I'd use them w/o concern. I think it's UV that causes deterioration. And drops, obviously.

The young salesperson at the bike shop said helmets only start to age after they're purchased. :roflmao2:

Study on helmet life:
https://helmets.org/up1505a.htm

Crash or dropped on the ground, yes. But simply based on age, no need. That old myth. started by the helmet manufacturers, has been disproven.

It has been disproven? By whom? Where? When? I know it has been disagreed about but I haven't really seen great credible evidence that it is false.

Ariaa1 Again I am confused by your statement it was seemingly in response to no one. What are you agreeing to?

Links have been provided. See posts #9 and #53.

I usually replace my helmet every 3-5 years as they tend to improve incrementally.

Some of you claim not to rinse your helmet off every ride. Not sure why it'd matter about whether safety is a reason to replace them. I wouldn't be able to stand the smell or the grime!

Mines four years old. I'm just getting tired of it. Want something new. I was thinking about it on the ride this morning.

True, it's arbitrary. If you replace your helmet in 3 years or 7 years, it's probably not going to make much difference from 5. But the idea (from that Consumer Reports article linked above, they are not shilling for industry) is that helmet materials degrade with time, from UV and other factors, and also that helmet technology has gone through improvements (e.g., MIPS). So don't get fixated on 5. Just keep in mind that plastics change their physical properties with time.

It is an "idea." The article says this may be true. It doesn't say it is true.

Oh dear, another post-truth denizen of the internet who thinks that all statements are opinions or ideas.

Plastic degrades under UV light. Not an idea.

Common plastics in helmets include polycarbonate (the hard parts) and polystyrene (the foam parts)

https://link.springer.com/article/10...68-020-01002-9

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4320144/

I think the helmet makers play the odds. So to speak. And a older helmet has more chance of having been exposed to things that make the foam degrade. So if you keep everyone changing helmets often, then they don't have to worry as much about that one in a bajillion helmets that had degraded foam and also was involved in a crash and didn't protect the wearer.

You might think that the person probably should be able to look at the helmet and see. But there is always someone so oblivious that they don't think to. Nor consider the potential for them having a accident. Likely they will claim they aren't a expert to judge safety.

By no means does their limit on when you should change helmets mean that every ones helmet is going to become a crumbling mess on the day after. But it only takes one out of the many out there to ruin someone's day.

I doubt it. The changes in properties are microscopic. Some of them may cause discoloration, but others may not.

Do you think you could see this with the unaided eye? Note that this is an SEM (scanning electron microscope) image and that thecolors here are differences in electron scattering properties. In visible light, the "cracks" would not have the sharp color contrast as evident here. Also, that's a 200 micron scale bar, meaning that the cracks are each less than 10 microns wide - 1/3 the width of human hair

https://cimg0.ibsrv.net/gimg/bikefor...26b8a20b0f.png

Well the hypothesis still works even if that's true. Though I have very much over simplified it for the masses. Not for those expecting a scientific opinion. And in a manner more appropriate for when sitting in a tavern downing some beers with others.

Hah. My tavern company may not be typical.

Do you always communicate in such an uncivil manner?

You missed the point in any case.

My first helmet, a Bell Biker was purchased over a half century ago. I still have it somewhere. The foam pads have long since crumbled to dust. The helmet outer shell is made of Lexan which has been used to produce bulletproof windows, but the foam interior is badly eroded. It was replaced 30 years ago
I have lost count of the number of helmets I have bought since then

After a crash, I definitely would.

I've been wearing a hairnet for the last 30 years.

I always use a wicking skull cap, have been for many, many years. I originally started using them because I have thinning hair and thought they'd prevent a weird tan pattern on the scalp. I then found that, with the helmet I used to have, it prevented weird marks from the forehead pads on the helmet, which got comments from co-workers when commuted by bike. Then, I realized, skull caps make a huge difference in preventing funkiness of the helmet pads. I have several and wash them or at least give them a quick rinse, every time.

Has a bike helmet manufacturer ever been held liable or even been brought into a liability claim? I doubt it, unless the issue is that they are selling a helmet that purports to meet certain certification standards, but does not.

Agree 100%
You think this is new in the 21st century? Nah.

Good luck with that. If you find such a pure company that's making helmets, please post because I, and many others, I'll bet, would be glad to follow suit.

Just wondering if this is your requirement for helmet purchases, or if you do this for every item you buy, bike-related or not? If the latter, hats off to you, and how many hours/week do you spend researching the sources of your food, clothing, household items, etc.?

Yes, if "sufficient" time has gone by. Generally a half-dozen years or more. "Modern" materials do degrade over time. Hard to tell how a degraded unit might compare in performance versus a new one. Better safe than sorry, on this. (Plus, the sort of MIPS helmets I do for urban/commuting type cycling tend to be sub-$70, so it's like a dirt-cheap cycling insurance policy.

Yes, if getting banged-up. Haven't ever (yet) been in a crash that seriously dented a helmet, but I'd certainly discard it if crashing.

Until the helmet has a hard impact, with a hard surface. I would say you can still use it.

Maybe, maybe not. Sometimes bicycle helmets break up before absorbing a meaningful amount of impact energy. In such cases, the helmet has provided no benefit.

Without seeing the helmet pieces, it's impossible to determine whether it broke up before or after absorbing impact energies.

To be fair, MUSA manufacturers are often prone to similar sorts of cost-cutting measures in an effort to sustain their higher labor costs.