another helmet saves head injury story

"Mr. Benn" wrote in message
...
Tony Raven" wrote in message
...
Mr. Benn wrote:

"Tony Raving Loony" wrote in message

Don't tell me - it was broken. A broken helmet has failed pure and
simple and not worked as it is designed to do.

Is that so?


No it isn't. the anti helmet brigade regularly trot this out, just as they
regularly trot out the opinions of Brian Walker - except of course those
that embarrass their argument, eg;

"As it is impacted,
the expanded polystyrene shell of
the helmet dissipates the energy
over a rapidly increasing area like
a cone. Movement of a helmet
about the head and breakage of
the helmet shell also assist with
the reduction of some energy"
Cycle July 2005

pk

pk wrote:

No it isn't. the anti helmet brigade

whoever they are... but since you persist in this fiction of an "anti
helmet brigade" it appears you mean the likes of me and folk who point
to work on cyclehelmets.org

regularly trot this out, just as
they regularly trot out the opinions of Brian Walker - except of course
those that embarrass their argument, eg;

Brian Walker is on the editorial board of BHRF. The article you point
to is quite openly referenced there, and often referenced by "the anti
helmet brigade" as a good heads-up on what one can expect. So hardly
brushed under the carpet.

"As it is impacted,
the expanded polystyrene shell of
the helmet dissipates the energy
over a rapidly increasing area like
a cone. Movement of a helmet
about the head and breakage of
the helmet shell also assist with
the reduction of some energy"

Read that again, and realise it doesn't contradict what you imply it
contradicts. "Some energy" is not very well quantified, is it? Or
perhaps since movement absorbs "some energy" it's a good idea to leave
the straps really loose?

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/

Mr. Benn wrote:
I'm inclined to believe him, especially after he showed
me what remained of the helmet.

Don't tell me - it was broken. A broken helmet has failed pure and
simple and not worked as it is designed to do.

Is that so?

Yes. Brittle fracture absorbs virtually no energy. Try it for
yourself. Try crushing an inch thick sheet of polystyrene foam and then
try snapping it.


And whatever your friend told you, the overwhelming probability is
that he wouldn't have been much worse off.

You witnessed the accident did you?

No and neither did you. All we have is his anecdotal tale to go by and
statistics that say that at best only 30 a year "helmet saved my life"
stories can be true and that's assuming helmets are 100% effective at
saving lives. More detailed analysis by TRT says that, even if helmets
are 50% effective, only 3-5 can be true. I doubt very much your friend
is one of them, especially as the best evidence shows helmet
effectiveness to be about 0%.


He is one of the many thousands who make that claim annually yet the
statistics say the vast majority of them cannot be true or the
hospitals, morgues and care homes would be full to the brim with all
the cyclists who suffered a brain injury or death because they weren't
wearing a helmet when they had their accidents.

There is nothing better than speaking from personal experience.

There were lots of people that attested from their personal experience
that smoking was good for their health, including many doctors, before
Sir Richard Doll put their anecdotes aside and gathered the statistics.
And there were lots that attested from personal experience that MMR
triggered autism in their child or that their silicone implant had
triggered their autoimmune disease. Except it has since been shown
pretty conclusively that their personal experience based view was wrong.

Not that I expect that to change your belief in your friends opinion one
iota.

Tony

"pk" wrote in message
...
"Mr. Benn" wrote in message
...
Tony Raven" wrote in message
...
Mr. Benn wrote:

"Tony Raving Loony" wrote in message

Don't tell me - it was broken. A broken helmet has failed pure and
simple and not worked as it is designed to do.

Is that so?


No it isn't. the anti helmet brigade regularly trot this out, just as they
regularly trot out the opinions of Brian Walker - except of course those
that embarrass their argument, eg;

"As it is impacted,
the expanded polystyrene shell of
the helmet dissipates the energy
over a rapidly increasing area like
a cone. Movement of a helmet
about the head and breakage of
the helmet shell also assist with
the reduction of some energy"
Cycle July 2005

pk

Yes, that is what I understood to be the case. The helmet fractures as part
of the impact-absorbing process. It's impossible to argue with the deniers.

