Swingweight Calc
docs.google.com
All the cells except the ones in borders are locked to protect the formulas. Feel free to use it.
Polarization, Recoil Weight & MgR/I demystified?
- Thread starter Brando
- Start date
docs.google.com
All the cells except the ones in borders are locked to protect the formulas. Feel free to use it.
I have just noticed that I forgot to unlock customization rangeI created a spreadsheet to calculate SW,RW,PI, and MgR/I after customizations.Swingweight Calc
All the cells except the ones in borders are locked to protect the formulas. Feel free to use it.
. Now it is usable.Btw I am also working on a similar spreadsheet which uses excel solver to find where to add how much weight to reach the desired rw, sw, and weight. I can also share it when it is finished. It is like twu auto customisation tool but an advanced version that considers recoil weight etc.
anarosevoli
Professional
Great, thanks. But Twistweight seems to be calculated wrongly: In the formula is "minus 10 cm" like in SW calculation.
I thought the width from the center. 10 cm is used for swing weight because it is where your hand is. For twist weight hands are in the middle of the racquet, so it is 0.
anarosevoli
Professional
That's what I meant. But in your sheet in field J7 it calculates -10 for TW also.
Omg you are right. I copy pasted formula over them at some point I guess.
In case anyone is interested I have built an excel/solver automatic customiser. It tells you where to add weight to reach the desired rw, sw, mgr/i etc.
Racquet SW/Weight/Balance/RW/MgR/I Auto Optimiser
I had previously created a spreadsheet to calculate the swingweight and others based on extra weights on the racquet. Swingweight Calc Spreadsheet I took it one step further and created a racquet spec auto optimizer using excel and solver. It works by setting target parameters and allowed...
tt.tennis-warehouse.com
y0035215
Rookie
Quick question about modifying.
I have two rackets:
#1 = SW: 323 - W: 324g - W: 32.7cm - RW: 156.05 - Pole: 0.48 - MgR/I: 20.67
#2 = SW: 327 - W: 324g - W: 32.7cm - RW: 160.05 - Pol: 0.49 - MgR/I: 20.51
I have found that I play best with #2 when I attach about 6.5g (at 20cm) to the throat (= #2m).
I would like #1 to play like #2m. If I try to get similar results for all specs (SW, W, B, RW, Pol, MgR/I), I would have to distribute weights differently (e.g. #1m gets 1.5g@tip and 5g@handle at 10cm).
I'm just afraid that the racket will feel different if the weights are placed in different places despite the almost similar specs. Is it better to place the weights in the same places? What is most likely to result in the same behaviour?
I have two rackets:
#1 = SW: 323 - W: 324g - W: 32.7cm - RW: 156.05 - Pole: 0.48 - MgR/I: 20.67
#2 = SW: 327 - W: 324g - W: 32.7cm - RW: 160.05 - Pol: 0.49 - MgR/I: 20.51
I have found that I play best with #2 when I attach about 6.5g (at 20cm) to the throat (= #2m).
I would like #1 to play like #2m. If I try to get similar results for all specs (SW, W, B, RW, Pol, MgR/I), I would have to distribute weights differently (e.g. #1m gets 1.5g@tip and 5g@handle at 10cm).
I'm just afraid that the racket will feel different if the weights are placed in different places despite the almost similar specs. Is it better to place the weights in the same places? What is most likely to result in the same behaviour?
tele
Hall of Fame
if twistweight is held constant, two racquets with the same mass, balance, and swingweight should swing the same, regardless of how you get there
You're missing an axis.
Yes. You're still missing an axis.
Have you heard of the word "orthogonal?"
tele
Hall of Fame
based on the customization worksheet tool, 1 gram at 12 o'clock, 3.5 at 20cm, and 2 grams at the butt should get you pretty close to your other racquet with the weight added (same static weight and an 0.7 sw difference and an 0.3mm balance difference) You could probably get even closer, but I am not sure if the difference would be noticeable.
