ProKennex Black Ace 98 + Syn Gut (16x10 Proportional)

I have unfinished business with this frame...

Initially, I bought this to experience how a comfortable frame ought to play and feel (link). After all, Pro Kennex is the epitome of comfortable frames.

Now, I am exceedingly curious how to "optimise" stringing for this very low-powered 18x20 racket, and add some control and spin as well. Power, control, spin and comfort are always squabbling.

I've tried many combinations (some are not posted in this blog):
- low tension (28lbs)(link)
- low tension box method (35lbs)(link)
- normal tension (55lbs)
- proportional stringing (reference tension 60lbs)
- proportional stringing (reference tension 50lbs)

But I could not get the right mix of the above four factors. Not to my satisfaction.

So I listed down some "problems" I had with this racket. When summarised, my dis-satisfactions were primarily:
1. too low-powered due to very flexible hoop/throat,
2. low-mid spin from dense string pattern,
3. possible directional inaccuracies due to flex.

To solve 1 & 2, conventional methods would be to drop tension. However, for this racket, I found that the hoop flexes a lot at low tensions but played stable at high tensions. I need to string tight to "hold" the hoop together. So that option is out.

From previous playtests, I know the sweetspot and my regular contact area on the stringbed is within the centre 8 mains and between crosses 5 to12 from the top. (See pic below)

This got me thinking, what if I "mess around" with the other strings that I use less of?

So, that's how I arrived at this 16x10 proportional stringing pattern.

The length and width before stringing are 34.7cm and 26.4cm (link).

Length and width after stringing are 34.5cm and 26.4cm. Distortion is amazingly low given the very soft and flexy hoop!

Playtest:
- I only managed to rally with this racket for about 15 minutes.
- The stringbed felt extremely comfortable and yet tight. There was a slight loss of control only for shots I believe was contacted in the gap between cross strings.
- I had anticipated this problem as I've tried skipping crosses before. So while stringing the crosses, I pulled and released tension several times to pre-stretch the string so it would hold tension better. I think it helped.
- Spin looks very good from my side but my partner claims it was ordinary. So that's debatable.
- Power was good. Not excessive nor trampoline like. It made volleys and swinging volleys easy, comfortable and accurate.
- Directional control was not bad. Out of about 10 shots I tried to aim down the line and crosscourt, I nailed about 7. Two misses coincided with a weird feel from the stringbed. It could be the ball "penetrating" the wide gap between the crosses. But the miss was not huge, maybe by about 2 feet?
- I tried light spin serves and was still able to place them quite accurately.
- The main takeaway from this session is how to mitigate the problem of the ball "penetrating" the wide gap. If this can be solved, I see a big potential for this setup. I'll let the strings settle-in and try them again next session.

05Aug2013 update:
- I always enjoy the second session of use for newly strung rackets. Somehow, the strings always perform the best on its second use.
- Tension felt as good as it did in the first outing. Tight and controlled would be how to describe it. Yet it was very very comfortable!
- I was early on court so I had about 10 minutes of practice serves. Both flats and spins were very good. Flats could be directed confidently and accurately. Spins were really spinny! Side spins easily curled 3 to 4 feet sideways as it entered the service box. Topspin serves kicked up almost 6 ft near the baseline.
- During warm-up volleys, the stringbed did not give any hint of skipped crosses at all. I thought I was playing with a normally strung racket with all strings filled. Control was surprisingly fully intact!
- I played a set and was leading 5-1 when it started raining and play stopped. Every aspect (serves, overheads, volleys, return-of-serve and groundstrokes) performed almost as well as my ultimate control stick which was strung with kevlar (link).
- My partner finally admitted this played more spinny than usual.
- The mains were tensioned proportionately starting from 50lbs. To equalize pressure in the crosses, increase overall control and also "stretch-out" the elasticity to improve tension holding, some of the cross strings were tensioned close to 80lbs! (Isn't it surprising that the frame distortion is so low?)
- During play, the mains move a lot and with very loud crackling sounds! Ball fur pic below...

- The only downside so far is severe notching. Total play is only about one hour so far... see pic below...

- This setup is very comfortable, controllable, spinny and fun! I like it!