Mike P wrote:
On Sun, 22 Aug 2010 16:43:28 +0000, Tony Raven boggled us with:

Or not since he got a grazed eyebrow and when I last checked eyebrows
were still considered to be located on the head. OTOH the grazed
eyebrow is indisputable proof of his claim that his helmet saved his
life.

Sometimes I wear a helmet. Sometimes I don't.

I fail to see how something a fraction of the cost of my £300 Shoei
motorcycle helmet can provide a similar level of protection - lets face
it, doing 20mph around town on a pushbike isn't that much slower than
30mph on a motorbike.

If helmets provide so much protection, make them better, and make them
the law.

If, however, I suspect they're not that great, don't..


I think your irony detectors need a service.

Tony

"Tony Raven" wrote in message
...
Mr. Benn wrote:

What name did you post under before you started using "Tony Raven"? I could
have sworn I have come across you before and you ended up in my killfile.

Derek C wrote:
On Aug 23, 12:15 pm, Tony Raven wrote:

Even though the main point of impact was clearly your teeth and upper
jawbone, neither of which are protected by cycle helmets other than the
full face ones? Curious, you clearly are a believer in TRT and Cook and
Sheikh's belief that helmets are able to project protection as a distance.


As you don't know exactly the manner in which my head hit the
kerbstone, I can't see how you can say that! A helmet would have
protruded an inch or so outside of my cranium, and would have taken
most of the initial impact.


There are limited scenarios in which you can damage your upper jawbone
and teeth on a kerbstone as the primary injury without significant
damage to your cheekbones or nose as well. Plus most people have a
flexible neck so even if a projecting helmet became the first point of
impact, it would not do much to mitigate an impact to the lower face.

Tony

Mr. Benn wrote:

Yes, that is what I understood to be the case. The helmet fractures as
part of the impact-absorbing process.

At about the very end of it, and it absorbs remarkably little.

It's impossible to argue with the deniers.

Who's denying it absorbs /some/ energy? A leather jacket will involve
/some/ of the energy of a rifle bullet, but that's not the same as
making a leather jacket good bulletproof armour.

In the meantime, perhaps you'd show us some figures indicating how the
use of helmets has made a clear improvement in serious head injury
amongst cyclists. If you can, that would be a more useful tangible
measure than "some energy is absorbed".

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/

Mr. Benn wrote:
"Tony Raven" wrote in message
...
Mr. Benn wrote:

What name did you post under before you started using "Tony Raven"? I
could have sworn I have come across you before and you ended up in my
killfile.

Same name since back to the early '90s although the email address
associated with it has changed over the years. Feel free to put me
there if you wish.

Tony

pk wrote:
"Mr. Benn" wrote in message
...
Tony Raven" wrote in message
...
Mr. Benn wrote:

"Tony Raving Loony" wrote in message

Don't tell me - it was broken. A broken helmet has failed pure and
simple and not worked as it is designed to do.

Is that so?


No it isn't. the anti helmet brigade regularly trot this out, just as
they regularly trot out the opinions of Brian Walker - except of course
those that embarrass their argument, eg;

"As it is impacted,
the expanded polystyrene shell of
the helmet dissipates the energy
over a rapidly increasing area like
a cone. Movement of a helmet
about the head and breakage of
the helmet shell also assist with
the reduction of some energy"
Cycle July 2005


You need to distinguish between (arc) cracking around the periphery of
the impact area where the compressed polystyrene is being stretched near
the surface where it joins the uncompressed bulk and cracking of the
polystyrene shell where it fractures. As noted in the Australian
Transportation Safety Board* testing of a wide range of motorbike and
cycle helmets:

"The majority of cracking displayed by samples was in the shape of an
arc outlining the spherical headform on impact. Arc-cracking has minimal
effect, as it is part of the crushing process.

However, cracks developing partly or fully through the thickness of the
foam-slab renders it useless in crushing and absorbing impact forces."

And that was testing within the normal design limits. At higher impact
speeds slab cracking becomes an all too common outcome as seen by the
number of broken helmets people hold up thinking it means they've done a
good job.

* Improved Shock Absorbing Liner for Helmets, Morgan D.E., Szabo L.S.,
ATSB, July 2001.

Tony


Tony