Join Date: Jul 2007
Location: Anaheim, CA, USA
I have been wearing Shoei helmets for 30+ years. Some years ago, I learned that they offer a free helmet inspection service. Since I moved back to Southern California, where their US headquarters are located, I have taken advantage of that free service several times.
Having used that service several times, I learned a few things from them:
1. They recommend replacing helmets ever five years. There is an age limit where they won't certify a helmet, period. I believe that age is seven years. (By the way, they make you sign a form acknowledging their inspection. You can't claim later that you didn't know your helmet had an issue if they find one.)
2. According to Shoei, a helmet's life-saving, shock absorbing materials lose their protective abilities over time. The primary cause is exposure to the stuff in the rider's hair - perspiration in particular, but also chemicals from shampoos, conditioners, sprays, colognes, etc. Ambient air pollutants also contribute. Washing your helmet liner frequently will slow that deterioration down.
3. Shoei frequently finds latent damage to the helmet's shock absorbing materials during their inspections. They found it in one of my helmets, so I replaced it soon after. A common cause is exposure to heat. In the case of my helmet, I believe it was that the helmet lock on the side of the motorcycle put the helmet too close to the muffler after riding.
4. Casually dropping a helmet is usually not the cause of latent damage, just cosmetic damage to the paint.