Steve Almond said:Very clever. Your attachment to 7 mph is touching. Does 8 mph mean instant
death? Is it possible that at 11 mph a helmet might mean the difference
between concussion and brain damage? How about at 20 mph where the effort to
avoid head injury is not completely successful, but the helmet just makes
that bit of difference.....?
Helmets work by slowing the rate of acceleration of the skull. The standard
is set so that under the test conditions the deceleration is reduced to just
under that which will cause physical damage to the brain (in a linear
impact). So the 'my helmet saved my life' story at 7mph is credible when
accompanied by a nasty headache, mild concussion from an exclusively linear
impact that would have been worse in the absence of a helmet.
At 11mph you would need a helmet (11x11)/(7x7) times thicker to get the same
degree of protection, or two and a half times. At 20 mph over 4 times
thicker.
Quoted message said:Your black and white calculations to support your views are, quite honestly,
naive.
As is the lack or realism that puts the risk into context of everyday
activities.
Quoted message said:My point was that at 30 mph (let's say 27 mph, not an impossible speed for a
bicycle), I had no say in my bodies attitude when it hit the deck.
But that's me, many people here have convinced themselves that either:
1. They are skilful enough to avoid all accidents (30 years without coming
off.....).
Seems reasonable to expect that one can avoid all but the rarest accidents
by being skillful and careful.
Quoted message said:2. They can defy the laws of physics (I'll keep my head from hitting
anything hard....).
That isn't defying the laws of physics, that is understanding them and
working with them..
Quoted message said:3. They decide helmets are useless in some defined cases (say, hit a car
head first which is travelling at 20/30/40 mph), therefore helmets are
useless in all cases and not worth wearing.
A gross distortion. Helmets are useless in a large number of cases, worse
than useless in a proportion that may or may not be larger than the
proportion in which they are beneficial.
Quoted message said:
And I guess the saddest are the ones who will teach their kids to ride
properly on a well-maintained bike, thus negating the need for a helmet.
No. The saddest are those who believe that cycling is so dangerous they
don't let their kids out on a bike AT ALL.
Quoted message said:Said kid is never to have a moment of inattention; never to be reaching into
back pocket for Mars bar at the moment when the braking tutorial in urgently
required; never to be admiring the countryside and just have a silly 'off'?
Of course they might, they have always done so. And the result is usually a
few scratches and bruises. It is extremely rare for a kid to be killed/brain
damaged in a single vehicle accident, a risk far lower than being killed by
their fellow school pupils, or catching leukemia.
Quoted message said:Despite this, I have found the arguments put forward (particularly in the
references quoted) to be compelling. I, too, thought the matter of helmet
wearing was black and white; now I see all shades of grey....
It is very much shades of grey. Unfortunately helmets are most likely to
help when you least need them, and most likely to harm when you would need
them most.
...d
