In this installment of “Technology” we focus on racquets. When it comes to tennis the racquet represents the major initial investment. Of course shoes, clothes, bags, etc. add up but the racquet is gong to be in the $150.00 to $200.00 range. Add in string and you are looking at a sizable investment.
So, lets make this investment really count. By that I mean lets make sure the racquet is right for the player. That is a tall order! With so many brands and models available you need help.
Starting with material, you can be sure, most current “performance” racquets are graphite composites. A raw racquet “tube” may weigh only 240 grams before all the other stuff is added on. About 40% of that is graphite with the remainder being epoxy resin and maybe some small percentage of other material, like BLX, Titanium, Kevlar, and others.
A finished racquet will weigh between 270 (9.52 oz) and 350 grams (12.34 oz). String will add about 17 grams (.6 oz). Add a vibration damper (3 grams) and an over grip (6-8 grams) and you have a significant impact on “feel”. Anything that is added at the butt end will have a minimum affect on dynamics.
The way the fibers are “arranged” determines the stiffness of the racquet. The characteristics of the racquet are determined by the various angles of the fiber layup. So, when you look at a racquet it is hard to “see” how stiff it is so you rely on marketing information.
The are several stiffness “areas” but the primary is longitudinal stiffness, which is from the butt cap to the tip of the racquet. Another, and less “considered” stiffness is the “in-plane” stiffness. This is how stiff the racquet is across the middle of the head area. One way to get a handle on the in-plane stiffness is to know that if the top of the section is flat it will be stiffer than if the top is very narrow.
The major characteristics of racquets that are positive are:
Weight: a heavier racquet will generate more power, absorb more shock, be more stable.
Swing Weight: is the characteristic that determines how forceful the racquet will “drive” through the ball. A larger swing weight is an advantage.
Stiffness: is the primary “spring” in the equation. Stiffnesses range from 50 to 75 as tested on the Babolat RDC. If you know the racquet stiffness it is easy to arrive at a string bed stiffness that will compliment the player. This is “effective stiffness”. For example a racquet with a stiffness of 69 and a string bed stiffness of 56 will have an effective stiffness of 30.91. I know, for example, that anything over 34.00 is too stiff for most players.
Grip size is another significant consideration. I believe, and it has been confirmed by some in the medical profession, that the grip should be as large as possible for the player.
We will continue with this “technology” series with a session on string!