How long do helmets last?

[OakLeaf]

I have no expertise, but that rarely stops me from offering an opinion.

Not only BHSI, but Snell also, still have the 5-year rule on their websites, which has been in place for decades.

I've read some speculation that the newer, lighter, more ventilated bicycle helmets - which have much more surface area per volume of EPS than older helmets used to when the standards organizations came up with that 5-year recommendation - are consequently less durable. The idea makes sense to me.

I've also noticed that my current helmet, which is about 3-1/2 years old, is looking pretty beat up around the edges, even though I'm careful to take good care of it. It's never been crashed, may have been dropped from handlebar height once or at absolute most twice, it's stored in a ventilated bag when it's not being worn so that it dries quickly. When I transport it, it lives in the bag on top of my shoes, and the only things I put inside/on top of it are plastic sunglasses, HRM strap and, in season, a knit cap. And gloves, when I park the bike for a rest break, but not when it's being stored (so the gloves dry separately from the helmet). I can't say it's never been in a hot car, but I don't make a habit of that. Maybe a total of 20 hours in the lifetime of the helmet, never more than three hours at a time, and those are both high estimates. So it's truly "normal wear and tear," but the EPS is visibly deteriorated.

I haven't been in a huge panicked rush to replace it, but maybe I should be. I'm definitely going to replace it within the next three to four months.