bowling ball

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| image1 = 1892 Ten Pins and Bowling Balls - advertisement - Spalding's Athletic Library.jpg

| caption1 = This 1892 ad shows Lignum vitae (hardwood) balls of various sizes.{{cite magazine |title=Bowling |url=http://www.hucosystems.com/articles/First%20Job.htg/bowling2.pdf |magazine=Spalding's Athletic Library |volume=1 |issue= 3 |publisher=American Sports Publishing Company |date=December 1892 |archive-url=https://web.archive.org/web/20200327135438/http://www.hucosystems.com/articles/First%20Job.htg/bowling2.pdf |archive-date=March 27, 2020 |location=New York |url-status=dead }}

| image2 = 18941218 Bowling ball - U.S. Patent 531,103.png

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| caption2 = This 1894 patent shows how bowling balls once had a thumb hole and only a single finger hole. Bowling balls of the era were made of lignum vitae (hardwood).

| image3 = 20190118A Plastic house bowling ball conventional grip.jpg

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| caption3 = A polyester ("plastic") house ball, having large, non-custom holes in a conventional grip (fingers insert to the second knuckle; thumb hole relatively close to the finger holes)

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| title = Balls with custom finger inserts in a fingertip grip
(fingers insert only to first knuckle)

| image4 = 20190118B Plastic bowling ball fingertip grip.jpg

| caption4 = A polyester ("plastic") ball. Pin location is between finger holes and thumb hole (pin down layout). Ball is used as a "straight ball" for some spare shots.

| image5 = 20190222 Urethane bowling ball fingertip grip.jpg

| caption5 = A polyurethane ("urethane") ball with a pin up layout. Urethane coverstocks provide gentler, less angular hooking motion than reactive resin balls.

| image6 = 20190118C Reactive resin bowling ball fingertip grip pin up.jpg

| caption6 = A reactive resin ball with a pin up layout (note green dot). Reactive resin coverstocks increase hook potential. Types include solid, hybrid, and pearl.

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The USBC and World Bowling promulgate bowling ball specifications. USBC specifications include physical requirements for weight (≤{{convert|16|lb|kg}}), diameter ({{convert|8.500|in|cm }}—{{convert|8.595|in|cm}}), surface hardness, surface roughness, hole drilling limitations (example: a single balance hole including the thumb hole for "two-handed" bowlers{{cite web |last1=Wiseman |first1=Lucas |author2=United States Bowling Congress (USBC) |title=USBC Modifies Rule on Bowling Ball Gripping holes |url=https://www.bowl.com/News/NewsDetails.aspx?id=23622321723 |website=bowl.com (United States Bowling Congress, USBC) |archive-url=https://web.archive.org/web/20170707095658/https://www.bowl.com/News/NewsDetails.aspx?id=23622321723 |archive-date=July 7, 2017 |date=May 7, 2014 |url-status=live }}), balance, plug limitations, and exterior markings (structural and commercial), as well as requirements for dynamic performance characteristics such as radius of gyration (RG; 2.46—2.80), RG differential (≤0.06), and coefficient of friction (≤0.32).{{cite web |title=USBC Equipment Specifications and Certifications Manual |url=https://bowl.com/uploadedFiles/Equipment_Specs/Information/2012FebESManualWEBINTERACTIVE.pdf |website=bowl.com (United States Bowling Congress, USBC) |archive-url=https://web.archive.org/web/20181229031504/https://bowl.com/uploadedFiles/Equipment_Specs/Information/2012FebESManualWEBINTERACTIVE.pdf |archive-date=December 29, 2018 |date=February 2012 |url-status=live }} The USBC banned weight holes (balance holes) in competition, effective August 1, 2020, to prevent their changing ball dynamics.{{cite web |last1=Bigham |first1=Terry |title=Bowling Technology Study Conclusion / Research Summary and Specification Updates |url=https://www.bowl.com/News/NewsDetails.aspx?id=23622331019 |website=Bowl.com |publisher=United States Bowling Congress (USBC) |archive-url=https://web.archive.org/web/20190526210733/https://www.bowl.com/News/NewsDetails.aspx?id=23622331019 |archive-date=May 26, 2019 |date=April 24, 2018 |url-status=live }} The USBC permits three ounces (85 grams) of static side weight and three ounces (85 grams) of top weight. These figures are up from one ounce (28 grams) following the August 1, 2020 rule change.{{cite web |url=https://www.bowlersmart.com/2020/03/19/2020-usbc-rule-changes-on-bowling-ball-weight-holes-by-mdm-coaching/ |title=2020 USBC Rule Changes On Bowling Ball Weight Holes By MDM Bowling Coaching |last=Barnes |first=Clifton |website=bowlersmart.com |date=March 19, 2020 |archive-url=https://web.archive.org/web/20201113213045/https://www.bowlersmart.com/2020/03/19/2020-usbc-rule-changes-on-bowling-ball-weight-holes-by-mdm-coaching/ |archive-date=November 13, 2020 |url-status=live }}

{{anchor|Coverstock technology|coverstock technology|Coverstock|coverstock|Coverstocks|coverstocks|Resin|resin|Reactive resin|reactive resin}}

{{see|#Effect of coverstock, core and layout on ball motion}}

File:20190310 Bowling ball coverstock timeline.png

Bowling balls were made of lignum vitae (hardwood) until the 1905 introduction of rubber balls.{{cite web |last1=Carrubba |first1=Rich |title=Bowling Ball Evolution |url=https://www.bowlingball.com/BowlVersity/bowling-ball-evolution |publisher=BowlingBall.com (Bowlversity educational section) |archive-url=https://web.archive.org/web/20180917215354/https://www.bowlingball.com/BowlVersity/bowling-ball-evolution |archive-date=September 17, 2018 |date=June 2012 |url-status=live }} Polyester ("plastic") balls were introduced in 1959 and, despite developing less hook-generating lane friction than rubber balls, by the 1970s plastic dominated over rubber balls. Briefly, "soaker" ball technology—involving softening coverstocks to achieve greater hook—were used, until rules for minimum hardness were implemented.{{cite web |last1=Martin |first1=Jimmy |title=The Evolution of Bowling Balls |url=https://www.bowlingball.com/bowlversity/the-evolution-of-bowling-balls |publisher=BowlingBall.com (Bowlversity educational section) |archive-url=https://web.archive.org/web/20220926092319/https://www.bowlingball.com/bowlversity/the-evolution-of-bowling-balls |archive-date=September 26, 2022 |date=May 12, 2011 |url-status=live}} The early-1980s development of polyurethane ("urethane") balls developed more friction with the newly developed polyurethane lane finishes of the day, sparking the evolution of coverstock technology to pursue ever-stronger hooks with correspondingly higher entry angles.{{cite magazine |title=Bowling Balls: An In-Depth Overview |url=https://www.bowlingthismonth.com/bowling-balls/ |magazine=Bowling This Month |archive-url=https://web.archive.org/web/20190412221716/https://www.bowlingthismonth.com/bowling-balls/ |archive-date=April 12, 2019 |date=March 31, 2017 |url-status=live }}

