When the discussion is about stiff polyester string, it will always include the word “hybrid”!  Typically this word is used to convince players that by putting a “soft” multi-filament string in the cross position the string bed will be easier on the wrist, elbow, and shoulder.

Intuitively this makes sense, but in reality, the reverse could be true!

I began analyzing hybrid string beds years ago and did many just to test the theory. At the time it did not seem so important because, frankly, the use of polyester based string did not approach the usage of current times.

I have nothing against the polyester string(s)! I do have an issue with bad applications of polyester string(s).

I am bringing this up again because recently an “interviewee” stated that that replacing the polyester cross string with a multi-filament would cure the ills of a very stiff string bed.

The bottom line:

A high elongation string of any material can increase the string bed stiffness of a hybrid string bed!

How can this be?

Stiff (polyester) strings are “stiff” and the tension applied to them during stringing is low. However, high elongation (multi-filament) strings will be influenced more by tension and become “stiffer”.  The cross stings are typically shorter, and there are more of them, so the combined affect is stiffness.

The initial reaction to this conundrum is to automatically reduce tension on the cross string by a certain amount. Again this raises another issue, and that is racquet distortion.

During the installation of the main strings most stringing machines will allow the racquet to become wider, sometimes a lot wider! So, reducing the cross string tension may not return the racquet to the designed shape. What happens then is the racquet will continue to move around trying to find a “safe” place and therefore the string bed stiffness changes.

In summary, the hybrid string bed will not be statistically different than the full string bed of polyester. This is even truer if the initial string tensions of the polyester are very low, such as 35 to 40 pounds.

So if you feel the need to use polyester just go with lower, lower,  tensions.