Jack,
Have you actually stopped to think about Goodwill's ball speed to ball spin ratio you keep talking about? Yes it exists. But if you do the math, you quickly realize that the effect is negligible. If you bother to do the math and change the frame of reference to the ball instead of the racquet (which Goodwill didn't bother to do), it's obvious that the effect of rebound angle is an order of magnitude greater then the ball speed to ball spin ratio effect.
Goodwill also didn't bother to do any checking on his "anecdotal evidence" that higher tensions give more spin. I'm guessing that he just pulled it off of Wilmot McCutchen's racquetresearch.com site, which still contains incorrect information on this subject, even though Wilmot has recently made some corrections in repsonse to other Talk Tennis posters' comments.
If Goodwill had bothered to interview high level players, his anecdotal evidence would have been the opposite of what he started with, which may have influenced his conclusions.
Pont 1 : You are now shifting the conversation to an area where you feel comfortable debating. Wilmot McCutchen, and his web site has nothing to do with this. This consistent browbeating of your peers, doesnt look good on you.
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Point 2 : I've done the math you mention. I've allways agreed with you that lower tensions create higher rebound trajectory. You keep bringing this up as if it were a big secret. This is well known, and not a contentious point with anybody who has studied the issue. I agree ( sort of ) that the change in rebound angle is greater than the change you'd get with the high tension increased rpm ratio. The point you are making here though is slim on substance for 2 reasons:
A - This is an apples to oranges comparison, i.e spin to rebound angle.
B - A higher rebound trajectory does not mean more spin. period. end of story. A higher rebound angle means what it is. If the player makes no adjustment, the ball sails a little higher, deeper, faster.
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Point 3 : "Lower tensions cause greater spin" This statment is patently false. It is an experimentally observed fact that this statement is false. I have provided
8 references in a previous thread to support this fact and could provide you with 100 more. The only thing preventing me from doing so is respect for the copyright of the authors, the rules of this board, and my own sense of personal integrity.
The 8 Refs begin on reply #28:
http://tt.tennis-warehouse.com/showthread.php?p=1113669#post1113669
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Point 4 : "The conclusion of the Sheffield study is flawed, they misinterpreted their own data and results, their data proved lower tensions produce more spin" This implication is patently false, because the statement is based on a false representation of the the purpose, methods, and conclusions of the study. I have submitted several
sections of text from the actual study itself that very clearly contradicts your falsehood.
See Reply #56:
http://tt.tennis-warehouse.com/showthread.php?t=106870&page=3
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Point 5 : "Lower tension produces greater spin potential" This statement has a solid element of truth to it, but is misleading by way of gross over simplification of a complex issue. If you want to expand the topic from the narrowly focused world of ball/string interactions, to the can of worms called ball/string/player interactions, then you have to let out all the worms. What is missing from this statement is two things:
A - Lower tensions might prompt a stroke adjustment, that is, a downward tilt of the racquet face. It is this downward tilt of the racquet face that produces extra spin.
B - Higher tensions can prompt a stroke adjustment as well, that is, increased swing speed to make up for the reduced depth.
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Point 6 : The effect of tilting the racquet face even a few degrees can alter spin dramatically. The effect you mention does exist. Rod Cross wrote a very good article explaining this phenomena in 2005, entitled "The inch that changed tennis forever", which I first posted here, in the summer of 06. This is also harmonious with the quote I provided: "Maximum spin is achieved at angles approaching 40 degrees". If lower tensions help you do this, then this is beneficial. On this much we agree, but I am not splitting hairs. The notion that the players stroke adjustment produces the spin is an important distinction, one well worth the effort of explaining. One which you continually leave out.
I prefer to give people all the information required for them to make and informed decision based on skill level and personal preferences. For example: A player who chooses to swing faster to create spin might see an increase in mishits. Hitting the ball with a more closed racquet face, might require a grip change. Both of these stroke adjustments may not be easy for players to make. Both deserve a mention. You seem to be intrested in boiling down the facts of a very complex issue so much that it scarcely resembles the original truth. Trying to give people the full and complete truth in a way that is easy to understand, is no easy task. That is what I am attempting.
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Point 7 : Just because you are right does not mean somebody else is wrong. Every Philosophy major knows this, and many Physics Phd's have difficulty living with this concept. High tension can promote faster swings. Low tension can produce steeper angles of contact. Both these things are true. It is counter-intuitive to the human species that two seemingly opposing ideas on the same topic can be true. All the more reason to stress the point at every opportunity.
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If you are determined to have the last word on this, then have it. You win by virtue of stubborn persistance, not substance.
-Jack