Gawnsoft
"Perhaps the main point of the one you cite is that it would
give responsible parents a lever to insist on their children
wearing cycle helmets. When I started riding motor cycles
nobody thought about wearing helmets except for racing but
now it is accepted practice and has saved lives. A similar
process is coming about with horse riders, without legal
sanctions. I can't quote the statistics off the cuff, but I
believe a significant number of cyclists' injuries are, in
fact, head injuries. A further point worth making is that a
law for wearing cycle helmets does appear to work well in
Australia."
I'm feeling compelled to reply, despite how off-topic the
posters comments were to the discussion of 'Online banking -
is it secure?'
==================
I realise this is now getting substantially off-topic, but
these are well circulated misapprehensions about bicycle
helmet efficacy which I feel quite strongly about and as
they have been raised here, I feel compelled to address
these points here.
These misapprehensions showed up earlier this week for
instance in a newspaper headline in Hull which proclaimed
'A helmet would have saved her' - written of a cyclist who
was killed when a distracted driver hit her with his cement
mixer. (The 'would' was amended to 'could' in later
editions of the paper.
[http://www.simonmason.karoo.net/zkilled.htm] )
I'll discuss the reasons why, even though a motorbike helmet
might have saved her, the headline is untrue.
> ...Perhaps the main point of the one you cite is that it
> would give responsible parents a lever to insist on
> their children wearing cycle helmets. When I started
> riding motor cycles nobody thought about wearing helmets
> except for racing but now it is accepted practice and
> has saved lives.
Motorcycle helmets are designed and manufactured to a
significantly different brief to bike helmets - they are
designed for protection in high speed collisions with
motor vehicles. They achieve this by being very
substantial objects.
In contrast, the most stringent bicycle helmet safety
standard (Snell) only designs for a 5 foot fall onto the
ground while stationary (110 Joules). i.e. the energy levels
it protects against are miniscule compared to those involved
in colllisions with motor vehicles. (A typical family saloon
car will possess sufficient energy to overwhelm such a
helmet 700 times over, at only 25mph)
In any event, most helmets available for purchase in the UK
do not meet even this standard, instead meeting only the
much laxer European EN1078.
A similar process is coming about with horse riders, without
legal sanctions.
Again, horse-riding helmets are quite different in design to
bicycle helmets. They are much more akin to construction
site hard hats - being a tough outer layer with good
penetration resistance and little if any holes for
ventilation held clear of the head by straps.
One key reason for the differences between bike helmets and
the others you mention is that neither horse riders nor
motorbikers are providing the motive power for their
transport. Additional weight of helmet does not cause the
same hardships, and there are not the same heat dissipation
requirements. Even at rest a human is typically dumping
100Watts of heat, (20Watts of that comes from the brain
alone) , and needs removed. + of heat from their head. When
carrying out continuous physical exertion this only
increases. Some cyclists are known to peak at over
800Watts). Expanded polystyrene, like that used in bicycle
helmets, is a very good insulator of heat.
In the case of horse helmets, there are also the facts that
horse riders generally have their head higher off the ground
than cyclists to begin with, so need greater protection in
the case of an unplanned dismount; horses are only directed,
not controlled, by their riders. For instance, in case of a
fall from a rearing horse, protection for the back of the
skull is required.
> "I can't quote the statistics off the cuff, but I believe
> a significant number of cyclists' injuries are, in fact,
> head injuries."
The question is, are they head injuries which would be
mitigated by bicycle helmets.
1) A lot of the head injuries recorded are to the face or
chin. Bike helmets do not cover these areas.
2) A lot of cases recorded as fatal head injuries are for
cases where the injuries to the other parts of the body
would, in any case, have been fatal.
3) While only 10% of head injuries while cycling happen due
to motor vehicles, 50% of the fatalities happen from
these. I've already discussed earlier how bike helmets,
unlike motorbike helmets, are only efficacious for drops
to the ground at gentle speed, not for being hit by over
a ton of metal at high speed.
