Strung Weight vs. Swing Weight

[Nadalgaenger]

Which is actually more important?

For example my Prostaff 90 has a higher strung weight than my Youtek Radical Pro, but the latter has a higher swing weight.

And the newer BLX 90s have lower swingweights than the older K90 and NCode90, no? Does this mean a dropoff in performance?

 

[TimothyO]

Static weight + balance is far more important than swingweight.

Take two frames with the same static weight and same balance but different swingweights. They'll feel about the same when you take full, long swings with them.

Now take two frames with very different static weights and balances but similar swingweights. They'll feel very different.

The issue is that swingweight is measured from a point on the handle which you might use for a really wristy slicing volley. But you'll never hit a groundstroke by swinging from that point. With SW mass in the handle gets discounted down to a value of zero at 10cm drom the butt cap. But since you swing from your core the weight in the handle DOES add to a frame's power and true swingweight.

Furthermore, balance is crucial for timing the frame's position at point of contact. If the balance is off your hand can be too early or two late relative to the point of contact which causes you to miss wide on groundstrokes. It can also cause wrist and elbow problems since you might compensate for the poor balance by arming the ball into contact.

The way swingweight is calculated from the handle you can almost think of it as "volley weight". And if you move the measurement reference point from +10cm above the butt cap (volley weight) to a point in space beyond the butt cap you start to get a more accurate value for true SW. And at that point you'll begin to notice how much more important total static weight + balance point are for racquet feel.

That's not to say SW isn't relevant in any way. It's just not nearly as important as some people make it out to be since nobody actuallu swings the way it's calculated. Focus on static weight and balance and you'll be much happier.

 

[morten]

Interresting.. I am still very sensitive to sw, as if a racket has too high swingweight, i have seldom managed to even it out by making it more headlight, adding weight to handle etc.. And i like heavy rackets...

 

[Irvin]

By far SW is more important. But unless you know what you're looking for neither is important. Adding weight to a racket without know what you're trying to achieve is senseless. If you add weight and like it you don't even know what you like, and if you don't you don't. You should have some way to identify the swing weight, twist weight, balance, and total weight. That way you can fine tune the frame for what you like. Also it is nice to have more than one frame strung the same so you can compare small differences.

 

[PMChambers]

Swing weight is an artificial measurement hence it has no units, however, it is a good representation for comparison.

Static weight is a real measurement and has units but only indicates the total weight and not the weight distributions. So really is not that valuable on it's own.

HL/HH or balance read in conjunction with weight will get you close to the swing weight.

So at the end of the day these three measurements will give you a good idea of the feel of the racquet interments of weight and inertia. But it's not the only effects, RA effects power as well, string pattern, type, tension are also factors that effect the racquet, so does the length or shape of the head.

At the end of the day you need to review several of the factors such as weight , balance, swing weight and RA, with the understanding you can effect them with lead / personalisation. This will give you a ball park idea of the racquet and then you really need to trial them without prejudices. Even RA does not describe where it flexes which give it feel.

BTW: What you call drop off in performance, low SW, is what I call benefit as racquet speed and power are not something I don't lack. I go out of my way to get a dead or control racquet.

 

[TimothyO]

PM,

Swingweight does have units: Kg-cm^2

And it's one of the misunderstood measurements.

For example, you can have two frames, A and B, with different swingweights measured at the conventional 10cm. Let's say A is higher. Move the reference point to something like an actual groundstroke and they can flip position with B having a higher SW. And, in fact, you'll be able to feel the difference. On volleys and delicate touch shots A will feel more solid. On full, long groundstrokes B will feel more powerful.

This is one reason racquet reviews often don't reflect SW values. In one case an open-level TW tester declared that he could enjoy playing with a certain wilson frame in stock form but the SW was only 306. In other cases low SW frames are described as "powerful" by testers.

SW in the context of weight and balance can describe how mass is distributed in the head. But because it heavily discounts mass in the lower head, throat, and handle it doesn't accurately reflect frame performance. Using that 10cm reference point you can add an infinite amount of mass to the handle and SW will literally not budge. And yet so many people swear by a measurement that says you can pick up and swing a frame with the mass of a neutron star.

