published helmet research - not troll

Bill Z. wrote:

Nope. We were talking about the brakes being *locked* so that the
front wheel stopped turning. At that point, *no* energy is being
dissapated in the brakes as nothing is sliding past the brake pads.
You can lock the front brakes with a negligible reduction in
your speed (but of course then you will immediately start to flip
over.)


If the front wheel locks, then one of two things happen:
the entire bike rotates around the front wheel, or the bike
skids on its front wheel. Of course, both could happen concurrently
(skidding with rotation). If the front doesn't skid then the
conservation of energy can be used, if it does, then things get a bit
complicated. It's not immediately clear that the front wheel won't
skid. The force transfer to the front wheel should help prevent it, but
is it sufficient? Is there an easy way to show that it is sufficient?

Joe

Joe Riel writes:

Bill Z. wrote:

Nope. We were talking about the brakes being *locked* so that the
front wheel stopped turning. At that point, *no* energy is being
dissapated in the brakes as nothing is sliding past the brake pads.
You can lock the front brakes with a negligible reduction in
your speed (but of course then you will immediately start to flip
over.)


If the front wheel locks, then one of two things happen:
the entire bike rotates around the front wheel, or the bike
skids on its front wheel. Of course, both could happen concurrently
(skidding with rotation). If the front doesn't skid then the
conservation of energy can be used, if it does, then things get a bit
complicated.

Except you won't skid and flip: the coefficient of static friction is
always higher than the coefficient of sliding friction. If you start
to skid, the tangential force drops.

It's not immediately clear that the front wheel won't
skid.

Yes it is. See above.

--
My real name backwards: nemuaZ lliB

Mitch Haley writes:

"Bill Z." wrote:
Dorothy Robinson has an axe to grind, as would be obvious from
her posts on rec.bicycles.soc 8 to 10 years ago.

Bill Zaumen like to lie about Dorre Robinson, as would be obvious
from his posts on r.b.s many years ago.
Mitch.

I've never lied about Dore. The fact is she has an axe to grind on
this subject, as should be evident by her inserting silly names in
quotes between my first name and last name for a full month. That
is *not* the sort of behavior you get from someone who does not have
an axe to grind (and I had been polite to her up to that point.)

I have told Dore off when she got particularly rude. Mitch, like the
rest of the anti-helmet people, follows the standard tactic - disparaging
anyone who they disagree with. They've done that consistently.

--
My real name backwards: nemuaZ lliB

Benjamin Lewis writes:

Bill Z. wrote:

Benjamin Lewis writes:

Bill Z. wrote:

Benjamin Lewis writes:

[...] That's a lot of articles, at least one of which is bogus.
Which ones do you recommend I start with?

Start at the top of the list and work down towards the bottom. I'm
not sure what you mean by "bogus" as I just pasted the list verbatim
and used a "fill paragraph" command to keep the line lengths to 72
characters. Did I somehow mangle a line?

No, I mean that it includes TR&T, which has, to me, adequately been
shown to be inaccurate. I'm not about to seek out and read all 80
articles right now, so I thought if you had you could point me to the
ones that are the most convincing.

Let's see. Out of a very long list nearly 100 long, you see that
particular one, and that is the only one you comment on. I wonder
why :-).

Because that's the only one I know to be inaccurate. What are you
implying?

I'm just curious why you'd complain about 1 citation in a list nearly
100 long (of what appears to be a broad spectrum of papers) and assume
all are bad because you have a low opinion of just one. Henderson seems
to have just created a list of citations with short comments about
what each contains. That's it. He saved you the time of tracing
citations on the subject.

BTW, I posted two other citations too, although in a different post from
the one you talked about. If you need a shorter list, start with those
two. One can be downloaded for free and shows that helmet laws are cost
effective only when the laws are limited to particular age groups. For
teens and adults, the laws are not cost effective.

I'll have a look, but I'm completely uninterested in cost effectiveness by
itself -- I'm just interested in safety effectiveness. (I'm aware that the
two are related). I would be against MHLs even if I believed that helmets
prevented *all* head injuries.

If there was no "safety effectivenss" the cost effectiveness number would
have been zero.

For that matter, I'm also not convinced that even if helmets *are* x%
effective, the danger of cycling is great enough to warrant wearing one.

That's a personal decision on your part.

One might surmise that, for a particular skill level, there is some
minimum mileage you have to put in before the cost of the helmets pays
for the savings in medical expenses, since the helmet cost is fixed
but your chances of an accident scale with how much you ride.

Not linearly, though, I believe -- high mileage cyclists are less likely
per hour to get into accidents.

