Not All Swingweights Are Created Equal

Discussion in 'Racquets' started by TimothyO, May 9, 2013.

  1. TimothyO

    TimothyO Hall of Fame

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    Two frames matched for weight, balance, and swingweight. Strung the same way too.

    The only difference is that to achieve the desired specs "Frame 12", as we'll call it, has extra mass added at 12. "Frame 39" has extra mass running from roughly just below 3/9 and up towards 2/10. Even with the same SW Frame 12 generated a lot more power (too much really). From 39 didn't feel anywhere close to as powerful.

    I've read somewhere that mass added towards the top of the hoop can cause a frame to play stiffer. Could that be the reason for the power difference? I should note that that when purchased the frames were matched for balance, weight, etc., and when modified with identical mass placement they play the same.
     
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  2. Maui19

    Maui19 Hall of Fame

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    Frame 39? LOL That is a lot of frames, dude.

    To your point, I can see how they could play differently. SW and moment of inertia would be different.
     
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  3. TimothyO

    TimothyO Hall of Fame

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    No, SW was the same.

    Not 39 frames either. I used "Frame 12" and "Frame 39" to denote the frame with more mass at 12 and the one with more mass at 3/9. I actually own 6 frames.
     
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  4. unorthodox stringing

    unorthodox stringing Rookie

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    Are both the same brand same model rackets?

    I am still struggling with the same problem myself. Two "matched" Wilsons with only a 4grams weight difference. Balance and weight are the same after lead tape. Same strings, grip, too.

    But one plays much more powerful than the other. Everyone who tried them displayed the same sentiments.
     
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  5. anubis

    anubis Hall of Fame

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    So you're saying that both frames have equal mass, swing weight and balance, yet one is more powerful than the other?

    Because you had to add mass to different places on the different racquets, that tells me they are two completely different makes and models.

    Frame 39 was likely very head light, so prior to the mods the majority of the mass was in @ the balance point and below, closer to the handle. Adding mass to the hoop, regardless of the placement, is only going to make more of an even distribution of mass on both ends of the racquet. It has the same swing weight as the other, but since the mass is more evenly distributed, it's not going to be terribly powerful.

    The other racquet was likely even balance or close to HH. The majority of the mass was already in the hoop, so you only added a little more to 12:00 making an already powerful racquet even more powerful.

    makes sense to me :)
     
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  6. BlueB

    BlueB Hall of Fame

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    You know what, you are right, not all the "equal" SW are the same...

    To answer your question (IMO), more polarised racquet 12, has more mass in the top and just inside or under your palm. So, the mass that you really swing around grip axis is acually less then with more non-polarised racquet 39, where the handle mass is more above your hand. In result the 12 will swing faser, thus producing more power.

    Now, some other observation of mine, that I wanted to share for quite some time:
    The higher SW produced by increase in lever (longbody racquet) swings easier and faster then the equal SW produced by increase in hoop mass. Has anyone else noticed this?
     
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  7. TimothyO

    TimothyO Hall of Fame

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    Yes. Both are Biomimetic 200 Lites.

    And like I noted above, when I match them using the same distribution of mass they play the same. TW did a perfect job matching. They're off just 1 point in SW in stock form and exactly the same in weight and balance.
     
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  8. Gasolina

    Gasolina Professional

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    I thought somebody explained in perfectly a few months ago.

    Say ====== is a racquet and () is the lead you put in. Two racquets, same specs, one you put lead at the throat, one you put at the buttcap and at the 12.

    so is Racquet 12 the ()====()
    and Racquet 39 is ==()()==

    I think both have the same static weight, balance, but not swingweight.
     
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  9. TimothyO

    TimothyO Hall of Fame

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    Looking at some other frames that I modded in the past and notes I had made in my log book (I record specs and observations when I test mods) I think the issue is the effect mass had on sweet spot.

    Conventional wisdom says that extra mass at a given location on a frame pulls the sweet spot in that direction. Since the sweet spot is the area of greatest comfort and decent pocketing it's more springy (but not the most powerful point on the frame according to one book).

    With Frame-12 higher SW was obtained with mass concentrated at 12. With Frame-39 it was obtained with extra mass along an arc from roughly the 7th/8th cross up towards roughly the 3rd main.

    In other words, the extra mass on Frame-12 at 12 is perfectly aligned with the center 8 main strings which compose the sweet spot.

    The extra mass on Frame-39 is concentrated on main and cross strings not aligned with my usual impact zone (black VS Touch leaves a nice record of your impact zone as it turns grey). Those mains and crosses are nearly pristine with just a few wear marks on some mains around the 7th and 8th cross.

    Maybe the extra mass on Frame-12 has a greater effect on the center 8 mains making them extra springy compared to the extra mass on Frame-39 which is not aligned with the sweet spot-related mains?
     
    Last edited: May 9, 2013
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  10. TimothyO

    TimothyO Hall of Fame

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    Need my buzzer: EEEERRRRRRR!

    Both have same SW.

    I'm very familiar with that explanation and have made it myself.

    However, you can have two frames with the same SW, weight, and balance but different distributions or concentrations of mass.

    The question here is since SW equates so closely to power, why is the frame with mass at 12 more powerful than the one with mass concentrated on an arc from 3/9 to 2/10. The only explanation I can think of is the effect on the string bed.
     
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  11. Chotobaka

    Chotobaka Hall of Fame

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    This is a case of a more polarized frame vs. a non-polarized frame. I would suspect that your racquet 39 is the more stable of the two.
     
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  12. heninfan99

    heninfan99 Legend

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    Maybe swing weight needs to be measured differently???

