Originally Posted by afatgirlafathorse
I think you are supposed to replace helmets annually or biannually and anytime after a fall.
The rule of thumb is 5 years after the date of manufacture or when you take a fall where your helmet impacts the ground, whichever comes first.
The safety materials in the helmet deteriorate over time, so even if it's never taken an impact it needs to be replaced every 5 years.
I have two helmets, so if one needs to be replaced I'm not riding without one until the new one arrives.