Balance and Swing Weight

[Fluffy_Skye]

After a year of racketholism, I am finally settling down with the Pro Staff 100 v13. Now I'm at the next stage, that is finding the right customization. I have owned two PS100 with the following specs:

#1: W:307g Bal:8pts HL SW:292
#2: W:305g Bal:7pts HL SW:289

What's interesting is that, even though #1 has a higher swing weight (just a smidge), #2 packs a noticeably larger punch. If I don't know the spec, I would definitely say #2 has a higher swing weight (not a smidge). I eventually sold off #1 as it just doesn't feel natural to swing, too much weight in the handle and not enough in the head, but even though I really like #2, I do find it a bit sluggish at times. I play well with both rackets and the feel and comfort makes me settle down with this model.

So now I am looking to buy another one as back up, also to try different strings. I will use TW matching service, but I'm not sure what spec to look for. Should I look for something with the same balance as #2 but at a lower swing weight, or should I look for something with the same balance as #1 but at a higher swing weight? Although it's quite possible that I might not find a suitable one even through matching service, I do want to be pointed at the right direction.

To add more to the topic, I've also owned a Gravity Tour with the following spec:

#3: W:305g Bal:7.5pts HL SW:294

Again, the difference in swing weight between #1 and #3 is quit small, but the difference is night and day. #3 is basically unplayably sluggish so I sold it off. This is completely opposite to #1 which I actually find the hoop to be too light.

Thus, it seems to me that balance point has a surprisingly large effect on the feel of swinging a racket, when the difference in swing weight is small. A retailer I know, however, thinks weight and swing weight already paint the general picture of a racket and balance point is negligible. Thoughts?

 

[esgee48]

Your posted spec appear to be unstrung. Would you have them when strung? Really need their all in playing specs.

There is a thread discussing MgR/I =~ 22 initiated by @travlerajm which you may want to look at. Your number may not be ~22 but whatever that number could be would give you some repeatability when swinging your frames. All my frames are between 21.7 and 21.8. I can switch between 6 racquets and they all feel the same thru the swing.

Not all posters subscribe to this derivation but I do since QC is an issue.

 

[Fluffy_Skye]

Your posted spec appear to be unstrung. Would you have them when strung?

There is a thread discussing MgR/I =~ 22 initiated by @travlerajm which you may want to look at. Your number may not be ~22 but whatever that number could be would give you some repeatability when swinging your frames. All my frames are between 21.7 and 21.8. I can switch between 6 racquets and they all feel the same thru the swing.

Not all posters subscribe to this derivation but I do since QC is an issue.

Unfortunately I don't have strung specs. Especially since I've already sold off other rackets and only have #2, so I can't compare them anyway. I don't know what MgR/I is but it deeply intrigues me, and worries me as it sucks me deeper into the wormhole of rackets.

 

[BlueB]

Wasn't that magic number 21?

 

[BlueB]

Unfortunately I don't have strung specs. Especially since I've already sold off other rackets and only have #2, so I can't compare them anyway. I don't know what MgR/I is but it deeply intrigues me, and worries me as it sucks me deeper into the wormhole of rackets.

It's basically the weight distribution.

 

[Fluffy_Skye]

Wasn't that magic number 21?

Is this number going to work magic on everyone? Isn't each person's biomechanics different?

 

[gazz1]

Perhaps the distribution of the weight in the hoop (how polarised it is).
For rackets with the same swingweight and specs - a more polarised racket will have a higher proportion of weiight around 12 & 6, and less polarised will have more at 3 and 9.
This affects how the racket feels when you swing it.
If I remember correctly from what I read from others on this forum, Polarised rackets feel more whippy and would have a lower twist weight (I hope I have that around the right way)?

 

[Fluffy_Skye]

Perhaps the distribution of the weight in the hoop (how polarised it is). This affects how the racket feels when you swing it.
If I remember correctly from what I read from others on this forum, Polarised rackets feel more whippy and would have a lower twist weight (I hope I have that around the right way)?

I am hoping that rackets of the same model, though may be different in terms of weight, center of mass, and swing weight, at least have the same type of weight distribution. Otherwise it seems incredibly unlikely to match how two racket swings.

 

[BlueB]

Is this number going to work magic on everyone? Isn't each person's biomechanics different?

Yes we are. However, it feels pretty good when a racquet is tuned around 21.

 

[gazz1]

I am hoping that rackets of the same model, though may be different in terms of weight, center of mass, and swing weight, at least have the same type of weight distribution. Otherwise it seems incredibly unlikely to match how two racket swings.

