In praise of Kevlar/ZX hybrid!!!

jumper67

New User
As much as I enjoy the Kev/ZX, and with so many posts in the thread. I have yet read about the SM reading from users. I confess I use SM for all my string job. And have not found high differential stringing resulting in actual high differential in strung main/cross string. The main remains low that's what I found when cross string is strung low. Just saying.
Sorry to stir the pot again.
Here you go. I just had my strings done at 70/45 using the Crossfire ZX. I pre-stretched the ZX about 18". No pre-stretch of the Kevlar was possible, but I requested the stringer to pre-stretch. He said the kevlar doesn't usually stretch any, but he'll try. This is in a Prince TT100p 18x20

I forgot to check before playing, so these StringMeter readings are after 1 hour of hitting. SM says the mains are 17g and the crosses are 16g

Mains from left to right:
32,55,70,71,72,64,56,53,44,43,51,51,60,63,68,66,51,27

Crosses from top to bottom:
31,34,34,33,33,32,30,31,29,30,30,31,30,33,32,32,31,31,29,19

I find it strange that the main tension is so low in the middle by the sweet spot.. Whereas the outer strings are very close to the 70 lbs requested. Do you think the lower middle mains is due to 1 hour of hitting?

The crosses are consistently reading ~ 30 lbs, despite requesting at 45 lbs. Maybe the ZX is stretching even futher past my pre-stretch. But no loss in the center there after 1 hour of hitting.

The feel of the racket is substantially different compared to before the new string job, where the kevlar was about to break. The tension must've been so low, because I have to completely re-adjust now. Previous strings were approx 5 months of playing ~2 times a week.
 
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Here you go. I just had my strings done at 70/45 using the Crossfire ZX. I pre-stretched the ZX about 18". No pre-stretch of the Kevlar was possible, but I requested the stringer to pre-stretch. He said the kevlar doesn't usually stretch any, but he'll try. This is in a Prince TT100p 18x20

I forgot to check before playing, so these readings are after 1 hour of hitting.

Mains from left to right:
32,55,70,71,72,64,56,53,44,43,51,51,60,63,68,66,51,27

Crosses from top to bottom:
31,34,34,33,33,32,30,31,29,30,30,31,30,33,32,32,31,31,29,19

I find it strange that the main tension is so low in the middle by the sweet spot.. Whereas the outer strings are very close to the 70 lbs requested. Do you think the lower middle mains is due to 1 hour of hitting?

The crosses are consistently reading ~ 30 lbs, despite requesting at 45 lbs. Maybe the ZX is stretching even futher past my pre-stretch. But no loss in the center there after 1 hour of hitting.

The feel of the racket is substantially different compared to the strings I previously had, where the kevlar was about to break. The tension must've been so low, because I have to completely re-adjust now. Previous strings were approx 5 months of playing ~2 times a week.
I think the middle mains are looser (for now) because the frame can deflect a lot more there than near the edge.
 

tennisbike

Semi-Pro
Thank you. Finally someone has SM data to share. Good for you. Now you will begin to observe the numbers. Few people are dedicated enough to learn from using SM. Too bad you do not string your sticks.

By the way, you did not describe how it played. You should have an subjective impression that goes with number and spec.
.. 70/45 using the Crossfire ZX. I pre-stretched the ZX about 18". No pre-stretch of the Kevlar ...after 1 hour of hitting. SM says the mains are 17g and the crosses are 16g

Mains from left to right:
32,55,70,71,72,64,56,53,44,43,51,51,60,63,68,66,51,27

Crosses from top to bottom:
31,34,34,33,33,32,30,31,29,30,30,31,30,33,32,32,31,31,29,19

I find it strange that the main tension is so low in the middle by the sweet spot.. Do you think the lower middle mains is due to 1 hour of hitting?
Yes, but ..
My theory is that the section outside the grommet got pulled inside as the center strings got hit. Now when I string Ashaway Kev I would press down main strings from #2 to outside sequentially to stretch that section. The other use is to increase center main tension to achieve a kind of proportional effect. With SM you can tune the tension gradient across the main strings as much as you like.

crosses are consistently reading ~ 30 lbs, despite requesting at 45 lbs. Maybe the ZX is stretching even futher past my pre-stretch. But no loss in the center there after 1 hour of hitting.
What you describe is perfectly normal for a regular FB sg, multi, poly without differential. I suggest you use the SM to check your friend's sticks. You will see the pattern.

I have been saying that although Kev/ZX last a long time on a stick, but the playing characteristic DOES change. If you track the SM over time the trend is very obvious. The change continued and did not seem to stop. But because Kev is so muted, somehow it would still be playable.
 