The early 1990s brought development of reactive resin ("reactive") balls by introducing additives in urethane surface materials to create microscopic oil-absorbing pores that increase the "tackiness" that enhances traction. In the "particle-enhanced" balls developed in the late 1990s, microscopic particles embedded in reactive coverstocks reach through oil lane coatings to provide even greater traction. Ball manufacturers developed closely guarded proprietary blends including ground-up material such as glass, ceramic or rubber, to enhance friction.{{cite news |last1=Barry |first1=Dan |title=Perfection Made Easy; Bowling a 300 Game Just Isn't the Feat It Used to Be |url=https://www.nytimes.com/2000/04/21/nyregion/perfection-made-easy-bowling-a-300-game-just-isn-t-the-feat-it-used-to-be.html |work=The New York Times |date=April 21, 2000 |archive-url=https://web.archive.org/web/20160607094256/http://www.nytimes.com/2000/04/21/nyregion/perfection-made-easy-bowling-a-300-game-just-isn-t-the-feat-it-used-to-be.html?pagewanted=all |archive-date=June 7, 2016 |url-status=live }}

Within the reactive category are solid reactive coverstocks (having the greatest amount of microscopic pores), pearl reactive coverstocks (including mica additives that enhance reaction on dry lane surfaces), hybrid reactive coverstocks (combining the mid-lane reaction of solid coverstocks and the back-end reaction of pearl coverstocks), and particle coverstocks (including microscopic silica particles, favored for use on heavy oil volumes).{{cite web |last1=Carrubba |first1=Rich |title=Reactive Bowling Balls |url=https://www.bowlingball.com/bowlversity/reactive-bowling-balls |publisher=BowlingBall.com (Bowlversity educational section) |archive-url=https://web.archive.org/web/20200806065244/https://www.bowlingball.com/bowlversity/reactive-bowling-balls |archive-date=August 6, 2020 |date=January 1, 2013 |url-status=live }}

Hook potential has increased so much that dry lane conditions or certain spare shots sometimes cause bowlers to use plastic or urethane balls, to purposely avoid the larger hook provided by reactive technology.{{cite web |last1=Siefers |first1=Nick (USBC research engineer) |title=Understanding the relationship between core and cover stock |url=https://www.bowlingdigital.com/bowl/node/2324 |website=BowlingDigital.com (Courtesy of USBC Equipment Specification and Certification) |archive-url=https://web.archive.org/web/20180920011257/https://www.bowlingdigital.com/bowl/node/2324 |archive-date=September 20, 2018 |date=April 23, 2007 |url-status=live }}

{{xref|See also: {{slink||Effect of coverstock, core and layout on ball motion}}}}

A ball's drilling layout refers to how and where holes are drilled, in relation to the ball's locator pin and mass bias (MB) marker.{{cite web |title=How Should My Bowling Ball Be Drilled? |url=https://www.bowlingball.com/wordpress/how-should-my-bowling-ball-be-drilled |publisher=BowlingBall.com (Bowlversity educational section) |archive-url=https://web.archive.org/web/20150711104913/https://www.bowlingball.com/wordpress/how-should-my-bowling-ball-be-drilled |archive-date=July 11, 2015 |date=January 2015 |url-status=live }} Layout is determined with reference to each bowler's positive axis point (PAP{{px2}}{{mdash}}{{hsp}}the pocket end of the ball's initial axis of rotation).{{cite web |last1=Carrubba |first1=Rich |title=Your Bowling Ball Positive Axis Point |url=https://www.bowlingball.com/BowlVersity/your-bowling-ball-positive-axis-point |publisher=BowlingBall.com (Bowlversity educational section) |archive-url=https://web.archive.org/web/20170709173226/https://www.bowlingball.com/BowlVersity/your-bowling-ball-positive-axis-point |archive-date=July 9, 2017 |date=November 2012 |url-status=live }} "Pin down" layouts place the pin between the finger holes and the thumb hole, while "pin up" layouts place the pin further from the thumb hole than the finger holes (see photos).{{cite web |last1=Hickland |first1=Ronald |title=What is the difference between Pin up and Pin down Drilling on a Bowling Ball? |url=https://ctdbowling.com/blogs/news/what-is-the-difference-between-pin-up-and-pin-down-drilling-on-a-bowling-ball |website=CTDbowling.com News section |date=April 11, 2017}} (Web page archiving attempts failed.) Bowling ball motion is influenced by how far the pin and the mass bias (MB) are from the PAP, the distances determining track flare. Track flare—the sequence of oil rings showing migration of the ball's axis on successive revolutions through the oil pattern—is popularly thought to influence entry angle, but Freeman & Hatfield (2018) discount its contribution to ball motion.{{sfn |Freeman |Hatfield |2018 |loc=Chapter 9 ("Track Flare, or Much Ado About Nothing?") }}

File:Bowlingball3.gif

Holes may be drilled for a conventional grip (fingers inserted to the second knuckle as with "house balls"), a fingertip grip (fingers inserted only to the first knuckle, enabling greater rev-generating torque), or less standard grips such as the Sarge Easter grip (ring finger inserted to the second knuckle but middle finger inserted only to the first knuckle).{{sfn |Freeman |Hatfield |2018 |loc=Chapter 5 ("You Say You Want a Revolution") }} Many bowlers using the so-called "two-handed delivery" (which is still a one-handed release) do not insert their thumbs, thus allowing their fingers to impart even more torque than the fingertip grip.{{sfn |Freeman |Hatfield |2018 |loc=Chapter 5 ("You Say You Want a Revolution") }}

Finger inserts and thumb slugs are custom-fit urethane tubes inserted into the drilled holes, generally for balls with a fingertip grip. Finger inserts enhance the torque provided by the fingers after the thumb exits the ball.{{cite web |title=Finger Inserts For New Bowlers |url=https://www.bowlingball.com/wordpress/finger-inserts-for-new-bowlers |publisher=BowlingBall.com (Bowlversity educational section) |archive-url=https://web.archive.org/web/20190116185722/https://www.bowlingball.com/wordpress/finger-inserts-for-new-bowlers |archive-date=January 16, 2019 |date=2013 |url-status=live }}

{{anchor|Ball motion|ball motion}}

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| image1 = 20200417 Bowling ball motion and release ratio.gif |caption1= Progression of various quantities as the ball moves down the lane:

• ball's changing direction and waning speed (direction and size of brown arrows)
• increasing rev rate (motion of yellow arrowheads)
• evolving axis rotation (direction of yellow arrowheads)
• convergence of the ball's forward (translational) speed and rev rate (rotational speed) (bottom chart)

| image2 = 2008 Critical factors in bowling ball motion.svg | caption2= A USBC study investigated the relative importance of various factors on ball motion.

