Helmets

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

Quoted message said:

OG said:

I'm sympathetic to the anti compulsion arguments, but I don't think that
helmets 'per se' are as bad as you seem to imply.

Owen

sorry you've failed the entrance exam ;-)

I know - :-)
But I can't resist it.

It really pisses me off when people assume 'X', just because I question 'Y'
(or even ask ask 'why?'😉

On Fri, 17 Nov 2006 23:28:49 -0000, "OG" <[email hidden]>

Quoted message said:

"Rob Morley" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

In article <[email hidden]>
Noel <[email hidden]> wrote:
Cycle helmet design is a trade-off in several ways:

impact protection vs. risk of rotation injury - to provide acceptable
deceleration the helmet needs a certain thickness of shock-absorbing
material, whic means it will stick out and is more likely to contact the
road than is a bare head - rotation injury is often more dangerous than
the rapid deceleration of a direct impact.

I'm not really sure what you are saying here - if a direct impact is
imminent it will either have some transverse element or not. If not, then
the helmet definitely helps; OTOH were there a significant transverse
element ov motion, surely the head would rotate anyway.

The points that you are mising are as follows:

a) the amount of "protection" proffered by the inch-or-so of
polystyrene foam is insufficient to prevent serious injury should a
direct impact of any size larger than a fall from standing height
occur;

b) both the size and surface covering of a bare head are likely to
diminish the ocurrance and degree of any rotation when compared to a
helmeted head;

c) the amount of energy required to produce an injury via rotation is
far less (figures in the range of an order of magnitude are common)
than that for a direct impact; and

d) population-level studies show no decrease in head injury rates when
helemt wearing suddenly and massively increases.

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

Quoted message said:

The points that you are mising are as follows:

a) the amount of "protection" proffered by the inch-or-so of
polystyrene foam is insufficient to prevent serious injury should a
direct impact of any size larger than a fall from standing height
occur;

Are you serious? There are three responses possible to this.
<A response> You claim the protection is 'insufficient' - justify your
assertion - as stated my niece had a road collision impact that left a
significant dint in her helmet. Had she had an equivalent 'dint' in her
skull she should have had a hospital visit at the very least.

<B response> Any cyclist (except maybe for a penny-farthing cyclist) is
going to fall from less height than 'stanidng height'- so your argument is
irrelevant except fot a tiny minority* <oops - see D response>

<C response> You are talking bollocks and do not have a re\asonable agument

<D response> particularly short people may have their head higher on a
standard bike than when standing - but this would be a tiny minority.

Quoted message said:

b) both the size and surface covering of a bare head are likely to
diminish the ocurrance and degree of any rotation when compared to a
helmeted head;

Please justify this assertion. IME most helmets have a smooth surface
compared to the rough 'hair covered' surfaces of most heads.

Quoted message said:

c) the amount of energy required to produce an injury via rotation is
far less (figures in the range of an order of magnitude are common)
than that for a direct impact; an

I've asked why rotation is more harmful if a helmet is worn relative to
without. I can see that your statement is broadly 'true', but not why it is
relevant to this discussion.

Quoted message said:

d) population-level studies show no decrease in head injury rates when
helemt wearing suddenly and massively increases.

To be honest I would want to check your 'evidence '.

In article <[email hidden]>

OG said:

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

Quoted message said:

The points that you are mising are as follows:

a) the amount of "protection" proffered by the inch-or-so of
polystyrene foam is insufficient to prevent serious injury should a
direct impact of any size larger than a fall from standing height
occur;

Are you serious? There are three responses possible to this.

So you list four - that's a good start.

Quoted message said:

<A response> You claim the protection is 'insufficient' - justify your
assertion - as stated my niece had a road collision impact that left a
significant dint in her helmet. Had she had an equivalent 'dint' in her
skull she should have had a hospital visit at the very least.

Or she may have had a minor bump, or her head may not even have touched
the ground, or she may not have fallen off because she wouldn't have
been going so fast because she wasn't afforded a false sense of security
by wearing a helmet, or ...

Quoted message said:

<B response> Any cyclist (except maybe for a penny-farthing cyclist) is
going to fall from less height than 'stanidng height'- so your argument is
irrelevant except fot a tiny minority* <oops - see D response>

That's falling from standing, not falling from running into a kerb at
20mph or because you've been clouted by a ton of metal doing 30mph.

