The 60 G research is based on a number of sources. The US Air Force did G research on pilots. They can experience very high side to side G forces during quick roll movements of fighter jets. The football research was done looking at the head with G sensors (accelerometers) between the helmet padding and the players head with EEG sensors and recording equipment recording the changes in brain wave form. The in-helmet sensors have recorded 120 G's or more for very small times (milliseconds). The NFL uses 98 G's as the threshold for concussions based on their research. Again, this is 98 G's at the skull, not at the exterior of the helmet.

This research has been going on in the US since the mid 1990's. I could give you a long list of names and research organizations but you would likely just discount them anyway. Here is just one : http://www.purdue.edu/newsroom/relea...0-percent.html Note they have seen 250 G's of force in their research.

What is your objection to the 60 G number ? Do you think it is too high or too low based on your understanding ?