RG And Differrential

RG Differential and RG What Does This Mean?

I will try to address this simply and with as little confusion as possible. I first must tell you I am not a scientist or a ball designer. I am always learning as are you. I am sure some of you have wondered what does some of the numbers on a bowling ball technical sheet mean and how does it affect me, the bowler. Why do I need to know it anyway. First I must address cover stocks and cores. The cover stock is like the tires on a car and the core is like the engine. These two things are what influence the bowling ball motion. You choose a bowling ball to match your style and the lane conditions you bowl on. Because of so many different style bowlers and bowling lane conditions, the ball companies make different types of balls, and are trying to make a ball that will sell. So that is why you see these numbers on a balls specs. sheet. Also, the USBC rates them to have a tolerance.

RG-
RG means Radius Of Gyration. The RG of a bowling ball tells you how soon the core is designed to roll. The lower the RG, the sooner the ball is designed to roll. The lowest allowed by the USBC is 2.43 the highest is RG 2.80. (USBC could change the rule anytime).

The RG Differential (also called just DIFFERENTIAL) -
This indicates the difference between the low RG and the high RG. The Differential indicates the potential for track flare which can be translated into hook potential. The higher the differential, the more hook potential the core possesses. The RG differential indicates the difference between the low RG and the high RG. The maximum differential allowed by the USBC is 0.060.Don’t get this confused with intermediate differential because that is different. This is used in asymmetrical bowling balls to measure the spin time of the bowling ball before drilling.
Note: All numbers on the spec. sheets are before drilling and that is an important factor as the numbers then change.
Ok this is what RG Differential and RG mean. But, the biggest influence in bowling ball motion is the surface of the ball and the force and direction of the bowler’s release. In addition, the condition of the bowling lane must also be taken into consideration...

Now here is a pretty good rule.

A lower RG ball with a low differential will produce an earlier rolling ball with a small arcing motion.
A lower RG ball with a high differential will produce an earlier rolling ball with a larger/stronger arcing motion.
A higher RG ball with a low differential will produce a later rolling ball with an angular backend motion.
A higher RG ball with a high differential will produce a later rolling ball with a strong, somewhat angular backend motion.

On differential:
The lower the differential the closer together the track flare. The higher the differential the further apart the track flare.The cover stock friction on the lane allows this to come together. Coverstock adjustment is needed to adjust to the conditions you are bowling on.Well I hope this helps and does not confuse you too much.

Good Luck and Good Bowling

Motion Of The Bowling Ball

The study of bowling ball motion are something that most bowlers know nothing about. In brief, there are three basic stages, or zones, a bowling ball must go through. These stages give the ball the proper reaction on a bowling lane. This has been the principal in bowling for the thirty years I’ve been in the game. Most bowlers don’t realize that a bowling ball goes through these stages.The bowling ball motion are as follows:


1. Slide – A bowling ball will first slide for a certain length of a bowling lane after it is released by the bowler. This is known as the head portion of the lane.

2. Hook – After the slide zone of the ball motion it will then transition into a hook zone.

3. Roll – Following the hook zone a ball will go into a roll stage. 

In summary – The stages of bowling ball motion are slide, hook, and roll.

You could Picture this like a rocket taking off from the earth to the outer space.

1. You must have a take off part so the rocket can get off the ground. = The slide.

2. After the rocket is off the ground it must transition to get out of the atmosphere. = The transition and hook.

3. Then transition again to adjust to the outer space itself. = The roll.

This is the same kind of concept involved in the study of bowling ball motion. 
Which is also true in bowling lane conditioning. The bowling lane conditions and the bowling ball motion must match for the best reaction.

If a ball slides, hooks, or rolls too early you will get roll out. If roll out is too early the ball stops and goes straight. If a ball slides, hooks, or rolls too late it will never grab the lane and could skid out. A bowler should study a ball rolling down the lane and realize that these stages happen. The study of Bowling ball motion is essential.

How To Position Yourself On The Appraoch

How To Position Yourself On The Bowling Approach

As a relative beginner bowler or newcomer to the game, learning how to position yourself on the bowling approach is a big step to improving accuracy and targeting the pocket or spares. A good way to begin is to first understand where the guides on the approach are located in reference to the foul line and to the targeting arrows about 15 feet past the foul line. By knowing a little about the "lane geometry", you will more easily understand how to position yourself on the bowling approach.

The arrows are located about 15 feet past the foul line toward the pins and are in a triangular configuration. The arrows are also commonly referred to as "guides" or "dovetails." From bowler's right to left (for right handed bowlers), the arrow nearest the edge of the lane is referred to as the "first arrow" and is located on the 5 board of the lane surface, about 5 inches from the edge of the lane. Continuing to the bowler's left, the next arrow is the "second arrow" which is located on the 10 board. The "third arrow" is located on the 15 board, the "fourth arrow", or center arrow, is located on the 20 board, "the fifth arrow" on the 25 board, the "sixth arrow" on the 30 board, and the final "seventh arrow" on the 35 board. The arrows are symmetrically placed on the lane. Using a reverse reference system is recommended for left handed bowlers.