Brando
Professional
Hi @y0035215. You’re looking to duplicate…
R#2: 324g, 32.7cm, 327sw, 160.05rw, 20.51 MgR/I, 0.49 Pi + 6.5g @ 20cm
→ 330.5g, 32.45cm, 327.6sw, 161.0rw, 20.66 MgR/I, 0.49 Pi
with…
R#1: 324g, 32.7cm, 323sw, 156.05rw, 20.67 MgR/I, 0.48 Pi + 5g @ 10cm + 1.5g @ tip
→ 330.5g, 32.5cm, 328sw, 160.7rw, 20.66 MgR/I, 0.49 Pi
My answer to your first question is, yes, it’s better to place mass differently in different racquets in order to mathematically match their specs. More, I’ve checked your math, and the numbers reveal you’ve done that really really well with your plan.
As to whether the racquets will feel identical, don’t count on it. How close you can get, firstly, depends on whether they’re the same model of frame. If so, then we move on to the fact that racquets are made by hand, and no two same-model frames are rolled with exactly identical lengths and widths of graphite sheets. This means, for instance, that R#2 may have a 1-2 point different twistweight from R#1's even if they're the same model.
The way, then, to maximize the potential that they’ll play the same is to A) use two identical model frames; and B) customize them, just as you’re planning, to as close to the same specs on paper as you can. After that, it’s about playing both racquets to see if R#2 indeed feels like R#1, and then maybe adjusting the weight from there. All to say, I think you’re on the right track and do let us know if #2 indeed plays like #1. ‘Till then, I’m crossing my fingers for you.
And, BTW, I think @tele's solution is good too, even as it takes R#2 slightly farther from #1:
R#2: 324g, 32.7cm, 323sw, 156.05rw, 20.67 MgR/I, 0.48 Pi + 2g butt + 3.5g @ 20cm + 1g tip
→ 330.5g, 32.48cm, 326.8sw, 159.8rw, 20.70 MgR/I, 0.48 Pi
If you find it easier to apply, it's worth considering.
Last edited:
Edward Li
New User
@Trip - thank you for the gentle correction in the other thread, it was wrong for me to post there. I have pasted my text from that thread here.
So I put in the published specs for the rackets I spoke of (in the other thread) and found (hope my formulas were right!) :
It seems clear that I have a preference for Recoil Weights above 160 and also probably explains why I am not happy with my Speed MP. This was very helpful!
That said, I did find it interesting that the polarization numbers were all very similar, perhaps a non-discriminator for me. But I was wondering if you had any thoughts on the MgR/I numbers? On the one hand, it looks like I prefer values in the 20.4 range based on the Speed Pro and ATS 98. But then I thought the PS 100 16x20 was fine (> 20.5), the PS 100 16x19 was too fast (20.46) and similarly with the Speed MP (> 20.5).
Should I not worry about MgR/I and be more attuned to Recoil Weight?
So I put in the published specs for the rackets I spoke of (in the other thread) and found (hope my formulas were right!) :
| Recoil | Polarization | MgR/I | |
| Head Speed Pro Auxetic 1.0 | 163.6 | 0.51 | 20.44 |
| Prince ATS Tour 98 | 163.1 | 0.51 | 20.43 |
| Babolat Pure Strike 100 16x20 | 162.7 | 0.50 | 20.52 |
| Babolat Pure Strike 100 16x19 | 156.5 | 0.49 | 20.46 |
| Head Speed MP Auxetic 1.0 | 154.5 | 0.49 | 20.54 |
It seems clear that I have a preference for Recoil Weights above 160 and also probably explains why I am not happy with my Speed MP. This was very helpful!
That said, I did find it interesting that the polarization numbers were all very similar, perhaps a non-discriminator for me. But I was wondering if you had any thoughts on the MgR/I numbers? On the one hand, it looks like I prefer values in the 20.4 range based on the Speed Pro and ATS 98. But then I thought the PS 100 16x20 was fine (> 20.5), the PS 100 16x19 was too fast (20.46) and similarly with the Speed MP (> 20.5).
Should I not worry about MgR/I and be more attuned to Recoil Weight?