With such high variances from the major manufacuters like Babolat, Wilson, Head, etc it's more common than you think.
You will have a far better chance with Yonex which have much better quality control.
Angel rackets are bang on.

Personally, I don't know how much of a difference it makes...others here know more about this than me.
I must admit though, I did have 2 Aero Pros years ago that were pretty close in spec and I felt a difference...real or perceived?...I don't know.

 

[BlueB]

I am hoping that rackets of the same model, though may be different in terms of weight, center of mass, and swing weight, at least have the same type of weight distribution. Otherwise it seems incredibly unlikely to match how two racket swings.

Unfortunately they don't necessarily...

 

[Fluffy_Skye]

Yes we are. However, it feels pretty good when a racquet is tuned around 21.

I see. I am currently trying to find out more about this, as I'm reading though physics on this forum lol.

 

[Fluffy_Skye]

With such high variances from the major manufacuters like Babolat, Wilson, Head, etc it's more common than you think.
You will have a far better chance with Yonex which have much better quality control.
Angel rackets are bang on.

Personally, I don't know how much of a difference it makes...others here know more about this than me.
I must admit though, I did have 2 Aero Pros years ago that were pretty close in spec and I felt a difference...real or perceived?...I don't know.

Unfortunately I just don't enjoy Yonex rackets. Also I've heard that even though Yonex are pretty precise on weight and balance, they still have large variation on swing weight, though I don't like Yonex rackets so I never look into this.

 

[Fluffy_Skye]

Unfortunately they don't necessarily...

That's just sad, but understandably difficult for mass production. I don't think pros will accept this though. Do they have specially made rackets with good quality tolerance or they also just have to try and find the rackets that feel right?

 

[esgee48]

Is this number going to work magic on everyone? Isn't each person's biomechanics different?

Wasn't that magic number 21?

You are correct. ~21 is the number. And my range is between 20.7 and 20.8.

Final tuning via actual hitting is needed. The derivation is based on double pendulums and the happenstance that many of the better pros have MgR/I ~21. The mass of the strings will contribute to final SW and balance as well ad OG.

If you plan to go for frame matching, might as well ask for all three since you will get a choice. Get less than what you want cuz you can mod them up to you desired specs.

 

[Fluffy_Skye]

You are correct. ~21 is the number. And my range is between 20.7 and 20.8.

Final tuning via actual hitting is needed. The derivation is based on double pendulums and the happenstance that many of the better pros have MgR/I ~21. The mass of the strings will contribute to final SW and balance as well ad OG.

If you plan to go for frame matching, might as well ask for all three since you will get a choice. Get less than what you want cuz you can mod them up to you desired specs.

Well, when buying a racket, TW can only provide unstrung specs. Would it be sufficient to match MgR/I for unstrung rackets, as long as I put on the same string and overgrip?

 

[esgee48]

MgR/I is done with strung frames etc. You want a frame less than what your current frame is which is unstrung. TWU has a calculator which will tell you how much lead and where to put it if you are matching a less than spec frame to your desired targets. When done, your strung frames should be very similar.

less than 305 g more than 7.5 pts hl and less than 289 sw units is what you are shooting for

 

[Fluffy_Skye]

MgR/I is done with strung frames etc. You want a frame less than what your current frame is which is unstrung. TWU has a calculator which will tell you how much lead and where to put it if you are matching a less than spec frame to your desired targets. When done, your strung frames should be very similar.

less than 305 g more than 7.5 pts hl and less than 289 sw units is what you are shooting for

Thanks for the conclusive answer!

 

[BlueB]

That's just sad, but understandably difficult for mass production. I don't think pros will accept this though. Do they have specially made rackets with good quality tolerance or they also just have to try and find the rackets that feel right?

Their racquets start very light, them get heavily customized and matched.

 

[Irvin]

Thus, it seems to me that balance point has a surprisingly large effect on the feel of swinging a racket, when the difference in swing weight is small. A retailer I know, however, thinks weight and swing weight already paint the general picture of a racket and balance point is negligible. Thoughts?

Mass and balance (radius) has EVERYTHING to do with inertia (SW.)

I = mr^2

 

[Irvin]

@Fluffy_Skye SW is nothing more that the conversion of the inertia at the center of mass (RW) to the inertia 10 cm from the butt (SW.)

SW = RW + (mr^2) where r is the distance from the 10 cm axis to the balance point.

