I see this helmet poll thread merrily chugging along with lots of folks invested in the 3-5 year expiration date for a helmet.

I asked this question in there but didn't get a reply (a little off topic):

So what do you think?

A few lazy minutes of Googling found me this statement (a little more at the link), from this page at the Bicycle Helmet Safety Institute. Unfortunately, I have no idea who they are or if they are really legit, but certainly it seems to be solid writing and I don't see anything way out there.

I've seen in a few places that the rule of thumb is based on UV light and weathering that could weaken the helmet's structure. Certainly if I stored it on my back deck in the noon sun, I could understand it being too far past its prime. But really?

I'll happily replace mine well before 5 if it is grungy, or banged up, or if I decide I don't like it, etc. So please no replies just saying don't be cheap or don't swim upstream. I'm interested if anyone has some real data or substantive knowledge that supports or refutes the industry's seemingly self-serving and uber-conservative, litigation-phobic recommendation that would indicate that either of these two folks have significantly compromised their safety:

• Fred has commuted daily for 7 years with the same helmet . He is out in the morning and the evening; the sun is at least low and, in winter, gone. He has never crashed and takes great care of his helmet. Every once in a while he defunks the strap and pads, but other than that, Fred is Fred.
• Fred's other brother Fred just cracked his favorite helmet, so it is time for a replacement. He had his old helmet on the shelf in his garage. He wore it for about a year, but it has been sitting in his garage on the shelf in a cool dry place since 2003. Replacement found.

After 3-5 years a helmet will be just as effective/ineffective at reducing bicycling risk as it was the day it was born.

If the materials are made from UV resistant plastics and the adhesives are still holding, why do you need to replace it. As long as you keep it clean, the only other reason to replace it is to upgrade to one with better ventilation, or a different color/style.

I haven't found compelling scientific evidence to keep or replace. What do they suggest about helmets stored in boxed that haven't been sold for 1-3 years?

I do know last January I found a pothole covered with snow (when it stopped my bicycle).

I think my helmet was 10 year old; it seemed to work fine, no problems due to age. I did replace after it was damaged in the crash.

I thought the horrible/great thing about styrofoam was that it never breaks down.

I guess that helmets should have an expiration date on them. Or at least a sell by date.

When it stinks so bad you can't wear it.

The foam in there will lost it's impact properties after a few year (The internal air bubbles deteriorate and whatnot), but I've found that helmets generally wear out due to other reasons long before it would become an issue.

My helmet has a warning label on the inside that says: "... destroy and replace after impact. Damage can be invisible".

It doesn't say anything about replacing after so many years of use. If periodic replacement was important I think you'd see marketers taking advantage of that and really pushing the message. I've only seen the "replace every few years" idea here.

I do know that child car seats are supposed to be replaced after they get to be so old. A child would usually grow out of it first. It's more of an issue for the 2nd or 3rd kid.

If it's crumbling from UV damage or was suffered more than a minor blow, replace it. Otherwise, it's good.

If the plastic cover comes unglued, you can easily re-glue it.

My impression is that at some point in the recent past there was an advance in helmet design such that at the time helmets older than 2-3 years should be replaced, and then I'm guessing that somehow the 2-3 year idea just stuck. I could be wrong.

I do replace my helmet after a single solid impact even if no damage is visible.

When I am bored of it. Roughly 3 years.

With car seats, I think that the reason is usually that the safety standards have been revised since the product came out - i.e. the old car seat, while still up to spec for the standards it met when new, doesn't meet new standards. This occurs with everything child-related - the $800 crib we bought less than a year ago is likely going to be "obsolete" soon for the same reason; I see no reason why the crib wouldn't meet the newer rules - it's not a drop-side, is very sturdy, and doesn't have any large gaps; but I'm guessing that we'd have a hard time selling it in a few years should we choose to do so.

qft!

When they go out of style?