 

[PMChambers]

Swingweight does have units: Kg-cm^2

OK, so it's Rotational Moment of Inertia is kg*m^2 at the point 10cm up from the butt. From this you can deduce,
Torque = I * a (a=angular velocity)
Momentum = I * V (V = angular velocity)
KE = (I * V^2)/2
Which at least have some use.

The main issues are that they take a point 0.01m from the handle and assume this is the pivot point which is done for ease of machine manufacture, IE Babolat RDC. So the number is just a guide for comparison. But the racquet does not swing through this point, most the pivot occurs a nearer the elbow/shoulder which would give the mass in the handle a lot more importance. (Note: the swing path is a compound motion using core, arm, elbow and wrist none of which are 0.01m up from the butt.).

As this is just representing the racquet at as a point mass rotating 10cm from the end, Balance and Static Mass are just as good at representing the effect. Manufacturers understand this and hence don't include swing weight, rather static mass and balance. (Note: I have not seen all manufactured racquets but I have seem a lot).

I look at it but it as a measure of "inertia", resistance to motion, but must be considered with too many other factors such as stiffness to represent potential power (KE), and power (KE) is a function of velocity so increasing HH can reduce power if you can't accelerate the mass, in the case of wristy or compact stroke players or low strength player. Having said that I tend to weight a racquet anyway so this figure is pointless to me as I can't measure it without a RCD m/c.

The first time I saw a babolat RCD was about 20 years ago in a shop that customises, I can see it's use in that job and as a generalisation of performance but is only making the balance characteristic redundant. Static Weight & Balance say the same to me that Static Weight and SW do.

 

[Irvin]

OK, so it's Rotational Moment of Inertia is kg*m^2 at the point 10cm up from the butt. From this you can deduce,
Torque = I * a (a=angular velocity)
Momentum = I * V (V = angular velocity)
KE = (I * V^2)/2
Which at least have some use.
...

Not true what your talking about is the Twist Weight. If you have something like a Babolat RDC, first you measure the SW using the normal procedure swing the frame in a normal swing path they rotate the frame 90* and measure it again. The time when the string plain is parallel to the swinging direction is always higher. Subtract the SW from the higher and you have TW.

 

[movdqa]

Swingweight is far more important. I used to have a 17-ounce frame with a swingweight of about 310. No power. My KPS88s, though, weighed about 13 ounces with a swingweight of around 345 - much more power. My current frames have a very high swingweight - tons of power but you have to be able to swing it.

 

[SpinToWin]

I find the two units to be equally important. Take a super light racquet and get it to a swingweight of 360. The result is a heavy feeling and low powered racquet. To get more power you need to up the swingweight, but similarly the static weight. For example, when adding mass at 12 (where the ratio of swingweight to static weight is the highest) you actually do not notice a large increase in power, as the increase in power is countered by the increased production of spin caused by the mass at the tip (IME).

I added 15g at 12 to one of my Pro Staffs. There was not a noticeable increase in power on groundstrokes, but a noticeable increase in spin and control which resulted in a higher margin for error.

No one unit says it all. The important thing is how all the units relate to one another.

 

[movdqa]

I find the two units to be equally important. Take a super light racquet and get it to a swingweight of 360. The result is a heavy feeling and low powered racquet. To get more power you need to up the swingweight, but similarly the static weight. For example, when adding mass at 12 (where the ratio of swingweight to static weight is the highest) you actually do not notice a large increase in power, as the increase in power is countered by the increased production of spin caused by the mass at the tip (IME).

I added 15g at 12 to one of my Pro Staffs. There was not a noticeable increase in power on groundstrokes, but a noticeable increase in spin and control which resulted in a higher margin for error.

No one unit says it all. The important thing is how all the units relate to one another.

It sounds like you lose RHS when increasing the SW so you're getting more play but losing power through decreased RHS. There's often an optimum point for each person.

 

[TimothyO]

Swingweight is far more important. I used to have a 17-ounce frame with a swingweight of about 310. No power. My KPS88s, though, weighed about 13 ounces with a swingweight of around 345 - much more power. My current frames have a very high swingweight - tons of power but you have to be able to swing it.

I strongly disagree that SW is more important.

You can have a two frames with the same SW of, say, 320, but one can weigh 11 ounces and the other 100 pounds. This is literally true since extra mass at 10cm is discounted to a value of 0 in the SW calculation. Mass in the handle, throat, and lower hoop is also heavily discounted. Go to the TW modification tool and try it. Add as much mass as you want to at 10cm and the SW doesn't move.

