String Tension and Effect on Racket Stability

In the past few weeks, more than a few very good players have asked me to add more lead to their racket hoops. 

All wanted a little more stability, especially when dealing with heavy balls, or when returning hard first serves.

Most of these folks already have their swingweights in the 320s to 340s region. So I thought it was decent enough.

After reviewing some of their shots in question, it seemed to me that the problem was a little more string related than racket.

Most were using stiff frames of RA68 and above. All were strung with full poly above 50 lbs. To me, that was the problem.

Let me explain...

Playing tennis is managing a series of collisions between stringbeds and a tennis ball. When both the racket and stringbed is very stiff, and the ball is new, hard and bouncy, where does the energy dissipate?

Some of the impact energy would be absorbed by the racket, stringbed or tennis ball. But not all. So the racket, deflects backwards or twists and turns. And the ball compresses too.

I have posted this slow motion video of Federer's racket wobbling on impact. Here it is again. Take a look at 1:16 in the video below. That's the racket flexing and absorbing the energy on impact. 

Stiff frames with tight strings would always be less stable than softer frames, or when strung looser.

To prove the point to an unbelieving player, we beefed up his stiff racket (with tight strings) to 365 swingweight, total weight about 360 grams and balance 32.5 cm. Then got him to try returning first serves from his coach.

Same twisting. Same instability.

Eventually, he moved a gauge up to a slightly thicker string to compensate for a slight drop in tension and obtained his desired stability.

Some may claim the thicker string added weight as well.

Yes it did.

Merely 2 grams.