When should I replace my mountain bike helmet?

Replace your helmet immediately after any crash where your head hits the ground or an object, even if no damage is visible—EPS foam compresses permanently during impact. Replace every 3-5 years even without crashes, as EPS foam gradually degrades, UV exposure weakens the shell, and retention system components wear out. Replace if you notice cracks, delamination, loose components, or if the retention system no longer holds adjustment. When in doubt, replace—a helmet is far less expensive than a head injury.