Racket Flex and String Tension Preference

Many users of very flexible frames like to string very tight. 

The most common reason was to improve accuracy and that they enjoyed the feel of the racket flex. When strung at normal tensions, these folks claimed the frame stopped flexing.

Out of curiousity, my friends and I tried stringing some very flexy frames (RA 50s) to investigate the flex response.

Tight (75 lbs)
Both the full poly and the full synthetic gut felt like a board. 

The stringbed was so stiff and tight we did not feel any string pocketing at all. 

However, impacts did not feel harsh as we could clearly feel the racket flexing on impact. 

Contrary to the beliefs about stringing it tight for greater accuracy, all our shots suffered some loss of directional control. Some forehands leaked to the right and backhands leaked left. It felt like our timings were slightly late and off.

We tried "swinging" the racket and "arming" the racket. (link) Well connected sweetspot hits felt nicer but it was still boardy, extremely low powered and inaccurate.

Neither could we generate any decent spin. Not even slices.

Serves were pathetic. No power, no pace, no spin, no height and plenty of double faults!


Normal (55 lbs)
This was near our usual tensions so everything felt familiar.

It was comfortable, spinny, accurate although still a tad low powered.

It was interesting to note that when we had sufficient time to prepare, step into the shot before "swinging" the frame, there was a very powerful delivery. The string and racket flex worked in unison.

Even when we were late, on the run and half-muscling through the shot, we were able to partially load the strings before flexing the racket.

After hitting with this, we discovered what and why we did not like about the racket flex earlier with the tight tension. 

Whenever it flexed, power was absorbed by the frame. The energy that was incoming from the ball, and the energy which we threw into the forward swing, was heavily dissipated by the racket flex. 

And before the flex could rebound, the ball has left the strings. Hence the very low power and poor directional control.

Swinging worked much better.


Loose (35 lbs)
For this tension, we chose a stiff poly string and strung it full bed.

The first thing we noticed was the extra huge sweetspot. It was so forgiving we thought we were using an oversized racket!

The second thing that impressed us was the abundance of power and spin. A huge increase over the normal tension.

Along with this was the ability to load and pocket the strings. With the added advantage that the harshness of any off-centred shots would be safely cushioned by the racket flex.

At this tension, the usual downsides were the high rebound angle of the stringbed and some light string buzzing. However, this had nothing to do with the racket flex. It was a common problem across all types of racket frames.

Most distinctly, we did not feel much of the racket flex.


Conclusion
Among the three, we preferred the one lowest tensioned. 

However, for practical play, mainly to mitigate the high rebound angle, we would string somewhere around the mid-40s lbs, depending on strings.

What we unanimously agreed was:
(1) flexible frames felt superior to very stiff frames,
(2) flexible frames are very demanding to wield properly, and
(3) stringing flexible frames loosely made them much easier to use for recreational players as it was much better to load the strings than to flex the racket.




     

Measuring String Left in Reel

Most who favour a particular brand of strings end up buying reels. 

However, many of my friends still get caught not knowing how much string there is left in the reel.

Depending on the brand, gauge and type of string, the more common strings weigh between 15 grams to 20 grams per set of 40 ft. It is easy to use weight as a proxy to estimate how much string there is left.

Below is a partially used reel of poly a friend handed to me. It weighs 331 grams.

He wanted 3 rackets strung with full poly, so I cut out 3 sets of 40 ft each, total 120 ft of string from the reel.

That left me with 275 grams.

The simple calculations that follow:

120 ft of string weighs 56 grams (331-275)

Each set of 40 ft weighs ~19 grams (56/3)

This full reel of strings only should weigh ~308 grams (56/120 x 660)

So when you next buy a new reel, measure and record the weight of the entire reel before using it. You will have a better idea how much string there is left.

     

Fastest Way to Increase Spin

Almost everyone wants more spin!

If I were to estimate, among all those whom I have worked with, about 80% wanted more spin. 

About 15% asked for comfort as top priority since they had some sort of pain in their arms.

Only a few (<5%) asked for more power or more control.

What these spin-obsessed folks did not realise, was how paramount power was to generating spin.

Let me make this statement boldly:
To achieve more spin, you have to obtain more power first!

The very nature of hitting topspin is inefficient. Compared to a flat shot, topspin robs power. 

And in many low to intermediate players' quest for more spin, they end up swiping the racket almost 60-70 degrees upwards. That further reduces the amount of forward drive they put into the ball.

