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Inflatable helmet, really



 
 
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  #81  
Old September 10th 10, 03:47 AM posted to rec.bicycles.tech
Clive George
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Posts: 5,394
Default Inflatable helmet, really

On 10/09/2010 03:44, !Jones wrote:
On Thu, 09 Sep 2010 21:20:02 +0100, in rec.bicycles.tech Clive George
wrote:

If one examines only the HIV and teen pregnancy rates, then one must
conclude that condoms are ineffective. "It said, 'Place on organ to
prevent infection,' but we don't have an organ, so I put it on the
piano, instead." We passed out condoms to the kids like candy in the
late '80s and '90s; they had no effect whatsoever.


No, one would conclude that the passing out of condoms like candy didn't
prevent all teenage pregnancy and HIV. It's not that they don't work,
it's that they're not being used. The analogy to helmet wearing doesn't
hold, because the method of failure differs.


Oh, I'm sure that one can explain it away... the bottom line is that,
if you crunch the numbers, condoms are an ineffective method of
controlling STDs and unwanted pregnancy. I never said that a helmet
and a condom functioned alike... gives a new meaning to the term "dick
head", huh?


Sorry, thought you might actually be interested in a discussion rather
than just shouting nonsense to yourself.
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  #82  
Old September 10th 10, 03:56 AM posted to rec.bicycles.tech
!Jones[_2_]
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Posts: 196
Default Inflatable helmet, really

On Thu, 9 Sep 2010 19:27:03 -0700 (PDT), in rec.bicycles.tech Frank
Krygowski wrote:

So... I plan to head out to some sleazy bar tonight, pick up some ****-
faced drunk person, and have sex with him or her. *Without passing
judgment on my hypothetical evening plans, would you suggest that
including a condom might be a good idea? *But, wait a minute! *I
thought we had established that they were ineffective. *I suggest that
it's simply impossible for protein to pass through latex... it cannot
happen!


Like most pro-helmet analogies, that's a bad one.

Here's how to improve it. Instead of a condom, try wrapping some
kleenex around your penis.


OK, I'm not aware of any data at all on that method.

You're boring me, Frank.

  #83  
Old September 10th 10, 04:18 AM posted to rec.bicycles.tech
kolldata
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Default Inflatable helmet, really a bottomless market, brilliant !

and the evergreen

http://www.google.com/imgres?imgurl=...w=1132&bih=579

  #84  
Old September 10th 10, 04:25 AM posted to rec.bicycles.tech
kolldata
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Posts: 2,836
Default Inflatable helmet, really a bottomless market, brilliant !



and don't forget the tights......
  #85  
Old September 10th 10, 04:40 AM posted to rec.bicycles.tech
Dan O
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Posts: 6,098
Default Inflatable helmet, really

On Sep 9, 9:19 am, Frank Krygowski wrote:
On Sep 8, 10:37 pm, !Jones wrote:



There are lots of sports wherein participants wear helmets, Frank.
Everyone from skaters to equestrian sports to motorcycle racers all
tend to wear helmets. Soldiers have historically worn helmets; riot
cops wear helmets; wild bull riders wear helmets (some of them,
anyway... never wanted to try it, myself); BASE jumpers wear helmets.
Heck, we had a publicity stunt where someone bungee jumped from a high
bridge and he wore a helmet; however, I haven't a clue what good it
would have done from that height!


Right - or, mostly right, anyway.

But when "Safety!!!" missionaries say that one should never ride a
bike without a helmet, they are putting ordinary bicycling into the
same category as soldiers, riot cops, bull riders, BASE jumpers and
bungee jumpers. All those are activities that most people will shun.


Most people will shun a lot of other activities that don't involve
helmets, too.

The implication that cycling is similarly dangerous...


.... is all in your head.

... cannot possibly be
good for cycling, and it adds evidence to the claims that "He knew the
risks!" when some motorist negligently harms a cyclist.


Well, he probably did. So what? Doesn't alter responsibility.


A few years ago, I had an "OH ****!" moment with a major component
failure. I had about half a second between the metallic "Pop!" and
impact. No, this isn't a "The helmet saved my life" story because my
head didn't hit... but, I guarantee that the thoughts flashing through
my mind in that half second were not: "I wish I wasn't wearing this
darned helmet!"


