JASON DUNN

Yes they are very different but I figured the concept of how the polystyrene
works and how it can get brittle and harden over time so it will not absorb
a impact, would be similar to the material of a bicycle helmet.

On May 12, 2010 1:58 AM, "mohair" wrote:

Motorcycle helmets are a lot different from bicycle helmets. The obvious
reason is that motorcycles go a lot faster. A modern bicycle helmet has a
very thin layer of brittle plastic that spreads the load to the "foam" body
which is designed to crush and further spread the impact. A motorcycle
helmet is layered and built to withstand skidding and multiple impacts as
well as simple impact. The bikers' term "skid lid" is very apt. Look at the
Snell Foundation testing guide for details.

Note that polystyrene is not "cushiony." The padding on the inside of a
motorcycle helmet is carefully designed to provide "progressive compression"
upon impact. To say that it is "worthless in protecting you in an
accident" is drivel. When I was racing motorcycles years ago, I saw several
riders go down hard and destroy helmets and live to tell the tale. As your
speed increases, the laws of physics take over, no matter how good your
helmet or body armor.

On May 11, 2010, at 10:39 PM, JASON DUNN wrote:

> I know with motorcycle helmets the the cushi...

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mohair

Motorcycle helmets are a lot different from bicycle helmets. The obvious reason is that motorcycles go a lot faster. A modern bicycle helmet has a very thin layer of brittle plastic that spreads the load to the "foam" body which is designed to crush and further spread the impact. A motorcycle helmet is layered and built to withstand skidding and multiple impacts as well as simple impact. The bikers' term "skid lid" is very apt. Look at the Snell Foundation testing guide for details.

Note that polystyrene is not "cushiony." The padding on the inside of a motorcycle helmet is carefully designed to provide "progressive compression" upon impact. To say that it is "worthless in protecting you in an accident" is drivel. When I was racing motorcycles years ago, I saw several riders go down hard and destroy helmets and live to tell the tale. As your speed increases, the laws of physics take over, no matter how good your helmet or body armor.

On May 11, 2010, at 10:39 PM, JASON DUNN wrote:

> I know with motorcycle helmets the the cushiony polystyrene layer inside that is designed to absorb the shock of an impact has already been compressed. This will make it worthless in protecting you in an accident. Also, age and exposure to certain elements can make the polystyrene lose its elasticity and become brittle, reducing the amount of protection it provides.
>
> I figured the statement above would apply to bicycle helmets too.
>

JASON DUNN

I know with motorcycle helmets the the cushiony polystyrene layer inside
that is designed to absorb the shock of an impact has already been
compressed. This will make it worthless in protecting you in an accident.
Also, age and exposure to certain elements can make the polystyrene lose its
elasticity and become brittle, reducing the amount of protection it
provides.

I figured the statement above would apply to bicycle helmets too.

On May 11, 2010 10:24 PM, "Mike Murray" wrote:

I would like to see some old helmets tested. My guess is that the drop off
in deceleration force mitigation, if present at all, is insignificant. That
stuff is pretty inert.

Mike Murray - Sent via BlackBerry from T-Mobile

-----Original Message-----
From: "Dan H" ; OBRA remailer
Subje...

Mike Murray

I would like to see some old helmets tested. My guess is that the drop off in deceleration force mitigation, if present at all, is insignificant. That stuff is pretty inert.
Mike Murray - Sent via BlackBerry from T-Mobile

-----Original Message-----
From: "Dan H"
Date: Tue, 11 May 2010 21:54:39
To: ; OBRA remailer
Subject: Re: [OBRA Chat] WTS: used helmet sM/L

The polystyrene in helmets is a little different than the Styrofoam in cups.
It's more dense for one thing. I think over time it loses some elasticity
and transmits more energy. I think a lot of stuff like Styrofoam
deteriorates a lot more when it's exposed to air and light. Stuff that's
buried can last centuries. A newspaper in the street will be gone in months.
A newspaper underground will last at least decades.
I happen to have a Bell V2 from the 70's. Shall we send it to ANSI and see
how it compares to a new helmet?

----- Original Message -----
From: "Mike Murray"
To: "OBRA remailer"
Sent: Tuesday, May 11, 2010 9:21 PM
Subject: Re: [OBRA Chat] WTS: used helmet sM/L

