Racket length
There is not much to say about racket length. It essentially just increases swingweight, without adding extra weight. We can see that from the equation for swingweight (1).
\(I _{p y}=\sum ^{n}_{i=1}\left( m_{i}\left( r_{i,y}\right) ^{2}\right)\)
(1)
The distance r of mass from the axis of rotation is increased so the swingweight increases also. Another benefit from extra length is more reach, which is especially helpful on the serve. An extra cm or two can mean a lot on the serve, but we also have to keep in mind that maneuvrability suffers from extra length, which is generally not good for the serve.
Another interesting thing with the extra length is that we get extra stability and we can achieve high swingweights with low mass and a depolarized racket.
The downsides that come with extra length are, as mentioned, reduced maneuvrability which is quite obvious, and also the loss of control. Every movement we make with our hand is transferred through a longer lever on to the racket head.
There are options to extend the racket. Every 0,25 inches or 6,2 mm of extension, adds about 10 SW points.
Go to how to extend a tennis racket to learn more.