Sometimes they get a lot of spin, but it is a sitter. It does not kick forward.

A simple visit to the physics classroom to understand the resultant force under "Vectors" easily explains why. (link)

If you search youtube videos of Federer or Nadal, or any other pro player, you will see their follow through is only about 30 degrees upwards. That's all they need to achieve their 3000+ rpm on their forehands.

If you observe carefully, their shots usually land near the service line and then kicks all the way to the baseline. Average net clearance was only about 60cm or so.

So how should amateurs and wannabes like us hit topspin?

Simply:
- keep the net clearance low (max 60 cm)
- smack the ball hard with a shallow 30 degrees follow through

Of course many other factors play a part, including:
- string type,
- string tension,
- racket flex,
- racket hoop size,
- racket string pattern,
- type of balls,
- court surface,
- swing timing, 
- footwork, etc

From my observations and experiments, power is the most critical and most neglected factor.

Specifically, swingweight.

When matched with the player's strength and abilities, this single variable has the most direct and strongest correlation with how much offensive kicking topspin he can generate.

All other spin factors have a poor correlation.




     

Babolat AeroPro Drive (2007)

I'm late to the Babolat party...

On many occasions, I tried different versions of the APD on court. It is such a popular racket that someone would surely show up with it.

However, this time I set aside my own and hit exclusively with the 2007 APD for about 20+ hours. Both to test the racket and some exotic strings which would remain unknown.

While the specs (link) may claim a total weight of about 320 grams with 324 swingweight, the one I tested was 330 grams strung and gripped. Swingweight was very close to 330.

Not a big deal to me since I am no stranger to heavy sticks. (link)

Strangely, this APD felt slow and unwieldy. My timing was late. Everything including serves, serve returns and forehands. I could not understand it. It felt like I just finished the ironman triathlon minutes before playing tennis.

Naturally, I ended up arming/muscling the racket through. But I was still late. And the power threw my control haywire. I could not control the ball depth nor direction!

After struggling like a clown, my NTRP 4.5+ friend, a decade-long APD user, chuckled and pointed out the "secret tip" to me...

"It's a swinger's stick... try standing further back..." he said. (link)

Ahhh....! Then I got it! My forehand and backhand started falling in place. The loud "thwack" of the ball impact on the full poly stringbed sounded and the spin started kicking. 

Serves took a little longer to get in tune as I had to adjust my toss and timing so I could "throw" the racket at the ball. 

Once attuned, I aced a few second serves. The spin turned the ball down when all four of us thought it was flying long. Then kicked forward to catch the receiver totally off-guard. Certainly not something I normally delivered.

I became very impressed by the APD. Just loosen up, grip down, start the foreward swing a tad earlier, and enjoy letting the release of the wrist-hinge slap through the ball. So effortless!

As long as I was early with both footwork and racket prep, sweetspot and near-sweetspot ball impacts felt plush and comfy. There was no hint of any frame stiffness at all. (Of course, the secret string played a part!!!)

Conversely, when I was late, like under attack or read the ball wrongly, the APD was very demanding to move. 

Like I had stacked too many plates on the barbell. Attempts to direct the racket at this stage meant a stiffening of the grip pressure. This engages the forearm and biceps while locking up the wrist. 

Instinctive, but very wrong and deadly move!

The punishment for this was the full, jarring impact of the ball landing on the hand, wrist, elbow or shoulder. Especially with the lack of racket momentum to buffer the incoming "punch" from the heavy ball.

It was nasty!

Another issue was power.

When I was in full balance and contacted out front, I could unleash the full swing, load the stringbed well, and let the topspin keep the ball in the court. When late, the power was too much.

To curb that power, many tightened up the tension. Or selected a much stiffer low-powered string. Then they ended up "arming" the ball even more. 

Disastrously, that was how the APD destroyed several of my former playing partners' elbows.

The polarization of weight in the APD is so deceptive. It fooled me and many into thinking it was fast and easy to maneuver. But it is not.

Don't be deceived. In my opinion, the APD is a player's frame. Beginners like it for it's easy power so learning tennis becomes faster. 

However, it is a very demanding frame that expects good read of the ball, fast footwork and very early swing prep. Without which, it could cause some serious havoc with the player's arm.

Now I understand why many deemed this the indisputable "arm killer".

Play safe!