How Top Weight Affects Ball Motion

Posted by Bold Apps on

In this Creating The Difference blog we take a look at how top weight effects ball performance. Top weight is defined as the actual weight difference between the Bottom Half and the Top Half of the Bowling Ball. When a bowling ball is designed, the ideal top weight is around 3 ounces. This allows for the holes to be drilled into the bowling ball removing top weight so that the ball’s top weight is close to zero when complete. USBC actually regulates static weights. After drilling, the top weight cannot be more than 3 ounces. There are other regulations regarding weight; however, for this blog, we will focus on top weight.

An experiment was set up which had different top weights by design. The balls were the same color, core, layout, drill depth, and surface to insure the main variable studied was in fact the top weight.





Figure 1: Core Displacement along Pin Axis



The balls were re-weighed after the drilling was complete. In Figure 2 below, the post-drill top weight data is shown for each of the 8 test balls in the experiment. The red area represents the region above the 3 ounce USBC top weight limit. Ball 3 is the closest representation of a typical bowling ball.


The graph below shows the results of the data collected from the test. Each line represents a 10 shot average of each ball thrown in a random order.





Figure 3, illustrating ball motion, shows the separation of ball motion. The ball which finished furthest from the gutter was Ball 8. Ball 8 had the highest amount of top weight at 6.6 ounces -- 3.6 ounces OVER the legal limit. The ball which finished closest to the gutter was Ball 1. Ball 1 had the least amount of top weight, at 0.3 ounces.





Figure 4, illustrating total hook, shows Ball 1 had the least amount of total hook and Ball 7 had the most amount of total hook.





The earliest ball in this test was Ball 8 with a breakpoint distance of 41.3 feet. The longest ball was Ball 1 with a breakpoint distance of 42.55 feet, shown in Figure 5.




In Figure 6, the Pocket Entry Angle is shown. The Pocket Entry Angle is the angle in which a ball is entering the 1-3 pin (right hand pocket). The closer the angle is to 0˚ the more the ball is rolling parallel to the lane boards. A higher entry angle is more desirable. A person with a higher rev rate, creates a higher entry angle.

The data shows the ball with the highest amount of top weight, Ball 8, has the highest amount of entry angle; while the ball with the lowest amount of top weight, Ball 1, has the least amount of entry angle. It’s important to keep the scale in perspective. Note that the differences in entry angle between Ball 1 and Ball 8 is less than 2 degrees. While testing, there was a noticeable shaking in balls 6, 7, and 8 as they went down the lane.


Bowling Ball Top Weight Comparison


So in summary, Top Weight can have an impact on performance in very high amounts. The rules set by the USBC with a maximum of 3 ounces on top or bottom would say that the measureable performance of top weight is minimal at best. The normal spec range of top weight from a manufacturer is 2 to 4 ounces on a new ball. Drilling will typically remove 1 to 2 ounces of top weight. It is important to have the pro shop check your ball after drilling to make sure it is legal. After that, don’t concern yourself with the amount of top weight in your bowling ball. As you can see from this blog, the effect won’t impact your ball performance enough on the lanes to matter.

Education is #CreatingTheDifference


  • @Leigh, the purpose of the graph is simply to share information. This is a comparison which people aren’t generally able to see because of the rule making this illegal.

    Creating the Difference on

  • Just a quick thought as I read through this. Knowing that USBC limits max differential top to bottom at 3 ounces, what purpose does your graph serve for anything over that limit. No one can legally drill a ball over that.

    Leigh on

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