Customizing Weight and Twistweight
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This tool shows the effect on twistweight of adding weight to your frame.
What is twistweight?
Twistweight is the resistance of the racquet to changes in its rotation about its long axis. This is very important on off-center hits.. The higher the twistweight, the less the ball impact will twist the racquet in your hand. A high twistweight means more stability. More stability means more control, power and comfort on any given impact.
How do you determine twistweight?
All racquets on the market fall between 12 and 20 kg·cm². This is significantly less than values for swingweight, which is usually between 220 and 400 kg·cm². That is why it is much easier to twirl a racquet than to flip it! There are no commercial devices presently on the market to measure twistweight. You have two options to determine twistweight:
- You can use a Babolat RDC machine as follows: Measure the swingweight the normal way with the string plane vertically aligned in the RDC clamp. Then turn the string plane 90 degrees to horizontal and run the RDC again. The twistweight will be within about 10 percent of the differences of these two measurements.
- Our on-line tool describes a procedure for swinging the racquet as a pendulum and timing the swing. This will give you the exact twistweight.
What determines twistweight?
Twistweight varies with the amount and location of weight in relation to the long axis. Twistweight increases linearly with weight but with the square of the distance from the axis. That's why wider racquets are more stable.
How do you change twistweight?
You increase twistweight by adding lead tape on opposite sides of the racquet head. The 3 and 9 o'clock positions (usually the widest points on the head) are best to maximize stability. Changing twistweight will also change swingweight. Making the racquet more stable to twisting will also make it less maneuverable to swinging. That is why it is best to buy a racquet that is lighter than you will ultimately play with. When you add weight to adjust the swingweight, you will typically add it in locations that will simultaneously maximize twistweight. In this way, increasing twistweight is usually seen simply as a beneficial by-product of increasing swingweight. However, coaches who can optimize both swingweight and twistweight and also be able to quantify the gains (see below) to their students will be much appreciated.
Using the Twistweight Calculator
Drag the top two sliders to the weight and twistweight of your current racquet. If you don't know the twistweight, simply experiment with twistweights anywhere in the range given above (12 to 20 kg·cm²), though 14 or 15 is where most racquets will fall. This is your starting point for twistweight customization.
To increase the weight and twistweight of this racquet, use the bottom two sliders to add lead tape to specific locations on the racquet. As you drag either slider, the new weight and twingweight will be displayed in the red box at the bottom of the screen.
You can see that you can make very large improvements to racquet stability by adding lead tape. For example, for a 300 gram racquet with a twistweight of 15, adding just 6 grams (3 grams on each side of the head) 15 cm from the axis would increase twistweight (stability) by 9 percent. Adding 10 grams at 15 cm will increase twistweight 15 percent. However, as mentioned above, this gain will have to be analyzed by considering the resulting change in swingweight (see the swingweight calculator).
Being able to offer students this kind of improvement should be in every coach's bag of tricks.
Note: Additional advanced on-line tools for customization exist for USRSA members.