• {{cite web |last1=Stremmel |first1=Neil |last2=Ridenour |first2=Paul |last3=Stervenz |first3=Scott |title=Identifying the Critical Factors That Contribute to Bowling Ball Motion on a Bowling Lane |url=http://usbcongress.http.internapcdn.net/usbcongress/bowl/equipandspecs/pdfs/BallMotionASQ.pdf |publisher=United States Bowling Congress |archive-url=https://web.archive.org/web/20120603180429/http://usbcongress.http.internapcdn.net/usbcongress/bowl/equipandspecs/pdfs/BallMotionASQ.pdf |archive-date=June 3, 2012 |date=2008 |url-status=live }} Study began in 2005. Publication date is estimated based on article content.
• {{cite web |author1=USBC Equipment Specifications and Certification Team |title=Ball Motion Study: Phase I and II Final Report |url=https://images.bowl.com/bowl/media/legacy/internap/bowl/equipandspecs/pdfs/08ballmotionstudy.pdf |archive-url=https://web.archive.org/web/20230327230846/https://images.bowl.com/bowl/media/legacy/internap/bowl/equipandspecs/pdfs/08ballmotionstudy.pdf |archive-date=March 27, 2023 |date=2008 |url-status=live}}

Click through graphic and click the "More details" button for brief descriptions of each factor. Sources in footnote provide more detail.

}}

A complex interaction of a variety of factors influences ball motion and its effect on scoring results.{{cite web |last1=Carrubba |first1=Rich |title=Understanding Bowling Ball Motion |url=https://www.bowlingball.com/bowlversity/understanding-bowling-ball-motion |publisher=BowlingBall.com (Bowlversity educational section) |archive-url=https://web.archive.org/web/20230505092332/https://www.bowlingball.com/bowlversity/understanding-bowling-ball-motion |archive-date=May 5, 2023 |date=October 2, 2011 |url-status=live}}{{cite web |title=What Are The Boiled Down Factors Affecting Bowling Ball Motion? |url=https://www.bowlingball.com/bowlversity/what-are-the-boiled-down-factors-affecting-bowling-ball-motion |publisher=BowlingBall.com (Bowlversity educational section) |archive-url=https://web.archive.org/web/20150818212830/https://www.bowlingball.com/bowlversity/what-are-the-boiled-down-factors-affecting-bowling-ball-motion |archive-date=August 18, 2015 |date=April 13, 2015 |url-status=live}} The factors may be categorized as the bowler's delivery, the bowling ball's design, and the condition of the lane.

Bowling ball motion{{cite web |last1=Carrubba |first1=Rich |title=The Simple Keys Of Bowling Ball Motion |url=https://www.bowlingball.com/bowlversity/the-simple-keys-of-bowling-ball-motion?bowlversityarticleid=13127 |publisher=BowlingBall.com (Bowlversity educational section) |archive-url=https://web.archive.org/web/20210723194311/https://www.bowlingball.com/bowlversity/the-simple-keys-of-bowling-ball-motion?bowlversityarticleid=13127 |archive-date=July 23, 2021 |date=February 5, 2013 |url-status=live }} is commonly broken down into sequential skid, hook, and roll phases.{{sfn |Stremmel |Ridenour | Stervenz |2008 |p=3 }}{{cite web |title=Bowling Ball Reaction Keys |url=https://www.bowlingball.com/bowlversity/bowling-ball-reaction-keys |publisher=BowlingBall.com (Bowlversity educational section) |archive-url=https://web.archive.org/web/20161110035756/http://www.bowlingball.com/BowlVersity/bowling-ball-reaction-keys |archive-date=November 10, 2016 |date=July 28, 2016 |url-status=live}} As the ball travels down the lane in the skid and hook phases, frictional contact with the lane causes the ball's forward (translational) speed to continually decrease, but to continually increase its rev rate (rotational speed).{{sfn |Freeman |Hatfield |2018 |loc=Chapter 8 ("Why Does My Ball Hook?") }} Especially as the ball encounters greater friction in the last ≈20 feet (approximate) of the lane, the ball's axis rotation (side rotation) causes the ball to hook away from its original direction.{{sfn |Freeman |Hatfield |2018 |loc=Chapter 8 ("Why Does My Ball Hook?") }} Concurrently, lane friction continually decreases the angle of axis rotation until it exactly matches the direction of the ball's forward motion, and rev rate (rotational speed) increases until it exactly matches the ball's forward speed: full traction is achieved and the ball enters the roll phase in which forward speed continues to decrease.{{sfn |Freeman |Hatfield |2018 |loc=Chapter 8 ("Why Does My Ball Hook?") }}

Release ratio denotes the ratio of the ball's forward (translational) speed to its rev rate (rotational speed) at time of release. This ratio continually decreases throughout the ball's travel until it reaches exactly 1.0 when full traction is achieved upon entering the roll phase. A too-high release ratio, also known as a speed-dominant release, causes the ball to reach the pins while still in the hook phase, resulting in a shallow angle of entry that permits ball deflection and resultant leaves of the 10-pin, while a too-low release ratio, also called a rev-dominant release, causes the ball to enter the roll phase before reaching the pins, sacrificing power to friction that would ideally be delivered to the pins to enhance pin scatter. Ball speed and rev rate are said to be matched if the ball enters the roll phase immediately before impacting the pins, maximizing power imparted to the pins yet helping to provide an entry angle that minimizes ball deflection.• {{cite web |last1=O'Keefe |first1=Bryan |title=Bowling Release Ratio |url=https://www.usbcbowlingacademy.com/video/bowling-release-ratio-006859/ |website=usbcbowlingacademy.com |archive-url=https://web.archive.org/web/20160402000022/https://www.usbcbowlingacademy.com/video/bowling-release-ratio-006859/ |archive-date=April 2, 2016 |date=2015 |url-status=live}} (date is approximate)
• {{cite web |title=Adjusting Entry Angle |url=https://www.bowl.com/Source/Source_Home/Adjusting_Entry_Angle/ |website=bowl.com (United States Bowling Congress, USBC) |archive-url=https://web.archive.org/web/20170417014440/https://www.bowl.com/Source/Source_Home/Adjusting_Entry_Angle/ |archive-date=April 17, 2017 |date=2015 |url-status=live}} (date is approximate)

