Re: Helmet Wankers

[Bernie]

David Kerber wrote:

>In article <[email protected]>,
>[email protected] says...
>
>>On Sat, 7 Feb 2004 13:15:06 -0500, David Kerber
>><ns_dkerber@ns_ids.net> wrote in message
>><[email protected]>:
>>
>>>If you hit a rock or tree at 60mph, it's not
>>>going to matter one bit whether you have that helmet on or not. At 20
>>>or 25, it probably would because the helmet will absorb a significant
>>>portion of the impact energy.
>>>
>>Up to a point, Lord Copper. Actually a helmet will absorb the energy
>>of a fall onto a flat surface from a standing start at about 5'4"
>>height.
>>
>
>Exactly. And that leaves that much less energy to be transmitted to my
>skull. It won't absorb it all, but it will absorb whatever it can,
>reducing what hits my scull.
>
>>>I've found that I don't ride noticeably different with a helmet than
>>>without.
>>>
>>Keyword: noticeably - i.e. you don't notice. Which is precisely the
>>point. I ride much more cautiously without a helmet on my drop-bar
>>bike, and am much more nervous at speed on my drop-bar bike than on my
>>recumbent.
>>
>
>Not everybody is that way, though. It just sounds like I'm a more
>cautious rider than you are, whether I have my helmet on or not.
>
If I can put my 2 cents worth in here.. In the last 41/2 years of mostly
daily commuting I've gone down four times. Once because I was
unfamiliar with harder skinnier tires, twice on black ice, once because
I tried an impossible move around a car that could not actually stop at
a stop sign. They just slowed down and very gently rolled in front of
me... (I'll try not to be bitter}
My point is: and remember this is a helmet ****:
In 4 instances I went down. twice my helmet protected me, no question.
One time I slid downhill , even crossed a set of railway tracks (under
the skytrain at Canfor Industrial Park in New Westminster, BC if ya
wanna know) and I do believe, was protected from concussion and
abrasions by my helmet.
The other serious crash happened last summer when that little Honda just
couldn't quite stop and I tried to skew around her and not be messed up
by the rr tracks i was crossing at the same time. Lost it big time,
slid for home, no concussive fall, but the helmet definitely saved the
side of my face from a major scrape, protected my glasses. For this I
am thankful.
Do I support helmet wearing? Yes! Should it be mandatory? Leave me
out of it!
Best regards, Bernie

 

[Tony Raven]

David Kerber wrote:
>
> Do you have any cites for the claim that helmets "amplify the rotational
> component" of a head impact to any significant degree? I don't need to
> see them for the fact that rotational acclerations are more damaging to
> the brain; that is well-known, and has been for many years.
>

Curnow WJ "The efficacy of bicycle helmets against brain injury", Accident
Analysis and Prevention, Vol 35, pp287-292 (2003)

http://tinyurl.com/3hnav (abstract plus link if you are registered to full
article)

In other sports, the role of helmets in increasing rotational injuries is also
known. See for example:
http://www.ipvca.org/coaches_connection_medical_helmets.htm

Tony

 

[Just zis Guy, you know?]

On Sat, 7 Feb 2004 20:03:46 -0500, David Kerber
<ns_dkerber@ns_ids.net> wrote in message
<[email protected]>:

>Do you have any cites for the claim that helmets "amplify the rotational
>component" of a head impact to any significant degree?

Cites? No, the jury is still out. But it is a concern whihc has been
raised by a number of doctors, and the proposed mechanism is credible
- it is also one possible explanation for the rise in seriousness of
injuries since 1985, as helmets have become more common. Other
factors could also account for this.

>But because the difference in riding style is small for me, I think I
>personally gain in _overall_ safety. I.E. the small increase (not
>noticeable by me) in risky behavior is more than compensated for by the
>increased protection from the helmet. Obviously that will not be the
>case for every cyclist.

That's your choice. I don't see from the data anything which makes a
good case for even strong encouragement of helmet use, let alone the
current emphasis on helmet use to the exclusion of all else.

