Many riders believe that a helmet that has never suffered a crash will last a lifetime. In reality, chemical degradation and foam compression dictate a strict replacement schedule recommended by Snell, ECE laboratories, and helmet manufacturers.
1. The 5-Year Rule from Date of Use
Helmet manufacturers (including Arai, Shoei, and AGV) recommend replacing helmets 5 years from the start of regular use or 7 years from the manufacturing date stamped on the chin strap tag. Key reasons include:
- EPS Foam Hardening & Oxidation: Expanded Polystyrene (EPS) absorbs natural atmospheric moisture, UV rays, and ozone, gradually losing its elasticity and dynamic energy absorption capacity.
- Resin & Glue Degradation: Body oils, hair care products, and sweat break down the internal adhesives holding EPS layers to the composite shell.
- Chinstrap Webbing Fatigue: Repeated pulling, UV exposure, and perspiration weaken the tensile strength of the nylon retention webbing.
2. Did You Drop Your Helmet? Here is What to Do
- Empty Drop (from handlebar height): A drop without a head inside rarely damages the EPS liner, but can create hairline fractures in fiberglass or carbon outer clear coats. Inspect closely.
- Drop with Weight Inside (or an actual crash): The helmet must be replaced immediately. EPS foam crushes once to absorb impact energy and does NOT bounce back. Even if the shell looks undamaged, the internal shock absorber is permanently compromised.