Glossary of Bowling Terms

This document provides bowlers and proshops a comprehensive source of definitions of terms used in the sport of bowling and directly related fields by international and North American bowling specialists.

ACCU-Tread™: Our most aggressive reaction reactive coverstock.
Axis of Rotation: "An imaginary line, perpendicular to the track, along which a bowling ball rotates.
Axis Point: One of two points located on opposite poles marking the end points of the axis of rotation.
Back End: "The angle or degree of hook at the breakpoint. Back End is not where the ball hooks, but how much it hooks when it hooks.
Back Ends: "The last 20 feet of the lane, where the least amount of lane conditioner is found, and where a bowling ball usually makes its biggest break towards the pins.
Balance Hole: An extra hole drilled in a specific position in the bowling ball. This hole is used to balance the ball statically and alter the overall reaction of the bowling ball.
Ball Track: "The portion of the bowling ball, which comes in contact with the lane as it rolls down the lane.
Break Point: "The portion of the lane where the bowling ball completes its transition from skid to traction, and provides the greatest amount of hook. This generally occurs in the last 20 to 25 feet of the lane.
Cadmium™: "ACCU-Tread™ base coverstock material plus exclusive Storm particle. Provides high friction, especially on backends.
Carry-down: Refers to the oil that travels to the previously-dry backends. This condition results in less overall hook.
Center of Gravity (cg): The position in which the ball is evenly balanced statically in all directions. This is usually indicated by the position of the logo or punch mark. The "Eye of the Storm".
Core: "The large, round, inner portion of a "three piece" bowling ball. This area consists of the filler material and may have other high-density materials for dynamic purposes.
Core Torque: "The mass distribution within the arms created by the core (or weight block). Core torque is an assigned value of the ball's ability to combat rollout, the complete loss of axis tilt. High torque balls are more effective than lower torque balls at delaying "rollout". High torque balls will also tend to react more violently on the backend than lower torque balls, which roll more even, displaying a more predictable transition from skid to roll.
Coverstock: "The outer shell of bowling balls, which can be constructed with a variety of materials such as Polyester, Rubber, Urethane and Reactive Urethane.
Cranker: "High rev. rate …a player that prefers to play the swing shot, throwing the ball towards the gutter, looking for a big, late backend reaction.
Curelyon™: One of Storm's mild reactive coverstocks.
Differential (of Radius of Gyration): "The difference of the radius of gyration of a bowling ball's X axis (the weight block vertical) compared to the radius of gyration of the same ball's Y or Z axis (the weight block horizontal). Differential is an indicator of a bowling ball's track flare potential. Bowling balls with lower differentials are more stable, therefore generating less track flare potential. Bowling balls with higher differentials are unstable, therefore generating a much larger track flare potential. Also, differential is a guide to the internal versatility of a ball. It can indicate just how much of a length adjustment can be made through drilling. Balls with lower differential will allow only modest length adjustments whereas balls with higher differential may translate into a length window of up to 5-times that of low differential balls.
D-Scale: Refers to an instrument (Durometer) used to measure the hardness of the coverstock of a bowling ball.
Dull: The surface of a bowling ball appearing without reflection (Synonym - Sanded).
Flare: "The migration of the ball track from the bowler's initial axis (the axis upon release) to the final axis (the axis at the moment of impact with the pins). Flare is a length modifier. Flare is used to expose fresh, dry ball surface to the lane surface, the entire length of the lane. While on oil, this means little to the performance of the ball, but when the ball crosses from the oil to the dry, the dry ball surface bonds with the dry lane surface to increase friction which causes earlier hook and greater overall reaction.
Flare Potential: The maximum amount that the axis of a bowling ball can migrate given the construction of the ball provided that the bowler has a maximum power release. Flare potential can also be used to indicate which balls will be better suited for oily conditions (high flare balls) and which balls will be better suited for dryer lane conditions (low flare balls).
Friction: The energy released upon the bowling ball contacting the lane surface causing the transition from skid to roll.
Grit: "Pertaining to the texture of the surface of the ball, whether polished or sanded.
Heads: "The portion of the lane, which extends from the foul line, past the arrows, and to the pine. Usually, this is assumed to be the first 20 feet of the lane.
Hook Potential: Refers to the number of boards one ball will cover relative to another.
Lane Oil/Conditioner: "Substance that was developed to reduce friction between the ball and the lane, with the ultimate goal of protecting the lane surface. It also allows the ball to skid down to its desired roll and hook point, and its placement can greatly affect scores.
Length: "An evaluation of how far a ball will travel before it begins to hook. Length does not include skid caused by lane conditioner, additional fine sanding, or the use of polishes.
Leverage Point: The position located 3-3/8" from the bowler's positive axis point (PAP). Positioning the mass (or pin) of a bowling ball on this point creates the most track flare and over all hook of a bowling ball.
Mass Bias: "The position in a bowling ball, other than the pin, where the mass is closest to the outside circumference of a bowling ball. Mass Bias appears only in "pin out" balls. The offsetting of the weight block tilts the mass to one side creating a center of gravity away from the pin. There is now "Mass Biased" to one side of the ball.
Midlane: This is the middle part of the lane past the heads (1st 20 feet of the lane) and before the backends (last 20 feet of the lane).
