Kegel’s Revolutionary Slope Graphs

With the invention of the Kegel LaneMapper™, came a greater than ever extensive study of bowling lane topography. With that study, came a stark realization that gravity randomly affects the bowling ball much more on synthetic lanes versus regularly resurfaced wood lanes.

The reason gravity and topography comes into play more today is because synthetic lanes deviate from flatness more than wood lanes ever did.

Also, although a dry synthetic lane has more friction than a wood lane (smoother surface causes a greater footprint from the bowling ball), a conditioned synthetic lane has less friction than a conditioned (oiled) wood lane, making it easier for an object to move “off line” in a non-flat situation.

For years, people in the game of bowling only talked about thousands of an inch with regard to the level specifications of a bowling lane. In short, a certified bowling lane can not deviate from +/- .040” over the width of the lane (cross-tilts), nor can any crowns (hills) or depressions (valleys) along the surface be greater than the +/- .040” specification. This specification was implemented in 1939 by the American Bowling Congress along with the Annual Resurfacing Requirement, which was made for wood lanes.

Sometime before 1964, the Annual Resurfacing Requirement became the Bi-Annual Resurfacing Requirement. But in 1964 by pressure from the for-profit bowling industry, resurfacing requirements on any time line by sanctioned bowling centers was removed by the ABC, yet the level specifications remained.

The deletion of that rule created a huge asymmetric lane wear issue, which culminated with the PBA creating their own lane maintenance division, and implementing their own lane surface policies for PBA Tour events.

But today, with the large number of synthetic lanes, we have not only asymmetric wear issues, we found bowling lanes can also have severe asymmetric level issues. For Kegel and the LaneMapper project, our next challenge was to find a way to easily show the affects gravity had on a bowling ball on any one lane at any specific distance.

The breakthrough came by creating and defining a brand new term in bowling - Slope per Board™.

Although we explained Slope Per Board in our last Inside Line article, Lou Trunk's What a Shock - Newton Correct, we can't stress enough the importance of looking at a bowling lane in this manner. Remember, the bowling ball only reacts to the board it's on, and could care less about the boards it's not on.

Once we compile all the data of a lane the Kegel LaneMapper is able to give us, cross-tilt numbers and each board’s crown or depression values, we are able to calculate the individual side slope of any one board at any point the lane is measured at. 

For instance, we know a bowling lane consists of 39 boards, and if a bowling lane is tilted high right 40/1000” (1 mm), which is the maximum allowable amount under the specification rules, that would give us a slope per board value of about 1/1000” (.025 mm) for each board on the lane (.040”/39=~.001”).


If we double that cross-tilt to be .080”, which is two times the allowable amount under the specification rules, that would give us a Slope per Board value of .002” for each board (.080”/39=~.002”).

Another instance that would give us that same .002” Slope per Board value, but be within current specification, would be a .040” V-Shaped depression, or crown, directly to the center of the lane. The calculation is a .040” slope over 20 boards, which equals a .002” Slope per Board as well (.040”/20=.002”).

Understand, the ball doesn’t care about the lane being in specification or out of specification. The ball feels the exact same gravitational influence of .002” under each scenario – one scenario twice the allowable amount, and one perfectly within specifications.

However, as soon as we introduce crowns and depressions into the equation, that cross-tilt slope per board value can increase or decrease significantly, and depending on which way the gravitational slope is, it will influence the bowling ball to the left or to the right as it travels down and across the lane surface.

With synthetic lane installations, it is common to see crowns or depressions combined with tilts to produce Slope per Board values well over .005”, which is equal to a cross-tilt that is five times (.200”) the legal specification limit.

The breakthrough came by creating and defining a brand new term in bowling - Slope per Board.

The Slope Graph

Now that we realized the random deviation from levelness of a synthetic bowling lane, we began to experiment with different graphical representations of the data. After some experimentation, we settled on a seven color overhead graph, with varying shades of blue being right gravitational influence (the darker the color, the more influence), varying shades of red being left gravitational influences, and green being neutral to very little gravitational influence on the bowling ball (arrow graphic below).

Our current LaneMap Slope Graphs (pictured left) have been scaled to be much wider than an actual bowling lane so to easily see the left-to-right definition of the lane when a pair of lanes is on one sheet of paper.

To the left is an example of a bowling lane that has some severe depressions the first 28’ of the lane; this is very common with aging synthetic lanes installed over existing wood lanes.

After the 28’ mark, the lane becomes slightly crowned. This is evident from the blue colors outside on the right side of the lane, and the red spectrum colors on the outside on the left side of the lane.

To give you an example how much those front lane depressions affect a bowling ball; if a 15 pound ball is placed on the right side 8th board at the foul line, and it is straightly rolled end-over-end at 18 mph, by the time it reaches the 28 foot mark, based upon this actual lanes levelness in that area, the ball will have moved almost 3” to the left!

After 28’, and the ball being almost to the 11th board, the forces on this lane are basically non-existent, or cancel each other out, keeping the ball near the 11th board the rest of its journey to the pins.

Remember Andy Varipapa's “double hook trick where he spin rolls the ball at the foul line to the right side of the lane, and then it rolls to the left side of the lane, and then back to the right again to make the 10 pin? This is most likely gravity at work on a depressed lane surface - all wood lanes were cut with a depression. It’s only a trick because many assume slopes that are not visible to the naked eye will not affect a bowling ball’s path.

