Category Archives: Learning
Three Important Things
When dealing with tennis racquets, there are many significant performance parameters. We are going to list our three (3) most important ones:
- Swing Weight
- Overall Weight
- Effective Stiffness
These particular parameters are based on machine testing, physics, and experience.
- Swing Weight: we refer to this as a dynamic weight, meaning how heavy or light the racquet feels during the swing to the ball.
- Overall Weight: This is normally considered to be the weight found on a scale, electronic, or balance. Weight is your friend if properly associated with your capabilities and stature.
- Effective Stiffness: is a calculable and measurable stiffness of the ball hitting the string as you are holding the racquet and hitting a ball.
Why is it Important?:
- Swing Weight: contributes to power and stability, which contributes to control. A higher swing weight of, say, 320 to 340 will handle most incoming balls with ease. Swing weights of 300 to 319 will be easier to maneuver and require a little more energy from the player to handle aggressive incoming balls.
- Overall Weight: contributes to ease of movement and long play time and must be associated with the stature and style of the player. The heavier racquet will provide more power with less energy expended by the player.
- Effective Stiffness: this is a metric we use to ensure the racquet is within the stiffness range needed by the player. For example, if you come into the World Headquarters of Racquet Quest for the first time with your current racquet and the strings are intact, we can determine the effective stiffness and, based on your satisfaction with the current playability, arrive at a corresponding effective stiffness…not on a reference tension. A range of 24 to 30 pounds is acceptable. Anything over 30 becomes quite stiff and should be avoided by most players.
If you look at our racquet reviews, you will see a lot more than three (3) performance parameters! We believe they are all important, but players should understand the three (3) described here.
Power vs String Bed Stiffness
We have been testing strings for power potential since 1984! Currently, we have over 500 strings registered on our website, and we will put a link in this post that will take you there. Over the years, we have tested that several times that number but need to remove some strings that simply do not need to be in this data while keeping “legacy” strings for reference to today’s offerings.
What does the power potential of string have to do with String Bed stiffness? While a single strand of string tells us a lot about the performance characteristics of any string, it is the total string bed that you play with, not a single string!
We test for String Bed Stiffness in four (4) different ways: Babolat RDC, Flex Four, Master Tensometer, and our proprietary String Bed Master.
What we want to clarify is the power of the string bed stiffness, and to do that, we need to include the tennis ball, which is, by design, not very efficient. I believe the rebound percentage is about 53 to 58 percent. If the rebound percentage were closer to 100 percent, the ball would not stay in the court!
The graph below helps us understand what String Bed Stiffness will work in any given player situation.
Power vs String Bed Stiffness
I know there are a lot of lines, but I am certain you can understand them. We will help you along and explain why this is very important to you and us!
The vertical axis (Y) is Power, and the horizontal axis (X) is String Bed stiffness in pounds per inch. Every device we use for string bed stiffness presents the force in pounds per inch. The green dotted box represents the “normal” range (≈ 160. to 210.0) for string bed stiffness.
If we want to maximize the power of the ball contact and string, we would need a string bed stiffness of about 100 pounds per inch, which is achievable but not “normal.
The upper curve (brown or red) represents the sting bed only. So you see a power range of 20.0 down to 6.67. The lower curve (blue) introduces the ball and, due to the ball design, does not add any power but detracts from power. So you see a power range of 13.7 down to 8.38. Because we don’t know how hard the ball is being struck, we prefer to use the string bed-only curve. It is, however, critical for us to know how the ball is participating.
An interesting and important value of the graph is the power value. As the string bed becomes stiffer than the ball (≈ 210.0 pounds per inch range), the ball will provide more power than the string bed. Not much, but at least the ball will not detract from the power!
Another 1000 Word Picture!
What happens to a string if it gets scuffed or slightly damaged in terms of properties?
We know the string will not go in the clients’ racquet, but how bad is it, really?
The chart below shows exactly what happens to each string until both fail. We can see precisely how the scuffing affects the string. Both strings behave nearly the same through the three (3) cycles to 50 pounds. We then see that the scuffed string gives up a little earlier than the clean string by about 15%.
So, what’s the Difference?
However, the failure force for both of these strings is very high! Only a handful of strings we have tested exhibit this tensile strength.
So we know this string would never be used in a client racquet, but you could certainly use it for some “experimentation!” And, of course, depending on how many and where the “rough” spots are you can cut that portion away!
Racquet Quest, LLC
