On another site that is now closing down, I asked....
What is RG...and differential....?
The current moderator at the time took the time to post....
For those that might know him...Thanks BubbaRay
RG-
RG means Radius Of Gyration. The RG of a ball tells you how soon the core is designed to roll. The lower the RG, the sooner the ball is designed to roll. The lowest allowed by the USBC is 2.43 the highest is RG 2.80.
The RG Differential (also called just DIFFERENTIAL) -
This indicates the difference between the low RG and the high RG. The Differential indicates the potential for track flare which can be translated into hook potential. The higher the differential, the more hook potential the core possesses. The RG differential indicates the difference between the low RG and the high RG. The maximum differential allowed by the USBC is 0.060. Don�t get this confused with intermediate differential because that is different. This is used in asymmetrical balls to measure the spin time of the bowling ball before drilling.
this is what RG Differential and RG mean. But, the biggest influence in ball motion is the surface of the ball and the force and direction of the bowler�s release. In addition, the condition of the lane must also be taken into consideration...
Now here is a pretty good rule.
A lower RG ball with a low differential will produce an earlier rolling ball with a small arcing motion.
A lower RG ball with a high differential will produce an earlier rolling ball with a larger/stronger arcing motion.
A higher RG ball with a low differential will produce a later rolling ball with an angular backend motion.
A higher RG ball with a high differential will produce a later rolling ball with a strong, somewhat angular backend motion.
On differential:
The lower the differential the closer together the track flare. The higher the differential the further apart the track flare. The cover stock friction on the lane allows this to come together. Coverstock adjustment is needed to adjust to the conditions you are bowling on. Well I hope this helps and does not confuse you too much
