Helmets

Chris Slade said:

ISTM that having the
helmet fall off at the slightest impact would be a safety bonus. ;-)

So the answer to the question[1] is now 'indulging in preemptive
safety'..

...d

[1] Where's your h****t?

Simon Brooke said:

in message <[email hidden]>, OG
([email hidden]'😉 wrote:

Quoted message said:

Quoted message said:

Since nobody has responded to this post in the last few days is it fair
to assume that there is not any good scientific evidence that micro-shell
helmets give rise to a 'grab and rotate' hazard?

Quoted message said:

As far as I know, there's no hard data on the 'grab and rotate' hazard
of /any/ cycle helmet type. There's generally not enough research on cycle
safety altogether, and I think this is just another aspect which has never
actually been studied.

Tie one type of helmet to one foot, the other to the other foot, and
go for a walk up the road, trying to skid your feet under load. After
several minutes you should have gathered eough impressions either to
make up your mind, or to be able to design a better experiment.

--
Chris Malcolm [email hidden] DoD #205
IPAB, Informatics, JCMB, King's Buildings, Edinburgh, EH9 3JZ, UK
[http://www.dai.ed.ac.uk/homes/cam/]

"Chris Malcolm" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Simon Brooke said:

in message <[email hidden]>, OG
([email hidden]'😉 wrote:

Quoted message said:

Quoted message said:

Since nobody has responded to this post in the last few days is it fair
to assume that there is not any good scientific evidence that
micro-shell
helmets give rise to a 'grab and rotate' hazard?

Quoted message said:

As far as I know, there's no hard data on the 'grab and rotate' hazard
of /any/ cycle helmet type. There's generally not enough research on
cycle
safety altogether, and I think this is just another aspect which has
never
actually been studied.

Tie one type of helmet to one foot, the other to the other foot, and
go for a walk up the road, trying to skid your feet under load. After
several minutes you should have gathered eough impressions either to
make up your mind, or to be able to design a better experiment.

Can you imagine the reaction from h-sceptics if the pro-h case used a
similar level of experimental techniques?
:-)

OG wrote on 27/11/2006 22:09 +0100:

Quoted message said:

Can you imagine the reaction from h-sceptics if the pro-h case used a
similar level of experimental techniques?
:-)

Yes it would shock them. It's so much more sophisticated than the bulk
of their own work.

--
Tony

"Anyone who conducts an argument by appealing to authority is not using
his intelligence; he is just using his memory."
- Leonardo da Vinci

OG said:

Can you imagine the reaction from h-sceptics if the pro-h case used a
similar level of experimental techniques?
:-)

To do experiments you start with thought experiments, then do simple,
easy ones without proper measurements to give you an idea or two for the
Real Thing. The proposal falls into that latter category, but will
still give you some potentially useful qualitative information.

That is much better science than "this is the answer we've decided on up
front, and if the facts don't conform to the theory then we'll ignore them".

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 [email hidden] http://www.dundee.ac.uk/~pjclinch/

Peter Clinch said:

OG said:

Can you imagine the reaction from h-sceptics if the pro-h case used a
similar level of experimental techniques?
:-)

To do experiments you start with thought experiments, then do simple,
easy ones without proper measurements to give you an idea or two for the
Real Thing. The proposal falls into that latter category, but will
still give you some potentially useful qualitative information.

That is much better science than "this is the answer we've decided on up
front, and if the facts don't conform to the theory then we'll ignore
them".

Following up my own post, Richard Feynman said the following in the wake
of the Challenger disaster enquiry (where he did a /very/ influential
experiment on TV with just a glass of ice water, a clamp and some O-ring
material): "For a successful technology, reality must take precedence
over public relations, for nature cannot be fooled."

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 [email hidden] http://www.dundee.ac.uk/~pjclinch/

in message <[email hidden]>, Peter Clinch

(') said:

OG said:

Can you imagine the reaction from h-sceptics if the pro-h case used a
similar level of experimental techniques?
:-)

To do experiments you start with thought experiments, then do simple,
easy ones without proper measurements to give you an idea or two for the
Real Thing. The proposal falls into that latter category, but will
still give you some potentially useful qualitative information.

