01/04/bigImages/img01.gif>

Cracking. ;-)

Jon

[Jon Senior]

Just zis Guy, you know? opined the
following...
> On Mon, 14 Jun 2004 14:36:48 +0100, Mark Tranchant
> > wrote in message
> >:
>
> >http://www.topgear.com/content/my_topgear/prangs/05/03/
>
> The pictures in that site are a munument to stupidity, aren't they?
> So many of them are clearly the result of physics: 1 testosterone:
> nil. And the explanations? Not - ahem - universally plausible.

Absolutely staggering. The comments suggest that some of the muppets in
question (Not just referring to the muppet pictures!) are actually proud
of their handywork. It's a shame that the A+E services don't submit one
or two of the ones which ended a little worse!

Jon

[Dave Kahn]

On Mon, 14 Jun 2004 15:51:11 +0100, Peter Clinch
> wrote:

>Mark Tranchant wrote:
>
>> There are undoubtably situations where both seat belts and bicycle
>> helmets reduce one's survival chances. Take for example this accident:
>>
>> http://www.topgear.com/content/my_topgear/prangs/05/03/
>>
>> From the pictures, it's astonishing the driver survived. I'd suggest
>> that wearing a seatbelt would have given rise to a less fortunate outcome.
>
>This is indeed the case, but since you can't predict the sort of
>accident you'll have before it's too late, knowing that such cases exist
>isn't of much use. You've got to go with the overall probabilities
>every time for the best chance, though that doesn't guarantee you won't
>be caught in one of the uncommon accidents where your precautions work
>against you.

It's like playing backgammon. Over 2 or 3 games an indifferent player
can sometimes beat a professional. In the long term the pro will have
the shirt off his back.

--
Dave...

Get a bicycle. You will not regret it. If you live. - Mark Twain

[Dave Kahn]

On Mon, 14 Jun 2004 19:05:02 GMT, Simon Brooke >
wrote:

>Browsing that site as displacement activity because I have a
>particularly heavy workload just now, I came across this:
>
><URL:http://www.topgear.com/content/jsp/bigpic.html?car=/content/my_topgear/prangs/01/04/bigImages/img01.gif>

If they hadn't put the sign there he'd have been alright. :-)

--
Dave...

Get a bicycle. You will not regret it. If you live. - Mark Twain

[Just zis Guy, you know?]

anonymous coward wrote:

>> These things show correlations between things. The population level
>> studies on bike helmets show /no/ correlation - that's the point.
>> You can argue for ever about whether autosm is caused MMR or just
>> happens to manifest at around the time the MMR is administered; in
>> the case of helmets what you have is no discernible effect (see
>> Tony's "spot the year" charts posted earlier).

> Would even a large protective effect necessarily show up? Especially
> given that minor and major head injuries are grouped together (i.e.
> all the population studies use a blunt tool).

Absolutely. The charts as posted show the proportion of recorded cyclist
injuries which are head injuries. This varies very closely with the same
figure for the general population, and has no relationship at all to the
helmet wearing rate.

I suppose it is possible that helmets prevent large numbers of injuries but
there is some unrelated confounding factor which purely by coincidence
happens to wipe out the injury savings, and that happens to be increasing
with the differing rates of helmet use in different countries. It is also
possible that Elvis was abducted by aliens. Occam's Razor indicates that
neither of these is a sound basis for policy.

> Suppose helmets were 60% effective at preventing head injuries. If c.
> 30% of admissions include a head injury, if 40% more cyclists wore a
> helmet, we might only expect to see a reduction of 100x(0.6*0.4*0.3)
> = 7.2% in the total number of injuries that resulted in a head
> injury, or a 25% decrease in the number of head injuries.

But the charts show the /proportion/ of head injuries.

>>> Take the seatbelt paradox - seatbelts may not make the roads safer,
>>> but if I get into a car as a passenger I'm probably well advised to
>>> wear one. It's a while since I read John Adam's book, but IIRC the
>>> population statistics would have suggested I shouldn't bother.

>> Invalid comparison: Adams' population statistics show that for
>> optimum safety everybody except the driver should wear one :-) As a
>> passenger you will probably not materially affect the outcome of the
>> journey.

> There could be a similar argument for cycle-helmets. Assume that
> due to helmet compulsion, there are fewer cyclists and the balance of
> leisure v. transportational cyclists changes. Perhaps drivers will be
> less cyclist-aware and may believe that cyclists are now invulnerable
> - causing them to drive more dangerously and increase the proportion
> of accidents that result in a head injury. Perhaps cyclists who were
> less likely to have the sort of accident resulting in a head injury
> will stop cycling. Even if helmets are quite effective they may not
> be good enough to counter the increased risk, and the proportion of
> head injuries will go up.