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| image1 = 20190102 Bowling ball initial axis rotation.png

| caption1 = Axis rotation (top view) Blue arrows: ball rotation. Brown arrows: ball direction. Pink arrows: finger motion inducing axis rotation.

| image2 = 20190103 Bowling ball axis tilt oil tracks.png

| caption2 = Axis tilt (view from behind). Black rings show the smaller tracks characteristic of greater degrees of axis tilt.

| image3 = 20190105 Influence of delivery characteristics on ball motion.png

| caption3 = Bowling ball motion is affected by various characteristics of delivery, as discussed by, for example, Freeman & Hatfield (2018).{{sfn |Freeman |Hatfield |2018 |loc=Chapter 13 ("Create a Bowler's Tool Kit") }} Ball motion is determined by a complex interaction of a variety of factors.

}}

Various characteristics of ball delivery affect a ball's motion throughout its skid, hook and roll phases.{{sfn |Freeman |Hatfield |2018 |loc=Chapter 13 ("Create a Bowler's Tool Kit") }} The particular way in which energy is imparted to a ball—with varying proportions of that energy divided among ball speed, axis control and rev rate—determines the ball's motion.{{cite magazine |last1=Rose |first1=Tyrel |title=Improving Your Release / Tools, techniques, and practice drills for developing a more effective release |url=https://www.bowlingthismonth.com/bowling-tips/improving-your-release/?contactId=58283&linkType=freeArticle |magazine=Bowling This Month |archive-url=https://web.archive.org/web/20190405050019/https://www.bowlingthismonth.com/bowling-tips/improving-your-release/?contactId=58283&linkType=freeArticle |archive-date=April 5, 2019 |date=2019|url-status=live }} The following discussion considers delivery characteristics separately, with the understanding that ball motion is determined by a complex interaction of a variety of factors.{{cite web |title=Your Bowling Ball Motion |url=https://www.bowlingball.com/BowlVersity/your-bowling-ball-motion |publisher=BowlingBall.com (Bowlversity educational section) |archive-url=https://web.archive.org/web/20170209030127/https://www.bowlingball.com/BowlVersity/your-bowling-ball-motion |archive-date=February 9, 2017 |date=December 29, 2016 |url-status=live }}{{cite web |title=Variables You Encounter When Bowling |url=https://www.bowlingball.com/bowlversity/variables-you-encounter-when-bowling |publisher=BowlingBall.com (Bowlversity educational section) |archive-url=https://web.archive.org/web/20161012204113/http://www.bowlingball.com/bowlversity/variables-you-encounter-when-bowling |archive-date=October 12, 2016 |date=April 18, 2016 |url-status=live}}

Greater ball speeds give the ball less time to hook, thus reducing observed hook though imparting more kinetic energy to the pins; conversely, slower speeds allow more time for greater hook though reducing kinetic energy.{{sfn |Freeman |Hatfield |2018 |loc=Chapter 13 ("Create a Bowler's Tool Kit") }} A USBC ball motion study concluded that the optimal ball speed is approximately 21{{nbsp}}mph at release (17{{nbsp}}mph at the pins), speeds typically achievable by professionable bowlers.{{cite web |last1=Carrubba |first1=Rich |last2=Spear |first2=Keith |title=Ideal Bowling Ball Speed |url=https://www.bowlingball.com/bowlversity/ideal-bowling-ball-speed |publisher=Bowlingball.com (Bowlversity educational section) |archive-url=https://web.archive.org/web/20250205033219/https://www.bowlingball.com/bowlversity/ideal-bowling-ball-speed |archive-date=February 5, 2025 |date=September 9, 2016 |url-status=live}}

Greater rev rates cause the ball to experience more frictional lane contact per revolution and thus (assuming non-zero axis rotation) greater and earlier hook (less "length"— which is the distance from the foul line to the breakpoint at which hooking is maximum); conversely, smaller rev rates cause less frictional engagement and allow the ball to hook less and later (more "length").{{sfn |Freeman |Hatfield |2018 |loc=Chapter 13 ("Create a Bowler's Tool Kit") }}

Analysis of the influence of axis rotation (sometimes called side rotation) is more complex: There is a degree of axis rotation—generally 25° to 35° and varying with ball speed and rev rate—that may be considered optimal in that hook is maximized; however, this optimum axis rotation also causes minimal length.{{sfn |Freeman |Hatfield |2018 |loc=Chapter 13 ("Create a Bowler's Tool Kit") }} Specifically, Freeman & Hatfield (2018) report optimal axis rotation to be arcsin{{nbsp}}(ωr/v) where ω is rev rate (radians/sec), r is ball radius (m), and v is ball speed (m/s).{{sfn |Freeman |Hatfield |2018 |loc=Chapter 13 ("Create a Bowler's Tool Kit") }} Below and above optimal axis rotation, more length and less hook are encountered, with greater-than-optimal axis rotation causing a sharper hook.{{sfn |Freeman |Hatfield |2018 |loc=Chapter 13 ("Create a Bowler's Tool Kit") }} Another source states that strictly behind-the-ball release (0° axis rotation) causes an end-over-end rotation, with early hooking, while a release with large side rotation causes greater length before hooking.{{cite web |title=Being Able To Adjust Your Axis Rotation Is A Tool Worth Having |url=https://www.bowlingball.com/bowlversity/degrees-of-separation-being-able-to-adjust-your-axis-rotation-is-a-tool-worth-having |publisher=BowlingBall.com (Bowlversity educational section) |archive-url=https://web.archive.org/web/20210305101353/https://www.bowlingball.com/bowlversity/degrees-of-separation-being-able-to-adjust-your-axis-rotation-is-a-tool-worth-having |archive-date=March 5, 2021 |date=December 22, 2011 |url-status=live}}

Greater degrees of initial (at-the-foul-line) axis tilt cause the ball to rotate on smaller-circumference "tracks" (rings on the ball at which it contacts the lane on each revolution), thus reducing the amount of frictional contact to provide greater length and less hook; conversely, smaller degrees of axis tilt involve larger-circumference tracks with more frictional contact per revolution, thus providing less length and more hook.{{sfn |Freeman |Hatfield |2018 |loc=Chapter 13 ("Create a Bowler's Tool Kit") }}

Loft—the distance past the foul line at which the ball first contacts the lane—determines the effective length of the lane as experienced by the ball: greater loft distances effectively shorten the lane and provide greater length, while smaller loft distances engage the lane earlier and cause an earlier hook.{{sfn |Freeman |Hatfield |2018 |loc=Chapter 13 ("Create a Bowler's Tool Kit") }}

File:20181224 Influences on Bowling Ball Motion.png

{{multiple image | align = right | direction = horizontal | total_width = 500

| image1 = 20180920 Bowling ball RG and differential.png | caption1 = Commonly cited specifications, RG (radius of gyration) and Differential of RG (indicative of flare potential), plotted on orthogonal axes. Freeman & Hatfield (2018) minimize the contribution of differential to ball motion.{{sfn |Freeman |Hatfield |2018 |loc=Chapter 9 ("Track Flare, or Much Ado About Nothing?")}}

| image2 = 20200109 Simulated track flare lines on bowling ball.jpg | caption2 = Track flare—not to be confused with "flare potential"—is progression of the ball's oil track (simulated in blue) reflecting migration of the ball's axis of rotation on successive revolutions.

