Originally Posted by
Hypno Toad
Your right, rattling around doesn't quickly render a helmet ineffective. But that really wasn't the point.
Again, if you see the value in a helmet to protect your skull, you take care of it and keep it on your head. If you don't see it as valuable, than leave it at home or simply don't buy one.
And again, it might be fairly rational to say I need to wear the helmet for this part of the ride, but not the other.