Do helmets have a shelf life?
If a helmet is not used, is stored in it's bag on a shelf out of direct sunlight, how long is it good for?
I ask because I have lost so much weight (see the Keto thread) that my current helmet is now loose. I have gone from a Medium to a Small. I have found a new, but out of date helmet in new like condition. In all aspects except age, it's brand spanking new. It's an Arai Classic e.
Do helmets deteriorate or go bad with time?
If unworn and stored in a cool dry place I don't know how it would break down/deteriorate. When worn I know sweat, dirt, moisture etc. all take their toll.
It should be good to go, unless it was used a bunch before storage. The EPS (styrofoam in the cheap helmets) breaks down. But when new and stored like you said, good for a very long time.
Arai usually stamps the mfg date on one of the D-Rings
First, it is your call --it's your head. However, Arai (and every other mfg. I have checked) does have a position on replacement as do untold thousands of riders that have opinions, too.
https://support.whyarai.com/support/solutions/articles/5000625957-how-do-i-know-when-my-helmet-is-past-its-best-
Well, there you go. I thought it was wearing it that broke it down, but clearly that's not the case. Lesson learned.
At work we were told that hard hats should be replaced at certain intervals. If a 50' length of 24" diameter pipe fell on my head, don't think it would matter if my hard hat was 5 years old, or 5 years and 2 months. A less severe impact in a mc accident is surely different, the manufacturer should have data.
The 7 year rule, I never knew that. I'm sure some of us have been using helmets well over 7 years old. Oh well, I guess it also helps keep the helmet manufacturers in business when they know people will be returning every 7 years to buy a new helmet.