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Use and distribution of this article is subject to our terms and conditions
whereby's information and copyright must be included. BowlVersity Q & A Part 2 wishes to continue to share with our readers a few of the many questions we receive relating to articles posted on our site. This bowlingball BowlVersity Q & A Part 2 article features three questions sent to us by our community guests. Let's address a few more questions randomly submitted as comments and provide the second of a series of articles known as BowlVersity Q & A Part 2.

We hope our responses to these questions below lead to helping you improve your bowling game. Most of the responses are to questions we received from bowlers ranging from beginners to 180 average players.

As we indicated in our first article in this series last month, if you are an advanced player or a highly skilled and experienced player, you are most welcome to join in and offer your comments with the intent of sharing your knowledge from your personal experiences on the lanes with our fellow bowlers. We cannot possibly keep our responses to questions short and direct in content without omitting information which could expand the range of answers to a more acceptable level, thus another reason we invite you to share your thoughts by making a comment under the posted article and help us pass along useful ideas.

Here are the three questions for this article:

Q. Which is most important, a bowling ball coverstock or a drilling layout?

A. The coverstock of any bowling ball is the key factor in determining ball symmetry, the friction factor generated when in contact with the lane surface, and the shape of the overall ball motion. Next would be the core design which is key in determining the length and hook potential ratings in a given bowling ball. The drilling layout changes the degree of symmetry once holes are drilled into a ball and will either increase or decrease track flare potential depending on the given layout. Track flare influences the ball motion on the back end of the lane. When selecting your next new bowling ball, your first consideration should be the type of coverstock to match best with the lane conditions where you compete. The leading bowling ball manufacturers provide a variety of coverstock options ranging from polyester, to regular urethane, to reactive resin classifications such as pearl reactive, solid reactive, and hybrid reactive, to particle coverstock choices.

Q. What are the primary differences between Symmetrical and Asymmetrical bowling balls?

A. Let's examine the primary differences in core designs. A Symmetrical Core (undrilled) in a given bowling ball is 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.

An Asymmetrical Core (undrilled) in a given bowling ball is 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.

Q. Which are the most effective ranges of grit pads to use when altering bowling ball surfaces?

A. Using grit pads ranging from a low of 500 to a high grit of 4000 is the standard manufacturers will use in preparing the factory finish you get in an out-of-the-box bowling ball. The lower the grit, the more texture is applied to the ball surface which increases traction and friction when the ball is in contact with the lane. Higher grit pad produce a fine texture surface on a given bowling ball and creates less traction on the lane surface.

Solid reactive bowling balls use lower grit to medium grit pads, 500-100-1500 grit, in preparing the surface of a ball to create sufficient traction for use on medium to heavy oil conditions. Pearl reactive coverstocks are intended for use in medium to dry lane conditions by using 1500-200-4000 grit pads which provide sufficient skid length on the high friction lane surface.

Layering the grit pads such as 500-1000-1500 will produce sufficient surface friction for heavier oil conditions providing so the given ball will not slide too far and react after the mid-lane. Same holds true in the case of drier lane conditions where a layered grit preparation such as 1500-2000-4000 provides enough skid length so the ball won't react before the mid-lane.

If you are a bowler who likes to prepare your own ball surfaces, there are cleaners, polishes, and Abralon grit pads ranging in texture available here at We recommend to carry these items in your accessory bag to the bowling center so you can maintain the surface of your bowling ball equipment during and after your sessions on the lanes. It is always recommended to visit your area pro shop and periodically resurface the coverstocks of your equipment after 60 games of use so you get the oil and dirt removed from the pores of the coverstock material and prepare the precise grit finish you need to combat the oil conditions you will face in competition.

We thank the bowlers who shared their questions with us for this article. We hope our responses serve a useful purpose. Feel free to offer your comments; they are most welcomed. Be sure to check the "Improve Your Game" link in "BowlVersity" on the home page of our site for future posts. Thank you.

Rich Carrubba

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