... and that's what it's come to. Any fall off a bike immediately
generates helmet stories - either "My helmet touched the ground, and
that proves I'd have died without it!" Or "He died. He should have
been wearing a helmet." Or "He died, even though he was wearing a
helmet." Or "He died. We'd better not mention that he was wearing a
helmet."


Ridiculous hyperbole.


There was a time when almost all falls off bikes were just falls off
bikes.


All falls off bikes are just falls off bikes. Your logic works (to a
point :-)

You got up. You rode on. Exceptions were as rare then as
they are now.


You have data on this?

But now every one is described as a near-death
experience.


Bull****. Sheer hyperbole.


Helmets work; that's simply a proven fact.


Oh?http://www.cyclehelmets.org/1041.html

For those who find clicking a link to be burdensome, that page
contains data on US head injuries for cyclists:
67,000 head injuries in 1991, when 18% of cyclists wore helmets.
74,000 head injuries in 2000, when 50% of cyclists wore helmets.
And in that time, cycling had fallen by 21%.


Only the numbers of injuries have a cited source, and any details of
whence came this data would have to be researched separately.

In any case, there is not even so much as a source cited for the
percentages of helmet wearing or the drop in "cycling".


Can you explain how this proves that helmets work?


Maybe they should make garlic flavored condoms. ;-)


  #86  
Old September 10th 10, 04:51 AM posted to rec.bicycles.tech
Frank Krygowski[_2_]
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Posts: 7,511
Default Inflatable helmet, really

On Sep 9, 8:37*pm, "MikeWhy" wrote:
Phil W Lee wrote:

Utter bull****.
If cycle helmets met the same standards, don't you think some
motorcyclists would be wearing them?


Not bull****. Look it up if you can figure out Google. Motorcycle helmets
have additional criteria not specified for bicycle helmets, including
coverage area and involving the chin bar when present. Retention criteria
are also more stringent. Impact loads and survivability, however, are
essentially the same.


A funny thing happens when one actually looks up what MikeWhy claims.
Specifically, they find that MikeWhy is either mistaken or lying.

Here's an article that discusses motorcycle helmet testing standards
in detail. (I've got it bookmarked.)
http://www.motorcyclistonline.com/ge...iew/index.html
or http://tinyurl.com/zglbq

What it says? "The killer—the hardest Snell test for a motorcycle
helmet to meet—is a two-strike test onto a hemispherical chunk of
stainless steel about the size of an orange. The first hit is at an
energy of 150 joules, which translates to dropping a 5-kilo weight
about 10 feet—an extremely high-energy impact. The next hit, on the
same spot, is set at 110 joules, or about an 8-foot drop. To pass, the
helmet is not allowed to transmit more than 300 Gs to the headform in
either hit."

Later, it says: "Where the Snell standard limits peak linear
acceleration to 300 G, the DOT effectively limits peak Gs to 250.
Softer impacts, lower G tolerance. In short, a kinder, gentler
standard."

I'm not sure about that "effectively." According to
http://www.smf.org/articles/mcomp2.html
DOT limits acceleration to 400 gs, but from a drop height (for a large
helmet) of about 7.35 feet, or 2.25 meters, which corresponds to 110
Joules for a 5 kg headform mass.

By contrast, the CPSC bicycle helmet standard calls for just a two
meter drop. It allows 300 gs acceleration of the same headform. The
standards are NOT the same.

Furthermore, the motorcycle helmet standard has much more rigid
penetration tests. This is what drives the design of their heavy,
hard shells. And this is pertinent, because a heavy, hard shell is
less likely to get traction with the road during a tangential impact,
and is more likely to have significant rotational inertia, to aid in
reducing the brain's rotational acceleration. This might be
considered an accidental benefit, because penetration of any helmet is
rare, but rotational brain accelerations are now commonly recognized
as being more likely than linear ones to cause serious brain injury.
(Still, NO helmet standard tests for them!)