I think my proposed experimental rig would probably be a weighted pendulum
(fixed mass) with an arm several metres long. The helmet would be mounted
on dummy head that pivoted on an axis parallel to the axis of swing of the
pendulum at a fixed distance from the point of contact, and that pivot
would have a clutch with constant pressure. The pendulum would be swung
from a fixed height calculated so that at the lowest point of the swing
the helmet would be travelling at 4.17m/s. A surface with a coefficient of
friction similar to road tarmac would be mounted so that it was 1mm higher
than the lowest point on the helmet at the lowest point of the swing, and
would be large enough that helmet would only ever hit the flat surface,
never an edge of it.

Procedure: for each type of helmet, run a series of swings and for each
swing measure the amount that the clutch has rotated; after each swing,
obviously, reset the clutch so that the helmet is normal to the arm. Score
each helmet type according to the average displacement of the clutch.

For control, run the test with a dummy head with a wig of real human hair
firmly attached.

I would need to take advice as to whether the clutch axis should be the
same distance from the 'scalp' of the dummy head as from the surface of
the helmets.

Any improvement on this experimental design?

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/

The Conservative Party is now dead. The corpse may still be
twitching, but resurrection is not an option - unless Satan
chucks them out of Hell as too objectionable even for him.

Simon Brooke said:

For control, run the test with a dummy head with a wig of real human hair
firmly attached.

Quoted message said:

Any improvement on this experimental design?

The wig doesn't have real human scalp, which is important to slapheads
like me as well as probably affecting how the hair will act to some degree.

You need a human head. One would hope that Mr. Martlew or Ms. Lee
would, in the spirit of proving the efficacy of their beloved hats, be
willing to volunteer...

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 [email hidden] http://www.dundee.ac.uk/~pjclinch/

Peter Clinch wrote on 29/11/2006 09:24 +0100:

Quoted message said:

You need a human head. One would hope that Mr. Martlew or Ms. Lee
would, in the spirit of proving the efficacy of their beloved hats, be
willing to volunteer...

Images of the next BMA AGM of a large number of doctors struggling to
invert and lift the bulks of Ms Lee and Mr Martlew so they can be
dropped on their helmeted heads from 1.5m. Like this year's infamous
melon experiment though I think it should be repeated without the helmet
to demonstrate the difference.

--
Tony

"...has many omissions and contains much that is apocryphal, or at least
wildly inaccurate..."
Douglas Adams; The Hitchhiker's Guide to the Galaxy

Quoted message said:

Images of the next BMA AGM of a large number of doctors struggling to
invert and lift the bulks of Ms Lee and Mr Martlew so they can be
dropped on their helmeted heads from 1.5m.

B'ah, a small drop like that won't convince anyone of the bicycle helmets
protective capabilities.

I vote for dropping a lorry or bus from a height of 1.5 metres above their
helmeted heads. Then test Snell-standard helmets using something a little
more demanding, like a cruise ship or perhaps an oil tanker.

Simon Brooke said:

in message <[email hidden]>, Peter Clinch

(') said:

OG said:

Can you imagine the reaction from h-sceptics if the pro-h case used a
similar level of experimental techniques?
:-)

To do experiments you start with thought experiments, then do simple,
easy ones without proper measurements to give you an idea or two for the
Real Thing. The proposal falls into that latter category, but will
still give you some potentially useful qualitative information.

I think my proposed experimental rig would probably be a weighted pendulum
(fixed mass) with an arm several metres long. The helmet would be mounted
on dummy head that pivoted on an axis parallel to the axis of swing of the
pendulum at a fixed distance from the point of contact, and that pivot
would have a clutch with constant pressure. The pendulum would be swung
from a fixed height calculated so that at the lowest point of the swing
the helmet would be travelling at 4.17m/s. A surface with a coefficient of
friction similar to road tarmac would be mounted so that it was 1mm higher
than the lowest point on the helmet at the lowest point of the swing, and
would be large enough that helmet would only ever hit the flat surface,
never an edge of it.

