Russell said:Now as a competetive roadie I spend a fair proportion of my time
travelling over 20mph, regularly over 30mph and occasionally over
50mph. Thankfully I've only had this one experience of falling at
around 30mph. It happened very quickly & there was no time to put out
a hand or foot or anything (although the fingers on the other hand got
mashed as I rolled I think). Consequently, my whole body hit the road
side on and as my body was decelerated by the ground, my head
continued on the short journey to the road to make its own impact.
Whether or not I would have suffered brain injury is something we will
never know but I still believe it saved me from a nasty head injury.
We need to be careful about defining "nasty head injury". Yes, your
head would have probably continued to the road and had its own special
impact, but having had it it would have probably bounced back up,
leaving you with a nasty graze and a fair sized bump. Brain injury?
Well, a mild concussion is technically a brain injury, but permanent
damage? Very, very, very unlikely, and I say that looking at the rash
of non-brain damaged old roadies who've had the odd fall at speed.
Is it worth protecting yourself against a nasty graze, a good size bump
and a bloody awful headache? Certainly, at least if all else is equal.
But I don't think it's completely safe to assume it is.
Quoted message said:With regard to accidents involving other vehicles, I do not suppose
the helmet provides very much protection, hence no discernable
difference in the brain injury figures. Surely though some protection
is better than none at all.
Only if it will make a /useful/ difference. If it makes the difference
between dying instantly and dying a minute later, or the difference
between having to identify the body from dental records or not then
that's a /difference/, but not, I would suggest, a useful one.
And since motor vehicle collisions involve forces far beyond the design
specs of cycle helmets this is the area you're in. A cycle helmet well
beyond its design spec will just smash to pieces with brittle failure
and absorb little tangible force (think of a very strong ceramic tile
with a nail being driven through the middle, and how it just smashed
having offered little real resistance), so it's not likely to do much to
help.
Think how a tough leather jacket would possibly be a fair bit of use
against stray duckshot. Would you really care whether you were wearing
one or not against targeted high velocity rifle fire?
The sorts of forces bike helmets will usefully deal with are not the
sort of forces that are likely to cause KSI accidents. They deal with
the sort of thing that will hurt, but will not likely do really serious
damage. Like gardening gloves they can save pain, but not usually
lives. Unlike gardening gloves they only deal with very uncommon acute
problems, not ever-present chronic ones.
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/