Total mass relative to balance is far more important while conventional SW helps fine tune that relationship.

The reason is that when we swing we're swinging the entire mass of the frame from butt cap to tip around an axis somewhere around your core to elbow depending on your form (be it good or bad!). SW doesn't capture that effort/force since it says that mass lower in the frame doesn't matter.

Balance is also more important than SW since it drives the relative timing of the hand and stringbed to contact. If balance is off for a given static weight and given player then either the hand will lag at contact or the stringbed will lag at contact. The result is poor contact instead of clean contact.

SW is useful to fine tune two frames already matched for mass and balance since it represents the details of mass distribution in the head of the frame. The best procedure when matching frames or seeking a particular playing experience is to first look at static weight relative to balance and then SW as a finer shade of choice.

In other words, if SW were really most important, then there would be virtually no difference between a 10 oz frame with SW 320 and a 13 oz frame with SW 320, which is absurd. And even if you match two frames for SW and static weight then if balance is not matched they're going to feel very different on your timing.

 

[TimothyO]

It sounds like you lose RHS when increasing the SW so you're getting more play but losing power through decreased RHS. There's often an optimum point for each person.

One can also lose RHS by increasing static weight too much or with a balance that's too far towards even balance instead of being more HL.

Neither of us could swing a frame that's 300 pounds with a SW of 320*. But we can both swing a frame that weighs 11 ounces with a SW of 350.

Most importantly (and realistically), a frame with a SW of 315 and slightly shaded towards even balance can be harder to swing than a frame with a SW of 325 if the first frame's mass is concentrated in the throat and lower hoop.

*If you think it's absurd to use a 300 pound frame as an example then you must agree that saying SW is most important is equally absurd since, using the SW formula with its 10cm reference point, a 300 pound, SW 320 frame is perfectly plausible.

 

[TimothyO]

I added 15g at 12 to one of my Pro Staffs. There was not a noticeable increase in power on groundstrokes, but a noticeable increase in spin and control which resulted in a higher margin for error.

I've noticed something very similar.

Sometimes extra mass in the head slows RHS to the point that power isn't increased or even decreased since total force is reduced.

And I've experienced extra spin by adding weight in the upper hoop as the sweet spot is stretched and I get more ball pocketing.

But at some point increasing mass, making a frame shaded to far to even balance, or increasing SW can all lead to lower RHS depending on technique and physique.

 

[morten]

I hear what you say, and i think... Hm.. But if i were to find matched frames, i would pick the similar sw, then add weight in the handle area for the matching..?

 

[TimothyO]

I hear what you say, and i think... Hm.. But if i were to find matched frames, i would pick the similar sw, then add weight in the handle area for the matching..?

You could do that as long as you also match total static mass and balance. Changing any one variable with additional mass shifts the others. In that case you'd be changing balance too and therefore relative timing of hand vs stringbed at contact. And while adding mass there doesn't shift conventional SW it does change how hard it is to swing the frame since you've added mass. There's no free lunch.

Another consideration is the effect on sweet spot. You can have two frames with the same mass, balance, and SW but depending on where you added lead in the head the frames can still play differently.

 

[SpinToWin]

I've noticed something very similar.

Sometimes extra mass in the head slows RHS to the point that power isn't increased or even decreased since total force is reduced.

And I've experienced extra spin by adding weight in the upper hoop as the sweet spot is stretched and I get more ball pocketing.

But at some point increasing mass, making a frame shaded to far to even balance, or increasing SW can all lead to lower RHS depending on technique and physique.

Anybody who says that lead at 12 doesn't slow down his swing at all isn't objective in my book. Increase the swingweight from 320 to 355 (same racquet without counterbalancing), no way there won't be some decrease in RHS.

I have technically good groundstrokes and especially my backhand has hardly slowed down. I am getting more net clearance (which shows that there is more intrinsic power), but the ball is dropping faster due to the added spin. This gives the feel of more control (and spin) as you have a much larger window to hit into.

 

[movdqa]

I strongly disagree that SW is more important.