RW racket #1 is 145 while the RW of racket #2 is 148. Racket #2‘s inertia (resistance to change in motion) is the higher of the 2 and the center of mass is closer to the contact point. Wouldn’t you expect the racket with the greatest force (#2) where that force is more directly behind the ball (#2) would have the most power? Don’t believe everything you hear about this magic SW number. Believe this the greater the RW and the closer the balance point is to the contact point the more power you have.

 

[Fluffy_Skye]

@Fluffy_Skye SW is nothing more that the conversion of the inertia at the center of mass (RW) to the inertia 10 cm from the butt (SW.)

SW = RW + (mr^2) where r is the distance from the 10 cm axis to the balance point.

RW racket #1 is 145 while the RW of racket #2 is 148. Racket #2‘s inertia (resistance to change in motion) is the higher of the 2 and the center of mass is closer to the contact point. Wouldn’t you expect the racket with the greatest force (#2) where that force is more directly behind the ball (#2) would have the most power? Don’t believe everything you hear about this magic SW number. Believe this the greater the RW and the closer the balance point is to the contact point the more power you have.

Wow, when you put it like that it makes sense!

 

[ryohazuki222]

I saw that somewhere else about mgr/i ideal being 21. But I didn’t see that to be true in my own experiments.

on one side: based on some analysis of atp players…. The average is about 20.5. For 1 handed backhand players its lower than for 2 handed backhand players.

I found targeting a number to be ineffective for me. Keep in mind I was building a stick for a modern, very rotational stroke… not a classic more linear stroke.

what worked better was to first ignore mgr/i to hone in on sw and static weight. Inevitable id end up with a really polarized racket only adding at 12 and butt as needed. Then to “even it out” I found slowly adding weight at the balance point would help make the racket more playable. This last bit is essentially “increasing the mgr/i” until the racket feels better.

 

[Fluffy_Skye]

MgR/I is done with strung frames etc. You want a frame less than what your current frame is which is unstrung. TWU has a calculator which will tell you how much lead and where to put it if you are matching a less than spec frame to your desired targets. When done, your strung frames should be very similar.

less than 305 g more than 7.5 pts hl and less than 289 sw units is what you are shooting for

The measured specs (with plastic on handle) just came in today:

N1: 305.89g, 7.0 HL, 290 SW
N2: 305.89g, 8.0 HL, 287 SW
N3: 306.17g, 8.0 HL, 290 SW
N4: 306.46g, 8.0 HL, 289 SW
N5: 307.03g, 7.0 HL, 292 SW
N6: 308.44g, 7.5 HL, 291 SW

I am tempted by the 7.5 balance on N6 as it may just be right sitting in between 7 and 8, but I do worry about it also being sluggish as my current racket (#2), or perhaps even more so. A safer approach is to get an 8 balance one, namely, N2, N3, N4, and then add maybe 2 grams of weight at 3&9, which should bring it to 7.5 balance while adding perhaps 2 point SW, according to TWU customization tool. I can always tweak the added weight if it proves to be too sluggish.

One doubt I have, however, is that even though adding 2 grams at 3&9 would bring 8 HL to 7.5 HL, would it feel the same with a racket that's naturally 7.5 HL? In particular, a concrete example in this setting is that, does adding 2 grams at 3&9 on N4 end up with the same swing feeling as N6? They would have almost the same weight, balance, and swing weight.

My suspicion is that the added weight would be very concentrated at a particular position, and thus may feel different to one that's evenly spread across the racket. This is a question that puzzled me a long time regarding adding weight to rackets.

 

[Irvin]

@Fluffy_Skye you do realize the difference between 7.0 - 7.5, and 7.5 - 8.0 could be from about 0-3 mm? You could do better than that using any other method known to man. Using 1/8" measurements for balance is a pathetic system of measuring balance. And you haven’t even strung the rackets yet.

EDIT: Your rackets are going to end up around 325 g strung and if you’re going to try to determine MGR/I your error in Inertia alone could amount to 0-5 kgcm. Good luck.

 

[Fluffy_Skye]

@Fluffy_Skye you do realize the difference between 7.0 - 7.5, and 7.5 - 8.0 could be from about 0-3 mm? You could do better than that using any other method known to man. Using 1/8" measurements for balance is a pathetic system of measuring balance. And you haven’t even strung the rackets yet.

EDIT: Your rackets are going to end up around 325 g strung and if you’re going to try to determine MGR/I your error in Inertia alone could amount to 0-5 kgcm. Good luck.