Just one more reason not to advance helmet compulsion. The greatest
indicator of cyclist safety is the numbers cycling; anything which reduces
numbers cycling is likely to be counter-productive as a safety measure.
Yes, the risk per cyclist stays the same or goes up when compulsion is
introduced. You can interpret that as "helmets work but there is something
else going on" or as "helmets don't work" but until the "something else" is
identified either of these grounds makes compulsion a stupid policy, because
it has always failed up to now and we clearly don't know why so stand little
chance of accidentally making it work here.

And everything I have seen suggests that it is the least experienced and
least committed cyclists who are deterred by compulsion - precisely those
who are /most/ likely to suffer injury (who is more likely to ride in the
gutter, an experienced confident cyclist or a novice?). So it may be that
the additional danger for the reamainiang cyclists, given that the injury
figures do not improve, is actually much worse, rather than about the same.

> If this scenario were accurate I would draw two conclusions:
> Cycle-helmet compulsion is wrong and dangerous
> As a cyclist, I should wear a helmet

"Should" is a difficult word to justify in this context, especially since
the Liddites have essentially deprived us of the right to make up our own
minds by persuading the Government that every person wearing a helmet is
voting for compulsion. One more thing I find hard to forgive.

> It wouldn't be inconsistent with a level / increasing trend in the
> proportion of injuries that include head injuries (though there may
> be data that I'm not aware of to counter it).

The trend indicates no measurable effect on serious / fatal head injuries.
If you want to wear a helmet to protect you against trivial injuries, then
I'm sure it will work as expected.

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

Victory is ours! Down with Eric the Half A Brain!

[Peter Clinch]

anonymous coward wrote:

> Velocity is a vector and includes a directional component; speed is a
> scalar.

Quite so if your pedant hat is on, but the bottom line is that you'll
still hit at 24 mph with a deflection effect. I really don't think you
can just assume this is the same as 12 mph with no deflection effect:
the overall system is too complex.

> You can try - that's what crash-test dummies and the like are for. For
> example, I think I'm right in saying that most of the evidence against
> bull bars is based on kinematics and the epidemiological data against
> them is relatively weak.

But crash test dummies strapped into car seats are a great deal easier
to pick up data from than anything simulating a cyclist. In a car
you're strapped reasonably securely into a box. On a bike there are all
sorts of things which current dummy technology just doesn't really allow
you to do at all well. Put simply, a crash test dummy will not fly like
a person, and will not take reflexive head injury prevention like a
flying person.

<snip>

> Did JA have enough population data that he could make this claim without
> recourse to other types of study?

Dunno, but as above testing seatbelt efficacy in simulated crashes is a
*lot* easier than testing cycle helmet efficacy IMHO.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net http://www.dundee.ac.uk/~pjclinch/

[Peter Clinch]

anonymous coward wrote:

> If this scenario were accurate I would draw two conclusions:
>
> Cycle-helmet compulsion is wrong and dangerous
>
> As a cyclist, I should wear a helmet

Define "should"...
It suggests an assumption of a net upsides to wearing one, but that in
turn assumes safety can easily be valued quantitatively against comfort
and convenience. But it /can't/, because if it could be you'd be
wearing all sorts of protective equipment for mundane everyday things
like going down stairs.

People like to trot out things like "safety is our number one priority"
but that's frankly a load of tosh when you look at it. I certainly
don't do big downhills in such a way as to maximise my chances of
arriving safely at the bottom, and that goes for the clothes I wear as
well as how I ride the bike. It goes for a lot of things in day to day
life for most people too.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net http://www.dundee.ac.uk/~pjclinch/

[anonymous coward]

On Tue, 15 Jun 2004 09:21:22 +0100, Peter Clinch wrote:

> anonymous coward wrote:
>
>> Velocity is a vector and includes a directional component; speed is a
>> scalar.
>
> Quite so if your pedant hat is on, but the bottom line is that you'll
> still hit at 24 mph with a deflection effect. I really don't think you
> can just assume this is the same as 12 mph with no deflection effect:
> the overall system is too complex.

