How can flexible racquets be powerful?

Relinquis said:

Guys,

Stop Swearing... There are kids around and... You could get this thread deleted... and... You could get banned.

Learn to discuss and disagree without fighting. Be respectful please.

Click to expand...

I was saying the same thing earlier in a very British polite way though. Didn't work for me:-?

Anyway looks like they have gone now, or at least are no longer arguing.

Am still hoping ChicagoJack returns to answer my questions from post56 on page 3, he is probably very busy, I will try to be more patient.

onehandbh said:

I disagree. I think it's a hard racquet to use. Felt like a heavy
wet noodle to me.


Again, I totally disagree. The babolat pure drive and APD are
two of the easiest racquets to use if you string them with
full poly at a low tension. I've seen park hackers using bunting
strokes, wristy strokes, and all kinds of homemade methods
of hitting spin and the babolats helped them keep the
ball in with more spin, power, and a big sweet spot. Plus
stock they are light enough for most people.

I love the pure drive with full lux and a little lead, but
my wallet and elbow didn't like it -- otherwise I would
have switched to it. I initially tried it with synth gut and
it was completely uncontrollable. btw, no racquet
has ever given me pain. Only the pure drive.

Click to expand...

I guess where I failed to make myself clear is the distinction between "being easy to use" and "being easy to use properly." Perhaps the correct phrasing would be that the APD is easy to use but more difficult to master (than the PT630).

Yes, lighter racquets inherently permit virtually everyone to pick up a racquet and to get some level of depth, pace, etc. This of course, just being a function of weight. I am not, however, speaking about this nor the tap-back game - I am talking about the use of the APD/PD in a competitive setting where one needs to hit with significant pace and/or spin. Contrary to the common perception, you can indeed take a full and strong cut with either the PD or APD - just as fast and hard as a Prestige or Radical. The common perception is that doing so will generally cause the ball to sail - which is true, very true. Once you learn to adjust, and then learn to adjust to maximize spin - this is rectified. That being said, you don't really have this issue with the PT630. With that racquet, you can hit a great traditional forehand or a nasty modern stroke presuming you have the strength to do so (especially over the match) - all without fearing that the ball will sail (overly so, at least).

jimbo333 said:

I was saying the same thing earlier in a very British polite way though. Didn't work for me:-?

Anyway looks like they have gone now, or at least are no longer arguing.

Am still hoping ChicagoJack returns to answer my questions from post56 on page 3, he is probably very busy, I will try to be more patient.

Click to expand...

Ok, you too busy-bodies really need to stop. I'm sure if someone directly criticized you, you would speak up. So save it.

Perhaps you should save it, Zed, you're spoiling an otherwise very enjoyable thread.

anubis said:

I am using BHB7, and I love it. I am not using blu tack, I have not yet experimented with weighting it at all. So far, I feel like the APD is perfectly weighted for me. I have issues with high swing weights, can't really whip that frame around fast enough.

As soon as I calibrate my new crank machine, I'm going to string it @ 48/46 lbs and see how it feels. I won't really know anything until it has about 8 hours on it though.

thanks for the help

Click to expand...

Hi, Anubis -

Yeah, the BHB7 is a great string at a wonderful cost. I really wish I could help further, but I understand your preference for keeping the weight down. Unfortunately going through the Blu Tack/lead mod will get the racquet to at least 12 oz. if not more. It does transform the feel and makes it a very, very solid racquet, but it does inherently change it. Funny enough had the chance to use another original APD (the Nadal version) yesterday, and disliked the feel right from the get-go (especially in comparison to the modded GT).

kaiser said:

Perhaps you should save it, Zed, you're spoiling an otherwise very enjoyable thread.

Click to expand...

Perhaps you should stay out of it, kaiser. No, you SHOULD stay out of it.

Again, sticking your nose where it doesn't belong?

jimbo333 said:

I was saying the same thing earlier in a very British polite way though. Didn't work for me:-?

Anyway looks like they have gone now, or at least are no longer arguing.