You can have a two frames with the same SW of, say, 320, but one can weigh 11 ounces and the other 100 pounds. This is literally true since extra mass at 10cm is discounted to a value of 0 in the SW calculation. Mass in the handle, throat, and lower hoop is also heavily discounted. Go to the TW modification tool and try it. Add as much mass as you want to at 10cm and the SW doesn't move.

Total mass relative to balance is far more important while conventional SW helps fine tune that relationship.

The reason is that when we swing we're swinging the entire mass of the frame from butt cap to tip around an axis somewhere around your core to elbow depending on your form (be it good or bad!). SW doesn't capture that effort/force since it says that mass lower in the frame doesn't matter.

Balance is also more important than SW since it drives the relative timing of the hand and stringbed to contact. If balance is off for a given static weight and given player then either the hand will lag at contact or the stringbed will lag at contact. The result is poor contact instead of clean contact.

SW is useful to fine tune two frames already matched for mass and balance since it represents the details of mass distribution in the head of the frame. The best procedure when matching frames or seeking a particular playing experience is to first look at static weight relative to balance and then SW as a finer shade of choice.

In other words, if SW were really most important, then there would be virtually no difference between a 10 oz frame with SW 320 and a 13 oz frame with SW 320, which is absurd. And even if you match two frames for SW and static weight then if balance is not matched they're going to feel very different on your timing.

Why is that absurd?

What's the most consistent spec for top ATP Pros? Swingweight or static weight? Swingweight is generally 350 and up whereas static weight can be below 12 ounces or 12.5 and up.

 

[movdqa]

One can also lose RHS by increasing static weight too much or with a balance that's too far towards even balance instead of being more HL.

Neither of us could swing a frame that's 300 pounds with a SW of 320*. But we can both swing a frame that weighs 11 ounces with a SW of 350.

Most importantly (and realistically), a frame with a SW of 315 and slightly shaded towards even balance can be harder to swing than a frame with a SW of 325 if the first frame's mass is concentrated in the throat and lower hoop.

*If you think it's absurd to use a 300 pound frame as an example then you must agree that saying SW is most important is equally absurd since, using the SW formula with its 10cm reference point, a 300 pound, SW 320 frame is perfectly plausible.

I suppose absurd examples may make you feel better but I've actually used a 17 ounce frame. My current frames are 13+ ounces and 386 SW.

As far as difficulty goes on static weight and balance - you get used to it and you adapt.

 

[movdqa]

You could do that as long as you also match total static mass and balance. Changing any one variable with additional mass shifts the others. In that case you'd be changing balance too and therefore relative timing of hand vs stringbed at contact. And while adding mass there doesn't shift conventional SW it does change how hard it is to swing the frame since you've added mass. There's no free lunch.

Another consideration is the effect on sweet spot. You can have two frames with the same mass, balance, and SW but depending on where you added lead in the head the frames can still play differently.

I just get matched pro stock sets. The hairpins start out lighter so there's potentially less chances of variance. At any rate, I'm quite pleased with the results.

 

[movdqa]

Anybody who says that lead at 12 doesn't slow down his swing at all isn't objective in my book. Increase the swingweight from 320 to 355 (same racquet without counterbalancing), no way there won't be some decrease in RHS.

I have technically good groundstrokes and especially my backhand has hardly slowed down. I am getting more net clearance (which shows that there is more intrinsic power), but the ball is dropping faster due to the added spin. This gives the feel of more control (and spin) as you have a much larger window to hit into.

Increasing the SW that much in a short period of time and you can wind up with an injury. You might be getting the benefit of polarization that Travlerjam always talks about.

You could increase the swingweight a little at a time and then get stronger to bring your RHS back up to what it was before. Then repeat.

 

[morten]

Generally, the rackets i have liked have the same swingweight, feks i prefer 310-315sw. I also like heavy headlight. But i would rather play a light racket within my preferred swingweight measurement, than a heavy headlight racket with a too high swingweight...

 

[SpinToWin]

Increasing the SW that much in a short period of time and you can wind up with an injury. You might be getting the benefit of polarization that Travlerjam always talks about.

You could increase the swingweight a little at a time and then get stronger to bring your RHS back up to what it was before. Then repeat.

I didn't do that, I was just making an example. If you go back to lighter racquet now, say with a swingweight of 330, your swing will inevitably be faster. That's all I was saying.