What's even more enlightening is that article's discussion of the
effect of various acclerations: "Newman is quoted in the COST study
on the impact levels likely to cause certain levels of injury. Back in
the '80s he stated that, as a rough guideline, a peak linear impact—
the kind we're measuring here&151of 200 to 250 Gs generally
corresponds to a head injury of AIS 4, or severe; that a 250 G to 300
G impact corresponds to AIS 5, or critical; and that anything over 300
Gs corresponds to AIS 6. That is, unsurvivable."

Bike helmets are designed to attenuate the acceleration of a
decapitated human head - no body attached - to 300 gs in a 14 mph
impact. 300 gs is the borderline between critical and unsurvivable,
according to that estimate. And that doesn't take into account
rotational acceleration, which is worse in its effect, and which
helmets may exacerbate (by their larger diameter and higher friction
compared to a bare head).

So leave the cyclist's head attached to his body, subject him to a
head impact greater than 14 mph, include a slight tangential component
to the impact, and you've blown away the "protection" of a bike
helmet.

Is it any wonder they haven't been shown to reduce serious head
injuries?

- Frank Krygowski
  #87  
Old September 10th 10, 04:56 AM posted to rec.bicycles.tech
Frank Krygowski[_2_]
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Posts: 7,511
Default Inflatable helmet, really

On Sep 9, 10:56*pm, !Jones wrote:
On Thu, 9 Sep 2010 19:27:03 -0700 (PDT), in rec.bicycles.tech Frank

Krygowski wrote:
So... I plan to head out to some sleazy bar tonight, pick up some ****-
faced drunk person, and have sex with him or her. *Without passing
judgment on my hypothetical evening plans, would you suggest that
including a condom might be a good idea? *But, wait a minute! *I
thought we had established that they were ineffective. *I suggest that
it's simply impossible for protein to pass through latex... it cannot
happen!


Like most pro-helmet analogies, that's a bad one.


Here's how to improve it. *Instead of a condom, try wrapping some
kleenex around your penis.


OK, I'm not aware of any data at all on that method.

You're boring me, Frank.


I don't care, Jones. I'm not typing for the entertainment of a
troll. I'm merely using you as an excuse to get logic and information
out to others who may be interested.

- Frank Krygowski
  #88  
Old September 10th 10, 05:20 AM posted to rec.bicycles.tech
!Jones[_2_]
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Posts: 196
Default Inflatable helmet, really

On Fri, 10 Sep 2010 00:30:43 +0100, in rec.bicycles.tech Phil W Lee
wrote:

Indeed - in almost all motorsport protective equipment includes a
helmet, HANS device, multi-point safety restraint and flame-retardant
overalls.

On your logic, this proves clearly that all motorists and their
passengers should do the same.


I never suggested that; however, that's the usual tack.

You see, if you sample the automotive groups, you find *exactly* the
same argument, only it's about seat belts. Well, they also gripe
about how the pollution controls don't work and how everyone is so
unfair to them and how misunderstood they are... same old stuff. I
suppose that the real hot-button that gets them wound up as tightly
and quickly as you and Frank is noise abatement... you know, muffler
laws and limitations on boom-box volume. These don't work either!
(Why don't they fine AmTrac? They're noisier than my car stereo.)

If you go over to the jet skiers, they gripe about no wake zones. For
the snow mobile bunch, it's the trail closures due to avalanche
danger... it doesn't work! The skateboarders pretty much whine about
everything.

I don't care if you whine, Phill; heck, everyone else does. I'd just
like to see an original thought process beyond that.

Jones

  #89  
Old September 10th 10, 05:33 AM posted to rec.bicycles.tech
!Jones[_2_]
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Posts: 196
Default Inflatable helmet, really

On Thu, 9 Sep 2010 09:19:32 -0700 (PDT), in rec.bicycles.tech Frank
Krygowski wrote:

But when "Safety!!!" missionaries say that one should never ride a
bike without a helmet, they are putting ordinary bicycling into the
same category as soldiers, riot cops, bull riders, BASE jumpers and
bungee jumpers.


But you *are* in the same category! First, nobody ever said that...
certainly not *me*; second, you're whining about it... dunno 'bout the
BASE jumpers, but, if you want to listen to some serious whining about
how unfair life is, check out the veteran's groups! The cops are
right behind 'em.

They're not whining about helmets, though... it's usually the VA and
how hard it is to get PTSD compensation.

