Life-span of a Helmet?



Ugur

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Nov 10, 2004
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Hi, I heard from a friend of mine that helmets have a life span of 2-3 years. He told that it is because of UVs, sweating,...etc.'s wearing effect. It didn't make much sense for me, is there sth like that?
 

shokhead

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Feb 9, 2003
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Thats about right and its mostly due to sweat i think. But one crash and you hit your helmet,replace it.
 

fixit

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Aug 19, 2004
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Ugur said:
Hi, I heard from a friend of mine that helmets have a life span of 2-3 years. He told that it is because of UVs, sweating,...etc.'s wearing effect. It didn't make much sense for me, is there sth like that?

Your friend is right.
Sunlight damages plastics and glues. And you lucky people in Turkey get a lot of sunshine.
 

OCRoadie

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Oct 5, 2004
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fixit said:
Your friend is right.
Sunlight damages plastics and glues. And you lucky people in Turkey get a lot of sunshine.
Good news, I've been looking for an excuse to justify buying a new helmet:)
 

tyler_derden

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Mar 22, 2004
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I've been wearing the same helmet for about 12 years now. There's no need to replace a helmet every couple years unless it is damaged (meaning more than scratched-up).

TD
 

Mansmind

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Aug 3, 2004
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tyler_derden said:
I've been wearing the same helmet for about 12 years now. There's no need to replace a helmet every couple years unless it is damaged (meaning more than scratched-up).

TD
The original post is indeed true, although the 2-3 years number can vary a lot depending on several factors. "Most" bicycle helmets are made from ABS and/or polycarbonate. In their natural states, neither is a very good performer where ultraviolet radiation is concerned. The most important factor for a helmet's performance is impact resistance. Unstabilized versions of either of these resins lose a large percentage of that property very quickly. Stabilized versions have a significantly longer life span... out to a maximum of approximately 7 years dependant upon the grade of polymer, type of stabilizer used, and the amount of stabilizer used.

Typically, the persons responsible for designing the specification concerning stabilization, will get by with as little as possible as quality stabilizers add significantly to the cost of the polymer. The people doing this aren't ALWAYS the manufacturer of the helmet, it can and is many times the colorant suppliers.

Certain coatings can also help with the stabilization of the polymer, as well as the colored pigments utilized. White, for example, does a relatively good job of enhancing UV stabilization if the percentages used are significant. Carbon black also does a very good job... providing it is present in the polymer at a level of ~2% and is of the correct particle size. Most other "colors" don't do much for it at all.

Some helmets are thermoformed from sheet stock, making it possible to use two different materials in the same "shell". The outer layer could be something such as acrylic, which is naturally extremely UV resistant, modified with a very heavy level of UV absorbers. This "barrier" serves to protect the underlying polymer, increasing its life more economically that stabilizing the base polymer.

All of the stabilizers are consumed as they work to protect the polymer, hence the affect of using different levels/types. At some point, they ALL cease to provide any protection, then the physical properties of the polymer, and thus the helmet, deteriorate.

I'd say a 2-3 year replacement policy is a good rule of thumb under the assumption we're talking about a reputable helmet manufacture.

John
 

shokhead

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Feb 9, 2003
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tyler_derden said:
I've been wearing the same helmet for about 12 years now. There's no need to replace a helmet every couple years unless it is damaged (meaning more than scratched-up).

TD

When you crash and your helmet brakes like glass,oh well.
 

bike4miles2

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Nov 13, 2004
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Ugur said:
Hi, I heard from a friend of mine that helmets have a life span of 2-3 years. He told that it is because of UVs, sweating,...etc.'s wearing effect. It didn't make much sense for me, is there sth like that?
This is the true time frame. I personally wore the same helmet for 5 years but you really shouldn't push it more than 4. It really donesn't protect as well after that.