Guy
===
May contain traces of irony. Contents liable to settle after posting.
http://chapmancentral.demon.co.uk

 

[Just zis Guy, you know?]

On Sat, 7 Feb 2004 20:14:07 -0500, David Kerber
<ns_dkerber@ns_ids.net> wrote in message
<[email protected]>:

>most EE's of my acquaintance (including me) aren't
>that big into theory to remember the basic equations years later, even
>though they certainly learned them at one time.

Always assuming that their lecturers, call them for the sake of
argument Professor Hammond, made the bloody things comprehensiuble in
the first place.

Guy
===
May contain traces of irony. Contents liable to settle after posting.
http://chapmancentral.demon.co.uk

 

[Just zis Guy, you know?]

On Sun, 08 Feb 2004 01:45:01 GMT, Graeme
<[email protected]> wrote in message
<[email protected]>:

>EE = electrical engineer? That's me (well, at least if what your degree was
>defines you). V=IR is about all I can remember instantly, most other stuff
>takes a bit of thinking or a book

Scarily true. I can't remember most calculus any more.

(B.Eng Hons, Electrical Engineering)

Guy
===
May contain traces of irony. Contents liable to settle after posting.
http://chapmancentral.demon.co.uk

 

[Graeme]

"Just zis Guy, you know?" <[email protected]> wrote in
news:[email protected]:
> Scarily true. I can't remember most calculus any more.
>
> (B.Eng Hons, Electrical Engineering)

Snap! This is getting scary Guy, I find myself agreeing with your posts
more and more, and now I find we both have the same degree. I live in fear
of waking up some day with a dodgy moustache (but I'll live with it if it
comes with the associated recumbent bike).

;-)

Graeme

 

[Mark Thompson]

> Curnow WJ "The efficacy of bicycle helmets against brain injury", Accident
> Analysis and Prevention, Vol 35, pp287-292 (2003)
>
> http://tinyurl.com/3hnav (abstract plus link if you are registered to full
> article)
>
> In other sports, the role of helmets in increasing rotational injuries is also
> known. See for example:
> http://www.ipvca.org/coaches_connection_medical_helmets.htm

wot he said, and

Bicyclists, helmets and head injuries: a rider-based study of helmet use and
effectiveness Wasserman RC, Waller JA, Monty MJ, Emery AB, Robinson DR 1988.
American Journal of Public Health: 1988 Sep;78(9):1220-1

suggests that helmeted riders are seven times more likely to hit their heads. I
guess that this is something to do with the control groups, but it's not hard to
think of several ways that helmets make you more likely to headbutt things
(size, weight, risk comp etc).


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[Nick Maclaren]

In article <[email protected]>,
David Kerber <ns_dkerber@ns_ids.net> wrote:
>In article <[email protected]>,
>[email protected] says...
>
>> >Exactly. And that leaves that much less energy to be transmitted to my
>> >skull. It won't absorb it all, but it will absorb whatever it can,
>> >reducing what hits my scull.
>>
>> And at the same time aplifying the rotational component which is the
>> most common cause of brain injury.
>
>Do you have any cites for the claim that helmets "amplify the rotational
>component" of a head impact to any significant degree? I don't need to
>see them for the fact that rotational acclerations are more damaging to
>the brain; that is well-known, and has been for many years.

I haven't seen any analyses of experimental data, though I have heard
that there may have been a little for motorcyclists and/or horse
riders. It is, however, immediate from the physics involved that they
are very LIKELY to do that.

Most accidents involving reasonably cautious cyclists have the cyclist
coming off sideways - even being hit from behind at a fairly low
relative speed will do that. If someone comes off sideways, the impact
is on hip, shoulder and sometimes knee and elbow. Because a helmet
increases both the width and the moment of the head by a significant
factor, it is very likely to cause head/helmet contact where it would
not otherwise have happened. Q.E.D.

What isn't so easy is to assign probabilities and severities to this,
but it is absolutely clear that the effect must exist, unless you
deny the reality of elementary physics (as many people and most of
our Lords and Masters do).