But they put in far more mileage. Forester claims that club cyclists
have about 5 times fewer accidents per mile than the average person.
In the New Zealand study we were talking about, the adult cyclists who had
to buy helmets because of the law probably averaged very few miles per
week. You might have someone who rides 5 miles per week for very short
trips to a train station (as some people around here do.)

Bill

--
My real name backwards: nemuaZ lliB

"Tom Kunich" writes:

"Bill Z." wrote in message
...

Do you understand the difference between a citation in a journal or
other high-quality publication and some number some activist-types,
looking for anything that helps their agenda, might put on some random
website?

Perhaps you like to suggest to us who refereed the paper by Thompson, Rivara
et. al.? Likewise who was consulted to critique the Henderson paper?

Obviously you understand what high quality publications demand in the way of
alleviating bias when the sponsors of a study have a business interest in
the outcome?

Perhaps you didn't notice that I called the Henderson paper a high-level
summary and useful primarily for its list of citations.

--
My real name backwards: nemuaZ lliB

"Bill Z." wrote:
I have told Dore off when she got particularly rude. Mitch, like the
rest of the anti-helmet people, follows the standard tactic - disparaging
anyone who they disagree with. They've done that consistently.

Pot-Kettle-Black

"Tom Kunich" writes:

"Bill Z." wrote in message
...
"Tom Kunich" writes:
Then you have read it have you? And you can report to us how they used
the
original data to achieve this change of opinion?

As the paper, I just found the URL a couple of hours ago and getting a
copy on-line would cost me thirty dollars, which is a non-starter. So,
you'll have to accept the author's word for it or shell out the $30
yourself. I presume the new results is due to a more comprehensive
study than the relatively crude one done over 10 years ago.

So in short you haven't read it and hence have no idea of how they suddenly
discovered effectiveness in the data which previously had no effectiveness
apparent to them. I'm not in the least bit surprised that you are commenting
on things even you admit you know nothing about.

I stated what was in the abstract. I posted it yesterday. To find
a copy and not pay $30, I'd have to drive to a library, all closed
on the 4th of July (a national holiday in case you don't know.)

Bill

--
My real name backwards: nemuaZ lliB

"Tom Kunich" writes:

"Bill Z." wrote in message
...
Start at the top of the list and work down towards the bottom. I'm
not sure what you mean by "bogus" as I just pasted the list verbatim
and used a "fill paragraph" command to keep the line lengths to 72
characters. Did I somehow mangle a line?

If you haven't read these articles perhaps you're the one who should be
following your own advice?

The majority of the articles cited were financed by the helmet industry or
used the data of the 'studies' financed by the helmet industry. As I
demonstrated in several of these the summary results often did not match the
interior discussion of the complete articles leading one to the inescapable
conclusion that the summary had been 'fixed' to obtain funding from a biased
source.

Conspiracy theory.



--
My real name backwards: nemuaZ lliB

"Tom Kunich" writes:

"Bill Z." wrote in message
...
"Tom Kunich" writes:
In fact, Bill "quoted" from the summary statements available on the
internet
without ever reading the studies under question.

How the hell would you know?

Because, for instance, you already told us that you listed all of the
citations of articles off of Henderson's article despite not having a clue
about what most of them had to say yourself.

Bill, when you cite something it indicates that you YOURSELF have read and
understand the data and are referencing it for a particular reason. That
seems to be significantly beyond your ability to understand.

Hey moron, as I said, I read the one I could get for free and cited what
I *read* in an abstract for the other, all in a short post where I mostly
just provided the reference for anyone who might be interested.



--
My real name backwards: nemuaZ lliB

Bill Z. wrote:

If you are not going to flip and the rear tire lifts off the ground,
the center of mass will rise up to some high point at which your
velocity (both rotational and linear) is *zero*. This height is
dependent *only* on the value of g (acceleration due to gravity) and
your initial velocity as I showed.

I can increase the moment of inertia by adding weights in various
positions so as to not change the position of the center of mass. The
high point will be identical regardless. Since the high point is
independent of the numerical value of the moment of inertia, the
moment of inertia is simply not relevant to the discussion.

OK, I see I made a mistake when I said "A bike with a higher moment of
inertia could do that from a higher speed." You're right that in the
limiting case (just balancing on its nose) it would have no rotational
kinetic energy, so the moment of inertia wouldn't affect the action.

On the other hand, when I said just following that, "Or it could give
the rider a few extra fractions of a second to react by lessening the
brake action," that is, I believe, still true.

[fk:] Again, it's a small effect, and relatively unimportant.

And that is still true. We're debating something which is so far into
minutae that it's really not worth discussing.


--
--------------------+
Frank Krygowski [To reply, remove rodent and vegetable dot com,
replace with cc.ysu dot edu]