Bowling Ball Terminology & Maintenance, by James Goulding III

Bowling Ball Terminology & Maintenance

by James Goulding III

Hello bowlers, and thank you once again for reading the bowler-2-bowler blog. my latest entry really combines the efforts of two of my older posts, one talking about Bowling Ball Terminology and the other one dealing with the maintenance aspect of your bowling equipment. I thought it would be nice to update both of those concepts, and combine them into one blog post, since they really go hand in hand with each other. I mean, what good does it do if you know a ton of information about how your bowling ball is set up, the reaction it is supposed to have on the lanes, but yet have no clue as to how to keep the bowling ball reacting the way you want it to over and over again with the proper care. This is why I have combined my blog posts into this one big post to make it easier for you, the bowler, to pull out the useful information needed to not only know about your equipmeny, but also how to take proper care of your equipment. The first part will deal with the terminology commonly used around pro shops and well educated bowlers out on the lanes, and the second part will deal with proper care of the equipment you just learned about. So, without further delay, let’s talk technology!

Bowling Ball Terminology (Ball Dynamics):

I am writing this blog post to give bowlers some basic, intermediate, and advanced information on terms used pertaining to ball dynamics. You have probably heard terms like Differential and Radius of Gyration (RG) and never really understood what they actually mean. I am going to list some of the terms myself, and other experienced bowlers and pro shop operators, use pertaining to ball dynamics. This list is a combination of terms used by experienced bowlers and ball drillers (like myself), and grouped together by a member of the site, whose name is Sean Cross. While I have added my own terminology and expertise to the list (which you can find on the FAQ section of ballreviews), the list was put together by Sean, so I feel he deserves some of the credit for combining everything together on this list. Thanks Sean, and I hope everyone can learn from these terms, and effectively use them in their bowling language dictionaries.


Internal or core torque refers to the mass distribution within the core and the internal lever arms created by the core. Core torque is an assigned value of the ball’s ability to combat roll out, the complete loss of axis tilt and axis rotation. High torque balls are more effective than lower torque balls at delaying roll out. Core torque can also be one indicator of the type of reaction that a bowler can expect at the break point with high torque balls having the propensity to be more “violent” and the lower torque balls tending to display a more even, predictable transition from skid to roll.


It is the difference between the lowest and highest RG values of a bowling ball. You compute the high rg value and subtract the low rg value, and you have the differential. There is no minimum for differential. What differential tells you: RG Differential is an indicator of track flare POTENTIAL in a bowling ball. Differentials in the .01 s to .02 s would mean that a ball has a lower track flare potential, .03 s to .04 s would be the medium range for track flare potential, and the .05 s to .08 s would indicate a high track flare potential. These ranges above are not based on cardinal rules. They are BTM (Bowling This Month) in-house rules of thumb because there are no published guidelines. 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. A low differential will allow for only a modest variance in length (from shortest drilling to longest) which may translate into as little as a foot or two on the lane. An extremely high differential may translate into a length window in the neighborhood of eight feet on the lane.


The planned apparent imbalance in balls due to high tech cores and drilling techniques. Many people claim that this has created balls that hook out of the box with a lessening requirement to have the skill to impart the hook and power by the bowler themselves. This is still up for debate, but the increase in scoring pace of the game of bowling over the past 15-20 years can not be ignored.


In the old days, before the advent of modern core design in bowling balls, the center of the ball was, more or less, symmetrical. In today’s high tech computer designed ball, in the cores and multiple cores designs, you can have cores that are not evenly balanced and distributed within the center of the ball. This allows balls to be drilled and designed in a manner that the apparent “weight” of the ball can shift depending on the drilling pattern i.e., it is not “static” it is “dynamic”.


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. The more flare created by the core, the more hook potential for a given cover stock. Higher differential bowling balls will flare, on average, significantly more than a lower differential bowling ball due to the increased track migration of the bowling ball with the higher differential.