> Is that because the styrofoam deteriorates? I thought one of the problems
> with disposable styrofoam products is that they basically never degrade
> and will be in the environment forever. Have you ever seen any testing
> that showed that the deceleration protection of a helmet degrades over a
> period of time?
> Mike Murray - Sent via BlackBerry from T-Mobile
>
> -----Original Message-----
> From: Dan H
> Date: Tue, 11 May 2010 14:10:23
> To: David Auker
> Cc: obra@list.obra.org
> Subject: Re: [OBRA Chat] WTS: used helmet sM/L
>
> David, are you planning on using that to protect your head? I would
> be wary of using a helmet that was either 2 years old or had an
> unknown history. Good new helmets can be had for about $45 & up.
>
> Dan Houghton
> Southwest Bicycle, LLC
> 3605 SW Multnomah Blvd
> 503-246-0333
> www.swbicycle.com
>
> On May 11, 2010, at 1:13 PM, David Auker wrote:
>
>> Want to scrounge: used helmets M/L
>> Anyone have a current race-style helmet lying around needing new life?
>> Doesn't matter if it's scratched, ugly color, sweated silly. Just
>> not cracked!
>> I'll clean it, and will affix decorative mylar (Metallized Biaxially-
>> oriented polyethylene terephthalate) in experimental fashion..
>> Thanks, and now back to our more regularly scheduled exchanges :-)
>> David
>>
>> _______________________________________________
>> OBRA mailing list
>> obra@list.obra.org
>> http://list.obra.org/mailman/listinfo/obra
>> Unsubscribe: obra-unsubscribe@list.obra.org
> _______________________________________________
> OBRA mailing list
> obra@list.obra.org
> http://list.obra.org/mailman/listinfo/obra
> Unsubscribe: obra-unsubscribe@list.obra.org
>
> _______________________________________________
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> obra@list.obra.org
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> Unsubscribe: obra-unsubscribe@list.obra.org

Dan H

The polystyrene in helmets is a little different than the Styrofoam in cups.
It's more dense for one thing. I think over time it loses some elasticity
and transmits more energy. I think a lot of stuff like Styrofoam
deteriorates a lot more when it's exposed to air and light. Stuff that's
buried can last centuries. A newspaper in the street will be gone in months.
A newspaper underground will last at least decades.
I happen to have a Bell V2 from the 70's. Shall we send it to ANSI and see
how it compares to a new helmet?

----- Original Message -----
From: "Mike Murray"
To: "OBRA remailer"
Sent: Tuesday, May 11, 2010 9:21 PM
Subject: Re: [OBRA Chat] WTS: used helmet sM/L

> Is that because the styrofoam deteriorates? I thought one of the problems
> with disposable styrofoam products is that they basically never degrade
> and will be in the environment forever. Have you ever seen any testing
> that showed that the deceleration protection of a helmet degrades over a
> period of time?
> Mike Murray - Sent via BlackBerry from T-Mobile
>
> -----Original Message-----
> From: Dan H
> Date: Tue, 11 May 2010 14:10:23
> To: David Auker
> Cc: obra@list.obra.org
> Subject: Re: [OBRA Chat] WTS: used helmet sM/L
>
> David, are you planning on using that to protect your head? I would
> be wary of using a helmet that was either 2 years old or had an
> unknown history. Good new helmets can be had for about $45 & up.
>
> Dan Houghton
> Southwest Bicycle, LLC
> 3605 SW Multnomah Blvd
> 503-246-0333
> www.swbicycle.com
>
> On May 11, 2010, at 1:13 PM, David Auker wrote:
>
>> Want to scrounge: used helmets M/L
>> Anyone have a current race-style helmet lying around needing new life?
>> Doesn't matter if it's scratched, ugly color, sweated silly. Just
>> not cracked!
>> I'll clean it, and will affix decorative mylar (Metallized Biaxially-
>> oriented polyethylene terephthalate) in experimental fashion..
>> Thanks, and now back to our more regularly scheduled exchanges :-)
>> David
>>
>> _______________________________________________
>> OBRA mailing list
>> obra@list.obra.org
>> http://list.obra.org/mailman/listinfo/obra
>> Unsubscribe: obra-unsubscribe@list.obra.org
> _______________________________________________
> OBRA mailing list
> obra@list.obra.org
> http://list.obra.org/mailman/listinfo/obra
> Unsubscribe: obra-unsubscribe@list.obra.org
>
> _______________________________________________
> OBRA mailing list
> obra@list.obra.org
> http://list.obra.org/mailman/listinfo/obra
> Unsubscribe: obra-unsubscribe@list.obra.org

Mike Murray

Is that because the styrofoam deteriorates? I thought one of the problems with disposable styrofoam products is that they basically never degrade and will be in the environment forever. Have you ever seen any testing that showed that the deceleration protection of a helmet degrades over a period of time?
Mike Murray - Sent via BlackBerry from T-Mobile

-----Original Message-----
From: Dan H
Date: Tue, 11 May 2010 14:10:23
To: David Auker
Cc: obra@list.obra.org
Subject: Re: [OBRA Chat] WTS: used helmet sM/L

David, are you planning on using that to protect your head? I would
be wary of using a helmet that was either 2 years old or had an
unknown history. Good new helmets can be had for about $45 & up.