}}

Various characteristics of ball core structure and coverstock composition affect a ball's motion throughout its skid, hook and roll phases.{{sfn |Stremmel |Ridenour | Stervenz |2008 |p=3 }}{{cite web |title=Picking a New Bowling Ball for the Average Bowler |url=https://www.nationalbowlingacademy.com/post/picking-a-new-bowling-ball-for-the-average-bowler/ |publisher=National Bowling Academy |archive-url=https://web.archive.org/web/20240719002815/https://www.nationalbowlingacademy.com/post/picking-a-new-bowling-ball-for-the-average-bowler/ |archive-date=July 19, 2024 |date=May 13, 2024 |url-status=live}}{{cite web |last1=Spear |first1=Keith |title=Bowling Ball Core Dynamics: Understanding Core Types, RG, and Hook Potential |url=https://www.bowlingball.com/bowlversity/bowling-ball-core-dynamics-understanding-core-types-rg-and-hook-potential |publisher=Bowlingball.com (Bowlversity educational section) |archive-url=https://web.archive.org/web/20250206221538/https://www.bowlingball.com/bowlversity/bowling-ball-core-dynamics-understanding-core-types-rg-and-hook-potential |archive-date=February 6, 2025 |date=January 30, 2025 |url-status=live}} Such motion is largely (about 75%){{cite web |last1=McEwen |first1=Jason |title=A Guide to Bowling Ball Cores, RG, Differential, and Coverstock |url=https://www.nationalbowlingacademy.com/post/a-guide-to-bowling-ball-cores-rg-differential-and-coverstock/ |publisher=National Bowling Academy |archive-url=https://web.archive.org/web/20230321235230/https://www.nationalbowlingacademy.com/post/a-guide-to-bowling-ball-cores-rg-differential-and-coverstock/ |archive-date=March 21, 2023 |date=June 30, 2022 |url-status=live}} governed by the lane's frictional interaction with the ball, which exhibits both chemical friction characteristics and physical friction characteristics.{{sfn |Freeman |Hatfield |2018 |loc=Chapter 8 ("Why Does My Ball Hook?") }} Also, the ball's internal structure—especially the density, shape (symmetric vs. asymmetric), and orientation of its core (also called "weight block") relative to the ball's axis of rotation—substantially affect ball motion.{{sfn |Freeman |Hatfield |2018 |loc=Chapter 8 ("Why Does My Ball Hook?") }}

A "dull" (rough) ball surface, having spikes and pores,{{sfn |Stremmel |Ridenour | Stervenz |2008 |p=8 }} provides greater friction in the oil-covered front end of the lane but reduced frictional contact in the dry back end of the lane, and thus enables an earlier hook.{{sfn |Freeman |Hatfield |2018 |loc=Chapter 8 ("Why Does My Ball Hook?") }} In contrast, a "gloss" (smooth) ball surface tends to glide atop oil on the front end but establishes greater frictional contact in the dry back end, thus promoting a sharper hook downlane,{{sfn |Freeman |Hatfield |2018 |loc=Chapter 8 ("Why Does My Ball Hook?") }} such as in the "skid/flip" ball path.{{cite web |last1=Carrubba |first1=Rich |title=How To Find A Skid-Flip Bowling Ball |url=https://www.bowlingball.com/bowlversity/how-to-find-a-skid-flip-bowling-ball |publisher=BowlingBall.com (Bowlversity educational section) |archive-url=https://web.archive.org/web/20210226212958/https://www.bowlingball.com/bowlversity/how-to-find-a-skid-flip-bowling-ball |archive-date=February 26, 2021 |date=September 7, 2010 |url-status=live}} Accordingly, because different lane conditions and bowler styles favor different hook profiles, there is no single "best" surface.{{sfn |Freeman |Hatfield |2018 |loc=Chapter 8 ("Why Does My Ball Hook?") }}

A 2005-2008 USBC Ball Motion Study found that the ball design factors that most contributed to ball motion were the microscopic "spikes" and pores on the ball's surface (considered part of chemical frictional characteristics), the respective coefficients of friction between ball and lane in the oiled and dry parts of the lane, and the ball's oil absorption rate, followed in dominance by certain characteristics of the ball's core (mainly radius of gyration, and total differential).{{sfn |Stremmel |Ridenour |Stervenz |2008 }} Freeman and Hatfield (2018) explain that in most circumstances it is chemical friction—controlled by the manufacturer's proprietary coverstock formulation governing its "stickiness"—that primarily determines ball motion.{{sfn |Freeman |Hatfield |2018 |loc=Chapter 8 ("Why Does My Ball Hook?") }} Further, surface finish—modifiable by sandpaper, polish and the like—is also a material factor.{{sfn |Freeman |Hatfield |2018 |loc=Chapter 8 ("Why Does My Ball Hook?") }}

Though manufacturer literature often specifies track flare—exhibited by successive tracks of oil in a "bowtie" pattern and caused by RG differential—the USBC ball motion study showed flare's influence to be small,{{sfn |Stremmel |Ridenour | Stervenz |2008 }} assuming that a minimal threshold of flare exists to present a "dry" surface for successive ball revolutions.{{sfn |Freeman |Hatfield |2018 |loc=Chapter 9 ("Track Flare, or Much Ado About Nothing?") }} Similarly, though manufacturer literature often describes specific core shapes, differently-shaped cores can make exactly the same contribution to ball motion if they have the same overall RG characteristics.{{sfn |Freeman |Hatfield |2018 |loc=Chapter 9 ("Track Flare, or Much Ado About Nothing?") }}

"Weak" layouts ("pin down": pin between finger and thumb holes) hook sooner but have milder backend reaction, while "strong" layouts ("pin up": pin further from thumb hole than finger holes) enable greater skid lengths and more angular backend reaction.

