Optimum Racquet Balance for Performance II - MgR/I Data for ATP Pros

Discussion in 'Racquets' started by travlerajm, Jul 5, 2011.

  1. levrier

    levrier New User

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    very interesting, i have a Prince Original Graphite , i can't play with it because of the to high swingweight i can't manage, so i will try to cut it a bit.
     
  2. AMGF

    AMGF Semi-Pro

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    I gave this MgR/I a try this week end. Because my racquet is polarized (high SW and very HL for the static weight) it needs a LOT of weight just over the grip to bring the MgR/I closer to 21. The best I managed with 24g(!!!) of lead was 20.71.

    My observation, is that it didn't change my precision much or at all. Played with it for an hour and really couldn't feel a better alignment or precision of my frame. Maybe the hit against the wall test will show better precision. I'll see.

    Observation1, all this weight over the handle brought up the static weight while keeping the SW about the same. However, my hitting partner noticed that my balls were much heavier. So even with about the same SW, I could get faster balls over the net and overall heavier balls to my opponent, not a bad thing.

    Observation2, the data regarding the MgR/I seem to favor depolarized frames. It makes sense because depolarized frames have low SW and high static weight and this produces frames that have MgR/I close or above 21. But Traveljam correlated MgR/I@21 with better rankings among pros. I think that because the data is from a time where most pros used depolarized frames, this is why 21 seemed like the magic number. I'd be curious to see current data and see if the magic 21number is going down as more pros use polarized frames.

    Observation3, reading http://www.racquetresearch.com ant their bit on MR^2/I, they seem to think the best frame has the lowest MR^2/I. This means that frame with high SW and very HL for a low static weight perform best. That's my own personnal observation as well. When you have a very HL, light weight frame with a high swingweight, you pretty much have a lot going for you. Interestingly, my current frame would rank #2 of all the frames measured on racquetresearch.com.

    Observation4, I'm a firm believer that SW>350 is more important to frame performance than MgR/I=21. You can instantly feel the performance difference with higher SW. But higher MgR/I didn't do much to my game at all. I will test further to see if I can get some clearer evidence. In the mean time, I'm getting a ProStaff Classic 6.1 that has high static weight, low SW, over 21MgR/I stock and I will see what comes out of this.
     
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  3. FaultsNAces

    FaultsNAces Rookie

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    I'm curious about where the racket data came from, and the accuracy. I haven't analyzed all (nor even most) the publicly available pro racket specs, but many / most of the specs I have looked at would require lead above the handle to bring them to the magical 21 MgR/I. Yet from talking to the technicians that customize rackets for the pros, adding lead above the handle is not something they typically do. From what I understand, customization for pro use really focuses on raising the swingweight with lead in the hoop and counterbalancing with silicone in the butt to maintain head-light balance; the lead in the hoop is placed anywhere from the tip (12 o'clock) down to 3 & 9, depending on pro preference. But it's very rare to add weight to the throat or above the handle.

    It's interesting to think of MgR/I as some 'figure of merit' for a tennis racket, and I have no fundamental issue with this figure of merit not being readily understood from a physics perspective: many industries / application areas have figures of merit that don't readily relate back to the basic physics directly at play.

    But I am curious at where the pro data came from as it seems unlikely to me that (m)any pros are adding weight above the handle but below the hoop, as would seem to be required based on the rackets they are using. But again, I haven't analyzed all the data available, so this might not be the case - which is why I'm asking.

    Thanks in advance.
     
  4. torpantennis

    torpantennis Legend

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    Where you ADD weight depends on what are the starting specs. Pros probably use hairpin frames which have such starting specs that you can add lots of weight in the individual preferred spots on the head, and still have good end result specs. MgR/I is just basically a measure of how much a racquet has weight in the middle, in comparison to the weight in the racquethead. Higher MgR/I means more weight in the middle, around the throat.
     
  5. travlerajm

    travlerajm Hall of Fame

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    My raw data came from either Jura's posts from the 2005 French Open stringer's log, or Greg Raven's website. I made a request many years ago to Jura for him to get Tennis Federation France to authenticate his dataset (to make it easier for me to publish my analysis in a peer-reviewed journal), but he said that Tennis Federation France refused his request, since the stringers were not happy with racquet specs leaking. Nonetheless I believe his datasets are authentic.

    Keep in mind that the data does not imply that most pros add a lot of weight to the top of the handle - rather the data shows that most pros might be playing with suboptimally balanced frames. However, the data suggests that the subset of pros who counterbalance in a way that yields MgR/I in a certain range tend to have better results.
     
  6. travlerajm

    travlerajm Hall of Fame

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    By the way, I plan to republish my TW racquet review score vs MgR/I analysis results soon.
     
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  7. FaultsNAces

    FaultsNAces Rookie

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    Hmmm. The data that I see from Jura provides specs for unstrung rackets, so you need to make (big) assumptions about the mass and location the strings and any pads, etc. It also doesn't specify if the pro uses one or more overgrips, or vibe dampeners, etc. So seems rather odd that you claim wearing a sweatband is a big influence on results, but your base analysis is supported by raw data augmented with questionable assumptions. Good luck publishing.