(Despite this, insurance companies acting for drivers who
have killed or seriously injured cyclists have tried to
place contributory negligence on cyclists who were not
wearing helmets. So far, the courts have held that bike
helmets would not have affected the outcomes).
4) Bicycle helmets do not protect against penetrative
impacts by sharp objects - they are, quite literally,
full of holes.
5) Closed skull injuries can often cause the greatest brain
damage (due to rotational shear, etc), and helmets may
well increase the incidence and severity of such trauma
(due to increasing the effective diameter of the head)
US Consumer Product Safety Commission announced (reported in
The New York Times, 29th July 2001) that an increase in
helmet wearing from 18% to 50% between 1991 and 2001 was
associated with a 40% rise in risk of head injury.
6) A child a year dies in the UK from strangulation from
bike helmet chinstraps. It is far from clear that /any/
lives are actually saved by bike helmets. (Although it is
clear that helmets do protect against minor bumps and
scrapes to some parts of the head from unplanned
dismounts).
> "A further point worth making is that a law for wearing
> cycle helmets does appear to work well in Australia."
The Australian statistics show head injury levels were
maintained even once helmets became compulsory. They also
show that cycling levels fell dramatically when helmets
became compulsory.
The BMA's opinion is that any very slight additional risk
posed by cycling is overwhelmed by the benefits of exercise,
so that a law which depressed levels of cycling in children
would paradoxically provide, on balance, overwhelming levels
of health /dis/benefits.
Cheers, and my apologies for going on quite so long,
=======
My key concerns - did I get the annual strangulation
stat correct?
Is the 10% / 50% for RTA correct?
Finally, has anyone yet managed to obtain a copy of
the paper with the 'would have' headline and stick it
on the web?
Anyway - I feel better now I've written this.
--
Cheers, Euan Gawnsoft: http://www.gawnsoft.co.sr (http://www.gawnsoft.co.sr/)
Symbian/Epoc wiki: http://html.dnsalias.net:1122 (http://html.dnsalias.net:1122/) Smalltalk
links (harvested from comp.lang.smalltalk)
http://html.dnsalias.net/gawnsoft/smalltalk
give responsible parents a lever to insist on their children
wearing cycle helmets. When I started riding motor cycles
nobody thought about wearing helmets except for racing but
now it is accepted practice and has saved lives. A similar
process is coming about with horse riders, without legal
sanctions. I can't quote the statistics off the cuff, but I
believe a significant number of cyclists' injuries are, in
fact, head injuries. A further point worth making is that a
law for wearing cycle helmets does appear to work well in
Australia."
I'm feeling compelled to reply, despite how off-topic the
posters comments were to the discussion of 'Online banking -
is it secure?'
==================
I realise this is now getting substantially off-topic, but
these are well circulated misapprehensions about bicycle
helmet efficacy which I feel quite strongly about and as
they have been raised here, I feel compelled to address
these points here.
These misapprehensions showed up earlier this week for
instance in a newspaper headline in Hull which proclaimed
'A helmet would have saved her' - written of a cyclist who
was killed when a distracted driver hit her with his cement
mixer. (The 'would' was amended to 'could' in later
editions of the paper.
[http://www.simonmason.karoo.net/zkilled.htm] )
I'll discuss the reasons why, even though a motorbike helmet
might have saved her, the headline is untrue.
> ...Perhaps the main point of the one you cite is that it
> would give responsible parents a lever to insist on
> their children wearing cycle helmets. When I started
> riding motor cycles nobody thought about wearing helmets
> except for racing but now it is accepted practice and
> has saved lives.
Motorcycle helmets are designed and manufactured to a
significantly different brief to bike helmets - they are
designed for protection in high speed collisions with
motor vehicles. They achieve this by being very
substantial objects.
In contrast, the most stringent bicycle helmet safety
standard (Snell) only designs for a 5 foot fall onto the
ground while stationary (110 Joules). i.e. the energy levels
it protects against are miniscule compared to those involved
in colllisions with motor vehicles. (A typical family saloon
car will possess sufficient energy to overwhelm such a
helmet 700 times over, at only 25mph)
In any event, most helmets available for purchase in the UK
do not meet even this standard, instead meeting only the
much laxer European EN1078.