On my "whine-o-meter", the cyclists peg about a 5.6 out of 10...
better than the Masons but y'all wine a lot more 'n the faggots.

Jones

  #90  
Old September 10th 10, 05:53 AM posted to rec.bicycles.tech
Tom Sherman °_°[_2_]
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Posts: 2,312
Default Inflatable helmet, really

On 9/9/2010 10:51 PM, Frank Krygowski wrote:
On Sep 9, 8:37 pm, "MikeWhy" wrote:
Phil W Lee wrote:

Utter bull****.
If cycle helmets met the same standards, don't you think some
motorcyclists would be wearing them?

Not bull****. Look it up if you can figure out Google. Motorcycle helmets
have additional criteria not specified for bicycle helmets, including
coverage area and involving the chin bar when present. Retention criteria
are also more stringent. Impact loads and survivability, however, are
essentially the same.

A funny thing happens when one actually looks up what MikeWhy claims.
Specifically, they find that MikeWhy is either mistaken or lying.

Here's an article that discusses motorcycle helmet testing standards
in detail. (I've got it bookmarked.)
http://www.motorcyclistonline.com/ge...iew/index.html
or http://tinyurl.com/zglbq

What it says? "The killer—the hardest Snell test for a motorcycle
helmet to meet—is a two-strike test onto a hemispherical chunk of
stainless steel about the size of an orange. The first hit is at an
energy of 150 joules, which translates to dropping a 5-kilo weight
about 10 feet—an extremely high-energy impact. The next hit, on the
same spot, is set at 110 joules, or about an 8-foot drop. To pass, the
helmet is not allowed to transmit more than 300 Gs to the headform in
either hit."

Later, it says: "Where the Snell standard limits peak linear
acceleration to 300 G, the DOT effectively limits peak Gs to 250.
Softer impacts, lower G tolerance. In short, a kinder, gentler
standard."

I'm not sure about that "effectively." According to
http://www.smf.org/articles/mcomp2.html
DOT limits acceleration to 400 gs, but from a drop height (for a large
helmet) of about 7.35 feet, or 2.25 meters, which corresponds to 110
Joules for a 5 kg headform mass.

By contrast, the CPSC bicycle helmet standard calls for just a two
meter drop. It allows 300 gs acceleration of the same headform. The
standards are NOT the same.

Furthermore, the motorcycle helmet standard has much more rigid
penetration tests. This is what drives the design of their heavy,
hard shells. And this is pertinent, because a heavy, hard shell is
less likely to get traction with the road during a tangential impact,
and is more likely to have significant rotational inertia, to aid in
reducing the brain's rotational acceleration. This might be
considered an accidental benefit, because penetration of any helmet is
rare, but rotational brain accelerations are now commonly recognized
as being more likely than linear ones to cause serious brain injury.
(Still, NO helmet standard tests for them!)

What's even more enlightening is that article's discussion of the
effect of various acclerations: "Newman is quoted in the COST study
on the impact levels likely to cause certain levels of injury. Back in
the '80s he stated that, as a rough guideline, a peak linear impact—
the kind we're measuring here&151of 200 to 250 Gs generally
corresponds to a head injury of AIS 4, or severe; that a 250 G to 300
G impact corresponds to AIS 5, or critical; and that anything over 300
Gs corresponds to AIS 6. That is, unsurvivable."

Bike helmets are designed to attenuate the acceleration of a
decapitated human head - no body attached - to 300 gs in a 14 mph
impact. 300 gs is the borderline between critical and unsurvivable,
according to that estimate. And that doesn't take into account
rotational acceleration, which is worse in its effect, and which
helmets may exacerbate (by their larger diameter and higher friction
compared to a bare head).

So leave the cyclist's head attached to his body, subject him to a
head impact greater than 14 mph, include a slight tangential component
to the impact, and you've blown away the "protection" of a bike
helmet.

Is it any wonder they haven't been shown to reduce serious head
injuries?


Dear Frank,

Please stop confusing the Liddites™ with facts - it only makes them
angry that their religious belief in the Magic Foam Bicycle Hat™ is
challenged.

--
Tom Sherman - 42.435731,-83.985007
I am a vehicular cyclist.
 




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