I think a similar rig exists or existed except the helmet was not on
the arm but on a head. . Check out jousting training (quintain) cira
1500 AD. 🙂

John Kane, Kingston ON Canada

Tony Raven said:

dropped on their helmeted heads from 1.5m. Like this year's infamous
melon experiment though I think it should be repeated without the helmet
to demonstrate the difference.

But that's the crappiest thing about the whole seriously [censored]
incident - there was no experiment. Doctor melon-for-brains (I cba to
check what his name actually was) didn't actually do any experiment -
he merely asserted what the outcome would be, from a basis of complete
ignorance.

So it's not even the case that BMA policy is founded on the argument
that what's good for vegetables must be good for their patients - we
don't even actually know that it _is_ good for vegetables. BMA policy
is founded on the basis of what _might_ be good for vegetables _must_
be good for the hapless would-be-patients.

Doctor training doesn't seem to have developed much in some parts
from the middle ages...

regards, Ian SMith
--
|\ /| no .sig
|o o|
|/ \|

Ian Smith said:

BMA policy
is founded on the basis of what might be good for vegetables must
be good for the hapless would-be-patients.

Melon's are fruit. http://en.wikipedia.org/wiki/Melon :-)

Not that it makes any difference to the non-experiment being extrapolated to
potential patients.
--
Chris

"This isn't right. This isn't even wrong."
-- Wolfgang Pauli

Chris Slade wrote on 29/11/2006 18:04 +0100:

Quoted message said:

Ian Smith said:

BMA policy
is founded on the basis of what might be good for vegetables must
be good for the hapless would-be-patients.

Melon's are fruit. http://en.wikipedia.org/wiki/Melon :-)

Or not as the case may be:
http://en.wikipedia.org/wiki/Vegetable ;-)

--
Tony

"...has many omissions and contains much that is apocryphal, or at least
wildly inaccurate..."
Douglas Adams; The Hitchhiker's Guide to the Galaxy

Chris Slade said:

Ian Smith said:

BMA policy is founded on the basis of what might be good for
vegetables must be good for the hapless would-be-patients.

Melon's are fruit. http://en.wikipedia.org/wiki/Melon :-)

Melon's what are fruit?

Actually, I was using the term in sense 'edible part of a plant'.
It's not animal or mineral (nor even fungi), that makes it vegetable.

regards, Ian SMith
--
|\ /| no .sig
|o o|
|/ \|

Ian Smith said:

Chris Slade said:

Ian Smith said:

BMA policy is founded on the basis of what might be good for
vegetables must be good for the hapless would-be-patients.

Melon's are fruit. http://en.wikipedia.org/wiki/Melon :-)

Melon's what are fruit?

I've had a hard day...

Quoted message said:

Actually, I was using the term in sense 'edible part of a plant'.
It's not animal or mineral (nor even fungi), that makes it vegetable.

Looks like my pointless pedantry backfired. :-)
--
Chris

Chris Slade said:

Ian Smith said:

Chris Slade said:

Ian Smith wrote:

> BMA policy is founded on the basis of what might be good for
> vegetables must be good for the hapless would-be-patients.

Melon's are fruit. http://en.wikipedia.org/wiki/Melon :-)

Melon's what are fruit?

I've had a hard day...

Quoted message said:

Actually, I was using the term in sense 'edible part of a plant'.
It's not animal or mineral (nor even fungi), that makes it vegetable.

Looks like my pointless pedantry backfired. :-)

Au contraire, it did exactly what it's supposed to do: It caused an
avalanche of further nitpicks by which we all greatly* amused ourselves.

*for very small values of greatly.

--
A

Ambrose Nankivell said:

Au contraire, it did exactly what it's supposed to do: It caused an
avalanche of further nitpicks by which we all greatly* amused ourselves.

I'm glad somebody appreciated it...

Quoted message said:

*for very small values of greatly.

....even if just a little. :-)
--
Chris

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