Regards,
Nick Maclaren.

 

[Just zis Guy, you know?]

On Sun, 08 Feb 2004 11:07:25 GMT, Graeme
<[email protected]> wrote in message
<[email protected]>:

>This is getting scary Guy, I find myself agreeing with your posts
>more and more, and now I find we both have the same degree.

Luke, I am your father...

Where did you do the B.Eng? If it was Southampton please be aware
that the world will have reached a degree of smallness where China may
require a second layer.

Guy
===
May contain traces of irony. Contents liable to settle after posting.
http://chapmancentral.demon.co.uk

 

[Tim Woodall]

On Sat, 07 Feb 2004 19:26:05 -0800,
Benjamin Lewis <[email protected]> wrote:
> David Kerber wrote:
>
>>>>> God said, "div D = rho, div B = 0, curl E = - @B/@t, curl H = J +
>>>>> @D/@t," and there was light.
>>>>
>>>> So are you an EE or a Physicist?
>>>>
>>> Physicist.
>>>
>>> Tim.
>>
>> That was my guess; most EE's of my acquaintance (including me) aren't
>> that big into theory to remember the basic equations years later, even
>> though they certainly learned them at one time.
>
> Also, I was under the impression that EEs usually express these in a
> different format.
>
So do Physicists nowadays but, IIRC "dF = 0" just doesn't have the same
ring to it.

Tim.

--
God said, "div D = rho, div B = 0, curl E = - @B/@t, curl H = J + @D/@t,"
and there was light.

http://tjw.hn.org/ http://www.locofungus.btinternet.co.uk/

 

[Graeme]

"Just zis Guy, you know?" <[email protected]> wrote in
news:[email protected]:

> Luke, I am your father...

That explains it, the Dark Side has been calling for some years now.
Unfortunately SWMBO has been calling for different things (weddings,
moving to the other side of the world etc.) which means my bank balance
seldom reaches the relevant level (although I wouldn't have to pay
shipping on a Greenspeed trike now

> Where did you do the B.Eng? If it was Southampton please be aware
> that the world will have reached a degree of smallness where China may
> require a second layer.

Phew! It was Edinburgh. The only link I have to Southampton is having
been there a couple of times visiting the council for work purposes. So
the mutation may not reach the moustache stage.

Mind you, I'm sure I've got a virtual 'tache, here I am sitting in
Australia and I'm listening to Radio 4 via broadband- Gardener's
Question Time even! It may even be a virtual beard, pipe and slippers :-O



Graeme

 

[Tony Raven]

Graeme wrote:
>
> Mind you, I'm sure I've got a virtual 'tache, here I am sitting in
> Australia and I'm listening to Radio 4 via broadband- Gardener's
> Question Time even! It may even be a virtual beard, pipe and slippers :-O
>

Off to uk.rec.sheds with you ;-)

Tony

 

[David Reuteler]

In rec.bicycles.misc Graeme <[email protected]> wrote:
: EE = electrical engineer? That's me (well, at least if what your degree was
: defines you). V=IR is about all I can remember instantly, most other stuff
: takes a bit of thinking or a book :-/ Mind you, I fell into the computer
: side of things soon after graduating and even Ohm's law became irrelevant
: :-/

i was physics but otherwise resemble that remark. what with the ample
employment opportunities in physics proper i'd say 50% of my graduating
class (1993) went into computers. of 30 (physics had such wonderfully
small class sizes! & this at the university of minnesota twin cities)
half into computers, 2 went to graduate school in physics, 3 became
high school science teachers, couple went into engineering. a few found
jobs in physics. not sure about the rest. love the major, tho. it has
always served me well.
--
david reuteler
[email protected]

 

[dave]

