TW Customization Tool, Static Weight, and Power

[TimothyO]

According to the TW customization tool adding weight to the grip doesn't increase power, at least not significantly.

Recently I was experimenting with my 200 Tours and changed the grip on one from a very light grip to one of the heaviest available. There was a very significant boost in power with the increase in static weight.

It makes sense to me that smashing the ball with a significantly heavier mass will produce a more powerful shot. But the TW tool seems to not account for power increase beyond extra weight in the head or throat. Why would that be?

 

[anubis]

There shouldn't be any increase in swing weight or power when adding a small amount of mass, in the form of a grip, to the handle.

If you go here: http://www.racquettech.com/store/learningcenter/lc_swingweight.html

and enter in the starting weight and starting swingweight of your racquet, and then keep the very last slider bar all the way to the left (indicating weight in the handle), then you'll find that adding as much as 50 grams of lead wouldn't increase swing more than 5 kg*cm^2. Whereas if you put a mere 4 grams in the hoop, you increase it by almost 18 kg*cm^2.

 

[TimothyO]

Anubis,

Yes, I understand that, on paper, there's no increase.

But picking up one 200 Tour with a light grip and then using the other with a very heavy grip the heavier one produces a lot more power (strung the same).

The increase was great enough that I removed the heavy grip since I was unpleasantly surprised by the result.

 

[kaiser]

Pivoting a racket round an axis 10 cm from the butt in a RDC machine is not the same as swinging a racket with your whole arm and body. Although it is true that in the former case adding weight at the grip will have a negligeable effect on the measured RDC-SW, in the second case this is not necessarily so. Stoneage did a remarkeable job in elucidating this, I bet you can find your answer in his thread:
http://tt.tennis-warehouse.com/showthread.php?t=438238

 

[corners]

Recently I was experimenting with my 200 Tours and changed the grip on one from a very light grip to one of the heaviest available. There was a very significant boost in power with the increase in static weight.

How do you know there was a power boost? What evidence do you have?

And what do you mean by power? Greater ball speed? How did you measure it?

Unless you are precisely measuring ball speed and ball spin, there is no way to know that a racquet is more powerful than another. You may think it is, you may believe it is, you may perceive it to be, your hitting partner may agree with you. But these things are not knowledge.

It makes sense to me that smashing the ball with a significantly heavier mass will produce a more powerful shot. But the TW tool seems to not account for power increase beyond extra weight in the head or throat. Why would that be?

You are not hitting the ball with the handle. You're hitting the ball with the racquet head. Power Potential - otherwise known as ACOR, which is the percentage of energy that goes into the racquet-ball collision that comes out again as ball speed - is directly proportional to the racquet's effective mass. The effective mass varies by location, but is pretty proportional to swingweight. Swingweight, as you know, is primarily a function of how much mass is distributed to the racquet head. Adding mass to the butt does not increase swingweight, nor does it increase hittingweight, nor does it increase ACOR, or Power Potential, as you saw using the TWU tool.

Imagine a hammer. If you hit with the business end you impact the nail with a lot of mass. Now flip it around. Hitting the nail with the handle, does the mass of the hammer head (now in your palm) help you at all?

Tailweighting or handleweighting a racquet has many beneficial effects. Increasing power is not one of them. (Unless, somehow, adding mass to the handle improves your swingspeed. The difference in power potential between the least and most powerful frames on the market equates to a difference of about 6 miles per hour in swingspeed on a groundstroke. But heavier racquets swinging faster than lighter ones contradicts conventional wisdom. Not that conventional wisdom in tennis is actually wise.)

 

[TimothyO]

Corners,

I've enjoyed your many posts in the past. But I gotta say, this one is pretty weird.

Evidence? Really? Using the same stroke with both frames one Frame sent the ball way long (much heavier grip) vs a distance to which I've become accustomed (lighter grip). Then when I removed the heavy grip and put the lighter one back on, shot depth returned to normal. So the only evidence I have is actual court time with the two different setups. I guess one might ask, which should I believe, my lying eyes or a computer program?

The more I think about this, the more it makes sense that a frame nearly 3/4 of an ounce heavier, but otherwise the same, would be more powerful even if that weight is concentrated in the grip (ie from butt to near the throat).

We don't just hit with the head of the frame. Extra mass towards the butt also resists the recoil effect to some degree at least. That must count for something in that the frame with the lighter grip resists the recoil less. Remeber, this isn't just a gram or so. It's one of the lightest grips available (Wilson Hybrid) and one of the heaviest (Wilson Shock Shield).

We're also not talking about a difference between hitting the service line and putting the ball over the fence. With the light grip and a smooth, steady stroke using some topspin my ball lands a few feet inside the baseline. Add the heavy grip and I'm hitting just outside the baseline.

Maybe it's weight and less RHS too? Thus with fewer RPMs maybe the ball floats long?

 

[JohnB]

It could be due to different gripthickness.

What also could be happening is that because of the extra weight in the handle, you kinetic chain is a bit disturbed. In the second situation you need more force at the start of the swing for the same initial swingspeed, but you need about the same force at the end of swing. Maybe your musclememory causes the racket to swing faster at the end of your swing because you're used to a certain sequence and amount of applying force.