Am still hoping ChicagoJack returns to answer my questions from post56 on page 3, he is probably very busy, I will try to be more patient.

Click to expand...

Or you could just order the same book that he derives most of his information from.... You know, supporting the person, who actually went about engaging in the research and authoring the work....

So does anyone disagree with chicagojacks (even if it is recycled) information or conclusions? And if so can they provide research which would contradict it?

nope. chicagojack's posts seem legit.

i don't know what el zed is on about though. i can't see how a properly weighted up APD can magically provide more spin unless it was attributable to one of it's physical characteristics that relates to launch angle or spin, i.e. string pattern, or such.

i don't see how it's comparative stiffness is what allows it more spin or power compared to a more flexible stick (apart from an incremental amount of power at the tip, after adding weight to the stock babolat stick to get it's swing weight in line).

My ideal stiffness of a frame seem to be around 65. It's generally stiff but
it still flexes on high impact.

marosmith said:

So does anyone disagree with chicagojacks (even if it is recycled) information or conclusions? And if so can they provide research which would contradict it?

Click to expand...

I don't know of any published research that contradicts the view he presented. Bottom line: "power", and the role stiffness plays in power, has been grossly oversold by racquet manufacturers. I've posted this before, but in a paper published last year and financed by Prince, an analysis using a finite element computer model found that if you had two racquets, identical in all respects except that one was twice as stiff, say 65 RDC vs. 130 RDC, the stiffer frame would give you about 5 extra miles per hour on a hard groundstroke. But the frames on the market today differ by only 10-15 RDC points, not 65! The difference in power between a flexy (60 RDC) frame and stiff one (70 RDC) is really not that great.

Consider this comparison. 2012 Babolat Pure Drive Roddick vs. 2012 Head Youtek IG Radical Pro. This is a really good comparison because the frames that TW University tested both had the same swingweights (328 ) and nearly identical twistweights.



The Pure Drive Roddick had stiffness of 72 and the IG Rad Pro 64. And yet they pretty much have the same power. The PDR has slightly greater power potential at the three locations 2 inches above the center, and just a little bit greater power to either side of center. But look what this actually means to a player in terms of shot speed:



An extra MPH 2 inches above center, a couple extra MPH if you want to hit right below the tip. You can see from the second graphic that hitting in the center of the strings is where you get your fastest shots. And that is exactly where stiff frames help you the least. Basically, stiff racquets give you a tiny power boost near the tip and toward 3&9. This effectively expands the "sweetzone", in so far as your shots will be slightly faster if you miss the center of the strings. A better way than "powerful" to describe this would be "forgiving".

It should be clear to anyone looking at the above graphs, and even more clear to anyone looking through the TWU Power Potential database, that the key to power is swingweight. But manufacturers won't try to sell you racquets based on swingweight because swingweight is a double edged sword. High swingweight means a racquet is inherently powerful, but it also means that it is harder to swing fast. So if you get a high-swingweight stick in your quest for power you might find your swingspeed to be slower and your shots to end up being the same speed as before. So, in terms of power, there is no free lunch. Well, there is natural gut, but you'll lose a couple lunches to pay for it.

I think the only one who refutes it is LeeD. Although I'm not sure why. Something to do with inherent problems with science and the movie Predator. That's right. Predator.

Absolutely, The Head Radical IG Pro definitely fits this definition.

Corners, great post.

This thread should be stickey'ed!

Great contributions by corners.

When is the price of the EX03 tour going to come down so I can get my 52 flex rating game on?

dman72 said:

Great contributions by corners.

When is the price of the EX03 tour going to come down so I can get my 52 flex rating game on?

Click to expand...

Thanks. That's the thing though - lots of players that have tried many racquets, and whose opinions I respect, agree that the Exo3 Tour is low-powered. Going by the lab data, it is, but only a little bit lower-powered than "powerful" racquets in the same weight and swingweight class. So who is right? The players or the lab data? Are players really hurt by losing the 1-2 MPH on shots struck high in the stringbed with the Exo3 Tour that they could have got with a Pure Drive? Are those 1-2 MPH that big of a deal? Do we habitually exaggerate power differences when comparing racquets? Have we been brainwashed by twenty years of marketing propaganda?

