Correct if your body is restrained and you have an accident the weight of the helmet can break your neck. Helmets on bikes. I problem as the body is free to move, seatbelts in cars restrain the body and generally an airbag stops too much movement. The answer is a HANS restraint used in sports cars where helmets are worn. That said the Helen is really protection against flying stuff rather than impact - hence the lightness being key
