Expert: Kyle - 8/9/2006

Question
what does RG stand for?

Answer
It stands for the radius of gyration. This is a measurement of the effective weight distribution in a ball as it relates to the moment of inertia. It essentially is an indication of the resistance to rotation motion. It is equal to the square root of the moment of inertia divided by the weight.  Another common term is DRG or Differential RG.  This is the difference between the minimum and maximum RG axis in a ball. This property determines the track flare potential. The maximum allowable differential RG is 0.080 inches. The more the differential RG the more potential for track flare. Track flare increases the friction between the ball and the lane.
The difference in the Radius of Gyration or RG on the x-axis and the y-axis. RG differential indicates the amount of flare potential of a bowling ball.