Midline: A horizontal line half way between the fingers and thumb.
Midplane: A line perpendicular to the midline that extends through the positive and negative axis points. This line divides the top and bottom halves of the ball on the bowler's axis of rotation.
Oil Patterns: The way oil is distributed onto the lane. Here are the most common used in bowling centers. Top Hat – Heavy oil in the middle and very light on the outside. Christmas Tree – More oil in the middle than the outside. Tapered to the outside throughout the entire pattern. Sport – Permits ratio of 2:1 oil from inside to outside portion of the lane. Used on PBA and PWBA tours. Flat – Same amount of oil applied across the entire lane. Reverse Block – More oil applied to the outside boards than in the inside.
Particle: "Relates to coverstocks, particle technology consists of small units of various materials added to the shell. Particle coverstocks provide increased traction in the oil.
Pin: A small factory plug that signifies the center of the weight block in most bowling balls.
Pin In: "Refers to the weight block being centered in the ball. When this occurs, the pin is within 1" from the cg.
Pin Out: "Refers to the weight block not being centered in the ball. When this occurs, the pin will be more than 1" from the cg.
Pines: "Generally referred to as the middle 20 feet of the lanes. Actually, on wood lanes, it represents the 45 feet between the arrows and the head pin.
Polyester: "A coverstock comprised of plastic material. Generally displays a mild ball reaction, and limited durability.
Positive Axis Point (PAP): The point on the pocket side of the ball that is at the end of the bowler's axis of rotation upon delivery.
Preferred Spin Axis: "The axis which a ball desires to rotate around, and which it flares to achieve this rotation.
Pro-Glide™: Storm's most mild reactive coverstock.
Pro-Thane™ Coverstock: ACCU-Tread™ base coverstock material + TDR (TermoDynamic Response)Particles. Provides highest friction levels of all Storm coverstocks.
Pro-Thane™ LT: Lightest load of particles.
Pro-Thane™ LT Plus™: Medium-Light load of particles.
Pro-Thane™ MT: Medium load of particles.
Pro-Thane™ MT Plus™: Heaviest load of particles.
PSA (Intermediate Differential): "The Preferred Spin Axis (PSA) is defined as the highest Rg axis of a bowling ball, typically referred to as the Y-axis and normally marked with a symbol during manufacturing. The Rg value of a PSA is usually indicated by subtracing the high RG axis from the middle (intermediate) axis.
RAD™ Motion Control™ Technology: Radial Accelerating Dual Density Disk.
Radius of Gyration (rg): "An account of the location of the mass inside a bowling ball. Rg tells us whether the ball has the mass toward the center of the ball (low rg), toward the cover of the ball (high rg) or somewhere in between (medium rg). 1. Low rg balls rev up quickly. 2. Medium rg balls rev up slightly later. 3. High rg balls lope down the lane saving the energy until later.
Reacta-Fleck: "Polyester chips or flakes, that are added to the shell material for both performance and appearance characteristics. The Reacta-Fleck is large flakes that are added to the coverstock material and protrude from the surface of the ball. This provides for more friction between the ball and the lane than conventional reactive coverstock material.
Reactive Urethane: "A coverstock comprised of similar materials used in urethane formulations, however blended with different additives. This coverstock adheres to lane surface, creating the most backend reaction, the least deflection and the most hitting power of any coverstock manufactured today.
Revolutions: "The number of times in which the weight block makes one full rotation around the axis line, as it rolls from the foul line to the head pin.
roundness: "the state of being round, rotund, not pear shaped, but round
Scotch-Brite: This is an abrasive that is used to scuff or sand the ball surface to create different ball reactions or used to resurface the ball cover after the wear and tear from use. We recommend these 3 types of grits. 1. Burgundy – this is the roughest and equates to 240-grit sandpaper. 2. Green – this is the medium textured pad and it will produce a 500-600 grit finish. 3. Grey – this is the smoothest and finest grit pad. Will adjust the surface to an 800 finish.
Skid/Flip: Refers to a ball reaction that results in excessive backend reaction and increased entry angle.
Static Weights: "(top, side and finger): Fine tunes ball reaction.
Stroker: Slow rev. rate… a player that will play the lanes 'down and in' covering very few boards.
Surface: The composition of the outside of the bowling ball. Also refers to the texture of the coverstock of a bowling ball.
Three Piece Construction: "A bowling ball constructed of three elements: the coverstock, the filler material and the high-density puck.
Tweener: "Medium rev. rate… a player that likes to belly the ball slightly, but prefers a fairly controllable reaction overall.
Two Piece Construction: "A bowling ball constructed of two elements: the coverstock and the weight block. A modified two piece bowling ball has the same basic characteristics of a two piece ball, only the weight block has been modified to change the dynamics of the ball (i.e. dual density weight block).
Ultra-Fleck: This is a polyester chip or flake that is added to the shell material to both performance and appearance characteristics. This flake is only 50% of the size of flake in the Reacta-Fleck. These smaller flakes provide for a smoother ball reaction at the breakpoint.
Urethane: "A coverstock comprised of material from the polymer family which creates a hard, durable surface on the ball.
Weight Block: The inner portion of a two piece (or modified two piece) bowling ball which influences ball reaction based on its density and position to the bowlers axis.