Dan Houghton
Southwest Bicycle, LLC
3605 SW Multnomah Blvd
503-246-0333
www.swbicycle.com

On May 11, 2010, at 1:13 PM, David Auker wrote:

> Want to scrounge: used helmets M/L
> Anyone have a current race-style helmet lying around needing new life?
> Doesn't matter if it's scratched, ugly color, sweated silly. Just
> not cracked!
> I'll clean it, and will affix decorative mylar (Metallized Biaxially-
> oriented polyethylene terephthalate) in experimental fashion..
> Thanks, and now back to our more regularly scheduled exchanges :-)
> David
>
> _______________________________________________
> OBRA mailing list
> obra@list.obra.org
> http://list.obra.org/mailman/listinfo/obra
> Unsubscribe: obra-unsubscribe@list.obra.org
_______________________________________________
OBRA mailing list
obra@list.obra.org
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Unsubscribe: obra-unsubscribe@list.obra.org

David Auker

Dan, I agree! Known history (not crashed) and sub-2 years old is my
quest.

Dan H wrote:
> David, are you planning on using that to protect your head? I would
be wary of using a helmet that was either 2 years old or had an unknown
history. Good new helmets can be had for about $45 & up.
>
> Dan Houghton
> Southwest Bicycle, LLC
> 3605 SW Multnomah Blvd
> 503-246-0333
> www.swbicycle.com
>
> On May 11, 2010, at 1:13 PM, David Auker wrote:
>
>> Want to scrounge: used helmets M/L
>> Anyone have a current race-style helmet lying around needing new life?
>> Doesn't matter if it's scratched, ugly color, sweated silly. Just
not cracked!
>> I'll clean it, and will affix decorative mylar (Metallized
Biaxially-oriented polyethylene terephthalate) in experimental fashion..
>> Thanks, and now back to our more regularly scheduled exchanges :-)
>> David
>>
>> _______________________________________________
>> OBRA mailing list
>> obra@list.obra.org
>> http://list.obra.org/mailman/listinfo/obra
>> Unsubscribe: obra-unsubscribe@list.obra.org
>
>
>
>
> Checked by AVG - www.avg.com
> Version: 9.0.819 / Virus Database: 271.1.1/2867 - Release Date:
05/10/10 23:26:00
>

Rick Johnson

I've always said that people should spend on a helmet whatever they
think their brains are worth.

Rick Johnson
Bend, Oregon

Every revolutionary idea seems to evoke three stages of reaction...
One, it's completely impossible.
Two, it's possible, but it's not worth doing.
Three, I said it was a good idea all along.

Arthur C. Clarke

Dan H wrote:
> David, are you planning on using that to protect your head? I would
> be wary of using a helmet that was either 2 years old or had an
> unknown history. Good new helmets can be had for about $45 & up.
>
> Dan Houghton
> Southwest Bicycle, LLC
> 3605 SW Multnomah Blvd
> 503-246-0333
> www.swbicycle.com
>
> On May 11, 2010, at 1:13 PM, David Auker wrote:
>
>> Want to scrounge: used helmets M/L
>> Anyone have a current race-style helmet lying around needing new life?
>> Doesn't matter if it's scratched, ugly color, sweated silly. Just not
>> cracked!
>> I'll clean it, and will affix decorative mylar (Metallized
>> Biaxially-oriented polyethylene terephthalate) in experimental fashion..
>> Thanks, and now back to our more regularly scheduled exchanges :-)
>> David
>>
>> _______________________________________________
>> OBRA mailing list
>> obra@list.obra.org
>> http://list.obra.org/mailman/listinfo/obra
>> Unsubscribe: obra-unsubscribe@list.obra.org
> _______________________________________________
> OBRA mailing list
> obra@list.obra.org
> http://list.obra.org/mailman/listinfo/obra
> Unsubscribe: obra-unsubscribe@list.obra.org
>

Dan H

David, are you planning on using that to protect your head? I would
be wary of using a helmet that was either 2 years old or had an
unknown history. Good new helmets can be had for about $45 & up.

Dan Houghton
Southwest Bicycle, LLC
3605 SW Multnomah Blvd
503-246-0333
www.swbicycle.com

On May 11, 2010, at 1:13 PM, David Auker wrote:

> Want to scrounge: used helmets M/L
> Anyone have a current race-style helmet lying around needing new life?
> Doesn't matter if it's scratched, ugly color, sweated silly. Just
> not cracked!
> I'll clean it, and will affix decorative mylar (Metallized Biaxially-
> oriented polyethylene terephthalate) in experimental fashion..
> Thanks, and now back to our more regularly scheduled exchanges :-)
> David
>
> _______________________________________________
> OBRA mailing list
> obra@list.obra.org
> http://list.obra.org/mailman/listinfo/obra
> Unsubscribe: obra-unsubscribe@list.obra.org

David Auker

Want to scrounge: used helmets M/L
Anyone have a current race-style helmet lying around needing new life?
Doesn't matter if it's scratched, ugly color, sweated silly. Just not
cracked!
I'll clean it, and will affix decorative mylar (Metallized
Biaxially-oriented polyethylene terephthalate) in experimental fashion..
Thanks, and now back to our more regularly scheduled exchanges :-)
David