The figure to the right shows a traditional 3-piece construction. This bowling ball has a high radius of gyration (RG). Higher RG means that the weight inside sits closer to the coverstock than the center. Higher RG balls will have a lot of length and depending on the coverstock can react sharply to the friction on the lane.


Examples of High RG bowling balls: Brunswick Power Grooves, and Ebonite Tornados, Storm Tropical Storm

The figure on the left shows a typical 2-piece construction. This bowling ball has a lower RG. Lower RG means that the weight is located more towards the center of the ball. Lower RG bowling balls will tend to roll up early and have a smoother reaction.


Examples of Low RG bowling balls: Brunswick Ultimate Inferno, and Ebonite The Big One, Storm Paradigm

4 Types of Coverstocks

1. Polyester or Plastic: Most beginning bowlers will start out with a polyester bowling ball and lots of advances players use them for spare balls.This a very low friction surface and provides the longest length.
2. Urethane is the base for all performance bowling balls. Urethane gives a very smooth reaction and is medium friction surface.
3. Reactive Resin: This is an additive in the urethane base that provides a great amount of friction. This cover reacts drastically to the drier part of the lane.
4. Particle: This also is an additive to urethane. Some of the more common particle additives are glass and rubber beads. This cover starts to grab the lane earlier than reactive because of the 'teeth' or 'tread' in the coverstock. Usually, particle will give you a smoother reaction.

Surface

Surface is about 75% of a bowling ball's reaction, so it is key to have the correct surface for the condition you are trying to use it on. There are many ways to prepare a surface, but here are 3 basic surfaces

1. Shiny- Polishing a bowling ball will give the ball a smooth surface. A smooth surface will allow a bowling ball to skid longer and save the energy for the back end of the lane.
2. Matte- A matte finish is a very finely sanded finish, usually 1000 grit or higher. 1000 grit is a very smooth surface and will allow the ball moderate skid and earlier roll.
3. Dull or Sanded- This finish will give the ball the earliest roll because of the rough texture (think snow tire). Usually 360-800 will be used for this process.

Sandpaper grits in pro shops range from 180 up to 4000. The lower the number the rougher the texture.