Absolutely but it’s how TW measure the specs. Unless anyone had experience asking them to measure in cm. However, though the measure is in points HL, the largest error is not 1/8’’. The precision they use is 0.5 HL and thus it’s 1/16’’, about 1.6 mm.

 

[Irvin]

Absolutely but it’s how TW measure the specs. Unless anyone had experience asking them to measure in cm. However, though the measure is in points HL, the largest error is not 1/8’’. The precision they use is 0.5 HL and thus it’s 1/16’’, about 1.6 mm.

Let’s assume 7.0 points HL could be anywhere between 6.51 and 7.49 points HL. That a difference of 0.98/8”,and .98/8” is 3.11 mm. The difference between your 7.0 and 8.0 HL could be as little as 0.2/8” or as great as 1.98/8” or from 0.01 to 6.3 mm. If I were you I would not use TW’s balance measurements.

 

[Fluffy_Skye]

Let’s assume 7.0 points HL could be anywhere between 6.51 and 7.49 points HL. That a difference of 0.98/8”,and .98/8” is 3.11 mm. The difference between your 7.0 and 8.0 HL could be as little as 0.2/8” or as great as 1.98/8” or from 0.01 to 6.3 mm. If I were you I would not use TW’s balance measurements.

Actually if measured correctly, the largest measurement error would be half of the precision level. But you’re right, it’s still quite a large variation. Only TW sells this racket so I can’t do any better. I’ll ask them if they can do better measurement.

 

[Fluffy_Skye]

Let’s assume 7.0 points HL could be anywhere between 6.51 and 7.49 points HL. That a difference of 0.98/8”,and .98/8” is 3.11 mm. The difference between your 7.0 and 8.0 HL could be as little as 0.2/8” or as great as 1.98/8” or from 0.01 to 6.3 mm. If I were you I would not use TW’s balance measurements.

It was nice of TW to provide a more accurate measurement. What do you think of these?
1) 305.89g, 32.0cm, 290 SW
2) 305.89g, 31.6cm, 287 SW
3) 306.17g, 31.7cm, 290 SW
4) 306.46g, 31.8cm, 289 SW
5) 307.03g, 32.0cm, 292 SW
6) 308.44g, 31.8cm, 291 SW

 

[Irvin]

It was nice of TW to provide a more accurate measurement. What do you think of these?
1) 305.89g, 32.0cm, 290 SW
2) 305.89g, 31.6cm, 287 SW
3) 306.17g, 31.7cm, 290 SW
4) 306.46g, 31.8cm, 289 SW
5) 307.03g, 32.0cm, 292 SW
6) 308.44g, 31.8cm, 291 SW

Much better

 

[Fluffy_Skye]

Much better

Which one do you suggest?

 

[Irvin]

Which one do you suggest?

Length (balance) measurements in cm.

 

[Fluffy_Skye]

Length (balance) measurements in cm.

No I mean which one of the racket do you recommend.

 

[Irvin]

No I mean which one of the racket do you recommend.

Any of them would work for me but I’m not going to play with them.

 

[Fluffy_Skye]

Any of them would work for me but I’m not going to play with them.

Then what are you talking about…

 

[esgee48]

I vote for No. 2 as it is most HL and has lowest SW. Mass is a few grams higher but you could mod No.2 to what you like about the current frame. OR you could enter the specs from each frame using

Tennis Racquet Customization

A tennis racquet customization tool that calculates the amounts and locations of lead tape to place in order to achieve user defined desires for end-result racquet weight, balance, and swingweight.

twu.tennis-warehouse.com

and see what is needed to get to your desired specs assuming you only need a few grams. I think balance and SW are what you are shooting for. Start off wit a 1 gram increment.

 

[Irvin]

If I was going to choose 1 racket it would be #3. It has the highest Recoil Weight and a low balance. But all of these rackets could be matched easily. The way they are I would think #3 would have the most power.

Which one do you suggest?

 

[ryohazuki222]

Ya… I ask TW for measurements in grams and centimeters and they always oblige.

only one they wouldn’t do for me is twistweight — said it’s not something the measure.

 

[Irvin]

Ya… I ask TW for measurements in grams and centimeters and they always oblige.

only one they wouldn’t do for me is twistweight — said it’s not something the measure.

Assuming it not something they (TW) can measure, it is easy to measure twist weight with the SW1 machine.

 

[ryohazuki222]

Is it though? My takeaway was that it’s ok for relative comparison between two sticks but not for objective measurement.

 

[Irvin]

Is it though? My takeaway was that it’s ok for relative comparison between two sticks but not for objective measurement.

