Re: Helmets -- when do you change?

["A. Nguyen" <ahn@xxxxxxxxxxxxx>]

At 03:22 PM 12/5/2003 -0800, Marco S Hyman wrote:
>"A. Nguyen" writes:
>  > I replace mine at roughly the same interval
>  > as Snell standards,  every 5 years.
>
>Measuring helmet life in years seems so wrong.   My experience leads me
>to believe that normal helmet wear is the compression of the inner lining.

Yes it is,  but compression of the comfort liner is just
one issue.  Deterioration of the expanded polystyrene
liner  (the real impact absorbing layer)  is another.
People used to worry about fiberglass shells delaminating
from too many accidental drops, but I don't hear much
about that any more.  Or any number of cosmetic/convenience
features might be on the fritz.  Or may be you just got the
hots for the latest adolescent grafix.
http://www.agv.com/AGV%20Collection%202003/AGV%202003%20Collection%20RACE/XR2%20DETAILS.htm

And of course, there's the outside chance that since the
last time you bought a hat,  the Snell Foundation will have
discovered some magical way for helmets to make you
immortal  _and_  faster than flying snot.  %-)

>I assume that helmet lining compression is directly proportional to time
>worn.
>
>It my assumptions are correct then 5 years would be too short for
>someone who only rides 2K/year and too long for someone who rides
>25K/year.

Right, so we all should be going by hours of use like
the aviation guys.

>If the Snell folks assume an average use of 10K/year than
>there 5 years that matches the 50K miles that I've been using without
>thinking about it.

Snell folks assume you're racing,  the helmet only gets
used on Sundays for a couple of hundred miles, and
your sponsor will ante up for the latest lid with a new
paint scheme every season  (more often if you're
Valentino Rossi.)  %-)

   Au


And now, for the facts, straight from http://www.smf.org/

Why replace helmet every five years?
     The five year replacement recommendation is a consensus position from 
both the helmet manufacturers and the Snell Foundation. Glues, resins and 
other materials used in helmet production can affect liner materials, and 
general liner deterioration as a function of hair oils, body fluids and 
cosmetics, and normal "wear and tear" all contribute to helmet degradation. 
Additionally, experience indicates there will be a noticeable improvement 
in the protective characteristic of helmets over a five year period due to 
advances in materials, design and the standards. Thus, the recommendation 
for five year helmet replacement is a judgment call stemming from prudent 
safety philosophy.


>Of course using your helmet as a basketball voids all of the above.
>
>// marc

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