Symmetric vs Asymmetric Bowling Balls
Understanding symmetric versus asymmetric bowling balls
can be a help in selecting your next bowling ball
. Bowling ball symmetry varies from ball to ball based upon certain factors engineered into the ball construction process. Familiarizing yourself with symmetric versus asymmetric bowling balls
is also a step in understanding bowling ball motion.
Let's examine the primary differences between symmetric
1. Symmetrical Core (undrilled)
- A ball where the RG (radius of gyration) values of the Y (high RG) and Z (intermediate RG) axes of the ball do not differ by more than 5% of the total differential of the ball.
2. Asymmetrical Core (undrilled)
- A ball where the RG (radius of gyration) values of the Y (high RG) and Z (intermediate RG) axes of the ball differ by more than 5% of the total differential of the ball.
Symmetrical drilled balls yield small differential ratios. Small differential ratios will produce a smooth, controllable motion when compared to an asymmetrical ball.
Asymmetrical drilled balls show a defined, angular motion. These balls can create more area at the break point and will respond to friction faster at the break point than symmetrical balls.
It has been proven through United States Bowling Association (USBC) field studies that all drilled bowling balls are asymmetrical, whether they are symmetrical or asymmetrical before drilling.
The term differential in a bowling ball can be defined as the difference between the maximum and minimum Radius of Gyration. Radius of gyration, RG, is measured 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.
Total Differential is the difference between the X (low RG) and Y (high RG) axes values of any bowling ball. Intermediate Differential is the difference in radius of gyration between the Y (high RG) and Z (intermediate RG) axes on the bowling ball.
The differential of RG measurement indicates the bowling ball's track flare potential. The higher the number the greater the track flare potential.
A key to ball motion is intermediate differential which is the measure of a bowling ball’s degree of asymmetry. Differential ratio is simply defined as the intermediate differential divided by the total differential.
The larger the differential ratio, the more asymmetrical the bowling ball. Conversely, the smaller the differential ratio, the less asymmetrical the ball.
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We also recommend you consult your local pro shop professional before choosing your next bowling ball so you may discuss the important drilling layout options to help you achieve a desired ball motion.