I am not going to go digging for this information for you but essentially the way bike helmets are tested is a weight is dropped onto the helmet traveling at a

I am not going to go digging for this information for you but essentially the way bike helmets are tested is a weight is dropped onto the helmet traveling at a certain velocity and the result is recorded. It is not representative of the real world and it is only valid for speeds between 11 and 14 mph. There are no well-supported "facts" that helmets reduce serious head injury. In fact, among the cycling community, it is a very hot point of contention.