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Bowling Ball RG And Differential Range Ratings

When you're searching for your next bowling ball and would like to know more about bowling ball RG and differential range ratings quickly and easily with out doing a lot of tedious research, simply reference the information below. has worked to provide useful information shared by the industry to pass along to all of our friends, particularly those of you trying to make a good decision in purchasing your next bowling ball. Understanding bowling ball RG and differential range ratings is one important step in the equipment selection process.

The United States Bowling Congress defines the RG (Radius of Gyration) of a bowling ball as a measurement in inches and is the distance from the axis of rotation at which the total mass of a body might be concentrated without changing its moment of inertia. describes RG as a measurement by some manufacturers in a range from 2.460" to 2.800", but some companies have converted them to a 1-10 scale to help give the consumer a better frame of reference. The These numbers describe the distribution of mass in the given bowling ball and RG is an account of the location of that mass inside the given bowling ball.

High RG numbers indicate that the ball's mass is distributed more towards the cover (cover heavy) which promotes length through the front end of the bowling lane. Low RG numbers indicate that the balls mass is distributed more towards the center (center heavy) which promotes an earlier roll through the front part of the lane. Medium RG describes sufficient bowling ball skid length to reach the mid-lane before transitioning into the hook phase of overall motion.

Placing RG range measurements into three relative numerical spreads would be as follows:

Low RG: 2.460" - 2.570"
Med. RG: 2.570" - 2.680"
High RG: 2.680" - 2.800"

Differential of RG is the difference between the maximum and minimum Radius of Gyration. RG-Differential indicates the bowling ball's track flare potential. describes the Differential of RG as a measurement varying numerically from .01 - .06 in range. These measurements describe the bowling ball flare potential rating and indicate if the flare potential is low, medium, or high. The higher the number, the greater the track flare potential and the more angular motion the ball will produce from the break point to the pocket. The lower the flare potential, the ball will yield more of a smooth arc motion on the back end of the lane.

Placing Differential of RG range measurements into three relative numerical spreads would read as follows:

Low Diff.-RG: .01 - .02 (low flare potential)
Med. Diff.-RG: .021 - .04 (med flare Potential)
High Diff.-RG: .041 - .06 (high flare potential)

A third measurement relating to flare potential which can be used by pro shop operators as a fine tuning device when drilling bowling balls which is Intermediate Differential. The United States Bowling Congress defines Intermediate Differential of RG as the difference in radius of gyration between the Y (high RG) and Z (intermediate RG) axes on a bowling ball.

Some manufacturers use an Intermediate Differential rating (sometimes referred to as Mass Bias rating) to accompany the Differential and RG ratings when providing technical data on their given bowling ball products. also provides this information on Intermediate Differential, as necessary, when our visitors reference the technical specifications on any given bowling ball at our site.

Intermediate Differential of RG measurements range in inches from 0.008" - .037."

Low Int. Diff. .008 - .020
High Int. Diff. .021 - .037

The higher the measurement of Intermediate Differential, the greater the bowling ball asymmetry and the lower the Intermediate Differential, the lower the asymmetry of a given bowling ball. The greater the asymmetry, the more area is created at the break point and the ball will respond to friction faster than will symmetrical balls.

Next time you are searching for a new ball at our site, please check out the description details and the RG and Differential specifications to help you select a new ball with the appropriate length and hook potential ratings.

It should be mentioned that the coverstock surface texture influences both the length and hook potential of any given bowling ball and can be altered or modified to help you further control the overall ball motion.

When you are ready to place an order, follow our simple online instructions. Thanks for visiting


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