This is cool - just don't ride in the rain. cardboard bicycle helmets - able to absorb 4 times more collision force than a conventional polystyrene core helmets
Think you understand helmets. Here is a helmet for sale in Europe that meets all European standards (same as ours here in the US). The helmet liner is cardboard. See http://rec-law.us/RIhrxu
The kranium handmade series
The kranium handmade series : The number 9 Gulf Edition
Kranium Handmade series : Limited edition with beautiful veg tanned leather and custom stitching
La magia del cartón
Kranium helmet with carboard crush layer
The Kranium Evolutionary tree...Wonder what Darwin has to say about this...
Tour De France cyclist Mario Cippolini and the Kranium Gulf Edition
D2 : The Dual Density Honeycomb board specially designed to absorb the collision force.