    (#SorryNotSorry for my tone - this was all presented as rather scientific, so it's annoying to find that I've wasted my time wading through all of this.)
     
  8. AMGF

    AMGF Semi-Pro

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    I'm curious to see how would current player's frame would fit with regards to MgR/I. It seems the polarized set up has gained a lot of popularity lately. Doesn't Djokovik have a polarized frame and a very low MgR/I?

    The new Pure Aero+ has probably one of the lowest MgR/I of the modern frames and some pros play with it.

    Anyhow, I enjoy those analysis and it's fun to try different set up and see what works or not.
     
  9. levrier

    levrier New User

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    Hello friends, is there some people using a Prince Graphite 100 who experienced tuning and try to have a MgR/I of 21 ? i mean with overgrip and dampener, and original swingweight. thanks a lot.
     
  10. AMGF

    AMGF Semi-Pro

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    I tested back to back my Angell TC97 that has 20.46mgr/i and my Wilson PSClassic 6.1 that has a 20.91mgr/i. Honestly, I don't believe in mgr/i at the moment. I couldn't noticed a difference in precision between the two very differently polarized frames. Angell has more spin, PSC more stability but I could hit my marks equally between the two. Or maybe I'm just not good enough of player to notice the small differences they may have between them.

    to me, MgR/I is just a measure of polarization. The more polarized the frame, the lower the MgR/I. Lastly, manufacturer have been trying to get out polarized frames on the market. By maximizing the MgR/I to 21, you're adding weight without adding SW. To me, after some testing (up to 24g(!) over the handle of my Angell), I didn't notice any improvement in accuracy. Niet. Just a much harder racquet to swing...

    So the questions are:
    1-are the top players at the top because they play unpolarized (MgR/I=21)?
    2-are the top players need more unpolarized set up to be competitive at the very top?
    3-are top players, players that started playing unpolarized frames when they were young and these guys are now at the top with their MgR/I close to 21?
    4-are we gonna see the MgR/I "ideal" go down as the young up and coming players play more polarized set up?

    I think the MgR/I is the product of top players using what they like(d) and not the cause behind top players being at the top. If I'm not mistaken, Nadal and Djokovic have polarized frames (low MgR/I) if we were to get the same study today, maybe the conclusion would be different just because these two top players are not playing heavy/low swingweight frames. Also, maybe a lot of the new top players are also using depolarized, wihtout the data it's hard to know.

    *disclaimer, I have not done the wall test yet. Maybe then I'll see the revelation. But for actual tennis play, no significant difference for me. If anything, the polarized set up is more precise as it helps me with my depth as I can better use the extra spin to get longer or shorter balls.
     
    Last edited: Dec 22, 2015
  11. levrier

    levrier New User

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    my experience : in the past i played with a juice 100 wilson, low mgr/i, a lot of spin but not accurate. Lately i have tested a customized prince response 97 with a mgr/i at 21.4 : not accurate. Actually i play with a customized pro staff 97ls, mgr/i at 21.03 : very accurate...
    in the past i played with a prince graphite 100, in the original version mgr/i = 21, it was my best racquet ever...
    that's why i will come back to her !!!
    in fact, by customizing my pro staff 97ls, i arrived at 334gr, balance at 32cm and sw of 318, exactly the prince graphite 100 specs...
     
  12. Zielmann

    Zielmann Semi-Pro

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    This. The data is just a snapshot of what racquets top players used at one time, but is then presented as if this calculated value is the reason the players were at the top. It's an interesting concept, and the calculations make sense. But in the end it's just another way to represent a playing characteristic of a frame.
     
  13. BlueB

    BlueB Hall of Fame

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    Actually more polarized the frame, lower the MgR/I.
    But yes, it is the measure of polarization.
     
  14. Shroud

    Shroud Legend

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    I don't understand this stuff.

    I thought SW was a measure of polarization???
     
  15. AMGF

    AMGF Semi-Pro

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    Yes yes, indeed, my mistake. I edited my post. :)
     
    Last edited: Dec 22, 2015
  16. Cerps

    Cerps Semi-Pro

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    No you could have a very unpolarized frame with a high SW but that fram would of course also be very heavy.
     
  17. levrier

    levrier New User

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    Hello Customizers ! question to specialists :
    the fact is i play well with a swingweight of 315, max 320.
    When i try to tune my prince graphite 100 to MGR/I=21, it match with a swingweight of 324.
    my question is : is it easier (or more natural) to swing a racquet with a too high swingweight but a MGR/I perfectly tuned at 21, or is it easier to swing a racquet with the ideal swingweight BUT non optimum MGR/I ? What is more important ?
    With my graphite 100, i achieved two possibilities :
    1. 339gr, balance 31.6, SW 318, MGR/I=21.15
    2. 340gr, balance 32, SW 324, MGR/I=21.01
     
  18. levrier

    levrier New User

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    oups little mistake, the 1st scenario is : 339gr, balance 31.8, SW 318, MGR/I=21.15
     
  19. RanchDressing

    RanchDressing Hall of Fame

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    This video talks a little bit about where MGR/I comes from, and some further opinions...
     
