There is lots of confusing about when to buy a new motorcycle helmet, some say, you should replace a motorcycle helmet after five years other say ten years. What is the truth, if there is any, behind this belief.
We inspected a few motorcycle helmet sales points around the Bangkok area, and we found some alarming results, many helmets we found at the shops where 12 to 18 months old, with some more famous brand coming close to be older then 2 years. Some shops, when questioned about this, told us it's OK as long as the helmet is stored in the packing and in a climate-controlled warehouse.
My 'personal' thought is that the shock-absorption layer of the helmet, or EPS (Expanded Polystyrene), begins curing as soon as it has set up and never stops, just like concrete or other materials.
We asked some Thai manufacturers, called them and asked them to call back, we still waiting - 5 minutes will take a hell of a time if you work with helmets. INDEX was honest and did almost directly confessed that decay happens, but insured us that helmets of INDEX are not falling basic safety standards for at least 3 years.
The professional angle of a European safety institute, who was most willing to inform us: The motorcycle helmet age question is a good one. Some manufacturers say five-year, but that is so arbitrary and random that it really doesn't matter when you start the 'age' clock. A year or more stored in a box is limbo land for a helmet, so one can certainly start the clock when you buy it, Snell Helmets added the five-year rule without any real reason or research, sort of like its standard, and some manufacturers have followed suit.
But that's good for them for liability reasons, and they get to sell us new ones every five years as well.
Modern motorcycle helmets don't deteriorate to any meaningful degree in the short term, which could easily be a decade. Old plastic shells, from before 1970, weren't too good, but fiberglass or carbon-fiber is basically timeless. At TNO (Netherlands Organization for Applied Scientific Research) tested 25-year-old helmets that still meet the standard that they were build to, which leads us to the fact that helmets deteriorate is so small, if any, that it is not detectable in the lifetime of any helmet.
Of course the situation changes if the helmet falls, even the smallest impact, can change the safety of the helmet. To test don by independent American researchers it was found that a helmet can suffer great protection lose from a relative small impact from falling of a motorcycle seat.
Be aware of fakes, the helmet in the picture looks like a BMW System 5 helmet, but is in fact a 100% fake, and the protection the fake helmet offers is questionable.