that helmet has failed – it provided little protection. A helmet that has worked has crushed not split
Rotational forces from helmets are real and proven experimentally as shown by the TRL amongst others.
I'm quite interested in what type of polystyrene crushes rather than splits or cracks. Oh, here's some scientific facts.
1/ My first helmet, cracked when i landed hard after a bad crash
2/My second helmet also cracked after i crashed and
3/ guess what, my own science proved that my 3rd helemt also split after craching hard.
Now 2 of these were specialized and 1 was a giro. I think my own science has proved that a cracked helmet has done its job properly.
Beats men in white coats in a lab i bet as well.
Also, his 'non protected' back looks worse off than his 'failed, but protected' head i bet