| The big issue on fitting is that arai manufacture more different shell sizes than any other company, so they can have less un-needed padding in the helmet just to make it fit.
That means that it stays better fitting longer.
I've had mine race-fitted, and it is the most comfortable fit I've ever had, while seeming to hardly need the strap to keep it on.
That all adds up to less likelihood of your head suddenly twisting inside the helmet in a crash, which should lessen brain damage. |