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jumper67

New User
Thank you. Finally someone has SM data to share. Good for you. Now you will begin to observe the numbers. Few people are dedicated enough to learn from using SM. Too bad you do not string your sticks.
I've tried the Racquet Tune mobile app in the past, but could never get consistent results. I like the Stringmeter better

By the way, you did not describe how it played. You should have an subjective impression that goes with number and spec.
It was hard to judge how it played, because I played so poorly. A lot of my shots were hitting the bottom of the net. Other swings that I thought would go way long, ended up dropping in. The strings felt so tight. But my last job I also got done at 70/45. My only conclusion is that before getting them re-done, the strings were so so so loose. The kev/zx must have lost so much tension by the end of those 5 months. We'll see this time. Now I can measure with the Stringmeter.
 

tennisbike

Semi-Pro
From Jumper67's SM number:
Mains from left to right:
32,55,70,71,72,64,56,53,44,43,51,51,60,63,68,66,51,27

I really hate seeing over 10 lbs difference between adjacent strings. And then between 70 and 44 lb, oh my god 26 lbs difference. Mine had similar pattern 60 to 44 lbs right off the stringer. I redid the cross in about a week. While the cross was out, I "walked" the main strings so that the spread is like 60, 63, 58|61, 63 in the middle and I took out the peak on 5th and 6th main. Quite surely the main tension went down as the play hour mounted. Free string tension, after tuned was 23, then 20, finally about 10 lbs. When I restring, I slowly increased the cross tension. Original ZXP cross was at 45, then 51, broken, then poly at 53 then 50 lbs. I played that stick from July 2019 to Apr. 2019.
Lastly, when I got bored, I cut out the cross and cut the Kev. in the middle and restrung it with SG cross. The Kev. main was very short so I had to do funny clamp dance to fill the SG onto the last side main. Did not like the tension on the last Kev. main. Now this stick just sits in the pile. Got too many sticks to mess around with.

At the end, it is not that Kev. stretches out a lot, but any tiny amount of frame flex can lead to a large amount of tension loose on the Kev. Again if you are sensitive about the setup, Kev/ZX is a finicky one to get spot on. If you just want something to last, this can be the one. But if you do not play the stick much, it will last forever. Well, anything string would last forever if you do not play it.
 

2nd Serve Ace

Hall of Fame
That last paragraph is correct in observing that the bend of the frame is greatest at the top of the hoop and therefore reducing tension on the middle mains more.

I would suggest staying with 60 for the mains next time and seeing if your stringer will start middle out on the crosses. (50/50 method)
 

jumper67

New User
At the end, it is not that Kev. stretches out a lot, but any tiny amount of frame flex can lead to a large amount of tension loose on the Kev. Again if you are sensitive about the setup, Kev/ZX is a finicky one to get spot on. If you just want something to last, this can be the one. But if you do not play the stick much, it will last forever. Well, anything string would last forever if you do not play it.
So then what's the solution?
 

tennisbike

Semi-Pro
So then what's the solution?
It is going to do what it is going to do. You cannot have the cake and eat it too.

I have described what I know about this Kev/ZX setup. My limited experience consists of using one set of CrossFire Kev/ZX with multiple cross repulled. I wonder how pre-stretched Kev/ZX will perform over time. I suspect the change might be more gradual but will be continuous as my experience. People who pre-stretch had not shared out any SM observation over time. The strung string bed plays stiffer at first, break in and continue to change. If you got used to it after broken in, you will probably enjoy it for a long time. If you cannot "connect" with it, tweaking the setup may get you there. Or maybe you will not like the setup.

We know that each string change over time, racket flexes.. but our hand, our body also change too. You may be in love with one particular setup/stick, but at a different time with a different you, love may not be there. It is .. life!
 

tlm

G.O.A.T.
Just got back from hitting with Ashaway Kevlar 18 gauge at 58lbs. with ALU power 17 gauge at 58lbs. and it played very good. Great spin and control and in my Clash it felt very comfortable too. This set up was with no pre stretch so I will see how long it plays well.
 

jumper67

New User
Now you will begin to observe the numbers.
Ok so I took more StringMeter readings, a week later, after 3 days of approx 2 hours of play each.

First readings from last week, after 1 hour of play (initially requested to be strung at 70/45):

Mains from left to right:
32,55,70,71,72,64,56,53,44,43,51,51,60,63,68,66,51,27
Crosses from top to bottom:
31,34,34,33,33,32,30,31,29,30,30,31,30,33,32,32,31,31,29,19

Second reading, today, a week later, after approx 7 hours of play:

Mains (not sure if same left/right direction)
27,44,61,62,59,55,47,47,42,42,46,51,51,70,67,68,50,31
Crosses
34,36,36,35,34,35,31,34,31,32,32,34,33,35,34,34,33,33,30,24

The kevlar mains have dropped tension, which is no surprise. But its very quickly getting farther and farther away from the 70 lbs requested. Now that the racket is broken in, I feel like I have very good control on my topspin shots. I can control direction and height pretty well. I'm happy with how its playing. What is interesting is that the ZX crosses have slightly gotten tighter. I don't really understand that, since the ZX was so stretchy.
 
Ok so I took more StringMeter readings, a week later, after 3 days of approx 2 hours of play each.