I have been playing around with increased swingweight for about 3/4 of a year and have slowly gone from about 325 to 355, while playing regularly.

 

[movdqa]

Well, that's a reasonable way to do it. I went from about 310 to 386 in about five or six years. I have some racquets which are 390-400 SW but I haven't used them in a while.

Maybe we should have a high SW club (> 345).

 

[JohnB]

I've noticed something very similar.

Sometimes extra mass in the head slows RHS to the point that power isn't increased or even decreased since total force is reduced.

And I've experienced extra spin by adding weight in the upper hoop as the sweet spot is stretched and I get more ball pocketing.

But at some point increasing mass, making a frame shaded to far to even balance, or increasing SW can all lead to lower RHS depending on technique and physique.

This is called, I believe, SW2.

 

[SpinToWin]

Well, that's a reasonable way to do it. I went from about 310 to 386 in about five or six years. I have some racquets which are 390-400 SW but I haven't used them in a while.

Maybe we should have a high SW club (> 345).

oh please let's do this

 

[PMChambers]

Not true what your talking about is the Twist Weight. If you have something like a Babolat RDC, first you measure the SW using the normal procedure swing the frame in a normal swing path they rotate the frame 90* and measure it again. The time when the string plain is parallel to the swinging direction is always higher. Subtract the SW from the higher and you have TW.

Sorry, I don't understand in terms of physics or "real" measurement what you're describing as a Twist Weight. I've used a RDC machine only twice, and from what I gather they're trying to represent Rotational Inertia at a point 10cm up from the but cap. The unit's seems to represent Rotational Inertia to me, so unless the measurement is purely made up, I don't know what it is. The description of TW manual calculation method would indicate that it's Rotational Inertia also. I also think measuring Rotational Inertia at a point 10cm from the butt is deceptive to reality because the actual rotation will be closer to to the elbow on most shots or preparation, which makes the mass in the handle more relevant. At the end of the day the only people using SW are TW and Babalot RDC machines. I've never seen a SW measure on a racquet from a manufacture, as weight and balance are effectively enough to determine the characteristic. The point of reference should be measured as close to reality for the average shot as possible, which is not 10cm up from the butt, I think they should measure RI from about 45cm down from the but cap.
As a method of balancing two racquets the method is fine but describing how they react to different strokes this numeric number is flawed due to the point of rotation.
Weight, balance and RA will give a good guide to how a racquet will play, SW is nice but not necessary.

Please note I'm not 100% with a Babolat RDC machine as they don't give the numeric calculation for they're machine. I have used one twice and they have a use for balancing similar racquets. The SW measurement I've seen from TW are not that useful compared to Weight, balance and RA in my book.

 

[SpinToWin]

Sorry, I don't understand in terms of physics or "real" measurement what you're describing as a Twist Weight. I've used a RDC machine only twice, and from what I gather they're trying to represent Rotational Inertia at a point 10cm up from the but cap. The unit's seems to represent Rotational Inertia to me, so unless the measurement is purely made up, I don't know what it is. The description of TW manual calculation method would indicate that it's Rotational Inertia also. I also think measuring Rotational Inertia at a point 10cm from the butt is deceptive to reality because the actual rotation will be closer to to the elbow on most shots or preparation, which makes the mass in the handle more relevant. At the end of the day the only people using SW are TW and Babalot RDC machines. I've never seen a SW measure on a racquet from a manufacture, as weight and balance are effectively enough to determine the characteristic. The point of reference should be measured as close to reality for the average shot as possible, which is not 10cm up from the butt, I think they should measure RI from about 45cm down from the but cap.
As a method of balancing two racquets the method is fine but describing how they react to different strokes this numeric number is flawed due to the point of rotation.
Weight, balance and RA will give a good guide to how a racquet will play, SW is nice but not necessary.

Please note I'm not 100% with a Babolat RDC machine as they don't give the numeric calculation for they're machine. I have used one twice and they have a use for balancing similar racquets. The SW measurement I've seen from TW are not that useful compared to Weight, balance and RA in my book.

Swingweight is important. Add 20g at 12 and 20g to the buttcap in one racquet. Then add 40g in the throat to another racquet (same model with identical specs). You will have approximately the same static weight and balance, but the polarized racquet will feel much much much heavier.

