Lab Test & Calculations versus Pro Specs

[TimothyO]

According to the lab test for racquet power potential and the manner in which Swing Weight is calculated handle mass has a negligible effect on racquet performance. You can use the TWU racquet customization tool to add vast amounts of mass from the butt to a point 10cm up from the butt and besides static weight the frame's calculated SW, power, and plow will barely budge.

We also know that the vast majority of tennis pros use frames that are head light in balance, have high static weights, and have high SWs.

Here's the interesting bit: according to the lab tests and theoretical calculations tennis pros should be using extremely light, very head heavy frames.

It doesn't take much mass to significantly boost calculated SW. And since the theory is that SW correlates closely with racquet power and that handle weight adds nothing to the equation (literally in this case since adding handle weight doesn't budge calculated power potential) it would appear there's no reason for extra mass in the handle, at least according to calculations and lab tests.

Furthermore, we know that higher static weight reduces racquet head speed. And we know that higher RHS can generate more spin and more power. So again, according to calculations, that extra handle mass we see in pro frames is worse than a waste as it actually hurts a pro since it only reduces his RHS and therefore his spin and power potential.

The question: if handle mass adds NOTHING to frame power and plow and can only reduce RHS, what possible purpose does it serve when lab tests and calculations show no benefit from the extra mass?

In my opinion it does serve a crucial purpose with respect to power, stability, and plow. So this question is really to those who put great stock in lab tests and theoretical calculations. According to lab tests and theoretical calculations, these pros are only holding themselves back by playing with heavy, head light frames and they should be using very head heavy, light weight frames.

Same goes for higher level rec players: based on lab tests and calculations, higher level rec players should be using very light weight, very head heavy frames. And yet both higher level rec players and tennis pros gravitate towards heavier, head light frames. According to these lab tests and calculations they're all wrong, right?

edit: and yes, the question is a trap. If you assert that handle mass adds to torsional stability along the frame's long axis you're admitting that the mass had a role to play in imparting force to the ball at impact (i.e. it adds to the shot's power). In other words, to believe that the mass adds to torsional stability without adding to shot power you'd have to believe that in one instance the mass exists and in the other it doesn't.

 

[Anton]

Torsional stability is not everything, there is also longitudinal stability and racket balance.

 

[TimothyO]

Torsional stability is not everything, there is also longitudinal stability and racket balance.

Fully agree.

But according to the calculations and power tests extra handle mass has zero impact on longitudinal stability (which is just another name for force).

 

[Dimcorner]

Are lab tests done with a arm lever swinging the raquet?

From my experiences in badminton, 1cm balance point shift is very noticeable to me as well as a 1g overall weight difference. On paper it doesn't seem like much but when you attach it to the end of an arm and swing the whole arm it magnifies the variations.

I was thinking also that I wanted a headlight racquet so I added a few grams of weight to the end of my APD but it made the raquet feel unstable to me. Kinda like the ball was just pushed the hoop out of balance easier. So I moved it to about the 3-9 position and felt better, but a little slower.

 

[Power Player]

"Same goes for higher level rec players: based on lab tests and calculations, higher level rec players should be using very light weight, very head heavy frames. And yet both higher level rec players and tennis pros gravitate towards heavier, head light frames. According to these lab tests and calculations they're all wrong, right?"

I don't get this. You have to understand that swing path dictates a lot. And we all have different swing paths. A light, but head heavy racquet puts a ton of torque on the arm and can cause elbow issues.

Trying to figure out racquets by applying science is really cool in concept, but it will never replace court time. In fact, it may hinder your development, since you are thinking up numbers that you believe work for you, when in reality the specs that work best may be some that you did not even expect.

You want a racquet that works for you?

- develop a proper swing path
- develop proper footwork.
- ensure that you are able to consistently hit the ball out in front for ideal timing and weight transfer.

Then mess with your raquet specs to fine tune your timing to the ball. I guarantee you will be able to do it without even having to think much about it at that point.

 

[movdqa]

http://racquetresearch.com/

According to this site, arm health is enhanced by head-light, high-static-weight, flexible racquets. What good is all the power at low weight to a pro if he's missing tournaments due to arm injuries?

 

[TimothyO]

Are lab tests done with a arm lever swinging the raquet?

From my experiences in badminton, 1cm balance point shift is very noticeable to me as well as a 1g overall weight difference. On paper it doesn't seem like much but when you attach it to the end of an arm and swing the whole arm it magnifies the variations.

I was thinking also that I wanted a headlight racquet so I added a few grams of weight to the end of my APD but it made the raquet feel unstable to me. Kinda like the ball was just pushed the hoop out of balance easier. So I moved it to about the 3-9 position and felt better, but a little slower.

No. The power potential test uses a static racquet.

 

[TimothyO]

"Same goes for higher level rec players: based on lab tests and calculations, higher level rec players should be using very light weight, very head heavy frames. And yet both higher level rec players and tennis pros gravitate towards heavier, head light frames. According to these lab tests and calculations they're all wrong, right?"

I don't get this. You have to understand that swing path dictates a lot. And we all have different swing paths. A light, but head heavy racquet puts a ton of torque on the arm and can cause elbow issues.

