September 19, 2026
Understanding RG and Differential Without the Jargon
Ball specs sound complicated, but the core ideas are simple. Here's a plain explanation of RG and differential and why they actually matter.
Radius of gyration and differential show up on every ball's spec sheet, and most bowlers either ignore them entirely or treat them as marketing noise. Neither is right. Both numbers describe real, physical things about how a ball moves, once you strip away the jargon.
RG: How Quickly a Ball Wants to Roll
RG describes how the weight inside the ball is distributed relative to its center. A lower RG means weight sits closer to the core's center, which lets the ball pick up rotation, and start hooking, earlier. A higher RG delays that transition, giving the ball more length before it starts to hook.
Differential: How Much the Ball Wants to Flare
Differential measures how much difference exists between the ball's high and low RG axes, which determines how much track flare it can generate. A higher differential generally means a stronger, more angular backend motion, assuming the coverstock and lane condition allow that motion to show up.
The Takeaway
RG and differential aren't marketing numbers, they're a real description of when and how strongly a ball wants to change direction. Understanding them turns ball selection into an informed decision instead of a guess based on color or brand name.