I agree with you - but I don't think absolute accuracy is essential in
order to establish the principle. Perhaps a 12mph direct collision would
be equivalent to a 20mph deflection, or an 18mph one. Or a 26mph one -
perhaps our cyclist flies up and over the handlebars and so hits the
windscreen even more acutely. Or perhaps torsional effects would mean our
cyclist would end up worse off than if he wasn't wearing a helmet at all.

~~~~~~~~~~~~~~~

To recap, my original disagreement was with the statement:

'They were probably wearing bicycle helmets, which are appropriate for
up to about 12mph (about 19Km/h)'

I've seen it on a few anti-helmet websites, so wondering where it came
from I looked up some helmet-testing manuals, and found that they tested
helmets by bashing them against solid objects at 12mph.

I gave one example where a 12mph collision might (IMO) stress a helmet
much more than it was designed for. I also argued that a helmet
designed to be hit at 12mph might be useful even in some much speedier
collisions.

Either way I still think the 12mph claim is on dodgy ground - and is a
misunderstanding / misrepresentation of the testing-authorities'
intentions.

>> You can try - that's what crash-test dummies and the like are for. For
>> example, I think I'm right in saying that most of the evidence against
>> bull bars is based on kinematics and the epidemiological data against
>> them is relatively weak.
>
> But crash test dummies strapped into car seats are a great deal easier
> to pick up data from than anything simulating a cyclist. In a car
> you're strapped reasonably securely into a box. On a bike there are all
> sorts of things which current dummy technology just doesn't really allow
> you to do at all well. Put simply, a crash test dummy will not fly like
> a person, and will not take reflexive head injury prevention like a
> flying person.

This makes sense to me.

> <snip>
>
>> Did JA have enough population data that he could make this claim without
>> recourse to other types of study?
>
> Dunno, but as above testing seatbelt efficacy in simulated crashes is a
> *lot* easier than testing cycle helmet efficacy IMHO.

I'm sure that's true. I don't know how insurmountable the obstacles are.

AC

[Peter Clinch]

anonymous coward wrote:

> Either way I still think the 12mph claim is on dodgy ground - and is a
> misunderstanding / misrepresentation of the testing-authorities'
> intentions.

Bottom line is that in a collision with a motor vehicle all the bets are
off. The lids are designed to whitstand the 12 mph test, and if you're
accident doesn't conform to that test then you can't usefully predict
what the helmet will achieve. Helmets are built /down/ to standards as
they can be made cheaper and more comfortable that way.

> I'm sure that's true. I don't know how insurmountable the obstacles are.

Not insurmountable, *if* there's sufficient money and will to overcome
them. The will primarily comes from the people who are seen as "anti
helmet" who are having great trouble getting it seen as a problem, and
aren't in possession of the money. Those who want helmets very badly
are already convinced so they're not looking to do this.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net http://www.dundee.ac.uk/~pjclinch/

[James Annan]

anonymous coward wrote:


> Would even a large protective effect necessarily show up?

Not in the UK stats, where helmet usage has crept up slowly. But
according to stats I've seen from some of the compulsion cases, helmet
usage rose markedly from one year to the next, with the number of
unhelmeted riders dropping like a stone. If helmets were any good, then
head injuries should also have fallen markedly at that time.

James

[Just zis Guy, you know?]

James Annan wrote:

> according to stats I've seen from some of the compulsion cases, helmet
> usage rose markedly from one year to the next, with the number of
> unhelmeted riders dropping like a stone. If helmets were any good,
> then head injuries should also have fallen markedly at that time.

Indeed. It would also be hard for the US rates to have risen by 40% in a
period when helmet use rose from 18% to 50%.

This is one reason, in my view, why the likes of BeHIT are actively
dangerous. By focusing attention exclusively on something which is known
not to work, at the population level, they prevent proper consideration of
things which can and do work. Their continued existence depends on falsely
portraying cycling as dangerous, and falsely portraying helmet use as one
of, if not the, best thing a cyclist can do to ensure safety.

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

[Just zis Guy, you know?]

anonymous coward wrote:

> I agree with you - but I don't think absolute accuracy is essential in
> order to establish the principle. Perhaps a 12mph direct collision
> would be equivalent to a 20mph deflection, or an 18mph one. Or a
> 26mph one - perhaps our cyclist flies up and over the handlebars and
> so hits the windscreen even more acutely. Or perhaps torsional
> effects would mean our cyclist would end up worse off than if he
