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    High or low swingweight against heavy hitters?

    Anything under 365 feels too wimpy to me!
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    Theory of the American Twist Kick Serve

    The spin axis stays virtually constant in the court frame of reference during flight due to Newton’s third law (while the direction of ball's velocity vector is changing relative to the court frame of reference but staying constant in the 'ball" frame of reference). There are only two forces...
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    Theory of the American Twist Kick Serve

    I have more 20 papers on this topic on my hard drive from when I did some of my own research 15 years ago.
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    Theory of the American Twist Kick Serve

    You guys are violating the principle.
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    Theory of the American Twist Kick Serve

    The irony is that all available evidence suggests the Occam's razor principle does not apply to the number of blades on your shaving implement.
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    Observations on Universal Tennis Ratings

    From what I’ve seen, it’s currently easier to game your UTR rating one direction or another than it is your NTRP rating just by choosing which types of events to play. Seems like UTR would be a lot more accurate if it could take mixed into account, since that’s the only place in usta that you...
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    18×20 6 in the mains should not exist

    My BLX Blades have the outer mains super close to the frame. Skip the outer mains and you have a 16x20 like you describe.
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    Since RG05 Federer lost only to the new gen

    People started reading and returning my serve better when I got older.
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    Vancouver BC this weekend - Feb 16-18

    4.5+ player coming north for 3-day weekend. Would love to get in some tennis.
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    High or low swingweight against heavy hitters?

    You have no hope unless you have burly gorilla arms like Federer.
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    Theory of the American Twist Kick Serve

    Occam's razor, anyone?
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    Theory of the American Twist Kick Serve

    There are dozens of published academic papers on oblique impacts between a strung tennis racquet and a ball, and I have read most of them. Nearly all of them use the same approach of using the racquet frame of reference for clamped racquets (or in the example reference below, the "lab" frame...
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    Theory of the American Twist Kick Serve

    No. You are thinking in the court frame of reference. In the racquet (or ball) frame of reference at the moment of impact, the net resultant vector only has 2 dimensions ( the normal force component and the tangential force component).
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    FiReFTW vs J011yroger best of 3 - predict the scoreline

    Good point about Jolly having the good fortune to learn his strokes in tennis’s Cretaceous era before the comet of destructive new coaching techniques killed off the accurate forehand. 35 is the new 25, plus FiReFTW is at the same generational disadvantage that is holding back the next gen ATP...
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    Very TIGHT or very LOOSE

    Yep. I strongly believe this is not coincidence. In fact, every one I can think of who has a favorable record vs nadal (the ultimate spinner) is a high-tension outlier. Djokovic, Blake, Davydenko, Soderling. I would bet that you won’t find a low tension outlier who has ever beaten him.
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    Grip 4 1/2 vs 4 3/8

    The only time I feel any elbow pain is when I play with a racquet smaller than my usual size. I have smaller than average hands and use a grip size slightly smaller than 4-5/8. I play more confidently with the larger grip on everything but the serve, where the extra grip security of a 4-1/2...
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    Questions about Polarized & Depolarized set-ups

    I find I like to concentrate the weight in the 1-to-3 and 9-to-11 regions. Then I add mass to the handle until I reach my target weight and balance.
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    Very TIGHT or very LOOSE

    You guys are getting close...
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    Theory of the American Twist Kick Serve

    Of course there are many forces acting in all directions during the impact. But any forces acting outside of the 2D plane are balanced out by equal forces on the opposite side of the plane. We only care about the net resultant vector, which can be reduced to two components.
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    Theory of the American Twist Kick Serve

    Doesn't matter, since both "sides" are perpendicular to 2D plane that contains center of the ball as well as the normal and tangential force components.
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    Theory of the American Twist Kick Serve

    I just re-read the article. Indeed Rod Cross has made errors in his discussion of "gyrospin." This is not the first time that Cross has made a statement that can be easily disproved ( his gyrospin explanation can be disproved with a ball machine and a way to tilt it sideways). In the article...
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    Theory of the American Twist Kick Serve

    Do not fall ill to zoomitis! The same rules of motion apply whether the ball and racquet are rigid bodies or not. The rigidity of the bodies just changes the relative contributions from the normal and tangential forces.
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    Theory of the American Twist Kick Serve

    No. It is roughly 0% spiral spin immediately after impact. Yes. True. This would be true in a vacuum, but the frictional drag force can change the spin axis in the court frame of reference. No. Every tennis shot begins with zero spiral spin. Depending on the initial spin axis, the spiral...
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    Round, Oval (or isometric) or Egg-shaped - Advantages, Disadvantages

    The main effect of shape is that the elastic modulus of the hoop (i.e. the spring constant for Squashing by the mains) is a function of narrowness of the hoop. When you string up a mounted racquet, the mains are put in first at the reference tension. Then when you put in the crosses, the...
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    FiReFTW vs J011yroger best of 3 - predict the scoreline

    FiReFTW might be underestimating how easy it is for someone with a 2hb to choke up on the racquet handle with his left hand to hit a lefty forehand that feels similar to his 2hb. I think it would be more of an even matchup if the handicap were simplified so that Jolly has to play the entire...
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    FiReFTW vs J011yroger best of 3 - predict the scoreline

    FiReFTW will be crippled by lack of patience.
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    What to do against junk balls

    So what do I do if I don’t qualify to fit any of those categories?
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    Theory of the American Twist Kick Serve

    I did not misunderstand you.
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    What to do against junk balls

    My volleys were 9 out of 10 last week, but only 4 out 10 yesterday because my stringbed got too soft. Most people don’t realize that volley is the most equipment-sensitive shot in tennis. The serve is the least.
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    Theory of the American Twist Kick Serve

    No you can’t, at least not initially. Assuming you drop the ball onto your strings with a negligible drop velocity, the spin axis starts out perpendicular to the initial launch velocity vector with negligible spiralspin. However, by the time your sidespin dropshot hits the court, the sidespin...
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