 

[taurussable]

how to tell if my swingweight or static weight is too high? ground strokes are perfectly fine. I am learning the serve and want to make sure the racquet is not too heavy for serves.

 

[movdqa]

You can get golfer's elbow serving with a racquet that's too heavy (Swing or static). It looks like you have a lot of lead on your frames - it's best to add weight slowly until you get to what feels best. You've probably already gone through that process given that your swingweight is very close to the peak on retail frames.

 

[taurussable]

You can get golfer's elbow serving with a racquet that's too heavy (Swing or static). It looks like you have a lot of lead on your frames - it's best to add weight slowly until you get to what feels best. You've probably already gone through that process given that your swingweight is very close to the peak on retail frames.

thanks for the warning. I've been using that spec for more than a year now after some initial testing. my serve is lame and timing is a little late in the takeback, should I take the shortcut to decrease some swingweight or change my timing? I love the racquet for ground strokes and anything else. maybe volley is a little late too.

 

[movdqa]

Post video of your serve in the instruction/tips section and ask for you can improve.

 

[Fintft]

Interresting.. I am still very sensitive to sw, as if a racket has too high swingweight, i have seldom managed to even it out by making it more headlight, adding weight to handle etc.. And i like heavy rackets...

I agree with you and that's why while I've kept the static weight constant over the last 5 years I went for a lighter SW (From KFactor, to BLX 2010 to BLX Amplifeel 2012 in 6.1 95).

 

[morten]

I agree with you and that's why while I've kept the static weight constant over the last 5 years I went for a lighter SW (From KFactor, to BLX 2010 to BLX Amplifeel 2012 in 6.1 95).

so what is your ideal sw now, and then?

 

[Fintft]

so what is your ideal sw now, and then?

As per TW specs for 6.1 95 BLX:

Strung Weight: 12.2oz / 345.86g
Balance: 10 pts HL
Swingweight: 324

http://www.tennis-warehouse.com/Wilson_SixOne_95_BLX_16x18/descpageRCWILSON-WSO95O.html

The Kfactor had about 14g more SW so about 338-340g, if I remember correctly.

And the latest 2013 model has only changed by 1g SW and 3g Static weight:

http://www.tennis-warehouse.com/Wilson_SixOne_95_16x18/descpageRCWILSON-619516.html#spec

Strung Weight: 12.3oz / 348.7g
Balance: 12.31in / 31.27cm / 10 pts HL
Swingweight: 325

 

[SpinToWin]

As per TW specs for 6.1 95 BLX:

Strung Weight: 12.2oz / 345.86g
Balance: 10 pts HL
Swingweight: 324

http://www.tennis-warehouse.com/Wilson_SixOne_95_BLX_16x18/descpageRCWILSON-WSO95O.html

The Kfactor had about 14g more SW so about 338-340g, if I remember correctly.

And the latest 2013 model has only changed by 1g SW and 3g Static weight:

http://www.tennis-warehouse.com/Wilson_SixOne_95_16x18/descpageRCWILSON-619516.html#spec

Strung Weight: 12.3oz / 348.7g
Balance: 12.31in / 31.27cm / 10 pts HL
Swingweight: 325

Correction: Swingweight's Units are kg/cm²

 

[PMChambers]

Swingweight is important. Add 20g at 12 and 20g to the buttcap in one racquet. Then add 40g in the throat to another racquet (same model with identical specs). You will have approximately the same static weight and balance, but the polarized racquet will feel much much much heavier.

No, I don't see that at all. The racquet is rigid member. It has a center of gravity/mass if you add mass at the center of gravity or equal half masses either side it does not move the center of mass. All rotation outside of the mass are directly relevant to the centre of mass. SW is a function of measurement of center of mass by the distance to rational point. It does not matter how you distribute the mass rather the center of mass which is a function of mass x distance (kg/cm) if you then extrapolate that to a Rotational Inertia (kg/cm^2) it's a function of the distance from centre of mass to the the rotation location.

Swing weight is calculated at 10cm up from the butt of the racquet. Which means SW is calculating Rotational Inertia as though the whole racquet rotates around this point. It does not and can not as that would require the arm and elbow to be stationary and wrist joint to be located at 10 up from the racquet, when holding my racquet my wrist pivot point is about at the end of the butt, but more importantly when I swing I use my arm and elbow to generate most of my velocity and therefore the SW calculation is poor representation of reality.

