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

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

  1. corners

    corners Legend

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    To raise MgR/I closer to 21 you either need to add mass around the top of the grip or remove mass from close to the tip. In your case, I would try adding 12 grams at the top of the handle. This should get you pretty close. For a quick try that is easily reversible, you can simply tape two quarters (about 6 grams each) at the top of the handle. Tape them tightly, one on each side. If you like it, you can just unwrap your grip an inch or two and wrap some lead tape around to replace the quarters.
     
  2. Maroon_Tenniskid

    Maroon_Tenniskid Semi-Pro

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    Yeah I tried that and swung the racket around in the air a little bit and it felt pretty good! I didn't get a chance to hit, but i may tomorrow. Would you mind explaining how you did the math?
     
  3. Maroon_Tenniskid

    Maroon_Tenniskid Semi-Pro

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    So after adding lead, that brings the new specs to:

    Mass: 341.9g

    Balance 12.5in

    SW: 333

    MR^2: 344.6565688

    Moment of Inertia: 515.9165

    MgR/I: 20.63055972

    How did that not change MgR/I very much? It feels like it changed quite a bit, but the numbers aren't changing much
     
  4. Maroon_Tenniskid

    Maroon_Tenniskid Semi-Pro

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    Nevermind, I found out that I did swingweight wrong on the TW swingweight calculator. SW was actually 321, and I found that made MgR/I into 21.12. I will go on court sometime this week and see how it plays.
     
  5. TennisFan2

    TennisFan2 New User

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    So I have a question regarding the lead placement in the head and the handle.

    I read in one of your posts from a couple years ago about depolarization and polarization that you need to either add lead at 6/9 or 12 depending on which route you wish to take;however, adding at both places does not work out?

    Is this still true? Or did I make this up in my head? Because I have found with my racquet: SW: 318, Balance: 32cm, Weight: 335g. To move to the MgR/I value of 20.6 (from 21.1) I not only need to add lead at 7in (from the butt) but also at 6/9 and 12 to make the balance I am looking for work out and still maintain a MgR/I Value.

    Because the problem that I am having, I can get the MR^2 value in the perfect range by adding lead at 6/9 and counter balancing at 7". But then then MgR/I value is closer to 21. So I have to bring the SW of the racquet up into the ~360s to the MgR/I value to where I want it.

    Currently I have lead at 21" (10g), 27" (8g) and 7" (8) and that gives me:
    Mass: 361g
    Balance: 33cm
    SW: 364
    MgR/I: 20.61
    MR^2: 394

    There are other lead placements where I can achieve the same balance and the same weight; however, I do not want to place the lead in the butt of the racquet as I've read its better to balance at 7" in this forum.

    Any suggestions would be awesome!
     
  6. travlerajm

    travlerajm Hall of Fame

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    I'm not quite sure what you are trying to achieve. But if you take your current specs and continue to add lead at the top of the handle, eventually you will reach specs that feel really nice.

    My suggestion is to start by adding another 22.5g centered about 5.3" from the butt, then carefully go through the steps on post #2 of this thread.
     
  7. TennisFan2

    TennisFan2 New User

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    Sorry for the seemingly randomness to my original post, like I said I'm new to the customization game. So this is my first real attempt. I first came upon your thread from like 5 years back about polarization and depolarization. So i was concerned about adding weight at both 12 and 3/9.

    I was trying to make the racquet more stable by adding some mass in the hoop and then counter balance like you had suggested higher in the handle. While at the same time trying to stay around the MgR/I and MR^2 values that you say are optimal through the formulas.

    So I would add an additional 22.5g around 5.3" to make it more depolarized?
     
  8. ilovetennis212

    ilovetennis212 Professional

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    Great info
    Thanks
     
  9. JanowiczJ

    JanowiczJ Professional

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    Hi guys! Back in the day I was reading this thread and I remember someone posted an online excel sheet to help using traveljr formulas...

    At the time I decided to not try to change anything but recently I suffered a leg injury that kept me out of the courts and I decided to change some things of my strokes, try new racquets, etc.

    So, I used the search function but I can't find who posted it and on which thread it was posted, searched for "excel, excel sheet, spread sheet" but couldn't find anything...

    Can someone help me? Thanks in advance.
     
    Last edited: Aug 22, 2014
  10. Mig1NC

    Mig1NC Professional

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  11. Irvin

    Irvin G.O.A.T.

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    Was there ever a table listed showing optimum MgR/I values for men and women depending on height?
     
  12. newyorkstadium

    newyorkstadium Semi-Pro

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    No there isn't. I've wanted to setup a spreadsheet for a while now that calculates peoples personal MgR/I, based on arm height and other factors. It's not simple though. You would need to compare at least two players with perfectly tuned MgR/I, and know how much various factors like swingweight, forehand grip influence MgR/I.
     
  13. newyorkstadium

    newyorkstadium Semi-Pro

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    I forgot to add, if you are interested in a spreadsheet that shows an individuals Mg/RI for their height, you should try tuning your MgR/I against a wall. To do so, follow the instructions in the OP. An alternative method can be found here - http://tt.tennis-warehouse.com/showpost.php?p=7338377&postcount=332

    All we need is one person who can successfully precisely tune their MgR/I. Then this can be compared against travlerajm and we can roughly establish how height affects MgR/I.
     
  14. Circa 1762

    Circa 1762 New User

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    I gave up on MgR/I weighting in favor of more modern weighting (low static weight, high SW), but only because using my optimum MgR/I produced a racket that was too heavy for long match play. For the sake of science...

    Height: 5'8"
    Forehand MgR/I at 350g static weight: 21.10
    Backhand MgR/I at 350g static weight: 22.84
     
  15. newyorkstadium

    newyorkstadium Semi-Pro

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    Did you wall tune to get that number? I'm still looking for someone who could precisely tune their MgR/I. Then perhaps they could volunteer to do the experiments I tried and failed.
     
