What is Differential (Diff)?

What is Differential (Diff)?

What is differential? We see on every ball a spec called differential (diff) but what exactly does it mean? In technical terms it is the difference between the high rg (y axis) and the low rg (x axis) of a weight block. Ok, that doesn’t really help much. In less technical terms, the radius of gyration (rg) is measured from the height of the weight block (y axis) and measured from the width of the weight block (x axis). If the height measures 2.512 & the width measures 2.462, the difference is .050 & that is the number you will see on a ball’s spec sheet. The higher the diff, the more unstable the weight block is. This “instability” is what creates the flare on your bowling ball (the rings of oil that go around your ball) Each ring is one full rotation of the weight block as your ball rolls down the lane. The higher the differential, the more rings of flare you will see on the ball. If you have more rings of oil on your ball, that means more surface of the ball is touching the lane. If more of the ball’s surface touches the lane, the more the ball is going to hook. Translation….the higher the differential is on a bowling ball, the more hook potential the ball has. The maximum differential allowed in an UNDRILLED ball by USBC rules is .060.

When selecting balls for an arsenal, typically balls with lower differential are used when the lanes are drier and balls with higher differential are used when lanes are wet.

This is the bare basics of what differential is. There are a lot of ways ball drillers can manipulate the differential in a bowling ball based on how they drill the ball for you.

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