I was poking around the web trying to find out how companies measure flex and I came across these resources. http://www.acs.psu.edu/drussell/publications/russell-hunt-tpt-formatted.pdf http://twu.tennis-warehouse.com/learning_center/hockeyflex.php Apparently there's a formula for it.  Flex = [48EI/L^3]*D where, EI = the flextural rigidity of the material being measured, L = the length, and D = the distance of deflection. Any way before everyone's eyes glaze over. There'