  16. Circa 1762

    Circa 1762 New User

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    I didn't wall tune, but I tuned fairly scientifically (matched stock A and B rackets with same strings, etc.) through rallying and match play over the course of a year and a half.
     
  17. newyorkstadium

    newyorkstadium Semi-Pro

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    That's no good really. I need to find out how much swingweight affects MgR/I. So compare two matched stock rackets, with the same MgR/I, but 10pts different swingweight. Then try adding another 10pts and see if the MgR/I changes by a similar amount to the difference in MgR/I between the two rackets. Then I could establish how swingweight impacts MgR/I.

    That's the sort of thing I wanted to do. I'd even calculated precisely where to add lead tape to increase the swingweight by exactly 10pts, without changing the MgR/I.
     
    Last edited: Sep 14, 2014
  18. Don't Let It Bounce

    Don't Let It Bounce Hall of Fame

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    Isn't the "I" in "MgR/I" derived directly from swing weight?
     
  19. Mig1NC

    Mig1NC Professional

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    **** deleted


    I checked my spreadsheet and see what Joonas said below.
     
    Last edited: Sep 16, 2014
  20. Joonas

    Joonas Rookie

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    I=SW+20*M*R-100*SW

    Note:
    R in cm (balance)
    M in kgs
     
  21. Don't Let It Bounce

    Don't Let It Bounce Hall of Fame

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    That's the formula I have on my spreadsheet, too, and it seems like a clear answer to the question of how swing weight affects MgR/I.
     
  22. newyorkstadium

    newyorkstadium Semi-Pro

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    Here is a quote from travlerajm on why swingweight might affect MgR/I. There are probably others but I don't have time to search.

     
  23. colowhisper

    colowhisper Semi-Pro

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    NYS ^^wow, I am really glad you posted that old quote. I experimented with these specs for a while and tried tuning my sticks to ~21.0 but never liked the way they hit. When I tuned purely by "feel" then plugged in the measurements I always ended with 21.4 - 21.5. But now I realize that's because I like my swingweight 310-320, so my racquets tuned by feel actually make sense for Trav's formula. Epiphany.
     
    Last edited: Sep 19, 2014
  24. newyorkstadium

    newyorkstadium Semi-Pro

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    That's good to hear colowhisper. This is exactly why we need to find out how things like swingweight affect MgR/I. So people can feel the benefits, not just on this board, put perhaps on a larger scale.
     
  25. Mig1NC

    Mig1NC Professional

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    Interesting, I have found that in actual play, a shade over 21 works best for me too.

    I prefer SW the same as colowhisper, and I am 5'11" tall.
     
  26. taurussable

    taurussable Professional

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    to help me understand mgr/i better:

    adding weight to handle increase the number, adding weight to tip decrease the number,

    so balance is somewhat related to mgr/i

    so can I say that a racket with a big HL balance tend to have a bigger mgr/i?

    why shorter people need a bigger mgr/i and bigger HL balance?

    can you give me some intuition regarding these questions?
     
  27. torpantennis

    torpantennis Legend

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    Balance is that R. And no, mgr/i is not directly the balance. It turns out that:
    1) mgr/i remains constant if you add mass to the buttcap
    2) mgr/i increases if you add mass to the balance point
    3) mgr/i decreases if you add mass to the top parts of the racquet head

    So mgr/i is basically a measure of how much the racquet has mass around the throat, in relation to mass in the top of the racquet head. Let's assume a constant balance, like 6HL. Then racquets with low static weight/high SW have low mgr/i, and racquets with high static weight/low SW have high mgr/i.

    Most stock tweeners need a lot of mass around the throat to optimize mgr/i. Many player's racquets need mass around the tip to optimize mgr/i.
     
  28. taurussable

    taurussable Professional

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    very interesting stuff. With that said, can I say mgr/i is like a polarization index describing how polarized a racket is?
     
  29. taurussable

    taurussable Professional

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    travlerajm:

    do you think by filming myself using high speed cameras on fh side, I can have an idea if my current mgr/i value is too low or too high?

    wrist lag too much means mgr/i too low? and check how the racket face behaves in the contact zone?

    unfortunately i am pretty addicted to this stuff right now.
     
    Last edited: Nov 6, 2014
  30. torpantennis

    torpantennis Legend

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    Not trav, but will still answer. :) Yes, too low mgr/i in theory means too slow racquet part of the double pendulum, i.e too much racquet lag. It feels counter intuitive however that how can added mass around the throat make the racquet swing faster. But I think the answer is that it doesn't.

    I think the point is that the added mass around the throat slows down the arm MORE than it slows the racquet. But if it's so, the next question is, why doesn't .mass in the buttcap work the same way? :confused:
     
  31. taurussable

    taurussable Professional

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    Thanks. my mgr/i is at 20.64 now. when I review my hitting videos I do find my racket comes around too quickly(too whippy) in contact zone.

    +1 :confused: I have 25g lead in buttcap and 8g around the top hoop.
     
    Last edited: Nov 6, 2014
  32. BlueB

    BlueB Hall of Fame

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    I also found that with lower number the head comes around too quickly.
     
  33. Mig1NC

    Mig1NC Professional

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    Jim also said that other parameters needed to be considered when finding your ideal value. Not just height, but also if you have a western grip, things like that.
     
  34. Mig1NC

    Mig1NC Professional

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    So... In a way, you are describing the opposite of polarizing.

    Interestingly the new Head Graphine XT series claim high polarization, and when I plug them into my spreadsheet, it shows them having a low mgr/i. So maybe that's true?
     
  35. taurussable

    taurussable Professional

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    that's true low mgr/i == high polarization
     

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