However, our testing has shown these "invisible slopes" can affect the path of the ball significantly. It's possible Andy also knew that, and he might have known spinning the ball would decrease the friction between the ball surface and the lane surface, helping gravity “do its thing”. After all, the Laws of Motion were around long before Andy Varipapa.

It must be noted, in accordance to the Laws of Physics, that a side slope on an oiled lane (low friction) will make a ball move off line more than on a perfectly dry lane because less force is needed to move the ball offline. Think of a car on a side hill on an icy road versus dry pavement; the same physical forces apply to bowling balls.

We have also been studying how a rotating bowling ball is affected by these different side hill slopes, and with all the varying degrees of axis rotation, axis tilt, and rev rates of different styles, along with varying amounts of friction, ball weights, and ball speeds, it is very complicated math.

But basically, the Laws of Physics still apply - a ball rotating against the slide slope will deplete energy quicker than a ball rotating with a side slope.

For example, a player like Pete Weber, who has a high degree of axis rotation on his normal delivery, will be affected more on a side hill slope perpendicular to his axis of rotation than a player like Jason Belmonte, whose axis of rotation is much less. It could be a positive or negative effect depending on which way that side slope is and how the players must attack the lanes to find the most room for error and best pin carry.

However, with Kegel's Slope Graphs none of that matters because we are comparing different lanes to one another, with all those rotational and friction properties being near the same for any particular player.

So far the Kegel Slope Graphs have been spot on in real world situations. Not only have we been watching and proving them in action at many high level events and championships over the past two years, from a thousand miles away, after fully measuring a bowling center with the Kegel LaneMapper™ and creating a Kegel LaneMap™ Report and Guide, we can tell a proprietor what lanes in their bowling center have certain characteristics, or which pairs are the highest and lowest scoring, without ever steeping foot inside their center. Every time they are amazed what we can tell them from this data.

In addition, when having these Slope Graphs compiled into a full Kegel LaneMap Report of any bowling center holding a tournament or championship, we can also predict what lane is tighter, what lane hooks more, where a lane will play the fairest, and what pair topography will be least influential, or be the fairest for most styles, and therefore, to hold the finals on.

From our formal and concourse educational seminars, we find understanding these graphs and how it relates to ball motion takes very little time. But to this day, and with all the education on oil patterns, most still don’t understand oil patterns and how they relate to ball motion,

How many times have you heard, “the oil pattern didn’t play anything like it did at home”, or “the oil pattern says we should play here, but it seems to be better over there”?

With Kegel’s LaneMapper and the reports and Slope Graphs it generates, we now know exactly why that happens.



Below are links to download Kegel LaneMap Guides for a few bowling centers so we can show you real world examples on how lanes differ from one another.

The proprietors of these two centers, Werner Knoebl of Dream Bowl Palace in Munich, Germany and Ronald Dol of Dolfijn Bowling in Tilburg, The Netherlands, are very progressive and sport oriented bowling proprietors. It is their feeling that sharing this information makes for a more level playing field.

As any proprietor knows, one of the biggest challenges for the weekly bowler is trying to adjust to radically different lanes.

Kegel LaneMap Guide Downloads:
31 January 2012 - Dolfijn Bowling - Tilburg, The Netherlands : 1.3MB PDF - this report was made available to all players by the organizers of the 2012 European Bowling Tour's Hammer Bronzen Schietspoel International.

2 February 2011 - Dream Bowl Palace BEFORE the March 2011 re-leveling. After the re-leveling, lane play became very similar from lane to lane.

This example is one of the absolute best new synthetic installations we've seen: 20121015 LaneMap Report from Bowl for Fun in Langen, Germany

Weather, Topography, and Ball Motion
What a Shock - Newton Correct!
Topography: What does it all mean?

Ted Thompson

Ted Thompson began his career in the bowling business in 1976 at the age of 15 working for the Florida based Galaxy Lanes chain. Beginning from the ground up in center operations, he has also been a long time Pro Shop proprietor, 40 lane center General Manager, PBA National Tour player, multi PBA Regional Champion, PBA Player Services Director, and even a bowling writer. Since 2004 he has been working with Kegel.

Ted has also coached bowling on many different levels. From basic Learn to Bowl classes and private lessons while in the Pro Shop business, he was also head coach for Florida State University, countless PBA professionals, and even coached Lisa Wagner to her last Player of the Year award in 1993. While working for the PBA, the late great Dick Weber even asked for some of his time. An experience Ted says "he will always cherish". Dick immediately won a Senior Sweeper and gave him $300. It was the most Ted ever received for an hour lesson, and it came from one of the greatest players of all time.

Recently, Ted has been deeply studying topography and the effects it has on ball motion. He is also on the Kegel Team helping make decisions for many of the oil patterns Kegel uses in competitions world wide, which has led to further development of Kegel's lane machines. Ted has a complete and unique understanding of bowling from many different sides.

Ted also named the world's and Kegel's most popular lane machine the "Kustodian ION" (pronounced "EON" in Europe) and spearheaded the creation of Kegel's Navigation Oil Patterns. The creativity may be heredity. In 1968 Ted's father created the famous Dodge Super Bee logo and spearheaded that marketing campaign.