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Old 02-19-2013, 04:19 PM   #56
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Originally Posted by ChicagoJack View Post
Just to help illustrate my earlier points about stiff frames and inherent power:

1. The HEAD Radical Pro has 1% less power at the very tip, compared to the Aeropro, because it is more flexible. But it's basically a wash everywhere else.

2. The Donnay Pro One actually has more power at the tip, pretty even if not a bit higher everywhere else, even though it is more flexible, lower swingweight, and has a smaller head. It has no business pulling these numbers, but it does. It should show less rebound power near the tip, and slight less overall but it has more somehow. Perhaps it's the solid core construction.

3. And the massive 377 SW Boris Becker 11 Special Edition is listed there just in case anybody had any doubts about SW making the largest contribution to racquet power.

4. Bit of history here. Before we started firing real balls at real racquets, the brightest minds in all of tennis physics came up with a formula to estimate racquet power. They assigned a value to stiffness, swing weight, flex, and length, assigned a power number, then these digits were published at the United States Racquet Stringers Association database. From looking at that list, you'd conclude that stiffness is a very big deal. For a very long time, that educated guess was the best we had. In the link below you can see how (in 2005) I answered questions about racquet power using some of those estimates.

5. However, when we started firing real balls at real racquets and measuring rebound velocity, the results were shocking, and the old estimate formulas were thrown out the window pretty quickly. Here is a quote from Rod Cross speaking directly of that moment of astonishment I'm describing: Quote: " Figure 2 shows RP (Rebound Power) vs. swingweight for all racquets. The result is simply amazing. Instead of having the 268 dots scattered all over the place, the dots line up perfectly along four different curved lines. The four curves correspond to different racquet lengths. All racquets of the same length lie on the same curve, with short racquets having a bigger RP than long racquets. The result in Figure 2 shows that any two racquets of the same length and the same swingweight will have exactly the same RP, regardless of their weights and regardless of their balance points. The inbuilt power of a racquet in the middle of the strings therefore depends only on the length and swingweight of the racquet, and on nothing else." -- Rod Cross, Raw Racquet Power, Link [2]

Translation : What Mr. Cross is saying there, is that if stiffness played a huge factor in racquet power, what you would see is a gradual rise in power as SW increases, but that the gradual rise would look more like a stock market chart, with peaks and valleys punctuating the power levels btwn stiff frames, and flexible frames. But the results don't look anything like that. The results show a nearly perfect relationship, a perfectly smooth arc because nothing else really matters near the center of the frame.

Link [2] Raw Racquet Power, By Rod Cross

Nutshell: From this perspective, it's not so much a matter of making a gut wrenchingly difficult choice between Power vs Comfort, with a huge sacrifice at either end. It is more a matter of finding a racquet that feels good to hit with, within a specific swingweight/power range that suits your game. If you tend to swing slow and smooth, and that's your groove, then a higher SW frame might suit your style, and you'd get max power without incurring more unforced errors by swinging out of your comfort zone. You will get added stability on off center hits as an added bennie. If you want to swing faster, a lower sw frame will frame will help you do this. A faster swings speed might make for an increase in unforced errors, but you will get additional spin out of the trade off.


Hi Jack,
Yet again superb info, the best technical posts lately on here have come from you, great stuff, just a couple of questions please:-

1. So for the very fastest most powerful volleys, you will need a heavy and stiff racket, and need to hit the ball low in the hoop where the dampner would be, is that correct?

2. One thing you havn't discussed much is where the rackets flex. When measuring the standard racket RA, there is a lot of focus on the throat area of the racket. However I think the reason for the Donnay above, even though having a lower RA reading than the Babolat (mainly due to the Donnay's more flexy throat), demonstrating more power, is because the Donnay has a slightly stiffer hoop than the Babolat, and with the SW being very similar, this makes the difference in power, making the Donnay slightly more powerful than the apparent stiffer Babolat, what do you think about this please?

Last edited by jimbo333; 02-19-2013 at 05:14 PM.
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