Retention system testing

OFF THE WIRE
1) In my attempt to understand the testing methods outlined in 218, I find myself stuck on the retention system test.

What I am failing to grasp is under what crash conditions would I want my retention system subjected to a force of 250 lbs?
I cannot even fathom a crash situation in which my helmet would have an extreme force pulling at my safety helmet.

Can anyone help me with an example of an incident that would put that sort of stress on the retention system?
Donnie 'Mr. Breeze' Landsman

2)ANSWER In a 30 mph front line impact, a securely tightened chin strap could exert up to 200 pounds of resistance. This is why some accidents of this nature result in basal skull fractures. The retention of the chin strap against the chin, along with the 200 pounds of energy trying to move the helmet forward or towards the top of the head causes the basal skull plate to fracture. It's common and has been reported many times, although there is a reluctance on the part of authorities or NHTSA to admit that helmets cause injury. The test procedure helmet retention systems are subjected to is to insure that the helmet will not come off the head completely, thereby affording no protection at all. The test dummy measures the energy at the chin strap but I'm not sure if they take into account what pressures or energies are exerted on the basal skull area or cervical spine. There have been tests on cadavers by independant laboratories and from what I remember, there was evidence of basal skull injury.
Pan

3) ANSWER, Uh, yeah.
The reason my helmet weighs 2 1/2 ounces.

4) ANSWER,Reference that photo from Tulsa Oklahoma that was circulated two years ago despite the families objections. I intentionally do not have the photo, but it can be found at snopes. It was the one of the sportsbiker who rammed into the back of a tractor trailer truck, his helmet got stuck in the truck, and the retention system worked as the government wants it to, while he was dragged a long distance.

5)ANSWER, Interestingly enough, the helmet system did not kill him nor save him. There is a distinct probability that rider could have embedded his skull without the helmet and still have been dragged.