Modern Vespa

I've got quite a unique helmet, which I like the design of, and that I'm sure will be discontinued at some point.

I believe helmets are meant to be replaced every 5-10 years, but is that based on wear time or purely age from manufacture?

Contemplating buying another one of my helmets and storing it for when this one needs replacing.

Yes they age even if stored although I have read differing statements about this. I do think there are a number of factors that impact the aging so how one stores it matters.

I believe the general thought is the lifetime doesn't change, I think this also is because there is an assumption the helmet is worn and exposed after purchasing.

I personally go by condition. I just recently retired a 12 year old helmet that I stored for years.

A thread from adv rider on helmet life:
https://www.advrider.com/f/threads/helmet-lifespan.1624681/

My understanding is that the clock starts ticking from the date of manufacture, regardless of whether it's being used or not. I always look at the date of manufacture tag when I'm buying a new helmet. I don't want one that's been sitting on the shelf for more than a few months.

Polystyrene hardens over time.

If you're going to use it for 6 years the well worn in old one won't feel like the new one anyway.

Helmets last for 5 years if worn and 7 years from manufacturer date..I've just binned 2 Helmets that were out of date and hardly worn..not worth the risk

The biggest problem is the soft foam lining, falls apart over time.

I had an uber expensive beautiful Kiwi lid, fitted like a glove, lovely thing....lasted 5 years before lining went

Really depends on what you helmet is made of and how it was built.

Clear enough?

Thanks for all the replies, doesn't look to be a good idea so will just keep my normal one and buy a new one when this one needs replacement.

This will probably ruffle feathers of some of the "do what the manufacturers says crowd" but EPS, which is the predominate material the inner crush foam on MC helmets is made from, does not deteriorate like claimed by many manufacturers.

Also, according to an MEA forensic study on bicycle helmets done in 2015 they showed no significant impact performance change with age. They collected 1500 used bike helmets manufactured from 1987-2013 and used 675 to crash test. None of the helmets had previous damage. https://asmedigitalcollection.asme.org/biomechanical/article-abstract/138/4/041005/371203/Age-Does-Not-Affect-the-Material-Properties-of

They also took core samples after the test from the uncrashed areas of 63 of the helmets and test "crashed" them at the equivalent of a 6.2 m/s helmet impact. This generated data solely based on foam performance and indicated the foam did not deteriorate with age. https://pubmed.ncbi.nlm.nih.gov/26902784/

So why does Snell say 5 years? Why do manufacturers say anywhere from 3-10 years? I am guessing it is based on more than just EPS longevity and factors in other conditions like frequent use, shell condition, comfort padding and strap condition. Probably liability and marketing plays in there as well.

Conditions for when I will replace a helmet. YMMV.
1. Straps or buckles are worn or don't work.
2. Worn comfort padding (unless I can find a padding replacement kit like I did for my Shoei) because it effects the fit which I think is the most important piece of the equation for the effectiveness of a helmet.
3. If the shell shows cracking or signs of degradation like sun damage.
4. If the helmet receives a strong impact especially if my head is in it at the time. EPS may not degrade but once compressed it is toast for its intended use in a helmet. One and done.
5. Want new tech, lighter helmet or a different color. Especially if that is what all the other kids are getting.

Well, yes. Bicycle helmets?! Isn't that an apples to oranges comparison?

In case of accidents, a motorcycle helmet is ordinarily subjected to much greater impacts than a bicycle helmet.

Furthermore, it's also the shell that very much weakens with age. Take just for example ABS, short for acrylonitrile butadiene styrene. It is one of several common materials for helmet shells. This material degrades through exposure to UV.

From a conclusion of a study examining the impact of UV rays and outdoor exposure on ABS plastics:

"The behavior of stabilized ABS samples with light stabilizers and antioxidants exposed to Q-Sun Xe-3-Hs and outdoor conditions was evaluated aiming to establish a correlation between both weathering conditions and predict copolymer lifetime.

Similar oxidation rates as a function of radiant exposure dosage were found for ABS samples exposed to accelerated and outdoor conditions. These findings are supported by stress-strain experiments, showing that the mechanical properties of ABS are affected"

https://www.sciencedirect.com/science/article/abs/pii/S0141391013002383

If helmets do not age badly, why do bodies such as the American Sportbike Racing Association, have a five year rule?

I think it is likely because no experts are coming forward with recommendations to use helmets for longer time periods.

Sure, your helmet might hold up for a few years more, but why would you bet your life on it?

No it really is not because it is not a comparison of the effectiveness of a bicycle helmet in motorcycle conditions. It is two tests of the impact performance of EPS as it ages. In both it is shown that EPS is not degraded over time to show a significant impact in its performance. It does not matter what kind of helmet. This is important because the popular claim is that EPS degrades in 3, 5, 10 (you pick it) years and that is the main reason for helmet expiration dates. You spend a lot of time here discussing a point not in question. In fact, if you note my 3rd condition for replacement says, "If the shell shows cracking or signs of degradation like sun damage."

ABS does degrade in weather predominately from sun exposer. If you ride a lot or leave your helmet in a sunny location it may degrade at a faster pace. Discoloration is a good indicator. The problem is (and your link did not shed light on this, pardon the pun) that there are many environments and no set measure for when it is no longer viable as a helmet shell.

Also, consider that there are a number of other materials used for helmet shells. Organizations like Snell do not change recommendations based on shell material. I would guess mainly because of liability/legal reasons. If Snell is saying 5 years, and someone gets injured in a six year old helmet, that would be used in court regardless of its real world accuracy. Far more than a few years in my estimation and with everything that can maim and kill you when you ride I don't really think using my 10 year old helmet is a big add to the risk.

Just one point here, as I am slightly allergic to perceived or real science denial.

The damage from UV rays and other environmental factors is not necessarily visible. The same goes for microscopic surface cracks. This is very much like the safety of our build up environment. Someone, who for example isn't an expert in detecting material fatigue of steel, will not be able to make an assessment if structural steel has reached the end of its useful life.

Your helmet could appear to be in good condition, but might not withstand the impact of an accident in the same way a newer helmet would have. Different helmet constructions have different life spans, which is one reason for varying guidance from helmet manufacturers.

As I pointed out before, this appears to be nearly universal consensus. You would be hard pressed to find experts on motorcycle safety that would agree that age does not affect the safety of helmets. Or do you have other info on that?

Is it really five years that push your helmet over the edge? Who knows. It's akin to Piaggio recommending the fluid change intervals on your scooter. Are your brakes going to fade on the two year anniversary of your last brake fluid change? Of course not. But to have a margin of safety, taking into account prior experience and under consideration of the known degradation of brake fluid over time (for example because it is hygroscopic), two years is the recommended interval. Helmet guidance works similarly.

But please, do point us towards multitudes of organizations and individual experts that disagree with the notion that helmets should be changed in certain intervals and I stand corrected.

You are free to disagree but you have yet to show how ABS degradation is a major factor in companies and organizations using it as a factor in a determination that the useful life of a helmet is 3, 5, 10 os some other period.

You ignore the fact that they do not change these recommendations depending on what material the shell is made of.

You ignore actual science that refutes the denigration rate of poly foam which is the basis for most of the "expert" recommendations. But that is fine brother. You will always know you are safe right? Not here to argue with you. Just giving factual information for those that want it.

Considering that for seven months of the year I ride in T-shirt, shorts and (closed toe!) sandals, the actual age of my helmet is the least of my risk factors.

Let the rider decide, as always.

As always. ✔️