> wasn't wearing a helmet at all.

Or perhaps all this is angels dancing on the head of a pin. Modern helmets
are designed to withstand the equivalent of a fall from a stationary riding
position (according to the UK's leading tester of helmets, among other
authorities). Discussing the mechanisms by which a traffic crash might or
might not be reduced to the energy levels found in such a fall is largely
irrelevant since (a) the available energy is very much higher than the
helmet is designed for, so any reduction of that is down to blind luck, and
(b) the human skull has been protecting us from such falls for some time -
unless you ride an Ordinary your head is not substantially higher on a bike
than it is when standing.

Why do drunks suffer head injuries when falling over? Because they are
drunk, so don't react quickly enough to protect their heads. Does this mean
we should have mandatory drinking helmets? Or might it be smarter to tackle
binge drinking instead? Same with cycling. Most serious cycling head
injuries are the result of motor vehicle impact, and most motor vehicle
impacts are the driver's fault. Injury rates in Holland are far lower
despite the well-documented indiscipline of Dutch cyclists (similar to the
reported indiscipline of British pedestrians ;-P). There is a cultural
difference in the way motorists react to cyclists. That is what makes the
difference. We need to effect a cultural change here as well, and we'll
never do that as long as every injured cyclist raises calls for more plastic
hats.

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

[Gawnsoft]

On Tue, 15 Jun 2004 11:04:52 +0100, anonymous coward
> wrote (more or less):
....
>To recap, my original disagreement was with the statement:
>
>'They were probably wearing bicycle helmets, which are appropriate for
>up to about 12mph (about 19Km/h)'
>
>I've seen it on a few anti-helmet websites, so wondering where it came
>from I looked up some helmet-testing manuals, and found that they tested
>helmets by bashing them against solid objects at 12mph.
>
>I gave one example where a 12mph collision might (IMO) stress a helmet
>much more than it was designed for. I also argued that a helmet
>designed to be hit at 12mph might be useful even in some much speedier
>collisions.
>
>Either way I still think the 12mph claim is on dodgy ground - and is a
>misunderstanding / misrepresentation of the testing-authorities'
>intentions.
....

As the person who wrote the statement with which you disagree:

I feel the 12mph is quite a fine figure for indicative purposes.

As you have already discovered for yourself, the actual testing for
the /highest/ standard of helmet is a 110J collision, measured by a
fall from a relatively low height onto an anvil, with a weight inside
representative of a head.

You've already done the calculations for yourself that shows what the
speed of such a helmet is at the moment of impact.

For the 2.2m drop, the head will be doing over 16.3mph from its
freefall under gravity at moment of impact.

If I fall from my bicycle - I'm not particularly tall (below UK
average male height), and my saddle is probably on the low side of
recommended height - the centre of mass of my head rides at about
1.8m, so a 14.7mph collision with the ground results from a fall even
when my bicycle is stationary.

That means that to remain within the helmet's envelope of 16.3mph I
shouldn't be doing more than 7mph of forward travel.

I'm happy to amend my previous 12mph figure down to 7mph if you
prefer.

But on the whole it's probably less misleading to have said that
bicycle helmets are able to protect us from falls from near-stationary
bicycles.

Do you prefer that statement?


--
Cheers,
Euan
Gawnsoft: http://www.gawnsoft.co.sr
Symbian/Epoc wiki: http://html.dnsalias.net:1122
Smalltalk links (harvested from comp.lang.smalltalk) http://html.dnsalias.net/gawnsoft/smalltalk

[anonymous coward]

On Tue, 15 Jun 2004 12:58:01 +0100, Gawnsoft wrote:

> On Tue, 15 Jun 2004 11:04:52 +0100, anonymous coward
> > wrote (more or less):
> ...
>>To recap, my original disagreement was with the statement:
>>
>>'They were probably wearing bicycle helmets, which are appropriate for
>>up to about 12mph (about 19Km/h)'
>>
>>I've seen it on a few anti-helmet websites, so wondering where it came
>>from I looked up some helmet-testing manuals, and found that they tested
>>helmets by bashing them against solid objects at 12mph.
>>
>>I gave one example where a 12mph collision might (IMO) stress a helmet
>>much more than it was designed for. I also argued that a helmet
>>designed to be hit at 12mph might be useful even in some much speedier
>>collisions.
>>
>>Either way I still think the 12mph claim is on dodgy ground - and is a
>>misunderstanding / misrepresentation of the testing-authorities'
>>intentions.
> ...
>
> As the person who wrote the statement with which you disagree:
>
> I feel the 12mph is quite a fine figure for indicative purposes.
>
> As you have already discovered for yourself, the actual testing for
> the /highest/ standard of helmet is a 110J collision, measured by a