{{multiple image

| align = right | direction = horizontal | total_width= 500

| image1 = 20181226 Concepts of bowling ball cores.png

| caption1 = Bowling ball core ("weight block") technical specifications include RG, differential of RG, intermediate differential, and (a)symmetry.

| image2 = 20190406 Bowling ball cores.jpg

| caption2 = Bowling balls with cores exposed, as displayed in the International Bowling Museum.

}}

Manufacturers commonly cite specifications relating to a bowling ball's core, include radius of gyration (RG), differential of RG (commonly abbreviated differential), and intermediate differential (also called mass bias).

Analytically, the United States Bowling Congress defines RG as "the distance from the axis of rotation at which the total mass of a body

might be concentrated without changing its moment of inertia".{{cite web |title=Technical Terms |url=https://www.bowl.com/uploadedFiles/Equipment_Specs/Information/Updated_Terminology.pdf |website=bowl.com |publisher=United States Bowling Congress |access-date=25 September 2018 |archive-url=https://web.archive.org/web/20180920192721/https://www.bowl.com/uploadedFiles/Equipment_Specs/Information/Updated_Terminology.pdf |archive-date=September 20, 2018 |url-status=live }} In practice, a higher RG indicates that a ball's mass is distributed more toward its cover—making it "cover heavy"—which tends to make the ball enter the roll phase later (further down the lane). Conversely, a lower RG indicates the ball's mass is distributed more towards its center—making it "center heavy"—which tends to make it enter the roll phase sooner.

Differential of RG is the difference between maximum and minimum RGs measured with respect to different axes. Differential indicates the ball's track flare potential, and contributes to how sharply a ball can hook. A higher differential indicates greater track flare potential—more angular motion from the break point to the pocket—and a lower differential indicates lower flare potential and a smoother arc to the hook.{{cite web |title=Bowling Ball RG And Differential Range Ratings |url=https://www.bowlingball.com/wordpress/bowling-ball-rg-and-differential-range-ratings-2 |publisher=BowlingBall.com (Bowlversity educational section) |access-date=25 September 2018 |archive-url=https://web.archive.org/web/20141226063716/https://www.bowlingball.com/wordpress/bowling-ball-rg-and-differential-range-ratings-2 |archive-date=December 26, 2014 | date=2014 |url-status=live}}

Intermediate differential (ID; sometimes termed mass bias) quantifies the degree to which a bowling ball core is symmetrical or asymmetrical. Analytically, ID is defined by the USBC as the "difference in radius of gyration between the Y (high RG) and Z (intermediate RG) axes". A higher ID indicates greater asymmetry, which causes more area to be created at the break point to cause the ball to respond more quickly to friction than symmetrical balls. ID values .008"– .020" are considered low, while .021"– .037" is considered a high range.{{cite web |title=Differential of RG Specifications |url=https://www.bowlingball.com/BowlVersity/bowlingball-com-differential-of-rg-specifications |publisher=Bowlingball.com (Bowlversity educational section) |archive-url=https://web.archive.org/web/20230622195312/https://www.bowlingball.com/BowlVersity/bowlingball-com-differential-of-rg-specifications |archive-date=June 22, 2023 |date=January 25, 2012 |url-status=live}}

File:20230126 Bowling ball surface textures - grit granularity, skid length, and hook.svg" of abrasives used—affects ball path (skid distance and hook intensity).{{cite web |last1=Carrubba |first1=Rich |title=Bowling Ball Surface Grit Pads |url=https://www.bowlingball.com/BowlVersity/bowling-ball-surface-grit-pads |publisher=BowlingBall.com (Bowlversity educational section) |archive-url=https://web.archive.org/web/20201111234550/https://www.bowlingball.com/BowlVersity/bowling-ball-surface-grit-pads |archive-date=November 11, 2020 |date=February 4, 2013 |url-status=live}}{{cite web |last1=Carrubba |first1=Rich |title=BowlVersity Q & A Part 2 / Q. Which are the most effective ranges of grit pads to use when altering bowling ball surfaces? |url=https://www.bowlingball.com/BowlVersity/bowlingball-com-bowlversity-q-a-part-2 |publisher=BowlingBall.com (Bowlversity educational section) |archive-url=https://web.archive.org/web/20150918231608/https://www.bowlingball.com/BowlVersity/bowlingball-com-bowlversity-q-a-part-2 |archive-date=September 18, 2015 |date=2012 |url-status=live }}]]

Informally, a low-differential ball has been likened to one whose core is a spherical object (whose height and width are the same); a high-differential ball has been likened to a tall drinking glass (whose height and width are different); and a high-mass-bias ball has been likened to a tall drinking mug with a handle on the side (giving it different widths in different directions).{{cite web |title=Ball Dynamics and Hook Potential |url=https://www.bowlingball.com/info/ball-dynamics-and-hook-potential.html |publisher=BowlingBall.com (Bowlversity educational section) |access-date=25 September 2018 |archive-url=https://web.archive.org/web/20051124224223/https://www.bowlingball.com/info/ball-dynamics-and-hook-potential.html |archive-date=November 24, 2005 |date=2005 |url-status=live }}

Higher-friction surfaces (lower grit numbers) cause balls to hook earlier, and lower-friction surfaces (higher grit numbers) cause balls to skid longer before reacting (hooking).{{cite web |title=Understand Your Bowling Ball Reaction |url=https://www.bowlingball.com/bowlversity/understand-your-bowling-ball-reaction?bowlversityarticleid=16512 |publisher=BowlingBall.com (Bowlversity educational section) |archive-url=https://web.archive.org/web/20181202202315/https://www.bowlingball.com/bowlversity/understand-your-bowling-ball-reaction?bowlversityarticleid=16512 |archive-date=December 2, 2018 |date=May 22, 2016 |url-status=live}}

Reactive cover stocks finishes include matte (aggressive reaction), shiny (longer skid distance than matte finish), pearl (greatest skid distance among reactive cover stocks), and hybrid (combination of skid distance and back end reaction).

File:20190310 Influence of lane characteristics on ball motion.png

File:1895 Bowling lane cross section.jpg to provide a flat and level surface for repeatable ball motion.{{cite web |title=Bowling Catalog E |url=http://www.gutenberg.org/files/57337/57337-h/57337-h.htm |website=Gutenberg.org |publisher=Narragansett Machine Company |archive-url=https://web.archive.org/web/20180701141541/http://www.gutenberg.org/files/57337/57337-h/57337-h.htm |archive-date=July 1, 2018 |date=1895 |url-status=live}} Project Gutenberg release date: June 16, 2018.]]