In article <[email hidden]>

OG said:

"Rob Morley" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

In article <[email hidden]>
Noel <[email hidden]> wrote:
Cycle helmet design is a trade-off in several ways:

impact protection vs. risk of rotation injury - to provide acceptable
deceleration the helmet needs a certain thickness of shock-absorbing
material, whic means it will stick out and is more likely to contact the
road than is a bare head - rotation injury is often more dangerous than
the rapid deceleration of a direct impact.

I'm not really sure what you are saying here - if a direct impact is
imminent it will either have some transverse element or not. If not, then
the helmet definitely helps;

But does it really make the difference between a major and minor injury?
Or is it just the difference between a bump/graze and a dented helmet?

Quoted message said:

OTOH were there a significant transverse
element ov motion, surely the head would rotate anyway.

Helmets are soft and deform inelastically, so flatten against the road
presenting a larger area to drag against the surface and decelerate that
side of the head. Skulls are quite hard and deform elastically (within
limits obviously), so they're more likely to bounce and less likely to
drag. Plus helmets stick out more than heads.

Quoted message said:

The only time I can see it making a difference in a negative sense would be
if the head got within about 1.5cm (but no closer) of the road/kerb/whatever
*with* a significant transverse motion.

My niece came off her bike when her rear wheel lost grip on a curve at the
bottom of a steep hill - she ended up with nasty grazes on her arms and
wrist, a bit of bruising on her leg and a distinct dint in her helmet. In
that case the helmet helped.

There's no way you could know what would have happened - maybe you'd
like to go back and get her to do it again a few times to produce
consistent repeatable results.

Quoted message said:

Quoted message said:

cost vs. protection - manufacturers want to sell lots of helmets, so
reduce costs by manufacturing/testing helmets to the minimum acceptable
EU standard - the more expensive helmets generally have better
cooling/aerodynamics/weight/cosmetics while not being certified to any
higher standards.

Are there higher certification standards available for cycle helmets? It's
not clear whether the 'generally' refers to the advertised attributes or the
absence of higher certificated standards for retailed helmets.

Snell Foundation standards are among the best, but good luck finding a
bicycle helmet that has been tested to them. There's no shortage of
motorcycle helmets that meet the relevant Snell standards, because
motorcycle helmets actually do some good.

Quoted message said:

Quoted message said:

Motorcycle racers and freestylers use helmets that provide a credible
level of protection - downhill mountain bike racers use a similar design
because the events they ride are fairly short, don't involve extended
pedalling (with little or none up hill) and they don't have to worry
about traffic, while the chance of taking a tumble is fairly high. Even
then they're unlikely to hit much apart from the ground or a bike (not
many high kerbs, street lights or cars pulling out in front of you or
running into the back of you on a race track). The helmet is just part
of downhill protective gear that includes hip, knee, shin, elbow,
shoulder, chest and back armour and wrist guards - when you have that
lot on you can learn to slide or roll with minimal injury and keep your
head pretty safe anyway.

You seem to be claiming that you can 'learn' to keep your head safe - surely
that depends on lots of practise when falling off. Road riding is not a
place to learn such skills, and road riding is where most cyclists start.

Actually we've evolved to instinctively protect our heads, the body
armour just makes it easier to do without damaging other bits. ITYF the
most common fractures from falls are to the wrist and collarbone (and
the hip in the elderly). If you know you're falling, survival instinct
takes over. If you don't have time to react it's probably because it
happens with such speed/force that a little bit of plastic foam isn't
going to make much difference.

Quoted message said:

I'm sympathetic to the anti compulsion arguments, but I don't think that
helmets 'per se' are as bad as you seem to imply.

Despite the recent research which showed that motorists give less room
when passing a cyclist with a helmet than one without?

OG wrote on 18/11/2006 00:29 +0100:

Quoted message said:

It really pisses me off when people assume 'X', just because I question 'Y'
(or even ask ask 'why?'😉

But your next post and your anecdote show that people's assumptions were
correct. So should that be "It really pisses me off when I'm found out"

--
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 wrote on 18/11/2006 01:51 +0100:

Quoted message said:

Are you serious?

Yes.

There are three responses possible to this.