>
> Nearly right. In fact the motorcycle crashes tended to be more
> seriously injurious of the riders. The interesting point is that
> somehow this greater risk of injury in crashes balanced out the lesser
> incidence of crashes to produce the *same* risk of injury per mile.
>
> Was this just an extraordinary co-incidence?
>
> The suggestion of the author was that *if* risk compensation occurs,
> we should expect it to be most clearly demonstrated in the most
> experienced and capable people, because those are the people whose
> appreciation of the risks and of their own capabilities would be the
> most realistic.
>
> That's why he chose specially trained police drivers and riders, those
> who've graduated from the special advanced training courses.
>
> His suggestion was that these experienced capable drivers and riders
> had a certain level of injury risk which they felt comfortable with,
> and adjusted their behaviour on motorcycles or cars in such a way as
> to compensate for the very different characteristics and
> vulnerabilities of these different vehicles, so that they ended up,
> realistically, taking the same level of risk. Risk compensation.
>
> Of course that study didn't *prove* risk compensation, it simply
> either exemplified it well or was a remarkable coincidence. You need
> to pile up some more, and fail to find counter-examples, to strengthen
> the case.

And this intuitively feels right.

Someone is going to howl me down about this but it just seems obvious to
me that there is a perceived risk level I am ok with and one I am not.
And that the more experience one has the more likely the percieved risk
is to be close to the real risk.

Incidently my ex, a **** driver if anyone was went on to fail the
police pursuit course... twice

Dave

 

[David Kerber]

In article <[email protected]>, junk@raven-
family.com says...
> David Kerber wrote:
> >
> > Do you have any cites for the claim that helmets "amplify the rotational
> > component" of a head impact to any significant degree? I don't need to
> > see them for the fact that rotational acclerations are more damaging to
> > the brain; that is well-known, and has been for many years.
> >
>
> Curnow WJ "The efficacy of bicycle helmets against brain injury", Accident
> Analysis and Prevention, Vol 35, pp287-292 (2003)
>
> http://tinyurl.com/3hnav (abstract plus link if you are registered to full
> article)

That abstract draws no conclusions at all; it just says that the it
study it examined wasn't properly designed to draw the conclusions it
did. Kind of like declaring a defendent in a trial to be not guilty
because the prosecution didn't prove the case beyond a reasonable doubt:
it does not say the defendent didn't do it, only that it was not proven
that he did do it.


> In other sports, the role of helmets in increasing rotational injuries is also
> known. See for example:
> http://www.ipvca.org/coaches_connection_medical_helmets.htm

That one is more interesting, and presents an issue I hadn't thought of,
and which could certainly be an issue in bicycle crashes with the
projections they typically have in front of and behind the head. Of
course they are discussing neck injuries, and not head injuries, but it
still needs to be considered.


Note that neither one of these links you provided supports your
assertion that helmets exacerbate rotational injuries to the brain. Do
you have any others which do?


--
Dave Kerber
Fight spam: remove the ns_ from the return address before replying!

REAL programmers write self-modifying code.

 

[David Kerber]

In article <[email protected]>,
[email protected] says...
> On Sat, 7 Feb 2004 20:14:07 -0500, David Kerber
> <ns_dkerber@ns_ids.net> wrote in message
> <[email protected]>:
>
> >most EE's of my acquaintance (including me) aren't
> >that big into theory to remember the basic equations years later, even
> >though they certainly learned them at one time.
>
> Always assuming that their lecturers, call them for the sake of
> argument Professor Hammond, made the bloody things comprehensiuble in
> the first place.

LOL! I was pretty lucky that way: most of my professors had been
working engineers before coming back to teach.

--
Dave Kerber
Fight spam: remove the ns_ from the return address before replying!

REAL programmers write self-modifying code.

 

[David Kerber]

In article <[email protected]>,
[email protected] says...
> On Sun, 08 Feb 2004 01:45:01 GMT, Graeme
> <[email protected]> wrote in message
> <[email protected]>:
>
> >EE = electrical engineer? That's me (well, at least if what your degree was
> >defines you). V=IR is about all I can remember instantly, most other stuff
> >takes a bit of thinking or a book
>
> Scarily true. I can't remember most calculus any more.

I have forgotten some of mine, but I still use some, and I've been
learning a bit of linear algebra as well, in my current job working for
a statistician.

