Differential
The difference of the radius of gyration of a bowling balls X axis (the weight block vertical) compared to the radius of gyration of the same balls Y or Z axis (the weight block horizontal). Differential is an indicator of a bowling balls track flare potential. Bowling balls with lower differentials are more stable, therefore generating less track flare potential. Bowling balls with higher differentials are unstable, therefore generating a much larger track flare potential. Also, differential is a guide to the internal versatility of a ball. It can indicate just how much of a length adjustment can be made through drilling. Balls with lower differential will allow only modest length adjustments whereas balls with higher differential may translate into a length window of up to 5-times that of low differential balls
Radius of Gyration (RG)
An account of the location of the mass inside a bowling ball. Rg tells us whether the ball has the mass toward the center of the ball (low rg), toward the cover of the ball (high rg) or somewhere in between (medium rg). 1. Low rg balls rev up quickly. 2. Medium rg balls rev up slightly later. 3. High rg balls lope down the lane saving the energy until later.
Several ball sites have a Glossary. Hope this helps
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