> fall from a relatively low height onto an anvil, with a weight inside
> representative of a head.
>
> You've already done the calculations for yourself that shows what the
> speed of such a helmet is at the moment of impact.
>
> For the 2.2m drop, the head will be doing over 16.3mph from its
> freefall under gravity at moment of impact.
>
> If I fall from my bicycle - I'm not particularly tall (below UK
> average male height), and my saddle is probably on the low side of
> recommended height - the centre of mass of my head rides at about
> 1.8m, so a 14.7mph collision with the ground results from a fall even
> when my bicycle is stationary.
>
> That means that to remain within the helmet's envelope of 16.3mph I
> shouldn't be doing more than 7mph of forward travel.

sqrt(7^2 + 14.7^2) = 16mph - I see.

> I'm happy to amend my previous 12mph figure down to 7mph if you
> prefer.

You're missing my point - did I really make it so unclearly?

> But on the whole it's probably less misleading to have said that
> bicycle helmets are able to protect us from falls from near-stationary
> bicycles.
>
> Do you prefer that statement?

I do, but how about:

'Bicycle helmets are only designed to protect against modest impacts -
about as large as falling from a standing position and hitting your head
against the ground.'

It's accurate and simple. And it doesn't assume any particular scenario.

AC

[anonymous coward]

On Tue, 15 Jun 2004 09:19:59 +0100, Just zis Guy, you know? wrote:

> anonymous coward wrote:
>
>>> These things show correlations between things. The population level
>>> studies on bike helmets show /no/ correlation - that's the point.
>>> You can argue for ever about whether autosm is caused MMR or just
>>> happens to manifest at around the time the MMR is administered; in
>>> the case of helmets what you have is no discernible effect (see
>>> Tony's "spot the year" charts posted earlier).
>
>> Would even a large protective effect necessarily show up? Especially
>> given that minor and major head injuries are grouped together (i.e.
>> all the population studies use a blunt tool).
>
> Absolutely. The charts as posted show the proportion of recorded cyclist
> injuries which are head injuries. This varies very closely with the same
> figure for the general population, and has no relationship at all to the
> helmet wearing rate.
>
> I suppose it is possible that helmets prevent large numbers of injuries but
> there is some unrelated confounding factor which purely by coincidence
> happens to wipe out the injury savings, and that happens to be increasing
> with the differing rates of helmet use in different countries. It is also
> possible that Elvis was abducted by aliens. Occam's Razor indicates that
> neither of these is a sound basis for policy.
>
>> Suppose helmets were 60% effective at preventing head injuries. If c.
>> 30% of admissions include a head injury, if 40% more cyclists wore a
>> helmet, we might only expect to see a reduction of 100x(0.6*0.4*0.3)
>> = 7.2% in the total number of injuries that resulted in a head
>> injury, or a 25% decrease in the number of head injuries.
>
> But the charts show the /proportion/ of head injuries.

OK - but the numbers I made up would remain the same.

7% reduction in the proportion of injuries that result in head injuries; a
25% reduction from the baseline.

Looking at the Australian graph, after helmet compulsion there's an
_increase_ of about this order in the proportion of injuries that result
in head injuries. Almost every year, there's a random change of about
3-10% that is uncorrelated between pedestrians and cyclists. And between
1971 and 1995 the proportion of injuries resulting in head injuries has
varied between about 50% and 25%.

o) Many factors influence head-injuries/injuries other than bike helmets.

o) I still think it would be difficult to find a 7% change given that
amount of noise.

>>>> Take the seatbelt paradox - seatbelts may not make the roads safer,
>>>> but if I get into a car as a passenger I'm probably well advised to
>>>> wear one. It's a while since I read John Adam's book, but IIRC the
>>>> population statistics would have suggested I shouldn't bother.
>
>>> Invalid comparison: Adams' population statistics show that for
>>> optimum safety everybody except the driver should wear one :-) As a
>>> passenger you will probably not materially affect the outcome of the
>>> journey.

As I recall, the KSI rate didn't change much after seatbelt legislation
was passed. That's the population study I was referring to.

>> There could be a similar argument for cycle-helmets. Assume that due to
>> helmet compulsion, there are fewer cyclists and the balance of leisure
>> v. transportational cyclists changes. Perhaps drivers will be less
>> cyclist-aware and may believe that cyclists are now invulnerable -
>> causing them to drive more dangerously and increase the proportion of
>> accidents that result in a head injury. Perhaps cyclists who were less
>> likely to have the sort of accident resulting in a head injury will
>> stop cycling. Even if helmets are quite effective they may not be good