Simply put, the mass bias in a bowling ball occurs when the mass (weight block or portion of weight block) is bias (more dominant) in one direction inside of an object (in this case a bowling ball). If you took a bulb shaped, single density core and positioned it dead center from side to side inside the ball, there would be no mass bias. You also would have a ball that is a pin in ( 2″), you have to “tilt” the core inside the ball, or place the entire core slightly off center. This became a common practice among manufacturers as the demand for pin out balls increased. When this is done however, you create a “dynamic imbalance” inside the ball because the mass is more dominant or “bias” in the direction of the “tilt” or “offset”. That is the most important factor when discussing the mass bias, it is a DYNAMIC POINT ON THE BALL. Positioning the mass bias in different positions when laying out a ball will have a great impact on the “motion” the ball will make as it is going down the lane (even arc, hook/set, skid/flip and so on).

There are people who will argue that static imbalances (finger weight, side weight etc.) are more important than dynamic imbalances. My reply to this is that a dynamic imbalance is a real point in the ball, it is constant and does not change unless you alter it by drilling into it with a drill bit. A static imbalance, or the CG (center of gravity), will change as soon as you put one hole in the ball. It will change again with each additional hole you put in the ball as well. While static weights can be used to “fine tune” the reaction of the ball at the break point, it is the dynamic lay out that dictates the roll of the ball. If a pro shop operator truly understands the principals of the mass bias and how to apply them, they can greatly increase your overall satisfaction with the ball you purchase. On a ball that doesn’t have a pre-marked MB it’s theoretical position can be found by measuring from the pin through the CG 6.75″.


A Pin-in ball (when the pin is located within two inches of the CG) is excellent choice for control and less overall hook. A Pin-out ball (> 2″ away from the c.g.) usually can be made to hook more and flip more dramatically than pin-in balls. They (pin out balls) often give the driller more options as far as fine tuning reaction shapes of the bowling balls for varying styles of bowlers.


This is the final position of the axis after the ball has lost all axis rotation and tilt. The length of time it takes for the ball to reach it’s PSA and it’s post drilling PSA are influenced by the amount of friction, the drill layout, and bowler’s spec’s.


The measurement that tells us the core’s impact on the skid potential of the bowling ball. It identifies how fast a ball begins to rotate once it leaves the bowler’s hand. Three designations for the RG of bowling balls are: low, medium, and high. A high RG ball goes further down the lane before hooking because it takes longer to begin rotating and stores its energy on dryer conditions. A low RG ball revs up early and is a more evenly arcing ball used on wetter conditions. There are three axis on a bowling ball used to measure RG (radius of gyration). The lowest RG axis (usually denoted by the letter Z) is the axis through the pin. The highest RG axis (usually denoted by the letter X) is located 6-3/4 inches from the pin through the center of gravity (CG or heavy spot). The intermediate RG axis (usually denoted by the letter Y) is located 6-3/4 inches from both the low and high RG axis.

Even though all bowling balls of a given weight are about the same size (minimum diameter of 8.500 inches to a maximum of 8.595 inches), these balls are constructed differently. Some use two materials (one shell and one core), others use three, four or five or more pieces to construct the shell(s) and core(s). Each of the materials used has a density (which roughly translates into weight per unit of volume). Zirmonite (as used in the Columbia pin) is denser (heavier by volume) than Bismuth Graphite (used in the core of the Brunswick Zones) which is denser (heavier by volume) than the fired ceramic that is used in the Columbia and Track cores. These, and the other dense-material cores used by other manufacturers, are all heavier by volume than the material used in the main cores. The main core material is denser than the foam-like material used as outer cores or inner shells, the purpose of which is to keep some balls in compliance with the USBC (United States Bowling Congress) weight limitation and to help pinpoint a certain RG value. Then there is the urethane used for the outer shell of the ball, which by density fits in between the core materials.

Even though you may have a bowling ball with as few as two parts or as many as five or more, all balls have one characteristic: they will act as if all of their weight is located at a point some distance away from the rotational axis. This distance is the radius of gyration (RG).