A similar process is coming about with horse riders, without
legal sanctions.
Again, horse-riding helmets are quite different in design to
bicycle helmets. They are much more akin to construction
site hard hats - being a tough outer layer with good
penetration resistance and little if any holes for
ventilation held clear of the head by straps.
One key reason for the differences between bike helmets and
the others you mention is that neither horse riders nor
motorbikers are providing the motive power for their
transport. Additional weight of helmet does not cause the
same hardships, and there are not the same heat dissipation
requirements. Even at rest a human is typically dumping
100Watts of heat, (20Watts of that comes from the brain
alone) , and needs removed. + of heat from their head. When
carrying out continuous physical exertion this only
increases. Some cyclists are known to peak at over
800Watts). Expanded polystyrene, like that used in bicycle
helmets, is a very good insulator of heat.
In the case of horse helmets, there are also the facts that
horse riders generally have their head higher off the ground
than cyclists to begin with, so need greater protection in
the case of an unplanned dismount; horses are only directed,
not controlled, by their riders. For instance, in case of a
fall from a rearing horse, protection for the back of the
skull is required.
> "I can't quote the statistics off the cuff, but I believe
> a significant number of cyclists' injuries are, in fact,
> head injuries."
The question is, are they head injuries which would be
mitigated by bicycle helmets.
1) A lot of the head injuries recorded are to the face or
chin. Bike helmets do not cover these areas.
2) A lot of cases recorded as fatal head injuries are for
cases where the injuries to the other parts of the body
would, in any case, have been fatal.
3) While only 10% of head injuries while cycling happen due
to motor vehicles, 50% of the fatalities happen from
these. I've already discussed earlier how bike helmets,
unlike motorbike helmets, are only efficacious for drops
to the ground at gentle speed, not for being hit by over
a ton of metal at high speed.
(Despite this, insurance companies acting for drivers who
have killed or seriously injured cyclists have tried to
place contributory negligence on cyclists who were not
wearing helmets. So far, the courts have held that bike
helmets would not have affected the outcomes).
4) Bicycle helmets do not protect against penetrative
impacts by sharp objects - they are, quite literally,
full of holes.
5) Closed skull injuries can often cause the greatest brain
damage (due to rotational shear, etc), and helmets may
well increase the incidence and severity of such trauma
(due to increasing the effective diameter of the head)
US Consumer Product Safety Commission announced (reported in
The New York Times, 29th July 2001) that an increase in
helmet wearing from 18% to 50% between 1991 and 2001 was
associated with a 40% rise in risk of head injury.
6) A child a year dies in the UK from strangulation from
bike helmet chinstraps. It is far from clear that /any/
lives are actually saved by bike helmets. (Although it is
clear that helmets do protect against minor bumps and
scrapes to some parts of the head from unplanned
dismounts).
> "A further point worth making is that a law for wearing
> cycle helmets does appear to work well in Australia."
The Australian statistics show head injury levels were
maintained even once helmets became compulsory. They also
show that cycling levels fell dramatically when helmets
became compulsory.
The BMA's opinion is that any very slight additional risk
posed by cycling is overwhelmed by the benefits of exercise,
so that a law which depressed levels of cycling in children
would paradoxically provide, on balance, overwhelming levels
of health /dis/benefits.
Cheers, and my apologies for going on quite so long,
=======
My key concerns - did I get the annual strangulation
stat correct?
Is the 10% / 50% for RTA correct?
Finally, has anyone yet managed to obtain a copy of
the paper with the 'would have' headline and stick it
on the web?
Anyway - I feel better now I've written this.
--
Cheers, Euan Gawnsoft: http://www.gawnsoft.co.sr (http://www.gawnsoft.co.sr/)
Symbian/Epoc wiki: http://html.dnsalias.net:1122 (http://html.dnsalias.net:1122/) Smalltalk
links (harvested from comp.lang.smalltalk)
http://html.dnsalias.net/gawnsoft/smalltalk