>> enough to counter the increased risk, and the proportion of head
>> injuries will go up.
>
> Just one more reason not to advance helmet compulsion.

That's what I said...

> The greatest
> indicator of cyclist safety is the numbers cycling; anything which reduces
> numbers cycling is likely to be counter-productive as a safety measure.
> Yes, the risk per cyclist stays the same or goes up when compulsion is
> introduced. You can interpret that as "helmets work but there is something
> else going on" or as "helmets don't work" but until the "something else" is
> identified either of these grounds makes compulsion a stupid policy, because
> it has always failed up to now and we clearly don't know why so stand little
> chance of accidentally making it work here.
>
> And everything I have seen suggests that it is the least experienced and
> least committed cyclists who are deterred by compulsion - precisely those
> who are /most/ likely to suffer injury (who is more likely to ride in the
> gutter, an experienced confident cyclist or a novice?). So it may be that
> the additional danger for the reamainiang cyclists, given that the injury
> figures do not improve, is actually much worse, rather than about the same.

I thought you said that a factor linked to helmet compulsion that
increased the risk to cyclists was about as likely as Elvis being abducted
by aliens?

>> If this scenario were accurate I would draw two conclusions:
>> Cycle-helmet compulsion is wrong and dangerous
>> As a cyclist, I should wear a helmet
>
> "Should" is a difficult word to justify in this context, especially
> since the Liddites have essentially deprived us of the right to make up
> our own minds by persuading the Government that every person wearing a
> helmet is voting for compulsion. One more thing I find hard to forgive.
>
>> It wouldn't be inconsistent with a level / increasing trend in the
>> proportion of injuries that include head injuries (though there may be
>> data that I'm not aware of to counter it).
>
> The trend indicates no measurable effect on serious / fatal head
> injuries. If you want to wear a helmet to protect you against trivial
> injuries, then I'm sure it will work as expected.

[Just zis Guy, you know?]

anonymous coward wrote:

>>> Suppose helmets were 60% effective at preventing head injuries. If
>>> c. 30% of admissions include a head injury, if 40% more cyclists
>>> wore a helmet, we might only expect to see a reduction of
>>> 100x(0.6*0.4*0.3) = 7.2%

>> But the charts show the /proportion/ of head injuries.

> OK - but the numbers I made up would remain the same.

The Australian law caused an increase in very short order from <35% to >80%
usage. Around half of injuries requiring hospitalisation are head injuries,
so you're talking about more like 0.6 x 0.5 x 0.45, about 10% to an order of
magnitude. The onserved change is around 0% to an order of magnitude.
Therefore either (a) the 60% figure is wrong, or (b) the exercise is
essentially meaningless.

> Looking at the Australian graph, after helmet compulsion there's an
> _increase_ of about this order in the proportion of injuries that
> result in head injuries. Almost every year, there's a random change
> of about 3-10% that is uncorrelated between pedestrians and cyclists.

That's probably noise due to small sample size. Take a 5-year rolling
average and have another look.

> o) Many factors influence head-injuries/injuries other than bike
> helmets.

More likely, other factors account for all the variation :-)

> o) I still think it would be difficult to find a 7% change given that
> amount of noise.

Take a 5-year rolling average and try again.

> As I recall, the KSI rate didn't change much after seatbelt
> legislation was passed. That's the population study I was referring
> to.

Correct. But a significant number of fatalities were switched from drivers
to peds, cyclists and rear passengers (each of whom experienced the largest
recorded year on year rise in fatality rates, IIRC).

There are a lot of studies on seat belts, ABS and other devices wihch show
that drivers respond to a perceived increase in safety by driving less
carefully.

>> And everything I have seen suggests that it is the least experienced
>> and least committed cyclists who are deterred by compulsion -
>> precisely those who are /most/ likely to suffer injury (who is more
>> likely to ride in the gutter, an experienced confident cyclist or a
>> novice?). So it may be that the additional danger for the
>> reamainiang cyclists, given that the injury figures do not improve,
>> is actually much worse, rather than about the same.

> I thought you said that a factor linked to helmet compulsion that
> increased the risk to cyclists was about as likely as Elvis being
> abducted by aliens?

1. The suggested effect would balance the inrceased risk due to lower
numbers cycling with reduced casualties due to the most causalty-prone being
off the road; nett result: no change. As observed. No helmets were harmed
in the making of this argument.

2. The comment was that if you start from the assumption that the thing you
