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Old 01-26-2013, 09:48 AM   #169
ChicagoJack
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Quote:
Originally Posted by El Zed View Post
. where he admits that there is a difference of power (2 to 4 mph), but in terms of serve speed and when hit at the tip of the frame. While an interesting fact, and again explicitly proving that a difference in power exists, the practical worth of this point is questionable as it presumes that consistently hitting with the tip of a racquet is desirable.More importantly, however, is the admission that power increases are more manifest elsewhere on the frame. If you can't see how this directly contradicts his initial thoughts and the supposed answer to his "riddle," I don't know what to say. Finally, I think it holds that if you gain 2-4 mph at the tip, and the power differences are more pronounced elsewhere on the racquet, then yes it could feasibly reach 5 to 10 mph. Apologies if a 2 to 4 mph gain isn't much for you, perhaps 5 to 10 may be, but then again it doesn't really matter because to others even a 1 mph gain is significant.
1. The commentary above is a misinterpretation of a quote, so epic in scale, and so contorted in it's meaning, the thought has occurred to me it might be intentional misrepresentation. I hope this is not the case. I actually prefer the notion that this is a genuine misunderstanding. If that is what is going on here, it might offer some insight as to why you've been so unsatisfied with my contributions.

2. I did not "admit to a difference of 2-4 MPH" You only arrived at that number because I threw that out as a table scrap in the course of a larger conversation. Before my arrival here you posed the idea of 5-10 mph difference btwn the old classics and a modern Babolat. (ElZed posts 1, 33) When I questioned your frame of reference, this was quickly re-drafted to " I'm not sure, could be .1 or could be 10 MPH". (post 129) Now that I have provided you with a credible frame of reference, you want to beat me over the head with it and do a little victory dance. What you fail to comprehend, because I have not discussed it with you, is that there are many layers to this onion. That 2-4 mph (and 4 is a generous number) represents the spread between specs of frames with wildly differing weight distributions, and overall specs.

2. The quote I provided, does not concern the ball velocity in the instance when the ball hits the tip of the frame during a serve. The speed of the tip of the frame is mentioned because during the service motion, the tip is traveling much faster than the center of the strings, and the bottom of the string bed is traveling slower than the middle and the tip. Thus, it's an expression of racquet head speed in an uber precise way. Here is the original quote in its entirety:

Quote 2 : "In order to serve a ball 100 mph, a player must swing the racquet at a relatively high speed. Most people would guess the racquet needs to be swung about 60 mph or so depending upon the power of the racquet. In fact, the tip of the racquet needs to be swung at about 100 mph, give or take a few mph, depending upon the weight and the weight distribution of the racquet. There is a surprising lesson in this result. That is, the power of the racquet, and the power of the strings has only a small effect on serve speed. The serve speed is just about the same as the tip, regardless of the strings or the racquet. A different string or different frame will change the serve speed by a few mph, but almost all of the power comes directly from the players arm."
-- Rod Cross, And Howard Brody, Chapter 20, Serving Speed, The Physics and Technology of Tennis.

3. One last informational side note, the fact that the tip is traveling faster than the center of the strings is an important concept. Stiffer frames offer incrementally more power, most noticeably in the top 10% of the string bed. The stiffness helps the frame to overcome the dead spot (see post 135) that exists in all frames near the tip. But during the service motion, the tip is traveling very fast, so the dead spot deficiency gets a big fat boost of juice from the racquet head speed. This goes a long way to explain why racquet stiffness is a much bigger contributor to power on a volley (the racquet head is moving slowly), and not such a big deal for a serve. This is one example demonstrating the value of understanding racquet-ball impacts which have nothing to do with player technique. These fundamental building blocks I have been discussing have real world, on court implications.

4. The speed of the tip of the frame, coupled with the high sw of wooden racquets also explains the following event. In 1997, in a comparative test done by Tennis magazine, [7] Mark Philippoussis, the six-foot-five, 217-pound Australian renowned for his powerful serve, averaged 124 mph when serving with his own composite racket. With a classic wooden racket, (where the stiffness ratings average in the low 30's) he averaged 122 mph. Now, here is the punchline. To somebody that understands the fundamental building blocks of ball-racquet collisions, (which I have posted in 133-134-135) this tale would not be difficult to figure out, the clues are there for anybody to observe. To somebody who understands the basics intimately, the tale makes perfect sense upon first mention. Yet you've consistently floated the idea that my presentation of the finer points of these fundamental building blocks is not only pointless, it is disingenuous. (posts 146,165) This could not be further from the truth.


5. Regarding the effort to characterize me as thread Hijacker: Prior to my arrival in the thread, one of the major issues was racquet power (see ElZed posts 1, 6, 11, 16, 17, 30, 33, 41, 44, 52, 66, 70, 87, 91, 93) Everything I've posted is on topic and relevant. In fact, my participation here was born from an invitation I extended, and which ElZed accepted, to discuss the basics of racquet power. (see posts 117, 119.)

6. I have no idea where this thread is going, but I will be sure to respond to any future posts that contain the slightest levels of revisionist history, misunderstanding, misrepresentations, or falsehoods directed at me. It's a tedious exercise, but I find those kinds of comments exceptionally motivating.

References

Link [1] Basic Facts about Frames and Strings,
-The United States Racquet Stringers Association
http://www.racquettech.com/top/basic_facts.html
http://www.tennis-warehouse.com/lc/basicfacts.html

Link [2] Raw Racquet Power
By Rod Cross
http://www.racquetsportsindustry.com...uet_power.html

Link [4] The Inch That Changed Tennis Forever
By Rod Cross
http://www.racquetsportsindustry.com..._tennis_f.html

Link [5] Racquet Power Comparison Tool
http://twu.tennis-warehouse.com/cgi-...mparepower.cgi

Link [7] Mark Philippoussis Serve Test, Wood Vs Graphite
http://www.time.com/time/magazine/ar...899876,00.html

-Jack
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Last edited by ChicagoJack : 01-26-2013 at 02:44 PM.
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