Quoted message said:

<A response> You claim the protection is 'insufficient' - justify your
assertion - as stated my niece had a road collision impact that left a
significant dint in her helmet. Had she had an equivalent 'dint' in her
skull she should have had a hospital visit at the very least.

Sigh. This is known in the cycling community as the "Helmet saved my
life" fallacy. It even has its own FAQ.
http://www.cyclehelmets.org/mf.html?1019 Be aware that the energy
required to produce a "dint in her skull" is about ten times that
needed to put a dint in a helmet. At worst she might have had a scalp
bruise but quite likely would have had nothing.

Quoted message said:

<B response> Any cyclist (except maybe for a penny-farthing cyclist) is
going to fall from less height than 'stanidng height'- so your argument is
irrelevant except fot a tiny minority* <oops - see D response>

<C response> You are talking bollocks and do not have a re\asonable agument

Apart from getting the subject of the sentence wrong, that is the
closest you've come to being right.

Quoted message said:

<D response> particularly short people may have their head higher on a
standard bike than when standing - but this would be a tiny minority.

Quoted message said:

b) both the size and surface covering of a bare head are likely to
diminish the ocurrance and degree of any rotation when compared to a
helmeted head;

Please justify this assertion. IME most helmets have a smooth surface
compared to the rough 'hair covered' surfaces of most heads.

The skin of the scalp is mobile over the skull and the shape is designed
by years of evolution to be rounded and smooth so as to not catch on the
ground. The helmet is rigid, larger diameter (larger lever arm, more
likely to be hit) and full of angular protrusions and holes to catch on
the ground. There are some motorbike helmets now modelled on the MkI
human skull of a mobile skin over a hard shell.

Quoted message said:

Quoted message said:

c) the amount of energy required to produce an injury via rotation is
far less (figures in the range of an order of magnitude are common)
than that for a direct impact; an

I've asked why rotation is more harmful if a helmet is worn relative to
without. I can see that your statement is broadly 'true', but not why it is
relevant to this discussion.

http://dx.doi.org/10.1016/S0001-4575(02)00012-X (linked in
http://www.cyclehelmets.org)

Quoted message said:

To be honest I would want to check your 'evidence '.

http://www.cyclehelmets.org Now why don't you go and read up on a
subject you clearly know zip about and stop making wild and unfounded
assumptions here that most everyone has been over ad nauseam with helmet
newbies before. The above site was set up by some of those here along
with independent world experts to educate helmet newbies so please use
it first. If you have questions afterwards then come back and ask.

--
Tony

"Man is a credulous animal, and must believe something; in the absence
of good grounds for belief, he will be satisfied with bad ones."
- Bertrand Russell

"OG" <[email hidden]>typed

Quoted message said:

I've asked why rotation is more harmful if a helmet is worn relative to
without. I can see that your statement is broadly 'true', but not why it is
relevant to this discussion.

A helmeted head is larger and heavier; this makes it more likely to
strike anything, and increases rotation by simple leverage when a strike
occurs.

--
Helen D. Vecht: [email hidden]
Edgware.

Tony Raven said:

OG wrote on 18/11/2006 01:51 +0100:

Quoted message said:

Please justify this assertion. IME most helmets have a smooth surface
compared to the rough 'hair covered' surfaces of most heads.

The skin of the scalp is mobile over the skull and the shape is designed
by years of evolution to be rounded and smooth so as to not catch on the
ground. The helmet is rigid, larger diameter (larger lever arm, more
likely to be hit) and full of angular protrusions and holes to catch on
the ground. There are some motorbike helmets now modelled on the MkI
human skull of a mobile skin over a hard shell.

Plus, if you actually do any tests, it becomes immediately obvious
that the coefficient of friction of hair-covered-head on road surface
is massively less than that of helmet on road surface. I personally
have tried concrete and a few varieties of blacktop, also brickwork,
blockwork and precast concrete.

I'm yet to find a surface on which a helmet slides easier than a head.

Any one can try this - find surface, kneel down, place head on
surface, lean into surface, slide head. Add helmet and repeat.

It's immediately obvious that the soft polystyrene (? I'm not sure,
some similar plastic however) shell on most helmets is very grabby
when faced with a hard, rough surface.

It's astonishing the number of people that will swear blind the sort
of assertion quoted above (that helmets must slide easily), when it's
so easily demonstrated to be complete bollocks. Anyone making the
assertion has clearly not tried even the most basic investigations
before making their pronouncements.

