Re: Any helmet laws successfully overturned? - Cycling Mob: Road Cycling, Mountain Biking and More

07-01-2003, 06:28 PM

"David Kerber" <[Only registered and activated users can see links. ]> wrote
>
> Which makes no sense, so recheck your assumptions. There are a few
> possible confounding circumstances, though. One is that the people who
> put in the most miles may wear their helmet more consistently than
> occasional riders.

And those people with more miles should, by virtue of experience, be better
riders. *Less* likely to crash.

Pete

07-02-2003, 04:04 AM

In article <drrMa.6700$[Only registered and activated users can see links. ].com>, [Only registered and activated users can see links. ] says...
>
> "David Kerber" <[Only registered and activated users can see links. ]> wrote
> >
> > Which makes no sense, so recheck your assumptions. There are a few
> > possible confounding circumstances, though. One is that the people who
> > put in the most miles may wear their helmet more consistently than
> > occasional riders.
>
> And those people with more miles should, by virtue of experience, be better
> riders. *Less* likely to crash.

Less likely *per mile*, but with enough extra miles, they are going to
have more crashes overall. A guy who puts in 30 miles per day, every day
has a lot more chance of crashing in any given year than a kid who rides
only 1 block to his friends house twice in a year.

--
David Kerber
An optimist says "Good morning, Lord." While a pessimist says "Good
Lord, it's morning".

Remove the ns_ from the address before e-mailing.

07-02-2003, 03:34 PM

archer <[Only registered and activated users can see links. ]> wrote:
: In article <drrMa.6700$[Only registered and activated users can see links. ].com>, [Only registered and activated users can see links. ] says...
:>
:> "David Kerber" <[Only registered and activated users can see links. ]> wrote
:> > Which makes no sense, so recheck your assumptions. There are a few
:> > possible confounding circumstances, though. One is that the people who
:> > put in the most miles may wear their helmet more consistently than
:> > occasional riders.

Most people understand helmet wearing rates to be the proportion
of cyclists wearing helmets in street counts or other observational
surveys. This should be pretty close to the proportion of miles
ridden by helmeted cyclists. The chances of being counted in such
a survey are more or less proportional to the amount the rider
cycles.

My guess is that the claim in that paper that only 41% of TBI
happen to non-helmeted cyclists isn't correct. But it's only a guess.

There is a school of thought that a glancing blow to the
helmets can deliver a rotational force to the head.
A study of squirrel monkeys showed just how damaging rotations
of the brain can be. Gennarelli et al, (1972) subjected 12 to linear
acceleration with peak levels 665-1230 g, and 13 primarily to rotational
acceleration in the range of 348 to 1025 g. Contact phenomina were
minimised by the design of the apparatus producing the head acceleration.
Non of those subjected to the linear acceleration were concussed, whereas
all 13 receiving rotational acceleration suffered concussion, and the
group showed a high incidence of subdural haematoma, subarachnoid
haemorrhage and intracerebral petechial haemorrhage.

I don't know if the above is important or not, but I do know
that when helmet laws were introduced in Australia and millions
of cyclists were forced to wear healmets, there was no obvious'
effect on the rate of head injuries.

So, if helmet laws don't work, it would be a good thing to
repeal them and allow cyclist freedom of choice. As you suggest,
the main factors determining the risk of head injury are not
whether you wear a helmet, but how you ride, where you ride,
and how likely you are to be hit by a motor vehicle. Nearly
all serious TBI result from bike/motor vehicle crashes. The
best way a cyclist can avoid TBI is therefore to reduce this
risk by obeying traffic laws, using lights at night, riding
predicably and, if necessary, avoiding routes with high-speed,
erratic or irresponsible motoritsts.

Dorre

:> And those people with more miles should, by virtue of experience, be better
:> riders. *Less* likely to crash.

: Less likely *per mile*, but with enough extra miles, they are going to
: have more crashes overall. A guy who puts in 30 miles per day, every day
: has a lot more chance of crashing in any given year than a kid who rides
: only 1 block to his friends house twice in a year.
: David Kerber
: An optimist says "Good morning, Lord." While a pessimist says "Good
: Lord, it's morning".

: Remove the ns_ from the address before e-mailing.