# how to calculate swingweight???

Discussion in 'Racquets' started by Speedy_tennis, May 21, 2005.

1. ### Speedy_tennisSemi-Pro

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how to calculate swingweight???

2. ### MiesRookie

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You can't. Unless you take a frame and cut it pieces and weigh them so you know the exact weight distrubution in your frame.

3. ### p3kSemi-Pro

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sure but the swingweight MUST depend on the weight and balance of the racquet. i can't believe two different racquets with identical weight and balance have different swingweight can anyone explain this to me?

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5. ### Gaines HillixHall of Fame

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Well, just think about this scenario and how it would apply to a tennis racquet. Imagine a rod with two sliding weights of equal weight on it. Let's start with the weights on the ends of the bar. Since they weight the same the balance point will be right in the middle of the rod. The swingweight is going to be very high on this setup because the weight is at the extreme ends of the rod and the axis of rotation would be about 4" up from the butt end. Now let's move the weights to the middle of the rod. The total weight and balance point are exactly the same. However, the swingweight is going to be reduced because there is less weight at a distance which is further from your hand. Swingweight increases by the square of the distance from the AOR.

6. ### MiesRookie

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Before the new board, I wrote a very long post explaining exactly why this CAN be the case. If you do a search for swingweight or something along those lines on the old boards, I'm sure you can find it. I'll see if I can dig it up in the meantime.

Regards,
Maurice

7. ### Tennis Ball HitterSemi-Pro

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I would also be interested in understanding "Gaines Hillix's" post. I have not done any number crunching ... but the way I saw it was: assume a evenly balanced racquet we put 10grams at the 12'O-clock position on the head and 10 grams on the butt.

now we move both to the center of balance, so we now have 20 grams at the center ... so there is less weight far out on the head but more weight less far out.

But for those of you mathamatically inclined there is this page http://www.racquetresearch.com/sevencri.htm which explains some formulas to derive the swing weight ... however no matter what numbers I use I cannot seem to get the same specifications as that stated in the specs.

But the formulas require you to know the balance point, the weight AND the location of the sweetspot ... so it would appear balance and weight are not the only factors.

So if anyone has any success with those formulas please explain them to me

NOTE: for the LM presitge mid, I got 47cm from the butt as the position of the sweetspot ... this is below the center of the head ... I am ssuming this is wrong?

8. ### MiesRookie

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I did exactly this in a post I wrote about a month ago. Exact same question. Do a search on posts by me regarding swingweight and I'm sure it will turn up.

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10. ### MiesRookie

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Those were the two posts I mentioned ...