@Edward Li - In my experience, while RW and MGR/i numbers are best optimized in-tandem, as both effect swing mechanics in combination, it's really RW that tends to optimize around a single number for someone, more so than MGR/i, which can actually be optimal at several different values along a range, typically in "jumps" of 0.5 to 1.0 (where, for example, you may play great Federer/Lajovic/Lejecka flatter/attacking "pushing" the racquet through the motion style tennis at an MGR/i of approaching, let's say, 21, but you also play as well, maybe even more effectively, in a more Djokovic/Nadal/Zverev -style, highly polarized, rounder swing, more "pulling" the racquet through the motion, loopier style tennis, at an MGR/i of approaching closer to 20 (which a good the bulk of the better (dare I say best?) players are at these days). Many players discover that they can play effectively around at least 2, sometimes 3, distinctly separate MGR/i's (again, usually >= .5-.7 away from one another), but what tends to stay more constant, is an optimal Recoil Weight (even at different MGR/i). This is because a certain value of RW tends to apply the same physical phenomena to your swing, even as individual specs (static weight, balance point and/or swing weight) change. As such, finding that RW value is probably the best place to start. Then from there, you can pursue MGR/i tuning to your size, level, swing and play style, all while being armed with a best-known RW for you as you do so.
If you haven't yet, you might want to give @Brando's thread "Who Cares About Recoil Weight?" a read:
tt.tennis-warehouse.com
And after the initial post, post 11 is particularly good as well:
tt.tennis-warehouse.com
Before I let this post go, because I don't know much about you or your game, I will say that for this stuff to really be able to move the needle for a player, they really need to have enough fundamentally sound stroke mechanics for the dialing in of racket physics to make much benefit for them. If I had to gate-keep this stuff based on level, I'd say, typically a strong 4.0 to weak 4.5 at minimum. Much below that, and there are typically way more pressing items to address that are effecting how optimum a person's shots can be.
Hope that helps. Any further questions, happy to answer them here, or even chat about it elsewhere, for often it can just be easier to speak about it, rather than have to type it all out.
If you haven't yet, you might want to give @Brando's thread "Who Cares About Recoil Weight?" a read:
Who Cares about Recoil Weight?
Advanced players care about recoil, and here’s why. Swingweight, twist weight, and recoil weight (also called ‘hitting weight’) all measure the inertia of a racquet along different axes or planes. Recoil weight shares the same plane as swingweight but its axis is the balance point (vs. the...
tt.tennis-warehouse.com
And after the initial post, post 11 is particularly good as well:
Who Cares about Recoil Weight?
Advanced players care about recoil, and here’s why. Swingweight, twist weight, and recoil weight (also called ‘hitting weight’) all measure the inertia of a racquet along different axes or planes. Recoil weight shares the same plane as swingweight but its axis is the balance point (vs. the...
tt.tennis-warehouse.com
Before I let this post go, because I don't know much about you or your game, I will say that for this stuff to really be able to move the needle for a player, they really need to have enough fundamentally sound stroke mechanics for the dialing in of racket physics to make much benefit for them. If I had to gate-keep this stuff based on level, I'd say, typically a strong 4.0 to weak 4.5 at minimum. Much below that, and there are typically way more pressing items to address that are effecting how optimum a person's shots can be.
Hope that helps. Any further questions, happy to answer them here, or even chat about it elsewhere, for often it can just be easier to speak about it, rather than have to type it all out.
Last edited:
Brando
Professional
@Trip, you and I have discussed this phenomenon of how different MgR/I can feel differently good once you've found your apt recoil weight. But we've never discussed how these MgR/I tend to occur at "jumping" increments of ~0.5 MgR/I. So I'm kind of floored by your saying it here because I and others have found the same phenomenon. And yes! We too have found that it very much depends on whether your biomechanics beg the pushing the handle feel of a higher MgR/I or the pulling the hoop feel of a lower one. Anyway, I don't mean to interrupt your conversation with @Edward Li (only to add that I couldn't agree more with your post).
Myshoulderhurts
New User
@Brando I’ve found that a 161 RW seems to work well for me across at least 2 different racquets and I’m 5’ 8.5”.
I have a question as to the customization of a 2025 Gravity MP demo. The stock Gravity is at 324 SW, and that is as high as I’m willing to go with SW, which means I have to increase the RW without increasing the SW. I noticed that moving the balance lower triggers an increase in RW, but the balance of the Gravity is fairly high compared to sticks I have used and customized in the past. I noticed that I basically have to add all the additional weight in the buttcap to achieve the RW I desire at a reasonable static weight.
Will adding 12g in the buttcap to achieve my desired RW make the racquet behave strangely? It seems odd to put so much weight just at one single point but maybe my intuition is off.