Where SW fails most is in the positioning of weight behind the 10cm pivot. I have about 15g of lead in the butt cap. According to SW calculation that is a (-) neg swing weight of about 1.5 kg/cm^2. This means that the calculation is assuming the mass added to the ridged body is lowering the bodies inertia which is completely wrong. As a result I've seem people say adding mass to the handle makes a racquet more maneuverable, which is a fallacy, it makes a racquet less maneuverable but adds inertia or stability to the racquet.

The reality is there is very little mass below the 10cm point of a standard manufactured racquet. It is a hollow graphite shaft with a plastic bumper, usually the reinforcement in the handle finishes before the end. However, if you start adding weight to a raquets handle in the form of descent amount of lead, 10g+ or silicon filling the handle the hole SW calculation becomes pointless as it does not correspond to reality.

Swing weight does not represent reality because it picks a pivot that is significantly incorrect. Swing weight would be more accurate to measure at 45cm away from the butt rather than -10cm. The 55cm would make a lot of difference as it's MassxDistance^2 and represent something more functional.

I maybe wrong but my recollection of Swing Weight is that it appeared when Babolat brought out their RDC machine which I first saw around 1992. At that point no one mentioned SW as a racquet's characteristic as it effectively quantifies balance & mass into one number. The RDC machine was designed to match racquet's, not represent a playing stroke. SW was never meant to be used as a racquet's qualitative representation of play-ability, weight, balance and stiffness are all that's needed. I might be wrong as it's be a long time since I used a RDC machine but when I last used one to work out SW you need to first measure, weight, balance and then it determined inertia a a force applied to swing, thus calculating SW.

SW was meant for match pairing racquet's not numerically describing their play ability.

Anyway that's what my physics and engineering review determines. I could be wrong as I don't have all the information, but from the confusion about SW and it's play ability I think I'm close. I'm not indicating it's useless measurement, rather a measurement that still needs to be read in conjunction with at least to mass, balance and stiffness for any real world meaning.

 

[TimothyO]

No, I don't see that at all. The racquet is rigid member. It has a center of gravity/mass if you add mass at the center of gravity or equal half masses either side it does not move the center of mass. All rotation outside of the mass are directly relevant to the centre of mass. SW is a function of measurement of center of mass by the distance to rational point. It does not matter how you distribute the mass rather the center of mass which is a function of mass x distance (kg/cm) if you then extrapolate that to a Rotational Inertia (kg/cm^2) it's a function of the distance from centre of mass to the the rotation location.

Swing weight is calculated at 10cm up from the butt of the racquet. Which means SW is calculating Rotational Inertia as though the whole racquet rotates around this point. It does not and can not as that would require the arm and elbow to be stationary and wrist joint to be located at 10 up from the racquet, when holding my racquet my wrist pivot point is about at the end of the butt, but more importantly when I swing I use my arm and elbow to generate most of my velocity and therefore the SW calculation is poor representation of reality.

Where SW fails most is in the positioning of weight behind the 10cm pivot. I have about 15g of lead in the butt cap. According to SW calculation that is a (-) neg swing weight of about 1.5 kg/cm^2. This means that the calculation is assuming the mass added to the ridged body is lowering the bodies inertia which is completely wrong. As a result I've seem people say adding mass to the handle makes a racquet more maneuverable, which is a fallacy, it makes a racquet less maneuverable but adds inertia or stability to the racquet.

The reality is there is very little mass below the 10cm point of a standard manufactured racquet. It is a hollow graphite shaft with a plastic bumper, usually the reinforcement in the handle finishes before the end. However, if you start adding weight to a raquets handle in the form of descent amount of lead, 10g+ or silicon filling the handle the hole SW calculation becomes pointless as it does not correspond to reality.

Swing weight does not represent reality because it picks a pivot that is significantly incorrect. Swing weight would be more accurate to measure at 45cm away from the butt rather than -10cm. The 55cm would make a lot of difference as it's MassxDistance^2 and represent something more functional.

