If, as TW's power potential measurements indicate, the racquet is always more powerful in the throat area, why do players hit in the middle or higher on the stringbed? It would seem that players have found that they get more power higher in the racquet. Does this mean that TW's measurements are wrong and that the most powerful point on the racquet is closer to the tip than the throat?
The answer is "no." Surprisingly, the fastest shots do not occur where the racquet is most powerful. Let's look at the ingredients of maximum shot speed to see why.
Ingredient One: Built-in Power Potential
When a ball hits a stationary racquet, it bounces back at a speed that depends on the racquet's ability to rebound the ball. That ability depends on all the characteristics of the racquet such as weight, swingweight, stiffness, materials, and design. Each racquet has an innate ability to bounce the ball back. We call this the power potential.
Ingredient Two: Racquet Speed
If the racquet is moving when the bounce occurs, the rebound speed is a combination of the speed produced by this innate rebounding ability and the speed of the racquet from which the bounce takes place. The racquet speed is an "add-on" speed. It is a "running head start," so to speak. Hold that thought — the speed of the shot is the speed of the bounce plus the speed of the bounce surface.
Ingredient One Revised: Location Power Potential
Now add two wrinkles. First, points near the racquet's center of mass (the balance point, located near the throat area) have greater power potential than those near the tip. That's because there is more "stuff" there to do the rebounding. In other words, the power potential is different at each location on the stringbed.
Ingredient Two Revised: Location Speed
Second, the speed of the racquet is not the same at each point on the racquet. As you move from butt to tip, the speed gets faster and faster. The racquet as a whole swings in a giant circle, but each point along its length traces out a different size circle. Points near the handle or the throat trace smaller circles than those in the center of the strings or tip. For example, imagine the racquet swinging around the very end of the racquet. As you swing through any given angle, every point on the racquet sweeps through the angle in the same time (i.e., every location on the racquet, like each groove in a record revolving on a record player, travel the same revolutions per minute). However, the tip travels a greater linear distance than does a point farther toward the handle. In other words, the tip travels a greater linear distance in the same time as the throat, so it is moving faster. It is linear speed of the impact point that makes the difference in power.
For hits near the tip, we have more speed, less stuff. For hits near the throat we have more stuff, less speed. Said differently, near the tip we have a faster running start but less ability to bounce the ball, and near the throat we have greater ability to bounce the ball but a slower head start.
Ignoring the messy details, the maximum shot speed occurs at a point where the speed of the bounce plus the speed of the bounce surface add to a greater amount than any other combination. For most shots, this location occurs near the center of the strings to a couple inches above that — just where you are used to hitting. How convenient!
Here is the key point. It is the measured power potential in the location where you usually hit that is most important. A racquet with a higher power potential in that location will hit the ball faster than one with a lower power potential. The power potential tells all. It is a measurement of the combined performance contribution of every atom of the racquet to a particular shot situation. It is an absolute indicator of the racquet's structural contribution to the shot.