07Aug2013 update:
- It rained overnight but stopped about 2 hours before my game. I wanted to push this stringbed to its limits to test if the earlier notching would break the strings today.
- I usually use pressureless trainer balls in wet conditions because they bounce a little higher. US Opens or Slazengers don't play well when wet. 
- Even with the heavy, hard and wet balls, the stringbed felt incredibly comfortable! I cannot think of any more challenging test for stringbed comfort than this!
- For baseline rallies, I had expected the stringbed to lose some control but it didn't. Control was exactly the same as when it was dry. 
- The ground was a little too wet to play a game safely so I decided to test control with flat serves. I hit about 30 flat serves at 80% power. 10 each down the T, middle of service box and the sidelines. 22 serves made it where it was aimed. Service is not my forte and I'm very impressed by the accuracy of the stringbed and racket. I have no doubts on this stringbed's control and accuracy anymore.
- Spin was still very good. Perhaps the wet balls fluffed up more than when it's dry, so there's more "grab", but there is substantially more ball fur on the stringbed today. Quite a few balls my partner thought was going out curled in and kicked up. Yes! Those wet heavy balls kicked up!!!
- The "ball penetrating the crosses gap" problem did not re-surface at all. Not even once!
- Notching got deeper. That was expected. But the string did not break however hard I bashed the ball. That was surprising!
- I think this setup can stay. I really like it!

10Aug2013 update:
- Just as I was wondering how much longer can this strings last, it snapped!
- I had used it for less than 5 minutes today.
- All together, this stringbed lasted me only about 3 hours of use.

Residual Elasticity (Part 1)

This is an update from my previous post on "Pocketing" (link).

Whenever I use new strings, the three most important properties I would investigate are the string's:
1. Elasticity
2. Resiliency
3. Deformation

The first two have been discussed in a previous post. (link) 

To recap, elasticity is how much the string can stretch, like a rubber band. Resiliency is how much of that stretch can be recovered when tension is removed.

Deformation occurs when the string has been stretched beyond its capabilities and is no longer able to recover to its initial length or shape. 

For example, a string with initial length of 30cm may stretch to 31cm at 50lbs. When tension is removed, it may recover to only 30.2cm. 

For that string, elasticity is about 3.33% at 50lbs 
((31-30)/30 x 100%).

Deformation would be that 0.2cm that cannot be recovered.

So far, every tennis player or stringer I speak to are only concerned with what tension to string. That's what I was accustomed to as well.

But after studying the three properties mentioned earlier, my thoughts are, what if we string rackets based on managing these three properties?

I thought that would be a very revolutionary way to string!

In fact, I've already done a few stringing experiments based on managing these three important variables. So far, the results are promising.

Let me recount one which I thought can be considered as an acid test of this "theory".

I re-used natural gut and synthetic gut!

When both strings were new, I recorded detailed measurements to understand how their elasticity and resiliency would change with use.

The numbers were then compared after the strings were used. 

Depending on how much elasticity and resilience has deteriorated, I would lower the tension accordingly so that the "residual elasticity" after stringing would match or be close to when the string was new.

Here's some pics of the re-used gut and syn gut as a hybrid at 25/23.5 lbs. It's a straight-forward 2 piece job. Nothing fanciful.

Playtest:
- The racket was tested less than 24 hours after stringing so the stringbed was still fresh and tight.
- Initial hits are very promising. The strong rebound of the natural gut was unmistakable. No trampoline!
- Surprisingly, control was still intact and did not differ very much compared to new strings.
- Comfort and feel was surprisingly still very good despite the re-used syn gut. There was no trace nor any hints of the gut or syn gut playing dead or lifeless at all. 
- All of my playing partners who tried this racket commented on how "fresh" and lively this setup played. None suspected re-used strings nor the super low tension of 20+ lbs!
- After about 45 minutes of rally, I can feel tension loss creeping in. Pocketing from the natural gut became deeper and I felt more and more of the gut doing the "work" alone. The syn gut has lost too much tension.
- Another problem was the huge difference in speed of resilience between gut and syn gut.
- The tension after play was measured by frequency. Tension loss was estimated to be about 2.5lbs. I cut it out as the differential between mains and crosses became too large. (Tension loss from gut is about 5% and syn gut about 15%, so the initial 25/23.5 lbs could have become 23.75 and 19.98 respectively. The differential widened to almost 4 lbs from 1.5 initially!)

And what did I do after I cut the natural gut out?

Here's some pics of the natural gut re-used again in the same racket. This time, a set of fresh syn gut was installed using the box method. Tension was 33/35 lbs.