First readings from last week, after 1 hour of play (initially requested to be strung at 70/45):

Mains from left to right:
32,55,70,71,72,64,56,53,44,43,51,51,60,63,68,66,51,27
Crosses from top to bottom:
31,34,34,33,33,32,30,31,29,30,30,31,30,33,32,32,31,31,29,19

Second reading, today, a week later, after approx 7 hours of play:

Mains (not sure if same left/right direction)
27,44,61,62,59,55,47,47,42,42,46,51,51,70,67,68,50,31
Crosses
34,36,36,35,34,35,31,34,31,32,32,34,33,35,34,34,33,33,30,24

The kevlar mains have dropped tension, which is no surprise. But its very quickly getting farther and farther away from the 70 lbs requested. Now that the racket is broken in, I feel like I have very good control on my topspin shots. I can control direction and height pretty well. I'm happy with how its playing. What is interesting is that the ZX crosses have slightly gotten tighter. I don't really understand that, since the ZX was so stretchy.
It would be interesting to track the length of the hoop over time with this type of experiment.

It’s not surprising that the cross tension increased, as the large differential will diminish over time, with the crosses going up and the mains going down. Since the hoop elongates over time, and the kevlar is much stiffer than the zx, it’s possible for the overall average tension to actually increase or at least stay constant rather than dropping like a conventional sttingbed.
 
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tennisbike

Semi-Pro
Ok so I took more StringMeter readings, a week later, after 3 days of approx 2 hours of play each.

First readings from last week, after 1 hour of play (initially requested to be strung at 70/45):

Mains from left to right:
32,55,70,71,72,64,56,53,44,43,51,51,60,63,68,66,51,27

Second reading, today, a week later, after approx 7 hours of play:

Mains (not sure if same left/right direction)
27,44,61,62,59,55,47,47,42,42,46,51,51,70,67,68,50,31
I get the feeling that you are measuring from opposite side between the two readings. To get consistency, either reference butt cap or look at the knots. I do suggest being consistent about orientation. You can be more sure about how the changes are taking place.
No matter, I am glad it is playing better.
 

tennisbike

Semi-Pro
It would be interesting to track the length of the hoop over time with this type of experiment.

It’s not surprising that the cross tension increased, as the large differential will diminish over time, with the crosses going up and the mains going down. Since the hoop elongates over time, and the kevlar is much stiffer than the zx, it’s possible for the overall average tension to actually increase or at least stay constant rather than dropping like a conventional sttingbed.
I am not sure I agree or understand your hypothesis. But yes, tracking hoop dimension would be interesting.
 
I am not sure I agree or understand your hypothesis. But yes, tracking hoop dimension would be interesting.
Since the racquet is strung with mains much tighter than crosses, there is a lot of potential energy in the compressed hoop. As the racquet-stringbed system wears, the hoop elongates and relaxes, which transfers potential energy from the compressed hoop to the tensioned stringbed. If the original reference tension differential is great enough, the effective tension of the stringbed can actually increase over time.

As a first-order approximation, you can use the average tension of the middle 2 mains and the middle 2 crosses to give you the effective tension of the stringbed. In your case above with 75/45 reference tensions, the average of the middle 2 mains has dropped from 43.5 to 42, while the average of the middle 2 crosses has increased from 30 to 32 (i.e., the tensions of middle mains and crosses have gone from 43.5/30 to 42/32 as the stringbed wore). So the effective tension has increased slightly from 36.75 to 37, while the effective differential between mains and crosses has decreased from 13.5 to 10.
 

jumper67

New User
Ok so I took more StringMeter readings, a week later, after 3 days of approx 2 hours of play each.

First readings from last week, after 1 hour of play (initially requested to be strung at 70/45):

Mains from left to right:
32,55,70,71,72,64,56,53,44,43,51,51,60,63,68,66,51,27
Crosses from top to bottom:
31,34,34,33,33,32,30,31,29,30,30,31,30,33,32,32,31,31,29,19

Second reading, today, a week later, after approx 7 hours of play:

Mains (not sure if same left/right direction)
27,44,61,62,59,55,47,47,42,42,46,51,51,70,67,68,50,31
Crosses
34,36,36,35,34,35,31,34,31,32,32,34,33,35,34,34,33,33,30,24

The kevlar mains have dropped tension, which is no surprise. But its very quickly getting farther and farther away from the 70 lbs requested. Now that the racket is broken in, I feel like I have very good control on my topspin shots. I can control direction and height pretty well. I'm happy with how its playing. What is interesting is that the ZX crosses have slightly gotten tighter. I don't really understand that, since the ZX was so stretchy.
A week later, after another 6 hours of play:

Mains
29,45,65,66,61,56,50,45,39,41,45,50,53,60,60,61,43,27
Crosses
30,31,32,32,30,30,27,28,28,28,29,31,30,33,30,30,29,30,26,20

What I noticed was that the StringMeter was set at 17g, so probably the ZX cross readings last week were too high. That would explain the higher readings that I mentioned. I must have forgotten to change the SM to 16g before measuring. This week I did change it correctly to 16g.
 
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