All information provided by Storm Bowling Products
Ambient Temperature - Temperature of the surrounding area; same as room temperature.
Approach - The area immediately in front of the lane before the foul line measuring at least 15 feet in length and not
less than the width of the lane.
Approved- Used to describe equipment that has been sent in, reviewed, tested and found to meet all current
specifications at the time of approval.
ASQ- American Society for Quality.
ASTM- American Society of Testing Materials.
Asymmetrical Core (un-drilled)- 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.
Axis migration - Path of which the axis point travels across the surface of a ball as the ball travels down the lane; this
path will always have the approximate same RG measurement as the ball travels.
Axis Point - One of two points located on opposite poles marking the end points of the axis of rotation.
Axis of Rotation - An imaginary line, perpendicular to the track, along which a bowling ball rotates.
Axis tilt - The measurement of the vertical angle through which a ball rotates; tilt is synonymous with the amount of
“spin” a bowler has.
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.
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. (Axis holes are not allowed under current USBC rules)
Slower - initial velocity is less than 17mph
Medium - initial velocity is between 17mph and 19mph
Faster - initial velocity is greater than 19mph
There is a formula to calculate a player's velocity:
1. Determine the elapsed time (in seconds, i.e. 2.52) from the moment of the player's release to the moment of
impact on the pins.
2. Divide this number into 40.91 (i.e. 40.91/2.52 = 16.23 mph).
Ball Track - The portion of the bowling ball, which comes in contact with the lane as it rolls down the lane.
Bifilar - The use of two cords or wires to support the test cradle in testing the radius of gyration of a bowling pin.
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.
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.
Certified - Any competition, bowler, league, center or coach that is registered with USBC.
Coefficient of friction, COF - The ratio of the force opposing the relative motion of two surfaces and the normal force
acting perpendicular opposing force. In bowling, this term usually defines the interaction between the coverstock,
lane conditioner and lane.
Coefficient of restitution, COR - The ratio of the energy of two objects after impact to the energy before impact. In the
case of a ball striking a pin, this is the percentage of energy transfer from the ball to the pin.
Conventional Grip - The method of drilling in which the fingers are inserted to the second knuckle.
Core (aka: Weight Block) - 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 los of axis tilt. High torque balls are more effective than
lower torque bals 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.
Cover-stock - 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.
Crack - A partial break or split, slight or narrow, which appears on the surface of the ball. Also referred to as “stress
fractures” which often occur around thumb or finger inserts or through the bridge area between the finger holes; a
cracked bowling ball is not automatically disallowed from use in certified competition.
D-Scale - Refers to an instrument (Durometer) used to measure the hardness of the coverstock of a bowling ball.
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
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 minimum 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
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 middles 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 ration of 3:1 oil from inside to outside portion of the lane. Used on PBA Tour.
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 cover stocks, 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.
1. Pin and Center of Gravity (CG) are together on ball.
2. The weight block is perfectly center in the ball.
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.
1. Pin and CG are not together.
2. The weight block is not perfectly centered in the ball.
3. This offsetting of the weight block tilts mass to one side creating a center of gravity away from the pin.
4. We now have "Mass Biased" to one side of the ball.
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.
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.
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
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.
RAD - Radial Accelerating Dual Density Disk. When combined with a strong reactive or particle shell, this
asymmetrical design produces a very aggressive ball path.
Reactive Urethane - A cover-stock comprised of similar materials used in urethane formulations, however blended with
different additives. This cover-stock adheres to lane surface, creating the most backend reaction, the least deflection
and the most hitting power of any cover-stock 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.
Rev Rate - A player's Rev Rate will relate to selection of differential, or Flare Potential, for that Particular Condition!
*To Calculate a Player's Total Revolutions:
1. Place a stripe of tape from the player's axis point to their ring finger.
2. Count the revolutions between the player's release and the arrows.
3. Multiply this number by four (4).
Slower Rev Rate = Stroker - up to 11 revolutions
Medium Rev Rate = Tweener - from 11 to 17 revolutions
Faster Rev Rate = Cranker - greater than 17 revolutions
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 three 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. Gray - 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.
Stroker - Slow rev rate...a player that will play the lanes 'down and in' covering very few boards.
Static Weights - (top, side and finger): Fine tunes ball reaction.
Surface - The composition of the outside of the bowling ball. Also refers to the texture of the cover-stock of a bowling
Three Piece Construction - A bowling ball constructed of three elements: the cover-stock, the filler material, and the
Two Piece Construction - A bowling ball constructed of two elements: the cover-stock 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).
Tweener - Medium rev rate...a player that likes to belly the ball slightly, but prefers a fairly controllable reaction overall.
Urethane - A cover-stock comprised of material from the polymer family which creates a hard, durable surface on the
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.