I recognize that stores and manufacturers are going to recommend replacement at relatively frequent intervals for their revenue. I also recognize that with each passing year or so, improvements in helmet design and standards improve their ability to keep the wearer safer.

My current helmet may be 5-6 yrs old and has never been in an accident. I may have dropped it off the rear rack or handlebars a couple of times but no where on the helmet are there any visible cracks in the outer plastic shell (nor can I feel any), nor in the foam either.

Am I risking my safety by continuing with this helmet?

you choose.

Probably not. The CPSC standard for bike helmets in the US took effect in '99 and hasn't changed since then. The only test I've seen on an older helmet was of a 10 year old well-used Bell Biker and the report showed it did just as well as new ones had when first tested. There may be an advantage if you go for one of the few models that now market the MIPS technology - not clear how much difference this will make in real-world accident data. (My helmets are currently 39 and 21 years old and I have no plans to replace them.)

My understanding is that the foam breaks down and losses important strength over time. I accept that as probably valid. But I don't know how much time that takes. The helmet manufactures are obviously biased.

I'm betting it's somewhere between one and a thousand years

Probably not much, if any. 1, 2, 3, 4

I don't see a need to replace an otherwise undamaged helmet that is several years old.

This is from the FAQ on Helmets.org. Seems reasonable:

[h=3]An honest manufacturer: MET[/h]The Italian company MET says in their 2010 catalog:

"We are often asked 'For how long is a helmet safe?', or 'how often should I
replace my helmet?”' Until now it has been difficult to find any reliable
figures to help answer these queries. MET have now developed a series of tests
which are conducted on aged helmets to determine a 'best before' date (unless
the helmet is involved in an accident. In that case it should be replaced
immediately.). The results indicate that, if used properly accordingly to our
owner manual, our helmets will still do their job up to eight years after they
have been made. Not only is that good news for the customer, it’s great news for
the environment!"

We applaud MET for undertaking an actual testing program on helmet life and
for making that statement. We regard it as a triumph of integrity over
marketing. MET's helmets are made with industry standard shells and liners, so
there is no reason we can see that their recommendation should not be good for
many other helmet brands as well. If another manufacturer comes up with a
testing program that shows earlier deterioration in the protection from their
products we will review this page.
In sum, we don't find the case for replacing a helmet that meets the ASTM or
Snell standards that compelling if the helmet is still in good shape and fits
you well.

Excellent, many thanks all

More or less, give or take.

In my dialogues with various persons, the helmet is really only ruined by 2 things.... improper cleaning where chemicals weaken the foam or hard shell etc, and actual head-object impacts. If helmets were rendered useless by a few drops from a few feet, they wouldnt be very protective, now would they?

You're fine, but if you ride like i do in heavy traffic, err on the side of caution & replace if there are any scratches or other damage. Scuffs generally are OK, as long as its just cosmetic and not actually plastic removed from the scuff.

- Andy

This seems unlikely, considering how long it takes styrofoam to degrade when exposed to sun and the elements.

How long is that?
Ya mean helmet styrofoam takes either less than a year, or more than a thousand years to degrade, but degradation is unlikely during the one to a thousand year time period?

I mean it's unlikely "that the foam breaks down and loses important strength over time." At least not on the time scales we'd be concerned about. Sure, it might break down in a few hundred years. Or a few thousand. Or a few million. Realistically, until a helmet is actually damaged, the styrofoam portion should be as effective (or ineffective) as it was when new. The glue and the plastic shell on the other hand, who knows. Maybe only a few decades.

I have an old helmet, about 20 years old, at my parents' house, left over from my mountain bike riding days. I was looking it over a few days ago, comparing it to a much newer helmet that has hardly been used. The plastic shell seems to be in similar shape to the newer helmet, not at all brittle, and everything is still holding together well. It gave me no reason to think it wouldn't be suitable for use if anyone felt the need to wear a helmet while riding their bike.

I found this hunting on the subject



From the bit of research I've done it seems like time is not the determining factor on foam deterioration as much as UV light exposure.

Plastics last hundreds of years or more in landfills, because there is not a lot of oxygen & no UV to break it down. A plastic bag left out for a few years will actually feel thinner and be weaker than one kept away from UV sources. It's pretty amazing, actually.

Black UV resistant foam & UV/oxygen blocking lacquer on shell parts are not uncommon. My nutcase has both.

- Andy

I suspect marketing hype and profit motive are the determining factors behind claims about any need for helmet replacement due to foam degradation.

Another POV is why take a chance? Newer helmets are lighter, look better and many cool better. Shop around and you can find excellent deals on a year old model. Many things happen over six years that can damage it - UV exposure, chemicals, bumps or knocks of both sudden as well as continuous types, etc. A new helmet might work out to $5 a year, which is a good potential investment in your well bring.

That does it then, I'll only wear it at night!!!

All good information people. It appears that I am not "forced" to replace the helmet soon but may benefit from doing so.

UV, sweat and salt. How corrosive is that? If you buy a new helmet every five years and buy a cheap helmet, it's $10 a year. Consider it insurance. Helmets: Bicycle Helmets is an independent organization that has good data on helmets.

Stryrofoam isn't particularly reactive.