After completing the mains, I rubbed some coconut oil on the natural gut to lubricate it as it was quite dry. You can see the gloss on the strings.

Boxing...

Playtest:
- To me, the ultimate test is to play a game with an equally strong partner. I did just that today with M.
- When warming up, I could already feel the potential of this setup. It is like a sports car, where the harder you hit, the better the control.
- The stringbed was nice and tight but delivered very good spin and power. 
- With gut, it is almost always comfortable, so I will not delve into that.
- Both first and second serves were very good. Flats were accurate and powerful while spin seconds were curving well already in mid-air. A few were so spinny they kicked off M's stringbed upon contact and flew out. I had a few aces too.
- Even after about an hour, the tension held. I arrived at 33/35lbs based on residual elasticity and also projected tension loss of 5% and 15% for gut and syn gut respectively. If correct, then it should stabilise around 31.35/29.75 lbs with a 1.6lbs differential, which is what I wanted.
- I won the set 6-0 with this setup, and it is a 80 sq inch head size!
- This setup is good and I like it! Ball fur pic below.

29Jul2013 update:
- Played a set with this racket today.
- Control is remarkably good. Both serves and groundstrokes that I hit well were delivered very accurately.
- Even spin serves had a little more pace due to the fast rebound and power of natural gut.
- I could not feel any difference in tension from my last game and it was confirmed by my frequency meter the tension change since the last game was less than 0.5lb!
- Perhaps due to the heavy spin I was attempting, I noticed more fraying that could have occurred today.
- I estimate this gut has been in play for 40-50 hours.

Yonex RD7SP-UL2 + Syn Gut @ 60lbs (Proportional)

Following on the success of full proportional stringing of the Dunlop M-Fil300 (link1)(link2), M could not resist having his RD7 (link1)(link2) done the same way too.

As usual, he wanted to change only one variable at a time so he decided to start with a reference tension of 60 lbs, and test how it would play on the RD7.

With different tensions applied on different strings, frame warp comes to mind. So length and width measurements are taken before and after stringing to monitor if changes are within tolerances. If the measurements change too much, I will cut out the strings and re-string.

Length before and after are 34.0cm and 33.9cm respectively.

Width before and after are 25.6cm and 25.2cm respectively. Still within my limits.

Here's a pic of the last string being tensioned.

Playtest:
- M likes this 60lbs proportional stringing.
- From my receiving end, I can see that initially he had some problems with the stringbed rebound angle. It is vastly different from ELT which gives a much higher rebound. So, a lot of his practise serves and groundstrokes could not clear the net.
- In less than 10 minutes, M has adjusted to the new string tension.
- We played a game to determine how M would perform with proportional stringing.
- The massive spin from ELT disappeared. His serves and groundstrokes were back to those "normal" spin days. None of his serves "kicked off" at odd angles when it hit my stringbed. 
- Most of his shots were flatter compared to the previous loopy curving path that the ball used to take.
- Power has definitely increased. His shots were all harder and deeper although quite a few went out due to the lesser topspin.
- Control increased a lot. His drop shots are so accurate it cleared the net by mere inches! Even most of his volleys were very confidently directed and landed only inches away from the side lines.
- Given this is only the first session after stringing, it is still preliminary to conclude whether ELT or 60lbs proportional is better. Clearly, each has its merits.

19Jul2013 update:
- It is an understatement to merely say M's control increased.
- His accuracy with this stringbed gave him so much confidence to go for the extremities on court. Deep crosscourt baseline shots I hit were dropped crosscourt at the net so accurately I could not even get to the ball!
- His volleys from mid-court sent me from extreme left to right over and again. And I was already keeping my shots low, clearing the net by 8-10 inches at most!
- Somehow, with deliberate brushing, M was still able to summon extra spin at will. He did that on second serves and baseline topspin shots. It was still little spin compared to ELT though.
- This is the second session of use and the strings have developed a dark patch of wear on the sweetspot and also started to notch.
- Durability and tension holding is the next thing to watch.

A close-up of the notching below.

The Problem with Electronic Tensioners

I get asked very often why didn't I "upgrade" my stringing machine (link) to an electronic model. Why struggle with manual tensioning, flipping that tension arm up and down dozens of times per racket? 

My answers are dualfold.