For example, a bowling ball has a maximum allowable diameter of 8.595 inches (maximum radius = 4.2975 inches). Theoretically, the RG could be any distance from just over zero inches by placing ultra-dense materials in the center of the ball and extremely lightweight filler beyond, to just under 4.2975 inches by placing ultra-dense materials near the outer shell and filling the inner areas of the ball with lightweight foam.

In the first example, the ball would be as center heavy as possible. In the second, it would be as shell heavy as possible. The problem with unlimited RG is that the two extremes would produce variations in ball performance that would be enormous. One would roll immediately and the other would “lope” all the way through the pin deck.

The USBC (United States Bowling Congress), in an attempt to limit the amount of variation in ball performance that could be achieved through construction, placed minimums and maximums on RG. The rule states that the minimum RG can be no lower than 2.430 inches and no greater than 2.800 inches. This means that every ball must act as if its entire weight (mass) is rotating at a distance of not less than 2.430 inches or more than 2.800 inches from the axis. Since the total span of RGs ranges from 0 to 4.2975 inches, technically all bowling balls fall within the overall medium RG range. However, when anyone in bowling talks about RG, they are not referring to the total range of possible RGs, but instead only to the RG range allowed for the sport, which currently is 2.430 to 2.800.

In the At a Glance chart, and in ball reviews and comparisons in BTM, the following scale is used for low flare potential balls:

Low RG = 2.430 to 2.540
Med RG = 2.541 to 2.690
High RG = 2.691 to 2.80

There is a slight upward adjustment for high flare potential balls. Determining the RG for BTM and fellow ball geeks, the formula for finding the radius of gyration (usually denoted by the letter k) is: the square root of the ball’s moment of inertia divided by its mass (k squared = I / m). What RG tells you: like with everything else in bowling, RG in and of itself tells you very little. It is ONE indicator of length. The characteristics of the three types of balls are as follows:

A low RG ball will be easier to “rev up” and it will rev faster, quicker because most of the mass is located relatively close to the center of the ball. Since it revs faster, sooner, it also wants to hook earlier. Medium RG balls are intermediate length balls. They are a little more difficult to spin (takes more power), so most bowlers will see a slight loping characteristic through the heads and early mid lane, followed by a faster revving action and later hook than you would get with the low RG ball. High RG balls are the hardest to rev up, since the mass is concentrated farthest from the center, and therefore bowlers will see longer lope, much later revving action, and the latest hook from these balls.

Well, there it is in a nutshell. Hopefully by seeing what these terms mean, you can make more sense out of what goes into a bowling ball manufacturing process, as well as how these technical terms apply to you out on the lanes. Now we will move onto the next part of this blog post, and that is the proper care of your bowling equipment once you begin using it. If you follow the directions below, you will find that your bowling balls will last longer, react closer to the out of box finish that you require, and give you one more leg up on your competition. Here we go!

Keeping Equipment Clean: One Key to Success

Getting good coaching, watching video, and working in a pro shop have all been valuable tools that have helped me become a successful bowler. But, there is also another part of my game that is important on a weekly basis, and that is taking care of my bowling equipment so that it takes care of me on the lanes when I need it. What I mean is, I can’t expect to bowling balls to perform at their peak all the time if I am not willing to put in some time of my own to make sure factors such as lane oil, rubber marks, track grooves, and such don’t take away from the balls performance. A little bit of extra time spent on cleaning and maintaining your bowling equipment goes a long way to not only keeping your bowling balls working at their optimum level, but also extends their life so that it saves you money on buying new equipment in the long run. I am going to discuss a few areas where bowlers need to pay attention to, which is daily maintenance, bi-monthly maintenance, and annual maintenance.


When I write this, I don’t mean go in your bowling bag every day and do the following steps, but rather after each time you bowl a league set, tournament, etc. before the next time you bowl. First off, I recommend all bowlers use a microfiber towel to wipe the bowling ball off. This type of towel gets the oil off of the surface of the ball, without scratching the coverstock or leaving marks.

