On 24 May 2005 09:32:56 -0700, "gds" <[email hidden]> wrote in
message <[email hidden]>:
Quoted message said:Quoted message said:Quoted message said:Actually as far as I can see the major difference is not between
helmeted and unhelmeted cyclists, but between those who are risk
averse (and hence usually wear helmets) and those who are not. My
guess is that the OP will fit into the risk-averse category.
Quoted message said:Not really. I think the difference is more like between folks who want
to manage risk and those that are less inclined.
Well, you say that, but there are six jurisdictions where helmet use
has increased by 40 percentage points or more in a year, and not one
of them shows any measurable change ion head injuries as a percentage
of all cyclist injuries, so clearly the answer is more complex than at
first appears.
Quoted message said:In my own case I participate in activities with far more objective risk
than cycling. For example, back country trad rock climbing. A big part
of the fun of that is that one is able to manage and thus to a large
extent mitigate some very real risk.
I do too. Driving, for one.
Quoted message said:To me helmets accomplish just that- the management and mitigation of
risk.
Sure. A very small risk, that of a minor head injury while cycling.
No problem with that.
Quoted message said:However, it seems that the discussions on the subject take on the
air of religious arguments. Folks hold very strong beliefs and thus few
ever change their opinion.
Up to a point. Yes, there are True Believers and agnostics. But I
was a True Believer once, and so was Frank Krygowski, and I know many
others who have started from that position and ended up as sceptics
after reading the available evidence.
Quoted message said:Take aside the issue of compulsory use-which changes the argument from
safety to civil rights.
Up to a point - there is a bigger problem there. Helmet laws are
always presented as a "road safety" measure, but there is no reliable
evidence that helmets have ay meaningful effect against motor vehicle
impacts. So it's not just civil rights.
Helmet laws deter cycling. Reduced cycling increases the risk per
remaining cyclist. Helmet laws have increased the risk of cyclist
injury in several jurisdictions.
Quoted message said:How can it be seriously argued that helmets
"add no additional safety margin."
I have read extensively on this and have concluded that:
* helmets are very effective at preventing minor injuries
* helmets prevent no significant number of serious injuries
* serious injuries are rare anyway
* a cyclist is more prepared to take risks when helmeted
* cyclists who wear helmets voluntarily are likely to be more cautious
than non-wearers
This set of premises explains all the known facts. It explains the
large differences in injuries between helmeted and unhelmeted cyclists
in small-scale case-control studies; it explains the failure of time
trends to show any measurable benefit even where helmet use has
increased, often dramatically and in very short times; it takes due
cognisance of the standards and tests for which helmets are specified;
and it fits pretty all the available research evidence, pro-helmet or
sceptic.
Quoted message said:Since many of us have first hand
experience with situations where helmets have prevented or lessened
injury there are at least some excamples.
Well, you say that, but I have experienced something exactly like the
classic "helmet saved my life" story - I survived being thrown ten
feet through the air after being hit by a car - and my only protective
headgear was a knitted acrylic balaclava. The number of "helmet saved
my life" anecdotes vastly outweighs the number of unhelmeted cyclists
who die, and there is evidence that actually helmeted cyclists are
more likely to hit their heads in the first place, for whatever
reason. So it's not that simple.
Quoted message said:And I have yet to hear a
credible story of a modern helmet causing an injury.
There are several documented cases of children being fatally strangled
by helmet straps. But that's not the point - the point is, at the
population level, helmets make no measurable difference. In the few
appraisals I have seen of the relative merits of different cycle
safety interventions, every one has put helmets last.
Provided that you are of the view that helmets are last on the list
after maintenance, lights, riding technique, roadcraft and all the
other things that prevent crashes in the first place, and provided you
are not going to say that helmets save lives or protect against motor
vehicle collisions, then we have no disagreement whatever. I used to
wear one always, now I wear one sometimes. I wear it more when the
weather is wet and the roads slippery, less in summer.
Quoted message said:So, forget arguing
over the statistical merit of the studies. It may well be that they are
flawed. But that argument is only over how effective helmets might be-
not really over the more simple question "do they provide any marginal
safety."
No, that is not the right question. In terms of serious injuries at
least, it appears to be thus: helmets may or may not reduce the
probability of injury given crash, and may or may not increase the
provability of crash given ride, but the probability of injury given
ride remains the same.
The helmeted cohorts in some studies were more likely to crash. The
unhelmeted cohorts in others were more likely to suffer broken legs.
The evidence is simply too equivocal to make any definitive statement.
Guy
--
May contain traces of irony. Contents liable to settle after posting.
http://www.chapmancentral.co.uk
85% of helmet statistics are made up, 69% of them at CHS, Puget Sound