First, I am not a commercial stringer and have little interest stringing for other people. In fact, I do not even enjoy stringing rackets except for my own frames.

Second, dropweight machines are incredibly accurate, reliable and consistent. Among the three types of stringing machines (dropweights, cranks and electronics), dropweights are the most reliable and accurate.

Hard to believe? After all, electronic tensioners have been around for decades! Surely the technology is developed, proven and stable? Moreover, all the professional tour players' rackets are tensioned electronically! 

Or I must be comparing the dropweight with some cheapo, DIY home-made electronic tensioner designed by some third world country's technology?

Nope!

Read for yourself:
http://tt.tennis-warehouse.com/showthread.php?t=394502

http://tt.tennis-warehouse.com/showthread.php?t=309117

http://tt.tennis-warehouse.com/showthread.php?t=298995

http://tt.tennis-warehouse.com/showthread.php?t=201369

http://tt.tennis-warehouse.com/showthread.php?t=413893&page=2

http://tt.tennis-warehouse.com/showthread.php?p=6930240

http://tt.tennis-warehouse.com/showthread.php?t=452572&page=3

http://tt.tennis-warehouse.com/showthread.php?t=323567

http://tt.tennis-warehouse.com/showthread.php?t=441450


Very few people know about the tension overshoot problem with many electronic tensioners. Since all strings have elasticity, the tensioner would keep adjusting to try to maintain constant tension. 

The repeated over-pulling and over-releasing either "kills" the playability of the string or causes a very loose stringbed, depending on when the strings are clamped.

Observe the stringer when you next pass by his shop. Watch and listen to the electronic tensioner head "zipping" back and forth continuously when the tension button is pressed. The problem is worsened if the pull speed is set to fastest.

So far, I only know of a few electronic machines that does not have the overshoot problem:
1. Wilson Baiardo
2. Babolat Star 4
3. Yonex ES-5

If you have only played with rackets strung electronically, try the exact same string at the same tension strung using the same stringing pattern with a dropweight!

Feel the difference. The strings will play livelier, softer and last much longer too!

Pocketing

Other than swingweight (link), the other aspect I pay most attention to is pocketing.

Pocketing is how much the stringbed depresses upon contact with the ball. It is not the same as dwell time but they are inextricably linked. Deeper pocketing translates to longer dwell time.

Many focus on stringbed stiffness, which is a measure of how much the stringbed depresses per unit of weight. I think the concept is very similar, except that the level of pocketing I enjoy only appears with ELT. I don't even get that much from natural gut!

Why pocketing?

I tune swingweight based on (in order of priority):
1. how maneuverable I want the frame to move,
2. how stable and stiff the racket is,
3. how heavy most of my opponents' shots are,
4. how deep am I hitting most of my shots from the baseline.

Primarily, swingweight adjustments take care of speed, power, flex, stability and depth.

Pocketing deals with the feel, comfort, rebound angle, accuracy and most importantly, the amount of spin. Deeper pocketing equates better grab which means more spin!

And more spin means better accuracy and control.

So far, factors determining pocketing seems to be:
1. type of strings used,
2. tension applied,
3. type of stringing machine used.

I have been experimenting various methods of stringing to try to maximise pocketing while maintaining control. I will post an update if I find something interesting or promising.

Swingweight Addiction!

Whenever I see someone examining a new racket, the first, and almost the only aspect they talk about, is weight.

There seem to be a wrong association between a racket's weight and performance. 

To me, swingweight is paramount. Not only in tennis, but baseball bats, golf clubs and hockey sticks as well!

Swingweight determines power, affects racket flex, stability, string tension, plowthrough, impact feel, pocketing, racket balance, swing timing and many more.

Here's two excellent articles I found online:
1. Swing Weight of a Bat (Why MOI matters more than weight)
2. Tennis Racquet Weight. Does it Matter?

As a recreational player, I mainly play topspin from the baseline. Occasionally, I would change styles and do some serve and volley plus drop shots. I play both singles and doubles friendly games.

Naturally, as a baseline-basher, I like heavy sticks. Most of my preferred rackets are about 370g. A few are just shy of 390g.

It's not a conscious act. I did not go out to search for heavy sticks nor add lead till I hit my "target". There was no target weight in the first place. It was all based on feel.

