Grips
Grips and handles are perhaps the least talked about »parameters« but there are 3 characteristics that need to be considered. Grips vary between sizes, shapes and butt cap flare shape/size.
Grip sizes
I don’t believe in such a thing as a »correct grip size«. You play what you are comfortable with, but obviously, if you can’t manoeuvre the racket you might want a bigger grip. The main parameter to consider along with the grip size is twistweight. Because twistweight is the moment of inertia that we have to overcome by applying the torsional momentum on the grip. Rafael Nadal is notorious for his small grip (for his big hands). He is able to get away with it because he uses a low twistweight racket. Let’s take a look at the equation (1) which is basically the rotational Newton’s law.
\(M=I\cdot \alpha\)
(1)
In the equation, M is the momentum or torque that we have to apply to the racket with the moment of inertia I, to accelerate it with angular acceleration \(\alpha\). In our case the moment of inertia is TW, and we can write down the torque as the product of the force F (force of the hand) applied on a lever r.
\(F\cdot r=TW\cdot \alpha\)
(2)
We can see that if we want to accelerate the racket face with a constant angular momentum and we raise the TW, we either have to increase the force of the hand or increase the lever (grip size).
Grip shapes
In general, there are 3 grip shapes as shown in the picture below.
The grip shape A is most commonly used. The top and bottom bevels are a bit longer. Grip shape B is also called »flat-topped« and grip shape C even sided. Grip shapes are mostly just a preference, but it can be frustrating to change rackets when they have different grip shapes and that is the only reason I have ever done a grip shape modification. It’s a common practice for professional players to have custom made handles when they switch racket manufacturers. They usually stick with the shape they played before. I have come across some theories that grip shape B should help the palm to rest on the longer bevel better when using the western grip. Maybe one day I will dig deeper into grip shapes, but for now, this is it.
Butt cap flare and shape
One thing that does have an effect on performance is the butt cap shape. A big flare, for example, provides extra leverage when holding the grip. You can grip the handle lover and with a looser hand. A good example of this is Gasquet. It’s also common for players who switch racket manufacturers to use more flare. Yonex is notorious for their »straight« grips with almost no flare. For example, Wawrinka switched from head to Yonex later in his career and he uses a similar method to get more flare on the butt cap as shown in the video below.