want has happened, then look for explanations as to why it is not visible,
you will probably end up with the wrong answer (for details see P**l Sm*th).
If, on the other hand, you look at the injury figures and see how they
compare with other known factors, the obvious conclusion is that - well,
there is no conclusion to draw, there being basically no effect to explain.

The best response is to say that the data is equivocal, and leave it at
that. Unfortunately we are not alowed to. Every cyclist who wears a helmet
is counted as one vote for compulsion by the Government (this offends me
deeply, bu the way) and even suggestion that the data is equivocal is met
with strident cries of "irresponsible" because it might encourage people to
cycle without a helmet; the fact that this criticism is an example of
begging the question does not seem to occur to those making it.

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

[Tony Raven]

Jon Senior wrote:
> Just zis Guy, you know? opined the
> following...
>> On Mon, 14 Jun 2004 14:36:48 +0100, Mark Tranchant
>> > wrote in message
>> >:
>>
>>> http://www.topgear.com/content/my_topgear/prangs/05/03/
>>
>> The pictures in that site are a munument to stupidity, aren't they?
>> So many of them are clearly the result of physics: 1 testosterone:
>> nil. And the explanations? Not - ahem - universally plausible.
>
> Absolutely staggering. The comments suggest that some of the muppets in
> question (Not just referring to the muppet pictures!) are actually proud
> of their handywork. It's a shame that the A+E services don't submit one
> or two of the ones which ended a little worse!
>

A bit like the muppets at MBUK who publish pictures of this months reader
horrific cycling injury. Seems there is some competition to get your picture
published

Tony

[Tony Raven]

Just zis Guy, you know? wrote:
> On Mon, 14 Jun 2004 14:36:48 +0100, Mark Tranchant
> > wrote in message
> >:
>
>> http://www.topgear.com/content/my_topgear/prangs/05/03/
>
> The pictures in that site are a munument to stupidity, aren't they?
> So many of them are clearly the result of physics: 1 testosterone:
> nil. And the explanations? Not - ahem - universally plausible.
>

How do we check if this admission to multiple law breaking has been taken up
by the plod?

"Here's a scary one: Jenny Pincent's Ford Escort was literally torn in half
when she lost control at *100mph* on a wet road and slammed into a tree. The
front of the car ended up 30 yards from the rear, and Jenny was somewhere in
between. She *wasn't wearing a seatbelt*, and was thrown clear of the car upon
impact, emerging from the wreckage with only minor injuries."


Tony

[Ambrose Nankivell]

In ,
Tony Raven > typed:
> Just zis Guy, you know? wrote:
>> On Mon, 14 Jun 2004 14:36:48 +0100, Mark Tranchant
>> > wrote in message
>> >:
>>
>>> http://www.topgear.com/content/my_topgear/prangs/05/03/
>>
>> The pictures in that site are a munument to stupidity, aren't they?
>> So many of them are clearly the result of physics: 1 testosterone:
>> nil. And the explanations? Not - ahem - universally plausible.
>>
>
> How do we check if this admission to multiple law breaking has been
> taken up by the plod?
>
> "Here's a scary one: Jenny Pincent's Ford Escort was literally torn
> in half when she lost control at *100mph* on a wet road and slammed
> into a tree. The front of the car ended up 30 yards from the rear,
> and Jenny was somewhere in between. She *wasn't wearing a seatbelt*,
> and was thrown clear of the car upon impact, emerging from the
> wreckage with only minor injuries."

She was also driving a LHD car, so I imagine it was in another country.
Don't know which one, though.

[burt]

"Just zis Guy, you know?" > wrote in message
...
> anonymous coward wrote:
>
> Guy
> ===
> May contain traces of irony. Contents liable to settle after posting.
> http://www.chapmancentral.co.uk
>
> Victory is ours! Down with Eric the Half A Brain!

Please stop exaggerating! :-)
--
cheers

Rich

>
>

[Dave Kahn]

On Wed, 16 Jun 2004 18:02:34 +0100, "burt"
> wrote:

>> Victory is ours! Down with Eric the Half A Brain!
>
>Please stop exaggerating! :-)

About the victory, or the size of the brain?

--
Dave...

Get a bicycle. You will not regret it. If you live. - Mark Twain

[Patrick Herring]

anonymous coward > wrote:

| On Tue, 15 Jun 2004 12:58:01 +0100, Gawnsoft wrote:
....
| > But on the whole it's probably less misleading to have said that
| > bicycle helmets are able to protect us from falls from near-stationary
| > bicycles.
| >
| > Do you prefer that statement?
|
| I do, but how about:
|
| 'Bicycle helmets are only designed to protect against modest impacts -
| about as large as falling from a standing position and hitting your head
| against the ground.'

Which also means helmets aren't much use in their intended context -
protecting the heads in spills off-road on (or off <g>) mountain
bikes.



--
Patrick Herring, Sheffield, UK
http://www.anweald.co.uk

[Peter Clinch]

Patrick Herring wrote:

> Which also means helmets aren't much use in their intended context -