The phenomenon of lane transition occurs when balls remove oil from the lane as they pass, and deposit some of that oil on originally dry parts of the lane.{{sfn |Freeman |Hatfield |2018 |loc=Chapter 14 ("Applying Your Tools") }}{{cite web |title=Changing Lane Oil Conditions |url=https://www.bowlingball.com/bowlversity/changing-lane-oil-conditions |publisher=BowlingBall.com (Bowlversity educational section) |archive-url=https://web.archive.org/web/20150918190617/http://www.bowlingball.com/BowlVersity/changing-lane-oil-conditions |archive-date=September 18, 2015 |date=2015 |url-status=live}} The process of oil removal, commonly called breakdown, forms dry paths that subsequently cause balls to experience increased friction and to hook sooner.{{sfn |Freeman |Hatfield |2018 |loc=Chapter 14 ("Applying Your Tools") }} Conversely, the process of oil deposition, commonly called carry down, occurs when balls form oil tracks in formerly dry areas, tracks that subsequently cause balls to experience less friction and delayed hook.{{sfn |Freeman |Hatfield |2018 |loc=Chapter 14 ("Applying Your Tools") }} Balls tend to "roll out" (hook sooner but hook less) in response to breakdown, and, conversely, tend to skid longer (and hook later) in response to carry down—both resulting in light hits.{{sfn |Freeman |Hatfield |2018 |loc=Chapter 16 ("Advanced Considerations") }} Breakdown is influenced by the oil absorption characteristics and rev rates of the balls that were previously rolled,{{sfn |Freeman |Hatfield |2018 |loc=Chapter 14 ("Applying Your Tools") }} and carry down is mitigated by modern balls having substantial track flare.{{sfn |Freeman |Hatfield |2018 |loc=Chapter 16 ("Advanced Considerations") }}

Lane materials with softer surfaces such as wood engage the ball with more friction and thus provide more hook potential, while harder surfaces like synthetic compositions provide less friction and thus provide less hook potential.{{sfn |Freeman |Hatfield |2018 |loc=Chapter 14 ("Applying Your Tools") }}

Higher-viscosity lane oils (those with thicker consistency) engage balls with more friction and thus cause slower speeds and shorter length but provide more hook potential and reduced lane transition; conversely, lane oils of lower viscosity (thinner consistency) are more slippery and thus support greater speeds and length but offer less hook potential and allow faster lane transition.{{sfn |Freeman |Hatfield |2018 |loc=Chapter 14 ("Applying Your Tools") }} Various factors influence an oil's native viscosity, including temperature (with higher temperatures causing the oil to be thinner) and humidity (variations of which can cause crowning and cupping of the lane surface).{{sfn |Freeman |Hatfield |2018 |loc=Chapter 14 ("Applying Your Tools") }} Also, high humidity increases friction that reduces skid distance so the ball tends to hook sooner.{{cite web |title=Bowling Lane Adjusting From Pair To Pair |url=https://www.bowlingball.com/BowlVersity/bowling-lane-adjusting-from-pair-to-pair |publisher=BowlingBall.com (Bowlversity educational section) |archive-url=https://web.archive.org/web/20161031145511/https://www.bowlingball.com/BowlVersity/bowling-lane-adjusting-from-pair-to-pair |archive-date=October 31, 2016 |date=June 28, 2016 |url-status=live }}

The lanes' physical topography—hills and valleys that diverge from an ideal planar surface—can substantially and unpredictably affect ball motion, even if the lane is within permissible tolerances.{{sfn |Freeman |Hatfield |2018 |loc=Chapter 14 ("Applying Your Tools") }}

The USBC maintains a list,{{cite web |title=Approved Ball List |url=https://www.bowl.com/approvedballlist/ |website=bowl.com (United States Bowling Congress, USBC) |archive-url=https://web.archive.org/web/20181106004806/https://www.bowl.com/approvedballlist/ |archive-date=November 6, 2018 |url-status=live }} said to be updated weekly, of about 100 bowling ball manufacturers and their approved bowling balls.

File:20190609 Duckpin bowling ball in hand.jpg

Duckpin bowling balls are regulated to be from {{convert|4.75|–|5.00|in|cm}} in diameter and to weigh between {{convert|3|lb|6|oz|kg}} and {{convert|3|lb|12|oz|kg}}. They lack finger holes. Though duckpin balls are slightly larger than candlepin balls, they have less than 60% the diameter of ten-pin balls, to match the smaller size of duckpins.{{cite web |title=Duckpin Bowling |url=https://www.paramountindustriesinc.com/pages/duckpin-bowling |website=paramountindustriesinc.com |archive-url=https://web.archive.org/web/20170411214139/https://www.paramountindustriesinc.com/pages/duckpin-bowling |archive-date=April 11, 2017 |date=2017 |url-status=live }} Duckpin balls are sometimes used for scaled-down ten-pin bowling lanes installed in arcades and other amusement facilities.{{Citation needed|date=July 2019}}

The basic specifications of five-pin balls are the same a duckpin balls: diameters from {{convert|4.75|to|5.0|in|cm|abbr=on}}, weights from {{convert|3|lb|6|oz|kg}} to {{convert|3|lb|12|oz|kg}}; the balls have no finger holes.{{cite web |title=Accessories and Equipment / Accessoires et équipements (2015-2016 Season) |url=http://www.phippsbowling.com/PDF/2015-16.pdf |website=PhippsBowling.com |archive-url=https://web.archive.org/web/20170328022506/http://www.phippsbowling.com/PDF/2015-16.pdf |archive-date=March 28, 2017 |date=2016 |url-status=live }}

Candlepin bowling balls have a weight of between {{convert|2|lb|4|oz|kg|abbr=on}} and {{convert|2|lb|7|oz|kg|abbr=on}}, and a diameter of {{convert|4.5|in|cm|abbr=on}}—much smaller than the {{convert|8.5|in|cm|abbr=on}} balls in ten-pin bowling, and even smaller than the {{convert|5.0|in|cm|abbr=on}} balls in duckpin bowling .{{cite web |url=http://www.bowlnh.com/rules.htm |title=Candlepin Bowling Rules / Pin specifications and ~ / Ball specifications |author=New Hampshire Candlepin Bowling Association |date = 2013 |archive-url=https://web.archive.org/web/20160126015642/http://bowlnh.com/rules.htm | archive-date=January 26, 2016 |url-status=live }} 2013 date estimated based on earliest archive date.{{cite news |title=Basics of candlepin vs. tenpin bowling |url=https://www.bostonglobe.com/metro/regionals/north/2014/05/03/candlepin-tenpin/5Yrq85NQs2FkAlZ3w1AO0N/story.html |work=The Boston Globe |date=May 4, 2014 |archive-url=https://web.archive.org/web/20140513004313/https://www.bostonglobe.com/metro/regionals/north/2014/05/03/candlepin-tenpin/5Yrq85NQs2FkAlZ3w1AO0N/story.html |archive-date=May 13, 2014 |url-status=live }} Candlepin balls deflect significantly upon impact, being even lighter than the {{convert|2|lb|8|oz|kg|abbr=on}} candlepins themselves.

