Does anyone know if ski helmets are like Motorbike helmets, in that they should be replaced after a big impact?
Or….. are they simply plastic shells with foam linings?
They’re usually expanded polystyrene foam, same as cycle helmets. These should also be replaced after a big impact.
The foam compresses, as designed, and becomes ineffective in a big smash. The outer shell is more solid with a ski helmet and less just a thin bonded layer on the foam, so less likely the foam will crack in a smaller impact like cycle helmets can do, but still it would be worth checking for cracks.
Ski helmets serve additional functions though. They usually have a warm fleece liner, ear coverings and sometimes adjustable vents, which along with the larger head coverage shape all helps keep the head warm. Which is one of the major reasons I wear them. A white out blizzard in freezing conditions is miserable with a woolly hat.
Oh and goggles fit them quite well.