Originally Posted by
meanwhile
I understand why you thought that, but it's an important difference. In the real world a lot of helmets are found that have broken instead of compressing their foam - these helmet's didn't work. A broken helmet results when the shell fails before the liner compresses, the amount of energy then needed to destroy the helmet is trivial.
Interesting. The helmet I crashed on, while it is definitely compressed some, also has numerous cracks and is even missing a small chunk at the point of impact. After reading your, and other, comments here I'm convinced more than ever that my helmet did not do nearly as good a job as it could have even given the constraints of constructing a light and well ventilated helmet. I do believe that the next time I need a new helmet I'm going to seek out something that is Snell approved, just to play it safe (which isn't that the whole idea?).