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

"Tony Raven" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

It's well known from research that more cyclists disproportionately
increases the cycling safety. It is equally well known that helmets
discourage cycling. Which is probably part of the reason why lots of
people cycle in the Netherlands and its very safe while few cycle in the
US and its six times more dangerous.

Looking at the chart the UK has an unusually low number of cycling
fatalities given the low number of cycling trips. Do you know why this is?
Are the driving standards in the UK better than other countries?

Quoted message said:

The most interesting data is comparison of males and females in the same
country. In the UK the latter are twice as likely to be wearing a helmet,
likely to take far fewer risks cycling but have the same risk of head
injury as males. So either helmets have no effect on head injury or, if
you take the respective risk taking profiles into account, helmets
actually worsen the risk of head injuries, in line with the findings in
Australia and New Zealand.

Are the women having more accidents than men?

Adam Lea wrote on 18/11/2006 21:09 +0100:

Quoted message said:

Looking at the chart the UK has an unusually low number of cycling
fatalities given the low number of cycling trips. Do you know why this is?
Are the driving standards in the UK better than other countries?

Its not as simple as that. For example the Dutch cycle on average 12
times further in a year than the British whereas those figures are
against number of trips not distance cycled. OTOH if you factor in the
known change in risk with numbers cycling, the Netherlands comes out 1.8
times less safe than the UK despite (or probably because of) all the
cycle facilities it has.

Quoted message said:

Quoted message said:

The most interesting data is comparison of males and females in the same
country. In the UK the latter are twice as likely to be wearing a helmet,
likely to take far fewer risks cycling but have the same risk of head
injury as males. So either helmets have no effect on head injury or, if
you take the respective risk taking profiles into account, helmets
actually worsen the risk of head injuries, in line with the findings in
Australia and New Zealand.

Are the women having more accidents than men?

No, the other way round.

--
Tony

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

Adam Lea wrote on 18/11/2006 21:14 +0100:

Quoted message said:

That tells me that an MHL increases cycling risk through reduction in
cycling trips, which we know is strongly correlated with cycling safety. It
doesn't tell me whether the risk to myself would increase, decrease or stay
the same should I decide to start wearing a helmet for my commuting from now
on.

No, it tells you that the risk is not reduced and is probably increased
by wearing a helmet. The evidence comes from more than just MHL situations.

As for the risk to yourself as an individual, its true that you might be
able to smoke 60 a day and live to the ripe old age of 100 despite what
the statistics on smoking predict. However its almost certain that you
couldn't. Likewise wearing a helmet you might buck the statistics but
its very unlikely that you will and there is no way of knowing a priori
that you are that one in a million.

--
Tony

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

"Tony Raven" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Adam Lea wrote on 18/11/2006 21:09 +0100:

Quoted message said:

Looking at the chart the UK has an unusually low number of cycling
fatalities given the low number of cycling trips. Do you know why this
is? Are the driving standards in the UK better than other countries?

Its not as simple as that. For example the Dutch cycle on average 12
times further in a year than the British whereas those figures are against
number of trips not distance cycled. OTOH if you factor in the known
change in risk with numbers cycling, the Netherlands comes out 1.8 times
less safe than the UK despite (or probably because of) all the cycle
facilities it has.

Quoted message said:

Quoted message said:

The most interesting data is comparison of males and females in the same
country. In the UK the latter are twice as likely to be wearing a
helmet, likely to take far fewer risks cycling but have the same risk of
head injury as males. So either helmets have no effect on head injury
or, if you take the respective risk taking profiles into account,
helmets actually worsen the risk of head injuries, in line with the
findings in Australia and New Zealand.

Are the women having more accidents than men?

No, the other way round.

In that case it does seem that the helmets are not doing a lot of good.

Ian Smith wrote on 18/11/2006 16:22 +0100:

Quoted message said:

Plus, if you actually do any tests, it becomes immediately obvious
that the coefficient of friction of hair-covered-head on road surface
is massively less than that of helmet on road surface. I personally
have tried concrete and a few varieties of blacktop, also brickwork,
blockwork and precast concrete.

