Radius of Gyration (RG) is the ability of the of the core to resist energy when revolutions are added to the ball.
The lower the RG value is the faster the the core will rev up internally. Low
RG core balls rev more, roll sooner and smoother. The lower number indicates that the ball mass is distributed more towards the center(center heavy) which promotes an earlier roll through the front part of the lane.
The Higher the RG value is the slower the core will be to rev up. High RG core balls produce fewer revolutions, flare later down the lane and go longer before hooking. The higher the number indicates that the ball mass is distributed more towards the cover (cover heavy) which promotes length through the heads of the bowling lane.
RG Differential: is the difference between the High RG Axis value vs the Low RG axis value. RG differential directly relates to the flare potential of the ball. Flare potential is one of the factors in determining the balls hook potential because as the ball flares during rotation traveling down the lane, the sooner the ball will read lane surface friction which initiates the hook motion.
High RG vs Low RG Cores
High RG Cores
Resist Change
Require more energy to produce change
Delay the flare, travel further, hook later
Low RG Cores
Rev sooner and faster
Flare earlier
Hook motion is smoother