I maybe wrong but my recollection of Swing Weight is that it appeared when Babolat brought out their RDC machine which I first saw around 1992. At that point no one mentioned SW as a racquet's characteristic as it effectively quantifies balance & mass into one number. The RDC machine was designed to match racquet's, not represent a playing stroke. SW was never meant to be used as a racquet's qualitative representation of play-ability, weight, balance and stiffness are all that's needed. I might be wrong as it's be a long time since I used a RDC machine but when I last used one to work out SW you need to first measure, weight, balance and then it determined inertia a a force applied to swing, thus calculating SW.

SW was meant for match pairing racquet's not numerically describing their play ability.

Anyway that's what my physics and engineering review determines. I could be wrong as I don't have all the information, but from the confusion about SW and it's play ability I think I'm close. I'm not indicating it's useless measurement, rather a measurement that still needs to be read in conjunction with at least to mass, balance and stiffness for any real world meaning.

All of this is correct sir.

But here on TT folks think SW actually measures something useful. I guess most of them have terrible, wristy strokes and swing entirely that point on the handle.

Recently, while getting my Pro Staffs set up to my liking, I noticed yet again that SW fails to accurately represent the effects of mass lower in the frame when comparing various configurations of lead with the ProStaff and my Pure Storms. If SW measures anything practical its volley impact. But for serve and ground stroke it's useless.

 

[fuzz nation]

Which is actually more important?

For example my Prostaff 90 has a higher strung weight than my Youtek Radical Pro, but the latter has a higher swing weight.

And the newer BLX 90s have lower swingweights than the older K90 and NCode90, no? Does this mean a dropoff in performance?

I've found that it's taken a little sampling and maybe keeping some notes on the behavior of different racquets to build a picture of what works better or worse for me. I appreciate the comparative number that swing weight is supposed to represent, but it hasn't been helpful for me on its own.

As our pals have discussed above, two racquets with the same swing weight can also have significantly different personalities - by that, I mean handling, power, etc. Static weight also doesn't tell me much by itself because I've found that a frame can seem quite unfamiliar if it doesn't have a balance that gives me the "right" maneuverability.

The flex in a racquet can also contribute a lot to its response and feel. Too soft can mean too low-powered and "dead" (especially without enough weight), but too stiff can seem too hot and unpredictable. As with swing weight vs. static weight though, none of these specs tell the whole story without some others handy to generate some "context".

If I know the static weight, balance, and flex of a racquet, I can tell whether or not that option might have some potential for me. I usually encourage folks here who are trying to figure out all the racquet numbers to watch those three specs. Although they may not tell me if a frame has most of its flex in the throat or how its weight is distributed (just for example), these parameters have become the most important ones for helping me find a good fit.

 

[Fintft]

Correction: Swingweight's Units are kg/cm²

Well, I mainly go by TW figures and that's helpful enough for me.

 

[SpinToWin]

Well, I mainly go by TW figures and that's helpful enough for me.

Well yeah, but the units still are kg/cm²

 

[Fintft]

I'm not indicating that SW it's a useless measurement, rather a measurement that still needs to be read in conjunction with at least to mass, balance and stiffness for any real world meaning.

I agree, but if the mass and stiffness are kept constant and only balance is lighter (head lighter), than I've noticed that I prefer those models.

SW might be not of large significance, but just an indicator, as it seems that when I moved from:

Kfactor->2010 BLX->2012 BLX Amplifeel

in the same frame 6.1 95, I lost about 14 kg/cm²(ok not grams) in SW.

What's funny is that what they write on the frames in terms of ballance is usually wrong, in reality it was something like:

4 points HL-> 6 points HL-> 10 points HL in the above versions.

Same answer to TimothyO and no, I don't think that my strokes are writsy, on the contrary:

All of this is correct sir.

But here on TT folks think SW actually measures something useful. I guess most of them have terrible, wristy strokes and swing entirely that point on the handle.

Recently, while getting my Pro Staffs set up to my liking, I noticed yet again that SW fails to accurately represent the effects of mass lower in the frame when comparing various configurations of lead with the ProStaff and my Pure Storms. If SW measures anything practical its volley impact. But for serve and ground stroke it's useless.

I also agree with Fuzznation:

If I know the static weight, balance, and flex of a racquet, I can tell whether or not that option might have some potential for me. I usually encourage folks here who are trying to figure out all the racquet numbers to watch those three specs. Although they may not tell me if a frame has most of its flex in the throat or how its weight is distributed (just for example), these parameters have become the most important ones for helping me find a good fit.