    Your results kinda explain why Rafa put some lead in at 12 rather than anywhere else.
     
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  13. gameboy

    gameboy Hall of Fame

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    How did you measure the swing weight for both of the racquets? Are you sure they are identical?
     
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  14. TennisCJC

    TennisCJC Legend

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    I can see the setup you describe, same SW but one with lead at 3/9 and other at 12, and racket with weight at 12 plays more powerful.

    I want to think it would have something to do with polarized (12 o'c setup) being more whippy thus generating more RHSpeed. But, I am conflicted because if SW is the same, I would think the the 3/9 setup would have as much mass delivered to impact.

    But, my final answer is the 12 o'c setup is more whippy as the weight is further from the hand resulting in more RHSpeed and thus more power.

    I would think the difference would be small. And, it would come down to personal preference 12 o'c being the whippy setup, and 3/9 being the thumpy setup. Do you want to whip it or thump it?
     
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  15. Power Player

    Power Player Talk Tennis Guru

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    Lead at 12 adds ~ 3 SW points..3 and 9 adds ~ 2.

    That is all you really need to know unless you want to get super scientific about the process.
     
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  16. sureshs

    sureshs Bionic Poster

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    Lead at 12: sweetzone elongated along the mains
    Lead at 3,9: sweetzone elongated along the crosses

    Depending on the type of stroke and where you hit the ball, this could make a difference in what you perceive as power.
     
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  17. corners

    corners Legend

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    The frame with mass at 12 will be slightly more powerful on hits near the tip of the racquet. The frame with mass at 3&9 will be slightly more powerful on hits nearer the sides of the frame. Which will be more powerful for your game depends on where you typically strike the ball.

    In addition, 12 was mostly likely counterbalance higher on the handle, while 39 was counterbalanced nearer the butt. (This would have to be the case if the balance points were kept identical.) 12 will therefore feel slightly stiffer due to the counterbalance nearer the top of the handle, while 39 will feel slightly softer due to the counterbalancing mass added near the buttcap, where the handle vibration node lives when a hand is on the racquet.
     
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  18. Centryx

    Centryx Semi-Pro

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    this! 10 chars
     
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  19. user92626

    user92626 Legend

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    I was gonna say it, but Gasolina beat me to it.


    How do you get two frames with the same SW, weight, and balance but different distributions or concentrations of mass? Give me the equation that you use to calculate SW.
     
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  20. Carefree

    Carefree Rookie

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    That's what I assumed too.
     
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  21. johndagolfer

    johndagolfer Semi-Pro

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    I think that swing weight is being confused for overall static weight.
     
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  22. Povl Carstensen

    Povl Carstensen Legend

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    If they have the same weight and balance, then the only variation is how polarized they are, so the sw can not be the same, is my reasonably educated guess.
    Edit: However, you could go with more weight at 3 and 9 and less at the butt, or less weight at 12, and more at the top of the grip, and you would have the same weight, sw and balance, but different weight distribution, så I stand corrected...
     
    Last edited: May 9, 2013
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  23. Maui19

    Maui19 Hall of Fame

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    Ah sloppy writing on my part. I meant SW can be the same while MOI could be quite different.
     
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  24. user92626

    user92626 Legend

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    Sorry I don't understand what you just wrote.

    Like Gasolina said, if two rackets are different polarized, different distribution, how do they have different sw?

    ()====()
    ==()()==
     
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  25. gameboy

    gameboy Hall of Fame

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    Except that you are adding different amount of weight even if you go by that simple formula if you want the same swing weight. I am pretty sure the OP is confusing static weight with swingweight.
     
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  26. corners

    corners Legend

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    Swingweight is usually the same thing as moment of inertia (MOI). Moment of inertia is also known as 2nd Moment. Swingweight is moment of inertia around an axis 10cm from the butt of the racquet.

    There are two other swing weights, or moments of inertia, commonly measured or calculated:

    1) Recoil weight (moment of inertia about the balance point) which can be calculated is the swingweight, mass and balance point are known. Recoil weight = swingweight - mass x (balance point in cm - 10)

    2) Twistweight (moment of inertia around the longitudinal axis, also known as the polar moment of inertia.) Needs to be measured.
     
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  27. gameboy

    gameboy Hall of Fame

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    corners is correct. The above example would have the same "swing weight" if the balance point and cog are the same and the handle was in the middle of it. For tennis racquets, the above example would result in same static weight, balance point, but different swing weight.
     
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  28. Centryx

    Centryx Semi-Pro

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    so which is it he is talking about SW or static weight, I get the difference if he matched static and balance but don't understand how it can be that way if he matched SW
     
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  29. DE19702

    DE19702 Rookie

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    I bet that the frame with the weight at 12 flexes more than the one with weight at 3 and 9.
     
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  30. Povl Carstensen

    Povl Carstensen Legend

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    If the weight is the same, then the polarized has more sw. What I was describing was more like:

    (1)===(2)=
    =(2)===(1)

    (2) being more weight than (1).These two rackets could have (almost) the same weight, balance and sw, but their weight distribution is different.
     
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  31. Povl Carstensen

    Povl Carstensen Legend

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    My experience is that would be the feeling yes.
     
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  32. JGads

    JGads Hall of Fame

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    Corners, is this a general rule of thumb (ofnworts) to go by - counterbalancing 12 weight at or near the top of the handle, while 3/9 weight should be countered at the butt? I've usually responded pretty well to the top-of-grip lead, though I've never truly known why. And I'm also a guy who, most of the time, seems to get along more with 12 lead rather than 3/9 lead. ...

    And lastly, what if weight is at 2/10ish? Does that change the counterbalancing placement at all?

    Interesting thread.
     
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