I've never replaced a helmet based on the "shelf life" recommendation from manufacturers. Maybe I'm living dangerously....

I replace mine when they get a funk that won't wash out:) There have been some threads on when the foam degrades secondary to UV light etc, as I recall it is multiple years, should be easy enough to search. I'm guessing that if you don't use your aero helmet all that much, keep it somewhere relatively climate controlled etc it is probably ok.

Of course, another reason is for new tech. I think I am going to replace my road and off road helmets with something with MIPS once my team secures a helmet deal next spring, and they are both getting funky!

+1

I wont be replacing any helmets due to "shelf life" per manufacturer so I am living dangerously!!!

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Speed kills unless you have speed skills!!!

3-5 years from purchase/production date,Believe only the high end Moto helmets actual have an expiry date engraved

I think the ITU rule is technically 5 years... I had to scramble to replace my helmet before worlds in 2013 just in case they checked the label to see that the helmet I had then was 7 years old. My helmet is in its 5th season, so I just picked up a new one, that I will probably race in this weekend (primarily because of the cool and wet forecast, the new helmet is the Scott Cadence, might through the plugs in the vents, not so much for the aero gains as for the dryness gains...)

This article is interesting:

http://biomechanical.asmedigitalcollection.asme.org/...px?articleid=2497744

From my other hobby (auto racing---specifically harness restraint systems) material degradation testing is notoriously difficult to do reliably. AND, given the variability of use and storage conditions...it is even harder to apply to real world cases. From just a quick look at google results, it would appear that the situation isn't any different in the bike helmet world.

The short answer seems to be years and years and probably even more years for your daily use helmet. In other words, the foam padding is likely to deteriorate and smell funky long before the foam will stop protecting your head. For the race-only aero helmet stored in the top of your closet? Its unlikely to ever go bad.

7 years and going strong with my Giro Prolight. Just replaced some of the strip pads, but otherwise it looks like new. And yes i ride a lot.

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"For those who understand, no explanation is necessary. For those who don't understand, no explanation is possible."

Every three years.

Wow -- that's good to know. I thought I was pretty familiar with the rules, but don't remember seeing this one. Year of manufacture doesn't always match year of purchase... guess I'm going to go check my helmet! The only thing they checked at ITU Worlds was that the helmet chinstrap was tight enough. They also checked this at ITU Montreal.

this is correct.
on the other hand, a cost-benefit analysis quickly shows that the $50 to replace a helmet every 3-5 years versus the cost of a fractured skull if you happen to have degraded material in the old helmet, is worth it..

that said I do have an aero helmet that is ten years old, stored in a cool dark place, which I may yet ride with..

You guys must be a lot less clumsy than I! I replace mine whenever I have a crash that involves hitting my head against either pavement or concrete - so far that's about 1-2x a year :-/! Luckily the ones I've had (POC and Giro) both offered decent discounts on a crash replacement.

I replace mine every time I crash it or every other on a daily rider if not crashed. My tt helmet about every three years since it doesn’t get a lot of use.