P
Peter Clinch
Guest
GaryG wrote:
> By that "rationale", a cotton cycling cap would confer a greater degree of
> protection than a proper cycling helmet. Not sure if that's the argument
> you're trying to make, but that's the take-home message.
It depends on the accident. If the accident is one where a capped head
comes within an inch of an obstacle but a helmeted head hits it, then
that would indeed be the case. Another possibility is that a capped
head ends up concussed and grazed but a helmeted head is twisted by the
extra leverage allowed by the helmet and has its neck broken. But you
don't know if that would be the case up front, of course...
The take-home message is you cannot say for sure that after an accident
you were *surely* better off with a helmet, simply on the grounds that
it hit something. You might be, but you won't /definetly/ be.
> FWIW, the average human head weighs between 4.5 and 5 kg. An average
> bicycle helmet (e.g., Gyro Pneumo) weighs 0.26 kg, so the average increase
> in head weight is around 5%.
>
> You've implied in quite a few posts that an unhelmeted cyclist can keep
> their head from impacting the ground in a fall by use of their neck muscles,
> and you've also stated that a helmeted cyclist's neck muscles would not be
> able to overcome the additional momentum of the helmet. Given the small
> additional mass of a modern helmet, I strongly suspect your argument is
> specious (a nice way of saying you're pulling it out of your ass).
It's not just weight, it's size too. You'd have an easier job keeping
an unhelmeted head off the deck than a zero weight helmet because you
don't have to keep it up the extra distance required by the additional
size of the helmet.
The head is kept up by reflex action, and the reflexes are working on a
self-knowledge of where the head is and extends to. Unless you make a
habit of sliding around tarmac in a cycle helmet then the reflex to keep
the head up is using information on the head, not the helmeted head.
This is quite easy to see safely in practice: wear a helmet in a cave
and you'll bang your head far more often than if you don't (though in
this case since you'll almost certainly be banging it anyway, and are
never above walking pace, it's definitely worth wearing!).
> Yet again the clear message is that "helmets are dangerous".
No, it is that they are *potentially* dangerous and are *not* a clear win.
> Do you have any studies to back up your rather bizarre assertions that
> helmets increase the dangers of head impact/neck injuries? Or, is this
> merely yet more of your anti-helmet crusade?
Go to www.cyclehelmets.org and get reading.
For example, you can find one that suggests you're 7 times more likely
to hit your head in a crash with a helmet than without in
Wasserman RC, Waller JA, Monty MJ, Emery AB, Robinson DR. Bicyclists,
helmets and head injuries: a rider-based study of helmet use and
effectiveness. 1988. American Journal of Public Health: 1988
Sep;78(9):1220-1
Not a study, but an expert opinion you'll find there is, "the very
eminent QC under whose instruction I was privileged to work, tried
repeatedly to persuade the equally eminent neurosurgeons acting for
either side, and the technical expert, to state that one must be safer
wearing a helmet than without. All three refused to so do, stating that
they had seen severe brain damage and fatal injury both with and without
cycle helmets being worn. In their view, the performance of cycle
helmets is much too complex a subject for such a sweeping claim to be made."
It isn't an anti-helmet crusade, it's a get real about the realities of
what you can really expect crusade. If I was "anti helmet" I wouldn't
own and occasionally wear one.
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 protected] http://www.dundee.ac.uk/~pjclinch/
> By that "rationale", a cotton cycling cap would confer a greater degree of
> protection than a proper cycling helmet. Not sure if that's the argument
> you're trying to make, but that's the take-home message.
It depends on the accident. If the accident is one where a capped head
comes within an inch of an obstacle but a helmeted head hits it, then
that would indeed be the case. Another possibility is that a capped
head ends up concussed and grazed but a helmeted head is twisted by the
extra leverage allowed by the helmet and has its neck broken. But you
don't know if that would be the case up front, of course...
The take-home message is you cannot say for sure that after an accident
you were *surely* better off with a helmet, simply on the grounds that
it hit something. You might be, but you won't /definetly/ be.
> FWIW, the average human head weighs between 4.5 and 5 kg. An average
> bicycle helmet (e.g., Gyro Pneumo) weighs 0.26 kg, so the average increase
> in head weight is around 5%.
>
> You've implied in quite a few posts that an unhelmeted cyclist can keep
> their head from impacting the ground in a fall by use of their neck muscles,
> and you've also stated that a helmeted cyclist's neck muscles would not be
> able to overcome the additional momentum of the helmet. Given the small
> additional mass of a modern helmet, I strongly suspect your argument is
> specious (a nice way of saying you're pulling it out of your ass).
It's not just weight, it's size too. You'd have an easier job keeping
an unhelmeted head off the deck than a zero weight helmet because you
don't have to keep it up the extra distance required by the additional
size of the helmet.
The head is kept up by reflex action, and the reflexes are working on a
self-knowledge of where the head is and extends to. Unless you make a
habit of sliding around tarmac in a cycle helmet then the reflex to keep
the head up is using information on the head, not the helmeted head.
This is quite easy to see safely in practice: wear a helmet in a cave
and you'll bang your head far more often than if you don't (though in
this case since you'll almost certainly be banging it anyway, and are
never above walking pace, it's definitely worth wearing!).
> Yet again the clear message is that "helmets are dangerous".
No, it is that they are *potentially* dangerous and are *not* a clear win.
> Do you have any studies to back up your rather bizarre assertions that
> helmets increase the dangers of head impact/neck injuries? Or, is this
> merely yet more of your anti-helmet crusade?
Go to www.cyclehelmets.org and get reading.
For example, you can find one that suggests you're 7 times more likely
to hit your head in a crash with a helmet than without in
Wasserman RC, Waller JA, Monty MJ, Emery AB, Robinson DR. Bicyclists,
helmets and head injuries: a rider-based study of helmet use and
effectiveness. 1988. American Journal of Public Health: 1988
Sep;78(9):1220-1
Not a study, but an expert opinion you'll find there is, "the very
eminent QC under whose instruction I was privileged to work, tried
repeatedly to persuade the equally eminent neurosurgeons acting for
either side, and the technical expert, to state that one must be safer
wearing a helmet than without. All three refused to so do, stating that
they had seen severe brain damage and fatal injury both with and without
cycle helmets being worn. In their view, the performance of cycle
helmets is much too complex a subject for such a sweeping claim to be made."
It isn't an anti-helmet crusade, it's a get real about the realities of
what you can really expect crusade. If I was "anti helmet" I wouldn't
own and occasionally wear one.
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 protected] http://www.dundee.ac.uk/~pjclinch/