 

[corners]

Corners,

I've enjoyed your many posts in the past. But I gotta say, this one is pretty weird.

Evidence? Really? Using the same stroke with both frames one Frame sent the ball way long (much heavier grip) vs a distance to which I've become accustomed (lighter grip). Then when I removed the heavy grip and put the lighter one back on, shot depth returned to normal. So the only evidence I have is actual court time with the two different setups. I guess one might ask, which should I believe, my lying eyes or a computer program?

The more I think about this, the more it makes sense that a frame nearly 3/4 of an ounce heavier, but otherwise the same, would be more powerful even if that weight is concentrated in the grip (ie from butt to near the throat).

We don't just hit with the head of the frame. Extra mass towards the butt also resists the recoil effect to some degree at least. That must count for something in that the frame with the lighter grip resists the recoil less. Remeber, this isn't just a gram or so. It's one of the lightest grips available (Wilson Hybrid) and one of the heaviest (Wilson Shock Shield).

We're also not talking about a difference between hitting the service line and putting the ball over the fence. With the light grip and a smooth, steady stroke using some topspin my ball lands a few feet inside the baseline. Add the heavy grip and I'm hitting just outside the baseline.

Maybe it's weight and less RHS too? Thus with fewer RPMs maybe the ball floats long?

Tim, you just need to think about it a little more, IMHO. The ball landing long is what you are experiencing. This is not "power", it's depth. A 5% increase in power potential - which is a massive difference in terms of racquets, representing 20 grams of lead at 12 o'clock - will result in the more powerful frame hitting a shot about 4 feet deeper, if all other shot parameters are the same (swing speed, angle, racquet face angle, incoming shot parameters, etc.) 4 feet.

But use the same racquet on two consecutive shots but vary the racquet angle of one shot by ONE degree and the depth difference will be about 6 feet.

So is the increased depth you experienced with the addition of a heavier grip due to "power"? Or is it due to some change in the way you swing resulting in a tweaked racquet-face angle? I would put money on the latter. Of course, I don't know for sure because I don't have ultra-high speed video of yours shots, radar guns, etc. Maybe it's something else. But a couple hundred years of tried and true physics principles, and about 20 years of experimental evidence say that it's not "power."

 

[TimothyO]

Corners,

I see what you're saying and mostly agree. Thus my comment on the extra weight effecting my stroke with respect to RHS and spin. I hit this evening with the lighter grip and had zero problem with depth control. With the heavy grip I had a terrible time with depth control.

Maybe it's a combination of factors? Stroke and mass and how they interact?

 

[TimothyO]

It could be due to different gripthickness.

What also could be happening is that because of the extra weight in the handle, you kinetic chain is a bit disturbed. In the second situation you need more force at the start of the swing for the same initial swingspeed, but you need about the same force at the end of swing. Maybe your musclememory causes the racket to swing faster at the end of your swing because you're used to a certain sequence and amount of applying force.

Perhaps. The heavier grip is actually thinner and denser than the thick/poofy lighter grip.

 

[kaiser]

I think corners is right, he has to be... Perhaps the answer can be found here?
http://www.racquetsportsindustry.com/articles/2006/04/racquet_handle_weighting_and_m.html

 

[TimothyO]

Should also mention...after hitting Monday night with the light-grip setup and then again on Wednesday I decided to stick with the 200 Tours instead of the base model 200 (I have two 200s and two 200 Tours).

The Tours, when strung with VS/4g 16 approach the 200 in control while also providing more stability and plow. I definitely need to focus more with the Tours but on Monday I was keeping up with one of our better team members just fine and hitting heavier shots that guys at my level and below had trouble with. The Tours truly demand a relaxed full stroke and the reward is a plush, precise hitting experience.

 

[TimothyO]

Good find Kaiser, thanks!

 

[kaiser]

You're welcome!
Btw, forgot to mention: I've tailweighted both my 4D200Ts with Blue-Tack inside the buttcap to 10-11 pts HL! I find this significantly improves their manoeverability at the net, and in my perception it also helps with whipping the head through kickserves and W-W forehands. Have no problem with power, although there is plenty of that around...

 

[corners]

Corners,

I see what you're saying and mostly agree. Thus my comment on the extra weight effecting my stroke with respect to RHS and spin. I hit this evening with the lighter grip and had zero problem with depth control. With the heavy grip I had a terrible time with depth control.

Maybe it's a combination of factors? Stroke and mass and how they interact?

Yeah, probably a combination of factors. Another thing to consider is that the heavier handle may have slowed down your swing just enough to reduce your topspin, which would also result in greater depth. Flatter shots go longer.

And it may also be as simple as the thickness or density of the heavier grip changing the orientation of your hand on the handle enough to alter the racquet-face angle at impact. All of these things, though, seem to correct with a little practice/adjustment time.