> protecting the heads in spills off-road on (or off <g>) mountain
> bikes.

Most of my parting company with my MTB is when I grind to a halt and
keel over sideways in too awkward a fashion to save. Often there are
boulders involved, or at least nearby scattered festively about the
track, so to my mind that's exactly the sort of place they're good for.

Note how the Certificate Daft downhill brigade wear /much/ more serious
headgear.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net http://www.dundee.ac.uk/~pjclinch/

[Simon Brooke]

in message >, Patrick Herring
') wrote:

> anonymous coward > wrote:
>
> | On Tue, 15 Jun 2004 12:58:01 +0100, Gawnsoft wrote:
> ...
> | > But on the whole it's probably less misleading to have said that
> | > bicycle helmets are able to protect us from falls from
> | > near-stationary bicycles.
> | >
> | > Do you prefer that statement?
> |
> | I do, but how about:
> |
> | 'Bicycle helmets are only designed to protect against modest impacts
> | - about as large as falling from a standing position and hitting
> | your head against the ground.'
>
> Which also means helmets aren't much use in their intended context -
> protecting the heads in spills off-road on (or off <g>) mountain
> bikes.

Actually, they may be. Most mountain bike spills (lunatic downhilling
excepted - but the lunatic downhillers wear much stronger helmets) are
at very low speeds, and, although there are usually rocks and trees
around, nine times out of ten what you fall onto is softish.

I'm extremely skeptical of the effectiveness of helmets in road traffic
accidents and never wear one on the road - but I do sometimes wear one
off road. Mind you, I'm not wearing it in the expectation that it will
protect me if I hit a tree at speed, but in the expectation that I'll
protect myself from scalp lascerations and such.

--
(Simon Brooke) http://www.jasmine.org.uk/~simon/

See one nuclear war, you've seen them all.

[Patrick Herring]

Simon Brooke > wrote:

| in message >, Patrick Herring
| ') wrote:
|
| > anonymous coward > wrote:
| >
| > | On Tue, 15 Jun 2004 12:58:01 +0100, Gawnsoft wrote:
| > ...
| > | > But on the whole it's probably less misleading to have said that
| > | > bicycle helmets are able to protect us from falls from
| > | > near-stationary bicycles.
| > | >
| > | > Do you prefer that statement?
| > |
| > | I do, but how about:
| > |
| > | 'Bicycle helmets are only designed to protect against modest impacts
| > | - about as large as falling from a standing position and hitting
| > | your head against the ground.'
| >
| > Which also means helmets aren't much use in their intended context -
| > protecting the heads in spills off-road on (or off <g>) mountain
| > bikes.
|
| Actually, they may be. Most mountain bike spills (lunatic downhilling
| excepted - but the lunatic downhillers wear much stronger helmets) are
| at very low speeds, and, although there are usually rocks and trees
| around, nine times out of ten what you fall onto is softish.

Well, I'll take your and Peter's word for it. Didn't know about
lunatic downhill helmets.

| I'm extremely skeptical of the effectiveness of helmets in road traffic
| accidents and never wear one on the road - but I do sometimes wear one
| off road. Mind you, I'm not wearing it in the expectation that it will
| protect me if I hit a tree at speed, but in the expectation that I'll
| protect myself from scalp lascerations and such.

Yes, I'm extremely skeptical of the ability of most drivers to know
how much a helmet will protect you from their mistakes, and will
assume near infallibility in urban "accidents" (otherwise why would
"they" have authorised them?), whereas most trees will probably be
reciting elvish poetry to themselves and ignore you completely.

--
Patrick Herring, Sheffield, UK
http://www.anweald.co.uk

[Sue]

In message >, Patrick Herring
> writes
>
>Which also means helmets aren't much use in their intended context -
>protecting the heads in spills off-road on (or off <g>) mountain
>bikes.
>
I've had two dents put in mine while wearing it.

First, I had a really sucky fall caused by a slippery muddy branch lying
at an angle across the track, which sent my back wheel flying. I fell
harmlessly and rolled over, then hit my head on the corner of a log
which was lying on the ground minding its own business. Hard enough to
make my head ring, even with the helmet - without it I'd also have
needed stitches in a scalp wound.

Second, I faceplanted on the Ridgeway through not paying attention. I
landed on the lower part of my face and the rim of my helmet, luckily
onto smooth packed chalk without the loose stones that normally punch
holes in your face in this kind of fall.
My nose was bleeding and my lunchtime pint was drunk through a straw,
but the helmet could well have saved me a broken nose.

I don't think cycle helmets save many lives, but I do think they save
MTB riders quite a bit of pain and queueing in A&E. Alternatively, they
allow us to ride more playfully and less cautiously - it is a sport, not
a means of transport.

Like Simon, I don't wear one when riding on roads.

--
Sue ];(:)