There is a very good summary of helmet properties and brain injury
mechanisms at http://www.pcug.org.au/~psvansch/crag/h-i-mech.htm
including reference to Swedish studies that found bicycle helmets on
20mph asphalt impacts grabbed the surface and produced 4-6x the maximum
tolerable angular acceleration.

--
Tony

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

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

Quoted message said:

jtaylor said:

Troll.

"...innocently wondering..."

Innocence is not the prime characteristic of bridge sous-dwellers.

Er - sorry I thought it was abundantly clear I was not bating the
'normal'
dull helmet brigade but just asking about why helmet's are designed
as
they are. Trolling, no.

That is an important question actually, which people should ask more
often.

a) They must pass either the European or North American standards,
perhaps even both, although meeting both conflicts with criterion b)

b) They must be as light and as cool as possible, i.e. only just
meet criterion a)

c) They must have a high enough profit margin to pay various lawyers
fees etc. You will need to defend yourself against the lawsuits
from grieving relatives when your helmet doesn't actually work (Well,
not lawsuits preferably. It's best to settle out of court, because
then you can keep the amount of payouts secret, which is advisable.
I've heard it suggested that this cost might be about a third the
cost of a helmet, although I can't imagine ever being able to extract
good data from any helmet manufacturer)

d) They must make you look like Darth Vader rather than some dork
with a pudding basin on their head

Jeremy Parker

"Tony Raven" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Ian Smith wrote on 18/11/2006 16:22 +0100:

Quoted message said:

Plus, if you actually do any tests, it becomes immediately obvious that
the coefficient of friction of hair-covered-head on road surface is
massively less than that of helmet on road surface. I personally have
tried concrete and a few varieties of blacktop, also brickwork, blockwork
and precast concrete.

There is a very good summary of helmet properties and brain injury
mechanisms at http://www.pcug.org.au/~psvansch/crag/h-i-mech.htm including
reference to Swedish studies that found bicycle helmets on 20mph asphalt
impacts grabbed the surface and produced 4-6x the maximum tolerable
angular acceleration.

Is that hard shell, microshell or no-shell (polystyrene) helmets? PCUG don't
make it clear and I've not been able to find the complete text of the
original article ( Andersson, T., Larsson, P. and Sandberg, U., Chin strap
forces in bicycle helmets 1993).

However, it seems to be similar to a 1990 study by Hodgson at lower speeds
(10-14 km/h) which found that no-shell helmets had increased sliding
resistance (bad) compared to hard shell helmets. A follow up study in 1991
showed that microshell helmets were more like hard shell and did not give
the increased 'grab', so (as I say) it's not clear what type of helmet the
Swedish study included.

OG said:

However, it seems to be similar to a 1990 study by Hodgson at lower speeds
(10-14 km/h) which found that no-shell helmets had increased sliding
resistance (bad) compared to hard shell helmets. A follow up study in 1991
showed that microshell helmets were more like hard shell and did not give
the increased 'grab', so (as I say) it's not clear what type of helmet the
Swedish study included.

My testing has been with a microshell. The shell feels like varnished
polystyrene, but I don't know what it actually is.

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

Quoted message said:

Cycle helmets are designed first and foremost with _profit_ in mind

As, to be fair, is just about every mass-produced product ever.

That's how capitalism works, like it or not.

Neil

On 19 Nov 2006 11:00:10 -0800, "Neil Williams" <[email hidden]>

Quoted message said:

Quoted message said:

Cycle helmets are designed first and foremost with _profit_ in mind

As, to be fair, is just about every mass-produced product ever.

That's how capitalism works, like it or not.

The capitaism aspect is no trouble; what is is the advertising minions
and their puppets telling us that the things will save our lives if we
wear them, and the politicians taking this and making laws that
require such, and so ensuring profits.

"Ian Smith" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

OG said:

However, it seems to be similar to a 1990 study by Hodgson at lower
speeds
(10-14 km/h) which found that no-shell helmets had increased sliding
resistance (bad) compared to hard shell helmets. A follow up study in
1991
showed that microshell helmets were more like hard shell and did not
give
the increased 'grab', so (as I say) it's not clear what type of helmet
the
Swedish study included.

My testing has been with a microshell. The shell feels like varnished
polystyrene, but I don't know what it actually is.

It looks like the Swedish study was mainly to test chin straps, so i'm not
sure how relevant it is anyway.