 

[corners]

I think corners is right, he has to be... Perhaps the answer can be found here?
http://www.racquetsportsindustry.com/articles/2006/04/racquet_handle_weighting_and_m.html

This one is also good: http://www.racquetsportsindustry.com/articles/2006/02/raw_racquet_power.html

And this one from Cross's co-author and TW's very own Professor: http://twu.tennis-warehouse.com/learning_center/specsandspeed.php

 

[TimothyO]

Read Kaiser's link a couple of times and watched some pro videos on the intertubes including FYB.

I'm now convinced that it's not quite as simple as "extra handle weight adds zero power".

The piece by Rod Cross essentially says that the true point of rotation that determines SW is beyond the butt and actual SW is higher than what is calculated using the grip as a reference point.

To assert that additional weight has no effect on power one must believe that we hit with our wrist being the pivot point instead of our torso or even joints in the arm. True, we aim the butt at the ball, but not even pros flick the racquet with the wrist as in racket ball. Consistency, and a desire to avoid TE, demands a full stroke using the torso.

Essentially, we have a situation in which the tennis community and industry says we should hit with our cores and use the body to swing the arm+racquet instead of using the arm (or worse still, the elbow and wrist) to swing the racquet. But then we measure SW and associated values such as power using something close to the wrist as a reference point!

Since we DON'T hit using or wrist alone as the point of rotation it's odd to assert that adding weight to the hoop increases power but adding to the grip has no effect. Assertion assumes the wrist is the point of rotation.

The really weird part of Rod Cross' article is that not only does he note that actual SW based on the true point of rotation beyond the butt is higher than the standard reference model, he also says that pros feel frames are more stable with extra mass in the grip! Stability on impact is another form of force vs force or...power/energy.

It's as if some researchers decided X must be true based on their calculations and model but when that model can't handle reality they ignore it.

 

[TimothyO]

Here is one of the key posts from Cross' piece. The first line reveals the disconnect: the model used to measure SW is not based on the actual method of rotation.

A player swinging a racquet does not rotate it about a fixed axis, especially not the one used to measure swingweight. Just before the racquet hits the ball, in the last few inches of the swing, the racquet will be swinging about an axis that is somewhere beyond the end of the handle, not inside the handle itself. But the swing action starts well before that, when the racquet is back. The whole racquet is swung forward through a distance of about four or five feet and it covers that distance in a split second in a fast serve or groundstroke.

And later...

The effort required to rotate the racquet is determined mainly by the swingweight about an axis somewhere beyond the end of the handle. That particular swingweight will be typically about double the measured swingweight.

 

[JohnB]

Read Kaiser's link a couple of times and watched some pro videos on the intertubes including FYB.

I'm now convinced that it's not quite as simple as "extra handle weight adds zero power".

The piece by Rod Cross essentially says that the true point of rotation that determines SW is beyond the butt and actual SW is higher than what is calculated using the grip as a reference point.

To assert that additional weight has no effect on power one must believe that we hit with our wrist being the pivot point instead of our torso or even joints in the arm. True, we aim the butt at the ball, but not even pros flick the racquet with the wrist as in racket ball. Consistency, and a desire to avoid TE, demands a full stroke using the torso.

Essentially, we have a situation in which the tennis community and industry says we should hit with our cores and use the body to swing the arm+racquet instead of using the arm (or worse still, the elbow and wrist) to swing the racquet. But then we measure SW and associated values such as power using something close to the wrist as a reference point!

Since we DON'T hit using or wrist alone as the point of rotation it's odd to assert that adding weight to the hoop increases power but adding to the grip has no effect. Assertion assumes the wrist is the point of rotation.

The really weird part of Rod Cross' article is that not only does he note that actual SW based on the true point of rotation beyond the butt is higher than the standard reference model, he also says that pros feel frames are more stable with extra mass in the grip! Stability on impact is another form of force vs force or...power/energy.

It's as if some researchers decided X must be true based on their calculations and model but when that model can't handle reality they ignore it.

There's a thread started by Stoneage http://tt.tennis-warehouse.com/showthread.php?t=438238which gave me the last piece of the puzzle to customize a racket to perfection. It's about relative swingweight/equivalent mass.

 

[TimothyO]

Yes, that's closer to what I'm talking about. Some of his comments in this post...

http://tt.tennis-warehouse.com/showpost.php?p=5108451&postcount=1

are related.

Mass and force are related. If the center of rotation is not the butt then adding mass to the handle will effect its impact on the ball. It will do so to a lesser degree than any point further up the frame but it will do so none the less. As Stoneage points out, " And anyone who thinks that adding a 1 kg lump to the handle of a racquet doesn't affect the playability raise a hand."

 

[JohnB]

Yes, that's closer to what I'm talking about. Some of his comments in this post...

http://tt.tennis-warehouse.com/showpost.php?p=5108451&postcount=1

are related.

Mass and force are related. If the center of rotation is not the butt then adding mass to the handle will effect its impact on the ball. It will do so to a lesser degree than any point further up the frame but it will do so none the less. As Stoneage points out, " And anyone who thinks that adding a 1 kg lump to the handle of a racquet doesn't affect the playability raise a hand."

You may want to try putting a little mass in the head of the heavier grip racket and check it out on the court. I am thinking about maybe 3g total at 3 and 9 or 2g total more upward.