Secondly, you should take a USBC approved bowling ball cleaner with you in your bowling bag, and use it to thoroughly clean your bowling equipment IMMEDIATELY after you are done bowling, before you get home. I can not stress enough the importance of getting the lane oil and dirt out of the coverstock as soon as possible, as with the porous coverstocks on resin bowling equipment, it takes no time at all for the oil to “soak” into the cover and stay in the ball. This causes loss of hooking action, and possibly premature ball death due to it being contaminated with lane oil deep in the coverstock. By simply cleaning the ball as soon as you are done, you have a very good chance of removing most of the oil from the outer surface of the ball, before it has a chance to soak in and cause long-term damage to your bowling equipment.

Lastly, invest in a ball carrier to put each of your bowling balls in before you put them in your bowling bag. These carriers are fairly cheap (in the $10 range) but by putting your ball in them, you are protecting it against anything sticking out of your bowling bag that could damage it, as well as protecting it from getting cracked in case you accidently drop it. Also, if you have a locker, it prevents the ball from rolling around and getting scratched up from any rocks or debris in the locker.


Calling it bi-monthly maintenance is a “loose” term, what I mean is the following steps should be taken every 50 games or so (which would be bi-monthly if you bowl twice a week). What I am referring to is giving your ball a hot water bath so that you remove any lane oil that has been soaked into the deeper parts of the coverstock. Using the towel and cleaners works good to get MOST of the oil out of your ball night in and night out, but to get the oil that is missed, you need to do something that can extract the oil out where the cleaner and towel can’t reach. This is where the hot water bath comes in.

First, I recommend you sand your ball down to about a 400 grit surface before putting the ball in any water bath. This can be done with regular 400 grit sandpaper, or a maroon scotch brite pad, or even a 500 abralon pad will suffice. What this does is it opens up the pores of the ball, allowing the oil to escape out when the ball is submerged in the water bath. If you do not have any sandpaper, doing the bath is technically “better than nothing”, but you can always go to your local pro shop and ask them to sand it for you before you do the bath, so doing that would be an option as well.

As far as the actual bath goes, the biggest thing to remember is to make sure the water temp. does not exceed 140 degrees. If your water is hotter than 140 degrees, you run the risk or removing plasticisers in the ball, which will harden the resin and ruin the bowling ball. If you are not sure how hot your water temp. runs, as long as the water is not too hot to put your hand in for an extended period of time, that should suffice for the water bath. Using an actual thermometer is best, but use you head, don’t just “drop” the ball in the water if it is too hot to handle.

When you start running the water, put in a few drops of liquid dish soap (DAWN or equivalent) that will be used ot help break up the lane oil and grease in the coverstock. Fill a bucket up enough so that the ball will be completely submerged below the surface and then place the ball gently in the bucket. Some people like to tape over the finger and thumb holes, but I do not recommend doing this. You are blocking a route of escape for oil and dirt, and the bath does not hurt finger or thumb inserts since it is just water and dish soap. At this point, you let the ball soak for approximately 15 minutes and place on the counter on a towel ot let the remainder of the water drip off of the ball. You will notice an oily/water type mixture on the surface of the ball, especially if it has been a very long time since this process has been done (if ever). Wipe the surface clean using a microfiber towel (or equivalent) until it is dry. If you are seeing this oily mixture on the surface, you need to perform the water bath again, until you no longer see any oil come to the surface of the bowling ball. I would recommend changing the water each time to start fresh, and not have any oil floating around in the water when you re-submerge the ball. Once the ball has only water on the surface (and on oil or dirt), you are done. It may take 2-3 15 minute sessions to get all the oil out, but it is well worth it. Give the ball ample time to dry before use again, I would recommend 24 hours to make sure all the water has gotten out of the coverstock.

Now, once the water bath is complete, you need to take the coverstock of the ball back to whatever the factory finish was on the ball. This will ensure you get the same type of reaction you are used to out of your bowling ball. If you do not have the tools at home to do this, take it to your local pro shop and have them complete the process.