>
> (B.Eng Hons, Electrical Engineering)
>
> Guy
> ===
> May contain traces of irony. Contents liable to settle after posting.
> http://chapmancentral.demon.co.uk
>

--
Dave Kerber

B.S. EE, Magna Cum Laude, UMR

Fight spam: remove the ns_ from the return address before replying!

REAL programmers write self-modifying code.

 

[Tony Raven]

David Kerber wrote:
>
> That abstract draws no conclusions at all; it just says that the it
> study it examined wasn't properly designed to draw the conclusions it
> did. Kind of like declaring a defendent in a trial to be not guilty
> because the prosecution didn't prove the case beyond a reasonable doubt:
> it does not say the defendent didn't do it, only that it was not proven
> that he did do it.
>

Well pay your money and read the whole article then.

>
> Note that neither one of these links you provided supports your
> assertion that helmets exacerbate rotational injuries to the brain. Do
> you have any others which do?

In your enthusiasm to attack you miss the fact that I made no such assertion.
I was just responding to your request for information on helmets and
rotational injuries. Helmets can exacerbate the rotational effects for which
you should look at section 7 of http://www.bhsi.org/chinstrp.pdf which found
some helmets created rotational accelerations significantly in excess of the
recommended maximum.

Tony

 

[David Kerber]

In article <[email protected]>, junk@raven-
family.com says...
> David Kerber wrote:
> >
> > That abstract draws no conclusions at all; it just says that the it
> > study it examined wasn't properly designed to draw the conclusions it
> > did. Kind of like declaring a defendent in a trial to be not guilty
> > because the prosecution didn't prove the case beyond a reasonable doubt:
> > it does not say the defendent didn't do it, only that it was not proven
> > that he did do it.
> >
>
> Well pay your money and read the whole article then.
>
> >
> > Note that neither one of these links you provided supports your
> > assertion that helmets exacerbate rotational injuries to the brain. Do
> > you have any others which do?
>
> In your enthusiasm to attack you miss the fact that I made no such assertion.

I realized after making my post that you were not the one who posted the
message I was initially answering; he _did_ make that claim. I
apologize for that mistake.


> I was just responding to your request for information on helmets and
> rotational injuries. Helmets can exacerbate the rotational effects for which
> you should look at section 7 of http://www.bhsi.org/chinstrp.pdf which found
> some helmets created rotational accelerations significantly in excess of the
> recommended maximum.

That's an interesting study, but based on their descriptions, I'm not
sure it applies to most bicycle helmets that people actually wear. They
didn't describe in much detail what a "non-shell" helmet is, which they
noted was the only one which gave significant rotational force to the
head. Would that be the leather style ones which you used to see on
racers? Their description of "ribbed hard-shell" helmets seems to be
consistent with the description of the ones most riders wear these days.

--
Dave Kerber
Fight spam: remove the ns_ from the return address before replying!

REAL programmers write self-modifying code.

 

[Tony Raven]

David Kerber wrote:
>
> That's an interesting study, but based on their descriptions, I'm not
> sure it applies to most bicycle helmets that people actually wear. They
> didn't describe in much detail what a "non-shell" helmet is, which they
> noted was the only one which gave significant rotational force to the
> head. Would that be the leather style ones which you used to see on
> racers? Their description of "ribbed hard-shell" helmets seems to be
> consistent with the description of the ones most riders wear these days.

Hardshell is one like a motorbike helmet, microshell is what most of of are
used to with the thin glossy plastic outer layer and non-shell is the old
style bare polystyrene. Another interesting paper is
http://www.bhsi.org/hodgstud.htm. They say the 4500r/s/s is not exceeded on
any of the helmets but also their maximum speed is 6.4mph. If you look at the
traces near the end they are not that much below the limit to consider you
would stay within the limits at not much higher speeds. There is no control
data though on the bare human head. Its also noticeable that the vented
helmets they show have virtually no vents compared with today. It could do
with an updated study with current helmet designs.

Tony