So I gradually increased lead until I felt it was a little too heavy, then I backed off, removed a few grams and stopped there. It's something like the swingweight1 and swingweight2 concept. (link)

However, I did not test out my adjustments thoroughly enough. What worked well for baseline-bashing was disastrous for doubles volleys. And my heavy sticks tend to make me hit too hard for drop shots, turning them into sitting ducks in mid-court!

During crunch time, attempts to hit faster serves resulted in the racket swinging my hand instead of my hand leading the stick! And in very fast doubles volley wars, my wrist bears the full wrath from off-centre hits!

TFCC (link) crept-in. It was painful and I had to stop. Fortunately, I detected it very very early. Recovery was very fast. I was up and running in two weeks.

If you are baseline basher and like the powerful plowthrough of heavy rackets, remember to have a lighter setup for those other tennis shots you rarely play.

In case you are curious, the average swingweight of my baseline bashing sticks is about 375 kg-cm². I have since brought it down to about 340-350.

High swingweight is extremely addictive! Please play with care!

ProKennex Black Ace 98 + Syn Gut @ 28 lbs

After some calculations, I decided to restring this racket at 28 lbs. From the last few sessions, pocketing was missing and I wanted more (link).

While cutting out the strings, I noticed the frame moved a lot. There was plenty of "crackling" sounds. 

When the mains were cut, the racket "popped" and lengthened, pulling the cut mains string wide apart.

The same "pop" was experienced when I snipped the crosses. 

Immediately, I understood what was that "missing element" I was searching for in my last post! The hoop of this frame is extremely flexible!

So soft, that the hoop flexes not only during ball contact, but even during stringing! And that's where all the cushioning and dampening came from!

I have never used a racket with such a soft hoop. Not even some of the old woodies I had, nor the RA54 Yonex RD-7. That's why I could not understand this stick.

The downside is, with so much flex in the hoop, the cushioning absorbs a lot of feel and power as well. Upon contact with the ball, the racket bends backwards much more than stiff frames. 

All the pieces are coming together. Now I understand why I always miss the line to the right whenever I try to aim down the line. It's because the racket flexed more than what I am used to!

To "counter" this flex, I want a softer stringbed. Think about it, if the stringbed deflects more upon ball contact, then the frame would bend less.

I am not "boxing" the stringbed this round. Since the hoop is so soft, I will keep it simple to avoid any possible distortions.

Width before and after stringing is 26.4cm and 26.1cm respectively. Hoop narrowed by 3mm.

Length of hoop remained constant at 34.7cm.

Playtest:
- After a little play, I adjusted the swingweight down to about 340 from 345. Since the sweetspot is just a tad above the middle, I wanted the lead tape lower to be aligned with the sweetspot to add more mass there. That would "stiffen" up the hoop slightly through added stability.
- At 28lbs, the racket plays better than the previous 35lbs. Control and spin are still there.
- There is absolutely no trace of trampoline at all. Just a little bit more pocketing than at 35lbs.
- The 18x20 configuration is amazingly stable even at such low tensions.
- Needless to say, comfort and dampening reigns supreme in this racket.
- Since this is only the first session after re-stringing, I will post a more detailed review after the second or third use with this stick. Let the strings break-in first.
- If you cannot imagine a soft hoop/frame flexing during ball impact, take a look at the video below of Federer's forehand shot at 1:16.

06Jul2013 update:

- Used the BA98 for some drills and rally today.

- The previous "wobbly" frame feeling has gone. With the added lead tapes, I cannot feel anymore of that weird impact I felt previously.

- Overall, I added about 15 SW points, bringing the racket's swingweight to 346. Now, ball impacts are stable and I can feel the racket "going through" the ball instead of the ball pushing the racket off-balance.

- With the added "punch", ball impacts sounds much nicer too. It is now a "pop" instead of a "thud". Another confirmation that plowthrough has improved.

- From the previous string wear pictures, I know I am hitting the sweetspot consistently enough so it cannot be due to off-centre hits that cause the unstable feeling at almost every shot last time.

- Spin is good despite the 18x20 pattern as the gaps are quite big.

- Comfort is very good. Nothing to worry about even for injury prone wrists or elbows at all.

- If I want to continue fine-tuning this frame, the next challenge would be control. Not that it is bad now, but I want a greater degree of confidence when aiming for corners or down the lines. With this, my success rate is probably 6/10 whereas my stiff PSC6.1 can easily score 8/10.