What is the difference in Asymmetrical vs Symmetrical bowling balls? If you have bought several bowling balls you have likely seen the terms used quite often. Have you ever wondered what the terms meant?
We often see a cut-away view of the core in the sales description. The technical description indicates that the core of the ball is one or the other, Asymmetrical or Symmetrical bowling balls. So, what is the difference between the two? I thought you would never ask! Let’s find out!
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Defining Asymmetrical Vs Symmetrical Bowling Balls
Asymmetrical Core – The Weight is Offset
I will start with the Asymmetrical core first. An Asymmetrical ball is where the RG (radius of gyration) differential between the high and low axis’s differ by more than 5%.
To keep it in simple terms that do not involve the ratio of gyration, the Asymmetrical core is not in equal proportions top to bottom where as the Symmetrical core is.
So, this weight imbalance will cause the ball to change direction while trying to return to it’s most stable balance point. This will be shown in the videos below.
Symmetrical Core – The Weight is Distributed Equally
The Symmetrical Core is just the opposite where the RG differential between the high and low axis’s is less than 5% . To simplify this once again we will consider the shape of the core.
The Symmetrical core is normally longer, slimmer, more consistent profile. This will allow the ball to roll smoother because it is not affected by any counter weight on one area(axis)in relation to another(axis) on the core.
I know this is an over simplification, but if you look at different cores you will see what I mean when I say that. These are just examples, and many different styles are made.
Track Explains Asymmetrical Vs Symmetrical Cores
Here is a video that gives a description of the different cores and their differences.
So, depending on how the ball drilled, will determine the amount of effect the Asymmetric core will have. And remember that after a ball is drilled, the holes themselves will make the ball slightly asymmetrical.
You can read the Wikipedia description of Asymmetry here.
Asymmetrical Vs Symmetrical Visual Comparison
The Difference is Obvious!
If you notice above the Asymmetrical Core has a varied assortment of protrusions in different areas that are in an irregular shape, where as the Symmetrical Core is more uniform in respect to the ball, or basically in the same proportions all the way around the ball.
Because the proportions in the Asymmetrical are not uniform, the weight distribution when you hook your bowling ball, will cause a sharp angle to occur when the ball reaches the break point and will respond faster to friction on the lane compared to the Symmetrical Core.
It is producing a controlled off-balance situation which enhances the bowling balls hook, and changes the angle of entry to the pocket.This angle is changed when the axis of the ball moves in response to the core weight being affected by the friction of the lane.
Also known as the flare potential of the ball, the higher the differential of RG measurement number, the greater the track flare potential.
Asymmetrical cores in general will give you more skid length before beginning to hook, but will hook harder and stronger, sometimes referred to as the block flip.
When the ball reaches the break point, the direction changes abruptly as the weight block flips or starts to affect the balls direction of travel.
Who Needs An Asymmetrical Ball?
The needs of the bowler come into play, when you talk about what problems the bowler has. If a bowler thinks that his ball needs more hook, then he is more likely to pick an Asymmetrical core. These tend to help the ball finisher stronger on the back end.
If a bowler is having problems with his ball hooking too soon and feels he needs to get the ball further down the lane, then he also might turn to the Asymmetrical ball, with a less aggressive cover stock.
Why? This will provide the additional skid to get the ball farther down the lane. But, in heavy oil conditions, a more aggressive cover stock is needed.
Then, combined with the weight distribution of the Asymmetrical block, you get the most aggressive angular hooking balls. You also have the most options for a variable hook with Asymmetric bowling balls.
If you were league bowling and into the third game and were having issues with control or heads that were just to dry, then this is the condition where the less aggressive Asymmetrical ball would work too your advantage.
What Determines The Symmetrical Core – It’s The RG!
To clarify we are talking about cores here, and non-drilled balls. Because once the ball is drilled for fingers and thumb holes, then all balls become Asymmetrical to a point, and the differential of + or – 5% becomes the deciding factor.
The symmetrical core is where the RG(radius of gyration) differential between the high and low axes differ by less than 5%.
So since this differential number is going to be less, then we can expect the Flare Potential to be less, or less hook at the break point.The Symmetrical Core is the same all the way around the ball at least on one axis say horizontal, but not vertical.
This should deliver a smoother line, with less angle, and a ball that starts to hook sooner, with a smoother arc to the pocket. This is important because it means the lower the RG differential, the less Asymmetrical or lower the hook rating on the ball will be. Or the more Symmetrical or smoother the ball and less flare in the hook motion.
A Video Explaining RG ( Radius of Gyration), Differential, and Asymmetrical vs Symmetrical
Why Use a Symmetrical Core?
If you throw a slower speed ball or bowl on drier lanes then the Symmetrical Core will give you a smoother arc motion. Or maybe you find you ball hooking away from the spare shots you are trying to make? Then, the Symmetrical Core will tend to be smoother and less angular. Less snap or block flip gives you more control and helps make those shots a bit easier.
Asymmetrical vs Symmetrical cores should mean something to you now. If nothing else, you should have some idea what the two behave like on the lane.
To put is simply, the Symmetrical Core allows a smoother hook to occur sooner. In contrast, the Asymmetrical Core saves energy and gives the ball a more sharp angular aggressive action on the back end.
It’s all Up to You And The Type Of Motion You Want!
The biggest difference in the Asymmetrical vs the Symmetrical core is that Asymmetrical will deliver more aggressive movement. While the Symmetrical core will deliver a more consistent and smoother motion overall on any conditions.
But the key to know is that the core is not as important as the cover stock in terms of aggressive hooking balls. So, the less experienced bowler who doesn’t yet have enough knowledge about aggressive hooking balls would likely enjoy using a more controllable ball.
However, combine a strong cover stock to the Symmetrical Core and you can also produce a ball that hooks hard, but in a more predictable motion to the pocket. The Motive Forza is the Symmetrical Core pictured above.
Update: The Motive Forza is discontinued and retired. I was only using it as a demonstration in this article. It was a popular ball in it’s day.
Drill Baby Drill, It Makes a World of Difference!
The drilling layout is also a very important factor in how a ball is going to behave, because you are changing how the weight is distributed in the the ball as rolls going down the lane.
So, technically we could alter cover stocks and drilling layouts and get nearly similar results from both cores, but the Symmetrical Core is much more limited. There are many more options with the Asymmetrical core.
However, the Asymmetrical core will expose or magnify a bad release, for example. The bottom line would be your preference on how a particular core, cover stock and drill layout delivers the motion you tend to feel most comfortable with.
If you were bowling on dry conditions almost constantly, you would need a smooth controllable ball. A combination of shiny pearl type finish with a Symmetrical core delivers more controllable and limited hook motion. The more control you have, the easier it becomes to get the ball to the same spot over and over. Then the game becomes more enjoyable.
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