  20. newyorkstadium

    newyorkstadium Semi-Pro

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    Good video. I thought it was a **** take at first. To my memory, travlerajm has stated in the past that western forehands are less influenced by MgR/I but I couldn't find anything when I searched. I think he said a western forehand, like Nadals, lowers the MgR/I by 0.2. Again, I couldn't find anything, though.

    @travlerajm I have now managed to tune my MgR/I to an personal optimal value. I was going to try and create a personal (rough) optimal MgR/I calculator for people of different arm sizes and height, after I've tested for the influence of swingweight and forehand grip type. I'm just wondering if this a bit futile, since two people with similar height and arm length could have different arm mass. I.e one could be more muscular. This has been asked on here before. How much does arm mass influence MgR/I?

    Investigations have shown that the human arm weighs between 4.7 and 6.5% of the total body weight. So the difference in arm weight between two people of the exact same height/arm length, weighing 150lbs and 200lbs, could be between 2-3.25 lbs. The heavier arm will swing slower I think, thus slowing the forearm pendulum and changing the optimal MgR/I value.
     
    Last edited: Feb 5, 2016
  21. floydcouncil

    floydcouncil Semi-Pro

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    If only people would be willing to devote more time to actual practice/lessens/physio to strengthen their game..............
     
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  22. ls206

    ls206 Professional

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  23. swfh

    swfh Semi-Pro

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    Could anyone help me polarize a yonex Ezone XI 98 to optimal MGR/I specs? Im having a ton of trouble getting the numbers right. Ideally, Id like an MGR/I value of 20.95, as I am just shy of 6ft. Thanks for help!!
     
  24. AMGF

    AMGF Semi-Pro

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    You can't be polarized and have 20.95. To be at 20.95 you need to be de-polarized. That's the main reason why I think it's reverse engineering gone wrong. I'm pretty sure the same study by travellerjam today with current top players playing polarized frames that the magic number would be lower than 21...

    If you're in the low 20s, add a lot of weight just over the grip, it'll bring the MGR/I up. Let us know how it works for you.
     
  25. swfh

    swfh Semi-Pro

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    ahh that makes sense. I want to get the balance to 5 hl, so it looks like low 20's will have to do. Thanks
     
  26. AMGF

    AMGF Semi-Pro

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    You "could" probably get to 20.95 and 5HL, but the cost will be high static weight.
     
  27. travlerajm

    travlerajm Hall of Fame

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    It would be best to get accurate measurements for your frame. But if you were to assume your racquet has the same weighting as the specs on the TW site, then adding about 17g of lead tape just above the top of the grip (at about 8" from the butt end) will get you close.
     
  28. Irvin

    Irvin G.O.A.T.

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    As you add mass your I will go up and your balance may change. If you have RacquetTune you can see the relationship between all those values.
     
  29. Irvin

    Irvin G.O.A.T.

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    If you add mass to the butt I (assuming that's SW at 0 cm) will change very little raising MgR/I. Adding mass to the butt raises RW and makes the fame more polar. Or am I making some false assumptions here.
     
  30. AMGF

    AMGF Semi-Pro

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    Not to the butt, top of the grip. Little effect on the sw and balance but large effect on mgr/i. I am not a believer of mgr/i should = 21. Rafa and Djokovik aren't either.
     
  31. Irvin

    Irvin G.O.A.T.

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    I'm not a believer either as far as that goes. But if mass is added to the butt the R changes the most and the I at 0 cm changes very little (unrecognizeable.) Adding mass closer to the balance point changes the balance more yes I agree so your MgR value is larger, but the closer you get to the balance point the more I goes up because it is farther from the pivot of 0 cm. if you add 10 g of mass to the butt of an EZONE you MgR value will go up (slightly) and I will not change.
     
  32. AMGF

    AMGF Semi-Pro

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    Yes but then you change the balance by a wide margin. No free lunch.

    That's why I say MGR/I is reverse engineering gone wrong. These pros in that year had a mgr/i of ~21 because in that era, players used more de-polarized frame set ups. I'm pretty sure that today, the mgr/i is much lower. So what would the conclusion be? ideal mgr/i is now 20,5? Tennis evolved in that direction, so now 21 is not good anymore? Doesn't make sense.

    One thing that didn't change over the years, pros tend to use SW>350, no matter the era.
     
    Last edited: Feb 15, 2016
  33. newyorkstadium

    newyorkstadium Semi-Pro

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  34. Irvin

    Irvin G.O.A.T.

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    I agree with you because adding mass at the tip gives you a lower yet MgR/I value.
     
  35. beltsman

    beltsman Hall of Fame

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