Trying to figure out racquets by applying science is really cool in concept, but it will never replace court time. In fact, it may hinder your development, since you are thinking up numbers that you believe work for you, when in reality the specs that work best may be some that you did not even expect.

You want a racquet that works for you?

- develop a proper swing path
- develop proper footwork.
- ensure that you are able to consistently hit the ball out in front for ideal timing and weight transfer.

Then mess with your raquet specs to fine tune your timing to the ball. I guarantee you will be able to do it without even having to think much about it at that point.

I agree, I was being facetious when recommending that higher level rec players use light, HH frames.

As for your recommended test procedure I full agree and that's what led me to observe the disconnect between so many key reference values such as SW and on court experience.

I stopped angst-ing over the numbers and did mods based purely on feel and on-court performance. That's when I started noticing that total racquet mass does influence both power and RHS and that SW is just one factor. It's an important factor, but, assuming that a given static weight doesn't materially limit a given player's RHS, then even though two frames share the same calculated "reference SW" the heavier frame will provide more power on the shot.

 

[TimothyO]

http://racquetresearch.com/

According to this site, arm health is enhanced by head-light, high-static-weight, flexible racquets. What good is all the power at low weight to a pro if he's missing tournaments due to arm injuries?

Totally agree, I was being facetious.

 

[Shroud]

http://racquetresearch.com/

According to this site, arm health is enhanced by head-light, high-static-weight, flexible racquets. What good is all the power at low weight to a pro if he's missing tournaments due to arm injuries?

Yep. I got te from over playing and hitting with kevlar/gut at 63/65 on a stock POG.

I added a bunch of weight and made it super headlight, and with lowered tension it is such an arm friendly racket over stock. The weight is about 1/2 of the improvement, and mishits are a lot less jarring.

 

[movdqa]

The move to polarized setups by many ATP pros also increases dynamic flex which, I believe, helps with arm health. I'm using a polarized setup which is probably quite efficient at keeping swingweight up while maintaining even or light-headed balance.

 

[travlerajm]

Does this help explain?
http://tt.tennis-warehouse.com/showthread.php?t=390065

 

[stoneage]

The question: if handle mass adds NOTHING to frame power and plow and can only reduce RHS, what possible purpose does it serve when lab tests and calculations show no benefit from the extra mass?

There is nothing wrong with swingweight as a parameter, it is moment of inertia, which one of the fundamental parameters that describe the behaviour of the racquet. It also the only dynamic parameter we have since weight and balance are static values. The problem is that while the value you get from the tests and calculations only is valid for swings around a point 10 cm up the handle (not very common in tennis), people use it as a general (and sometimes the only) parameter for how heavy and powerful a racquet is. So while swingweight is useful it can never give you the whole story.

The choice of the rotation point for the swingweight definition is also a bit unfortunate and leads to the problems you describe (if you only use swingweight). It would have been better to choose a point 10-30 cm outside handle and call the moment of inertia around that point swingweight. But whatever point you choose the value would be strictly valid only for swings around that point.

This is the reason I created the swingweight curve described in this thread. While it also is a simplification, it illustrates the influence of swingweight, balance AND weight. Hopefully it can help increase the understanding how these parameters interact.

Sten

___________________________________________________________
racquetTune, stringBed and swingTool racquet apps for the iPhone/iPad.

 

[travlerajm]

There is nothing wrong with swingweight as a parameter, it is moment of inertia, which one of the fundamental parameters that describe the behaviour of the racquet. It also the only dynamic parameter we have since weight and balance are static values. The problem is that while the value you get from the tests and calculations only is valid for swings around a point 10 cm up the handle (not very common in tennis), people use it as a general (and sometimes the only) parameter for how heavy and powerful a racquet is.

The choice of the rotation point for the swingweight definition is also a bit unfortunate and leads to the problems you describe (if you only use swingweight). It would have been better to choose a point 10-30 cm outside handle and call the moment of inertia around that point swingweight. But whatever point you choose the value would be strictly valid only for swings around that point.

This is the reason I created the swingweight curve described in this thread. While it also is a simplification, it illustrates the influence of swingweight, balance AND weight. Hopefully it can help increase the understanding how these parameters interact.

Sten

___________________________________________________________
racquetTune, stringBed and swingTool racquet apps for the iPhone/iPad.

Swingweight is a static parameter just as much as mass and balance are. If you know the weight and balance, it doesn't matter about what axis you measure the swingweight.

 

[stoneage]

Swingweight is a static parameter just as much as mass and balance are. If you know the weight and balance, it doesn't matter about what axis you measure the swingweight.

It is a dynamic parameter in the sense that it describes a dynamic behaviour and can only be measured on an accelerating racquet. Just because you can transfer that value from one axis to another through the static parameters mass and balance doesn't change that fact.

 

[travlerajm]

It is a dynamic parameter in the sense that it describes a dynamic behaviour and can only be measured on an accelerating racquet. Just because you can transfer that value from one axis to another through the static parameters mass and balance doesn't change that fact.

Fair enough.