I have a question as to the customization of a 2025 Gravity MP demo. The stock Gravity is at 324 SW, and that is as high as I’m willing to go with SW, which means I have to increase the RW without increasing the SW. I noticed that moving the balance lower triggers an increase in RW, but the balance of the Gravity is fairly high compared to sticks I have used and customized in the past. I noticed that I basically have to add all the additional weight in the buttcap to achieve the RW I desire at a reasonable static weight.
Will adding 12g in the buttcap to achieve my desired RW make the racquet behave strangely? It seems odd to put so much weight just at one single point but maybe my intuition is off.
Irvin
Talk Tennis Guru
@Myshoulderhurts do you play with an over wrap? That will add about 2.75 points to RW, and little or nothing to SW. Are you using published specs or actual specs?
Myshoulderhurts
New User
Actual specs using Brifidi tools.
With just the over grip, it starts at about 150 RW, so I still need 11 points of RW to add. Static weight and balance starting at 320g and 33.33cm.
Edit: Maybe I just got a weirdly spec’d racquet or my balance measurement is off. The published balanced should be 33.48cm strung, so after overgrip it should be just under 33cm, not 33.33cm.
With just the over grip, it starts at about 150 RW, so I still need 11 points of RW to add. Static weight and balance starting at 320g and 33.33cm.
Edit: Maybe I just got a weirdly spec’d racquet or my balance measurement is off. The published balanced should be 33.48cm strung, so after overgrip it should be just under 33cm, not 33.33cm.
Last edited:
TW uses a lighter, 15 gram string to give their strung specs. Every single strung balance point they give would 0.2cm higher with a more regular, 18 gram string.
Tranqville
Hall of Fame
What do you guys think abou Tecnifibre massively depolarising Tfight 305? The manufacturer says, essentially, that it makes the frame better adapted to the demands of modern game. How so?
Going by the TW specs:
Old one: 320g 33.3cm 338sw -> 164RW
New one: 320g 32.5cm 324sw ->162RW
Almost no depolarisation was done, in fact they probably just moved around a 5 gram weight from 12 to the handle.
They adapted the racket to the preferences of the public, way easier to sell the new lower balance point and lower swingweight.
Irvin
Talk Tennis Guru
Are you sure the RW on the old racket wasn’t 154? Looks like the new racket is more polar with a lower torque making it swing faster. Also because the SW on the new racket is slightly lower it will have slightly less power.
Last edited:
Yes, im sure that my RW numbers for these specs are correct.
Could you please explain your idea of torque in isolation here, or start a new thread? I cant quite figure it out.
Irvin
Talk Tennis Guru
Torque is mass times balance. Torque is the amount of force you must apply to swing the racket
RW = SW - mr^2 = 338-(.32*23.3*23.3)=164.275 you’re right my mistake
Tranqville
Hall of Fame
In the racquet launch video, Tecnifibre representative explained how they "redistributed the weight of the racquet more towards the middle". That's clearly depolarization. Please see the at the time stamp:
tele
Hall of Fame
I noticed that as well, but I think (I could be wrong) one would expect the mgr/I to go up noticeably if that is all they did. I checked the mgr/I using the published specs out of curiosity when that video came out, and IIRC it only barely changed.
tele
Hall of Fame
You can just calculate it from the swingweight if you know the weight and balance (there are RW calculators, and you can also derive it from the parallel axis theorem formula). I think most people on this forum talk about strung recoil weight.
Edit: I realize Irvin gave the formula above, so no need to do the algebra.
Yes, and if we go by my rough estimation, weight at 12 was ~33cm away from the balance point, while the same weight moved to the handle is ~17cm away from the balance point. So yes, the weight was redistributed more towards the middle. The end result: 2kgcm^2 lower recoil weight. Depolarization? - Done. How much? - Barely any.
tele
Hall of Fame
The guy's body language seemed to imply the weight was moved to the middle of the racquet (rather than just to the "pole" on the other side of it), which indeed does not seem to be the case.