The circular guides embedded or stamped onto the approach just behind the foul line correspond to the 7 boards of the arrows down the lane. The largest guide is located on the 20 board, the center board of the lane and aligns with the center of the 7 targeting arrows. Each guide at the foul line, both to the right and to the left of the center guide, is positioned 5 boards apart from the adjacent guides in the same manner as are the arrows. If you trace back from the foul line, you will find another set of guides on the approach 12 feet behind the foul line and yet another set of guides 3 feet further back from the 12 foot guides. Usually, there are 5 guides at the 12 foot position on the approach and those guides align on the same boards as the center 5 guides at the foul line and down the lane with the center 5 arrows. The same is true 15 feet from the foul line where the center 5 guides align with the 5 guides at the 12 foot [position on the approach. There is generally seven to nine guides at the 15 foot position near the back of the approach.

The approach guides are used primarily for alignment to the targeting arrows. Since the maintenance team at any given bowling center typically sets up the lane oiling machine to apply the heaviest concentration of oil on the front end of the lane between the foul line up to a distance perhaps of 20 feet (just beyond the distance where the 4th arrow is located) and across the lane between the 2nd arrow and the 6th arrow (the 10th board from both edges of the lane). In this case, it is suggested that a bowler will align his strike ball delivery to the pocket in such a way as to roll the bowling ball toward the second arrow with an appropriate angle from the release point just beyond the foul line as to allow the ball to continue down the lane to the pocket. 

If a bowler rolls a slight curve or hook delivery, then the ball should contact the lane just beyond the foul line on about the 12 or 13 board, roll over the 2nd arrow (the 10 board), and then the ball will change directions about two-thirds of the way down the lane at the break point and head toward the pocket located at the 17.5 board. If this example of releasing the ball on the 13 board just past the foul line is used to target the 2nd arrow down the lane, then where shall you stand on the approach to properly position yourself before you walk to the line and deliver the bowling ball?

In the case if you are a right handed bowler, if the center of your bowling ball is released on the lane just beyond the foul line about 1-3 feet distance past the line, then your sliding shoe is normally the left shoe. The slide shoe should enter the sliding area of the approach very near the foul line (ending perhaps 2-4 inches behind the line) and the instep of the shoe should slide into the line pointing fairly straight so the toe faces the pins which also helps keeping your hips and shoulders aligned to your target down the lane. The instep of your sliding shoe is located about two boards right of the exact center of your slide shoe.

If you allow about 1 inch of space between the inner side of the bowling ball as it passes by your sliding shoe, then the instep of your sliding shoe will cover the 18 board on the approach at the foul line and your toe will point to the 20 board or the center guide. In this example, the reference to this alignment positioning on the approach goes as follows:

• Stand on 18 board - (with the instep of your sliding shoe covering the 18 board)


• Walk a straight line to the foul line and slide on the same 18 board - (if you walk either right or left 2 boards, as example, from your initial starting position on the 18 board, then adjust your starting position 2 boards to compensate)


• Slide with your sliding shoe covering the 18 board at the line.


• Release the ball where the center of the ball contacts the lane on the 13 board - (the diameter of the ball plus a small bit of room so the ball does not contact your ankle or shoe passing quickly into the release zone).


• Target the 2nd arrow (10 board) 15 feet down the lane. (you may have to sight to the right 1 or 2 boards of the 2nd arrow since most right handed bowlers miss the board they are sighting by 1 or 2 boards left of the target)

The 18 board is a good place to initially position yourself on the approach and the 2nd arrow is a good place for an initial alignment but it is not necessarily the correct board to stand or to sight when targeting the pins. You may have to use a board located to the right or to the left of the 2nd arrow and make the correct adjustment in order to roll your ball and contact the pocket depending on your type of delivery, the speed you roll your bowling ball, and the ball surface and core construction you select. 

Different Types of Bowling Balls

The Different Types of Bowling Balls 

 

 

Here are some of the different types of bowling ball cover-stocks and cores to date. First there are 5 types of cover-stocks that I am going to talk about they are plastic,
reactive pearl, reactive solid, reactive hybrid, and particle.

There are 3 main types of cores in a bowling ball which include 3 piece, 2 piece symmetrical, and asymmetrical. Now in more out lined detail
listed below.

Cover-stocks 

1. Plastic - is usually used in 3-piece cores.  It does not have much traction on the lane and is lower in price.  It is mainly used as a spare ball or a beginner ball.

2. Reactive Pearl - is used in all types or cores.  Normally it has more of a skid snap reaction.

3. Reactive Solid - is used in all types of cores.  It has an earlier and smoother reaction than the pearl.

4. Hybrid Reactive - is mainly used in 2-piece symmetrical and asymmetrical cores.  This type of cover is made to give the bowler the best of both worlds as it has a combination solid reactive and pearl reactive.  It is mainly used on over and under bowling lane conditions.

5. Particles - This was a cover-stock that was made to combat heavy oil.  It had pieces, or particles, in the reactive cover to help it grab the lane surface.  There are not many companies making particles anymore, but there are a few. It was mainly used In 2-piece symmetrical and asymmetrical cores.


Note: Urethane Cover-stocks that were popular in the 1980's are now making a comeback.  They are not as aggressive as reactive bowling balls and are more powerful than plastic.  In addition, they are usually smoother in transitioning but do not have the hitting power of the reactive balls.