As per title really – assuming no major impacts and weekly usage in rain, snow and occasionally sun.

4 years I think? They usually print the date in them..

I’ve just changed mine after noticing it was dated as 2002!

I think the real answer is no one really knows. Unless someone runs a programme to test old helmets then no one is ever going to know for sure. Anything else is just a best guess and manufactures seem to suggest anything between 3 – 7 years.

Official guidelines vary between brands, for example, Bell say 3 years IIRC. I’ve stopped using my ~3.5 year old Bell Alchera recently, albeit it’s still in the hallway, parked under my new ~£41 hi-vis Giro Savant from Wiggle.