At what point should a bicycle helmet be replaced?

[joe l]

Is the date on the inside when it was made or when it should be replaced?

 

[Stefatron]

I know that motorcycle helmets need to be replaced every three years. Also if you ever get in a crash with a helmet or if it gets dropped from up high it needs to be replaced. The foam inside of the helmet gets old and in a crash it will be effected and won't protect you like it should.