What is there to fail on a helmet other than the head liner and they ar replaceable.what happens to the material that the helmet is made out of, after 7 years?
the foam between your noggen and the outer shell breaks down over time...5 years is max for helmet materials to be guaranteed effectiveand the shell also gets brittle with age...some faster (polycarbonate) than others (fiberglass)
Gunny.
The Styrofoam that is designed to decelerate your brain starts to compress, thus making that component non-working to decelerate your brain. If the foam is compressed, how does it now slow down your brain in a safe way? The foam liner that contacts your hair and cheeks is for comfort and some fit.
Wearing a helmet every day also takes it's toll. The Styrofoam liner slowly compresses, soon it's real loose. After a year or so try on a brand new helmet the exact same helmet brand, model, and size, you'll by shocked by the compression of everything.
BTW - Just my opinion, but all those guys storing their helmets on their mirrors when parked, real cool looking, but each time they do it it's damaging that Styrofoam interior.
Know why the interior white Styrofoam is painted black, looks maybe? Nope. It's a visual. When the helmet compresses you'll now see white around the foam cells. That is bad, that means the helmet has been compressed or compromised in that spot. You have a helmet where white is showing around the cells etc, you have a spent helmet IMO. Just MO, take it or leave it. I take my head pretty serious.
I do like Arai best for fit, it's pricey, but... That's why I went to another brand this time. There are many opinions and great debates regarding SNELL Vs DOT. IMO as long as it's DOT you're good to go. SNELL takes the same impact twice (DOT once) which makes the helmet more rigid to endure this and could have an effect on the proper amount of deceleration.
Go do a Google search regarding how helmets work and their safety. You'll start thinking differently about how to choose a helmet.
Start reading here. Don't stop until you totally understand helmets and their safety features.
Good luck.