@Tranqville this was probably not the type of response you wanted. Let me try another way. I dont think the changes to Tf 305 model were made with depolarization/recoil weight in mind. I think they realised that its easier to appeal to the broader audience with a lower balance point and lower swingweight, while retaining most of the heavier racket fans because they are probably more willing to customize - add lead to the hoop. All that being said, i think this is the most significant spec change between the two generations we have seen recently. The big difference to me says that the model wasnt doing as well as they hoped, so they are trying to change that. Its a bit of a shame, as the rackets seem to be more alike than ever before, spec wise. Its going to take a very radical approach to disrupt the current racket "META"
iowaviking11
Rookie
Hi everyone. Looking to better understand this. I plan to go through tennis warehouse to customize and match racquets I am purchasing. is MGR/I values taking strings into account or not. Trying to figure out what specs to give.
What exactly do you want to acheive? Do you have a particular spec in mind?
ryohazuki222
Hall of Fame
Mgri values you see; like swingweights you see; are typically for strung rackets.
iowaviking11
Rookie
when getting unstrung specs should I assume 30g for strings?
ryohazuki222
Hall of Fame
If you’re asking that question, it’s pretty pointless to target MGRI, imo.
Mgri is sensitive to like everything. Gram here gram there. Grip, no grip. Different gauge of strings. Calculators typically measure it out at least 3 decimal places.
There are so many variables in all those things.
I recommend thinking about sw; mass; balance in that order. And once you get a final setup you like (string, gripped, etc); you tune Mgri from there.
@iowaviking11 - @ryohazuki222 hit the nail pretty much straight on the head. An "optimal" MGR/i has a fair amount of inputs: namely a player's physical stats, grip/mechanics, play style, string choice and of course the frame in question. Especially if you haven't invested the time up front to understand what's going on, including played around with varying MGR/i's in conjunction with different static, balance and SW values, you'll almost never "solve" for your optimal MGR/i in one request to TW's MRT department. Minimal to zero chance of that. As such, I wouldn't focus on it for right now, but rather, just get the racquet that plays best for you in stock form, in a weight class that is light enough for a reasonable level of customization without feeling too overly cumbersome, and then as you learn more about the physics and pickup more customization tools and knowledge, you can begin to tune for your optimal specs yourself, over time, MGR/i included (or not).
At least that would be how I would approach it. Hope that helps.
At least that would be how I would approach it. Hope that helps.
iowaviking11
Rookie
Appreciate the insight. That is where I will start!
Please consult the expert @travlerajm about this
Will certainly reach out one of these days.
José Fernando Barba
New User
Hi! Is anyone here playing with an MgR/I below 20? I received my briffidi SW1 yesterday and was completely amazed that the racquet I play the best with actually has 345 is SW, and the MgR/I is 19.75 IIRC. Static weight: 317, balance 33.3cm, RW 173.
I tend to frame quite a few shots with other racquets. I normally have a good amount of lag and racquet head speed with my normal stroke, so it seems to be that playing with high MgR/I values increases RHS in a way that, more than increase my spin, decreases a lot the stroke window at contact point. Hence, playing with a much lower MgR/I increases the stroke window. Has anyone tried and felt this same way? To put it into perspective, the rest of my racquets have SW in the 320's, and even with this one having 345 SW is extremely easier.
I tend to frame quite a few shots with other racquets. I normally have a good amount of lag and racquet head speed with my normal stroke, so it seems to be that playing with high MgR/I values increases RHS in a way that, more than increase my spin, decreases a lot the stroke window at contact point. Hence, playing with a much lower MgR/I increases the stroke window. Has anyone tried and felt this same way? To put it into perspective, the rest of my racquets have SW in the 320's, and even with this one having 345 SW is extremely easier.
That's a classic discovery right there, and not a surprise at all. A very modern-day spec, at least for singles. ie. the loopy, laggy battle axe (a spec used by most touring pros), as opposed to the more linear, quicker sword (Federer, and many attacking all-courters of yesteryear). Especially with a two-handed backhand, such a spec as you have discovered can certainly be closer to optimal, versus not.
Last edited:
ryohazuki222
Hall of Fame
No. I was getting closer to 20 out of curiosity but as I get closer and closer, I become more inconsistent with my timing. And then start adding some mass at the balance point until it feels good.
Closer down to 20 tends to feel better than higher for me in the event that I time it perfectly. But overall just not a stick I’d want to take into a match.
Do you play mostly singles/doubles and in what type of conditions? Fast hard court, outdoor clay? etc...
