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Understanding The Pro CG Bowling Ball

If you have heard the term “Pro CG” bowling ball, don’t be put off by the inference to professional bowlers or to a special group of players. Rather understand that the manufacturers sometimes produce bowling balls with the pin 2.5 inches or more from the Preferred Spin Axis. These bowling balls are labeled “Pro CG” bowling balls and are first line pieces of equipment with limited drilling options.

A “Pro CG” ball is one where the center of gravity (CG) ends up a certain distance left or right of the preferred spin axis (PSA).

Definition: Center of Gravity (CG) - The position in which the ball is evenly balanced statically from the right side to left side and from the finger quadrant to the thumb quadrant. The perfect balance point where the weight on any straight line drawn through the CG is zero on either side of the CG. This spot is usually indicated by the position of the label or a punch mark provided by the manufacturer.

Definition: PSA - Acronym for Preferred Spin Axis and often termed the Mass Bias as it has the highest radius of gyration (RG) value, the PSA can be viewed as a secondary pin which helps fine tune ball motion.


If you draw a line on the ball from the pin to the PSA, the CG marker must be 2.5 inches or more from the line to be categorized as a “Pro CG” bowling ball. Although a "Pro CG" ball is still a first line ball, it has limited drill options which require certain types of layouts.

The "Pro CG" bowling ball is created in the manufacturing process and when the pin area is drilled, the core can shift slightly. When the weight-block shifts a small amount (perhaps one-sixteenth of an inch to one-thirty second of an inch) it pulls the CG off the “Y axis” toward the “Z axis”. You will notice CG markings on some bowling balls are a far distance from the pin to PSA line. These small shifts do not affect the ball reaction or the quality of the product, but it can limit the drill options to remain within USBC specifications.

Often times "Pro CG" bowling balls can be found at good prices. If you wish to purchase a specific high-end Pro CG bowling ball, take advantage of the opportunity to save money on this first line item right here at bowlingball.com.

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