This section is going to deal with a few of the things bowlers should do once a season to their bowling balls to make sure they last long, and perform well. I have covered ways to keep oil out of the ball, but now I will get into what to do when the ball becomes “tracked up” with all the marks from the lanes. When a bowling ball has more than 80-100 games on it, it loses its polish (if it is a polished ball), and also gets a series of grooves in the coverstock form the places that the ball touches the lane consistently. This has an adverse effect on your ball motion, and causes it to not perform at a peak level. The only way to get these grooves out (an re-polish the ball) is with a resurfacing. This will remove the scratches and gouges and get the ball back to like-new performance.

When I resurface bowling balls, I like to take them down to a 220 grit surface, sanding the ball in (4) different directions in a ball spinner. The first two directions are having the finger holes and thumb holes both sit horizontally, parallel with the top of the ball spinner. Once you sand that side of the ball, flip it over 180 degrees to do the other side. Then when you’re done on both of those sides of the bowling ball, position the ball so that the fingers and thumb are on top, pretty much horizontal (perpindicular) to the ball spinner. Sand the ball with the fingers and thumb up, and then turn the ball 180 degrees to sand the other side of the ball. At this point, you are done with the 220 grit (or whatever other grit you might be using). Sand the ball this way for each grit, until you reach the final grit that the ball came in at from the factory. Refer to the bowling ball companies website or sheet that came with the ball to make sure you get the correct final surface for your bowling ball.

Also, if the ball requires a polishing process, polish it in the same (4) directions you sanded the ball in to ensure you are doing things the same way all the time. Refer to the company recommendations for what type of polish to use on your bowling ball to achieve the correct reaction on your bowling ball. If you do not feel comfortable doing this process, which can be very time-consuming, take the ball to your local pro shop and have them complete the process for you. Usually this costs in the $25-40 range, varying from shop to shop and how bad the ball was to begin with for the cost of resurfacing. That is still much cheaper than having to buy a new ball because your old one “died” from lack of proper maintenance.

The last thing I will recommend for yearly maintenance is to change your finger inserts (if you use them) in your ball. Over the course of a season, the inserts become worn out, causing them to feel big or slippery since there is a good chance there is some lane oil and dirt mixed into the rubber inserts. It costs between $5-10 for a new pair from your local pro shop, and should be done at least once a season (probably more if you bowl more than twice per week). When it comes to your thumb, also make sure you change out your thumb tape regularly, because the sweat from your thumb, as well as the oil and dirt from the lane, causes the tape to lose its grip. Those two simple steps can go a long way to making you feel comfortable all the time in your bowling ball.

Well, that is all I have for tips to keep your bowling equipment in tip-top shape, for now anyway. Today’s bowling balls are more aggressive and condition specific than ever, and hopefully with the methods I discussed earlier, you can keep those bowling balls running at peak performance, and able to be used for the right conditions they were intended for. The opinions expressed in this blog post are my own, and do not reflect the opinion of the MSUSBC. Thank you for reading, and feel free to comment on anything you see here, I will try and respond as quickly as possible. I hope you have been able to pull something out of both sections of this post, and have armed yourself with the most useful weapon out on the lanes…..knowledge! Good luck, and good bowling everyone!

James Goulding III
(M.I.S.T. Tournament Manager)


2 responses to “Bowling Ball Terminology & Maintenance, by James Goulding III

  1. Thanks for all of the information I would never have thought of.It has been a swell for mainlining my bowling balls.
    However, I do have a question. I have the original Track Triton Heat Bowling Ball and I believe its about 19 years old. The manufacturers code is 7V700217. How is the code read to get the manufacture date.
    Herb J

    • James Goulding III

      Herb, my knowledge from balls in the 90’s and early 2000’s is that the first digit of the serial number is the year it was produced. In your case, it would be 1997 because of the “7” as the first digit. I hope this helps. Thank you for reading!

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