Most cycling helmets come with broad instructions to replace them every 3-5 years. It’s a familiar line, but one that’s always struck me as suspicious – perhaps more about driving sales than ensuring safety. I wanted to dig deeper into the reasoning behind this guideline, so I spoke to safety experts and helmet brands to find out how long helmets really last.
When the conversation about helmet lifespan arises among friends, the discussion quickly turns to the degradation of EPS foam and the effects of UV light and sweat. These points are often brought up without anyone being able to point to where they first found this information. To understand more about what happens to helmets over time and when you really need to replace them, I spoke to Barry Miller, a PhD biomechanist and director of outreach and business development at the Virginia Tech Helmet Lab, along with Matteo Tenni, a project manager at Met Helmets, and Brian Turany, marketing manager at Trek.
What are helmets made of?
Whether you’re dropping serious cash on an aero lid or picking up something more affordable, most helmets share the same core construction. At its heart is EPS (expanded polystyrene) foam, a single-use material that absorbs impact by crumpling. Once it’s compressed in a crash, it won’t protect you properly again, which is why post-impact replacement is a must no matter how old a helmet is.
Wrapped around the EPS is a hard polycarbonate or ABS shell. This outer layer fends off minor knocks and scrapes and helps prevent cracks from small drops by spreading out the force.
Many helmets also include a rotational energy management system, most commonly Mips, designed to reduce the forces of angled impacts. These sit between your head and the foam and are usually made from polycarbonate or polypropylene, depending on the version.
Finally, straps (typically nylon or polyester), buckles and the retention cradle (often polycarbonate or nylon) round out the construction. These parts deal with daily wear and tear and plenty of sweat.
What are safety bodies' and brands' position on helmet replacement?
Some safety bodies recommend replacing your helmet every 3-5 years, even if it hasn’t suffered a major impact. The CPSC in the U.S. says 5-10 years, while the Snell Foundation leans closer to five, citing UV damage, sweat, and glue degradation. In Europe, the EN 1078 standard doesn’t mandate a strict replacement window, but manufacturers tend to align with the 3-5-year guideline. Australia and New Zealand’s tougher AS/NZS 2063 standard also points to a shorter lifespan, especially in sunny climates where UV exposure could accelerate wear.
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