TWU Spin Potential Metric

daggerman

Hall of Fame
I was doing some light research on poly strings and came across something surprising. When comparing the spin potential (as listed by the TWU lab review), I found the following stats on the various Solinco Hyper-G gauge sizes:

16: 7.0
16L: 6.1
17: 6.1
18: 7.5

Can anybody explain why the 16 gauge has a higher listed spin potential than both the 16L and 17? Is that an error? Sample size issue? Something else?

EDIT: I've noticed this with other strings, as well, not just Hyper-G
 

liftordie

Hall of Fame
I was doing some light research on poly strings and came across something surprising. When comparing the spin potential (as listed by the TWU lab review), I found the following stats on the various Solinco Hyper-G gauge sizes:

16: 7.0
16L: 6.1
17: 6.1
18: 7.5

Can anybody explain why the 16 gauge has a higher listed spin potential than both the 16L and 17? Is that an error? Sample size issue? Something else?

EDIT: I've noticed this with other strings, as well, not just Hyper-G
More string to ball friction.
More control.
More durability and tension maintenance.
Long live Hyper-G 16 (and 16g in general)!!!
 
I was doing some light research on poly strings and came across something surprising. When comparing the spin potential (as listed by the TWU lab review), I found the following stats on the various Solinco Hyper-G gauge sizes:

16: 7.0
16L: 6.1
17: 6.1
18: 7.5

Can anybody explain why the 16 gauge has a higher listed spin potential than both the 16L and 17? Is that an error? Sample size issue? Something else?

EDIT: I've noticed this with other strings, as well, not just Hyper-G

Spin potential is a function of friction and dwell time. That's how you get to a U-shape function.
 

esgee48

G.O.A.T.
Spin Potential is String/Ball COF divided by String/String COF. Whether this metric is accurate or usable is debatable since it is player, frame and tension sensitive. Use it as a guidance for comparing strings. Do not expect Theory to be Reality. :alien:
 

El_Yotamo

Hall of Fame
Do not expect Theory to be Reality.
I disagree. When the theory is physically accurate and complete it will match up with reality. The problem is that the "theory" given by TWU doesn't fully encompass the reality and complicated nature of spin generation. The TWU spin potential isn't directly correlated to spin in a complete way. All it can do is give some sort of an indication, and therefore does not match up with reality.
 

ron schaap

Hall of Fame
I disagree. When the theory is physically accurate and complete it will match up with reality. The problem is that the "theory" given by TWU doesn't fully encompass the reality and complicated nature of spin generation. The TWU spin potential isn't directly correlated to spin in a complete way. All it can do is give some sort of an indication, and therefore does not match up with reality.
So what is missing in the Twu data relating to spinpotential? Weisscanon ultra cable has among the highest spinpotential to Twu which is in agreement with my experience. However its a little short in power.
 

El_Yotamo

Hall of Fame
So what is missing in the Twu data relating to spinpotential? Weisscanon ultra cable has among the highest spinpotential to Twu which is in agreement with my experience. However its a little short in power.
There's no proof of an exact linear correlation between the amount of spin a shot has and some dimensionless ratio between friction coefficients. In fact on the contrary, we know that there isn't.

In fact, what is "spin"? Are we talking topspin? Sidespin? Slice/backspin/underspin? They're all different. But let's assume we're talking solely about topspin, because that's what most people (myself and TWU included it seems) put most weight on.

Topspin still depends on at least five factors other than pure friction coefficients in terms of the characteristics of tennis strings (thickness, stiffness, shape, viscous properties, dwell time, and more). Problem is, the factors themselves are interdependent, and on top of all of that some factors have more of an effect than others given different conditions (the player, the shot/swing, the incoming ball, the surface, the weather, the racquet/string pattern, and others) so you can't put an absolute stamp no matter how hard you try.

The fact of the matter which has to be accepted is that the TWU spin potential metric isn't what the scientific world calls a correlation, but rather it's an indicating factor. That means you can't calculate anything with it, you can only compare two things on a qualitative scale, if they have similar properties (ceteris paribus). So if you compare two strings which have similar properties across the board made from the same base material with the same gauge and string shape and they have different COF ratios, then the amount of certainty you can have is relatively high in comparing which will be the more effective spin producer. In reality we seldom have the luxury of making such straightforward comparisons.
 
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travlerajm

G.O.A.T.
How the string wears is missing. Synthetic guts have slick hard plastic coatings that wear off after 20 minutes of hitting, exposing a high-friction core for most of its playing life.
 

ron schaap

Hall of Fame
Good example of a poly that does the same is RPM Blast
with all respect but rpm blast is one of those strings that keeps playable even when losing tension and its profile. It does not have a high friction core!

And concerning topspin imparted on the ball thats just hit, ofcourse there are more ingluencing factors. Twu could measure spin in standardized experiments. That would mean a lot of work. An important factor you forgot is tennisballs. Sometimes they become so bold during play that it becomes nearly impossible to get reasonable spin on. A heaven for flathitters indeed.
 
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El_Yotamo

Hall of Fame
with all respect but rpm blast is one of those strings that keeps playable even when losing tension and its profile. It does not have a high friction core!

And concerning topspin imparted on the ball thats just hit, ofcourse there are more ingluencing factors. Twu could measure spin in standardized experiments. That would mean a lot of work. An important factor you forgot is tennisballs. Sometimes they become so bold during play that it becomes nearly impossible to get reasonable spin on. A heaven for flathitters indeed.
Sure, either way I hope you understand what I meant and why the spin potential metric is not accurate much of the time.

About RPM Blast I actually once measured its string-string dynamic COF before play and after 30 mins, 1 hr, and 6 hrs of play (when it broke). The results were something along the lines of 0.043, 0.058, 0.064, 0.067. Other strings also exhibited an increase over time but a lot less. It doesn't have a high-friction core and I didn't claim that it does, however at first it's a lot more slick and then the coating wears off from friction so COF goes up (frictionception :eek:).
 
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