American nine-pin bowling uses the same ball (and pins) as in ten-pin bowling.{{citation needed|date=February 2022}} European nine-pin bowling balls (such as those used in German kegel) are smaller, sized between ten-pin and duckpin balls, and have no holes.{{citation needed|date=February 2022}} The ball is {{convert|16|cm|in|abbr=on}} in diameter and weighs approximately {{convert|2.85|kg|lb|abbr=on}}.{{citation needed|date=February 2022}} There are also special balls for novice players, which is {{convert|14|cm|in|abbr=on}} in diameter and weigh {{convert|1.9|kg|lb|abbr=on}}, often with two finger holes.{{citation needed|date=February 2022}}

• Glossary of bowling

• {{cite web |last1=Benner |first1=Donald |last2=Mours |first2=Nicole |last3=Ridenour |first3=Paul |author4=USBC, Equipment Specifications and Certifications Division |title=Pin Carry Study: Bowl Expo 2009 |url=http://usbcongress.http.internapcdn.net/usbcongress/bowl/equipandspecs/pdfs/pinCarryStudy.pdf |website=bowl.com (United States Bowling Congress, USBC) |archive-url=https://web.archive.org/web/20101207110519/http://usbcongress.http.internapcdn.net/usbcongress/bowl/equipandspecs/pdfs/pinCarryStudy.pdf |archive-date=December 7, 2010 |format=Slide show presentation |date=2009 |url-status=live}}
• {{cite book |last1=Freeman |first1=James |last2=Hatfield |first2=Ron |title=Bowling Beyond the Basics: What's Really Happening on the Lanes, and What You Can Do about It |date=July 15, 2018 |publisher=BowlSmart |isbn=978-1 73 241000 8 |url=https://books.google.com/books?id=8thjDwAAQBAJ}}
• {{cite web |author1=USBC Equipment Specifications and Certification Team |title=Ball Motion Study: Phase I and II Final Report |url=https://images.bowl.com/bowl/media/legacy/internap/bowl/equipandspecs/pdfs/08ballmotionstudy.pdf |archive-url=https://web.archive.org/web/20230327230846/https://images.bowl.com/bowl/media/legacy/internap/bowl/equipandspecs/pdfs/08ballmotionstudy.pdf |archive-date=March 27, 2023 |date=2008 |url-status=live}}
• {{cite web |author1=United States Bowling Congress (USBC) |title=USBC Equipment Specifications and Certifications Manual |url=https://bowl.com/uploadedFiles/Equipment_Specs/Information/2012FebESManualWEBINTERACTIVE.pdf |website=bowl.com |archive-url=https://web.archive.org/web/20181229031504/https://bowl.com/uploadedFiles/Equipment_Specs/Information/2012FebESManualWEBINTERACTIVE.pdf |archive-date=December 29, 2018 |date=February 2012 |url-status=live}}
• {{cite web |author1=United States Bowling Congress (USBC) |title=Bowling Technology Study: An Examination and Discussion on Technology's Impact in the Sport of Bowling |url=https://bowlphilly.files.wordpress.com/2018/02/fullstudy.pdf |website=bowl.com |archive-url=https://web.archive.org/web/20181231014131/https://bowlphilly.files.wordpress.com/2018/02/fullstudy.pdf |archive-date=December 31, 2018 |date=February 2018 |url-status=live}}
• {{cite web |author1=United States Bowling Congress (USBC) |title=Playing Rules 2021-2022 |url=http://usbcongress.http.internapcdn.net/usbcongress/bowl/rulebook/2021-2022_Rulebook.pdf |website=bowl.com |archive-url=https://web.archive.org/web/20211102130258/http://usbcongress.http.internapcdn.net/usbcongress/bowl/rulebook/2021-2022_Rulebook.pdf |archive-date=November 2, 2021 |date=2021 |url-status=live }}

{{reflist|30em}}

• {{cite magazine |title=Bowling Balls: An In-Depth Overview |url=https://www.bowlingthismonth.com/bowling-balls/ |magazine=Bowling This Month |archive-url=https://web.archive.org/web/20190412221716/https://www.bowlingthismonth.com/bowling-balls/ |archive-date=April 12, 2019 |date=March 31, 2017 |url-status=live }}
• {{cite web |last1=Carrubba |first1=Rich |title=How Bowling Balls Are Made |url=https://www.bowlingball.com/bowlversity/how-bowling-balls-are-made |publisher=BowlingBall.com (Bowlversity educational section) |archive-url=https://web.archive.org/web/20230324193548/https://www.bowlingball.com/bowlversity/how-bowling-balls-are-made |archive-date=24 March 2023 |date=2011 |url-status=live}}
• {{cite web |last1=Carrubba |first1=Rich |title=Bowling Ball Evolution |url=https://www.bowlingball.com/BowlVersity/bowling-ball-evolution |publisher=BowlingBall.com (Bowlversity educational section) |archive-url=https://web.archive.org/web/20180917215354/https://www.bowlingball.com/BowlVersity/bowling-ball-evolution |archive-date=September 17, 2018 |date=June 2012 |url-status=live }}
• {{cite magazine |last1=Horaczek |first1=Stan |title=The insides of pro bowling balls will make your head spin |url=https://www.popsci.com/story/technology/bowling-ball-insides-photos/ |magazine=Popular Science |date=July 27, 2020 |archive-url=https://web.archive.org/web/20210827005550/https://www.popsci.com/story/technology/bowling-ball-insides-photos/ |archive-date=August 27, 2021 |url-status=live }}
• Muller, Derek and Zhang, Emily (September 25, 2021). [https://www.youtube.com/watch?v=aFPJf-wKTd0 "The Fascinating Physics of Bowling"], Veritasium.
• {{cite web |last1=Normani |first1=Franco |title=The Physics Of Bowling |url=https://www.real-world-physics-problems.com/physics-of-bowling.html |publisher=Real World Physics Problems |archive-url=https://web.archive.org/web/20240920002312/https://www.real-world-physics-problems.com/physics-of-bowling.html |archive-date=September 20, 2024 |date=2010 |url-status=live}}

{{Commons category|Bowling balls}}

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