If you’re talking about the SW1 I would take it over any other SW machine hands down. It is reasonably priced and as accurate as any other SW machine.

 

[Irvin]

Here is a screen shot from the SW1 using the TW function. Racket 1 was 13.17 kgcm and rackets 2 13.06. The TW cradle has 6.32 kgcm. No other SW machine can do that.

https://imgur.com/eiLJymt

EDIT: Readings were for 2 unstrung Tecnifibre 320 2013 16 main rackets.

 

[ryohazuki222]

Big fan of the SW1. Just got mine. My comment comes because when I used the above method, it was quite a bit different than the posted measurement from TW in their database. Briffidi wrote a blog post about the concept and my takeaway from that post is that there are better ways to calculate twistweight but that spinweight swingweight differential is a good method to see twistweight accurately relative to each other.

In that blog briffidi alluded to working on a better twistweight measuring tool.

on my end: I don’t know enough about twist weight and ballparks to know either way but the other day when measuring I kept getting the same spin weights and different swing weights. Using the calculation one was a TW of 10 which does seem off from what I put together.

 

[Brando]

After all that, @Fluffy_Skye , which racquet did you end up buying? And how'd it work out vs. your PS100 #2?

(For the record, I'd have gone with either #1 or #5 as your posts indicated a preference on the head heavier side. Regardless, @Irvin was right that they were all close enough to be equivalently customizable.)

 

[Fluffy_Skye]

After all that, @Fluffy_Skye , which racquet did you end up buying? And how'd it work out vs. your PS100 #2?

(For the record, I'd have gone with either #1 or #5 as your posts indicated a preference on the head heavier side. Regardless, @Irvin was right that they were all close enough to be equivalently customizable.)

I eventually went with #4 as its balance is in between 7HL and 8HL. #1 is almost exactly the same as my #2 and #5 would be even more head heavy than my #2.

However, as it turns out, #4 is still on the handle heavy side which I don’t like, but not as extremely as my #1. Interestingly, as the string on my #2 started to die, I decided to give #4 a more dedicated try. And finally I dialed in this handle heavy style of racket. It needs a faster racket head speed. I learn to relax my wrist and that creates the modern whippy swing. I ended up creating much stronger top spin and I can hit hard without sailing long. On the other hand with my #2, though it is easy to hit hard because of the head heavy balance, I couldn’t create sufficient top spin and it’s a gamble if the ball will stay in when I strike hard.

Now that my technique has improved, by simply learning how to relax my wrist, I play better with both my old #2 and the new #4 and their difference also seem to have decreased.

 

[Brando]

Sweet. Once you get the hang of pronation, it's kinda zen: to gain control you gotta master a sense of losing (and loosing) it . And if a racquet can aid your form, that's pretty much all you can ask of it.

 

[Brando]

For anyone switching to a heavier racquet, I have to point out that @Fluffy_Skye has just described (IMHO) the key to doing it:

...finally I dialed in this handle heavy style of racket. It needs a faster racket head speed. I learn to relax my wrist and that creates the modern whippy swing. I ended up creating much stronger top spin and I can hit hard without sailing long. On the other hand with my #2, though it is easy to hit hard because of the head heavy balance, I couldn’t create sufficient top spin...

Racquet makers make light racquets because they're easier to swing. Heavier frames are harder but they teach you to swing more efficiently, if you let them. And once you do, they'll remain harder to swing. But what you've learned will make you so much more consistent that it's worth it.

 

[Irvin]

For anyone switching to a heavier racquet, I have to point out that @Fluffy_Skye has just described (IMHO) the key to doing it:

Racquet makers make light racquets because they're easier to swing. Heavier frames are harder but they teach you to swing more efficiently, if you let them. And once you do, they'll remain harder to swing. But what you've learned will make you so much more consistent that it's worth it.

Reamed out softball bats hit softballs about 40 yards farther. The only reason you would want to ream out a bat it to increase bat speed by reducing weight and lowering the MOI.

 

[Brando]

As usual, the physics you're describing @Irvin , are irrefutable. The next gen pros play with far lighter, lower swingweighted (330s vs. 360+) racquets than the GOATS for this reason. But what I'm saying is less about physics than about how the physics can affect the form of your swing. And heavier racquets, in my experience at least, help loosen the wrist. And you don't need to go hog wild to experience this. I went from a 323g, 323 sw stick to one 326g and 338 sw and found the benefit to wrist pronation quite remarkable.