I suppose it depends on playing style and priorities. If arm health is an issue, one might gleefully give up that extra pop at the top of the stringbed. If hitting winners is most important, the marginal advantage a Pure Drive offers might be worth it. And whenever I think I should just forgot about racquet power and focus on other things - comfort, feel, precision, technique, footwork - I tend to remember Kim Clisters. I'm pretty sure she swings faster than I do, yet she used a stock Pure Drive strung with a full bed of natural gut. Just about the most powerful setup you could have. Would she have been as good using a stereotypical "control" setup, say a Prestige MP with full poly?

One additional thing that hasn't been mentioned in this thread, I think, is that the importance of a racquet's inherent power potential (ACOR, in physics terms) is greatest at low swingspeeds and becomes almost a non-issue at very fast swingspeeds. So if you're an older player with slow swings a racquet with greater inherent power will indeed give you a boost. But if you're young and quick, with swingspeeds on your groundies of 70+ mph, the inherent power of your racquet won't make much of a difference to the speed of your shots, and that 1-2 MPH difference becomes more like 0-1 MPH.

This article explains the physics of why this is the case very well: http://twu.tennis-warehouse.com/learning_center/racquetcontribution.php

And finally, a shout-out to Tennis Warehouse University: Just several years ago we knew much, much less about racquets and strings than we do now. Then Tennis Warehouse hired Crawford Lindsey, the former editor of Racquet Sports Industry Magazine, and the co-author of the two definitive books on tennis science, "The Physics and Technology of Tennis" and "Technical Tennis." Lindsey is also known as the "TW Professor" and in just a couple years he has created an absolutely first class collection of articles, databases and scientific papers on racquets and strings. All of it is free, and all of it is excellent. If more people took the time to read this stuff about half the threads on the racquet forum would not exist because everyone would already know the answers.

Check it out by clicking "TW UNIVERSITY" at the top of the page.

corners said:

Thanks. That's the thing though - lots of players that have tried many racquets, and whose opinions I respect, agree that the Exo3 Tour is low-powered. Going by the lab data, it is, but only a little bit lower-powered than "powerful" racquets in the same weight and swingweight class. So who is right? The players or the lab data? Are players really hurt by losing the 1-2 MPH on shots struck high in the stringbed with the Exo3 Tour that they could have got with a Pure Drive? Are those 1-2 MPH that big of a deal? Do we habitually exaggerate power differences when comparing racquets? Have we been brainwashed by twenty years of marketing propaganda?

I suppose it depends on playing style and priorities. If arm health is an issue, one might gleefully give up that extra pop at the top of the stringbed. If hitting winners is most important, the marginal advantage a Pure Drive offers might be worth it. And whenever I think I should just forgot about racquet power and focus on other things - comfort, feel, precision, technique, footwork - I tend to remember Kim Clisters. I'm pretty sure she swings faster than I do, yet she used a stock Pure Drive strung with a full bed of natural gut. Just about the most powerful setup you could have. Would she have been as good using a stereotypical "control" setup, say a Prestige MP with full poly?

One additional thing that hasn't been mentioned in this thread, I think, is that the importance of a racquet's inherent power potential (ACOR, in physics terms) is greatest at low swingspeeds and becomes almost a non-issue at very fast swingspeeds. So if you're an older player with slow swings a racquet with greater inherent power will indeed give you a boost. But if you're young and quick, with swingspeeds on your groundies of 70+ mph, the inherent power of your racquet won't make much of a difference to the speed of your shots, and that 1-2 MPH difference becomes more like 0-1 MPH.

This article explains the physics of why this is the case very well: http://twu.tennis-warehouse.com/learning_center/racquetcontribution.php

And finally, a shout-out to Tennis Warehouse University: Just several years ago we knew much, much less about racquets and strings than we do now. Then Tennis Warehouse hired Crawford Lindsey, the former editor of Racquet Sports Industry Magazine, and the co-author of the two definitive books on tennis science, "The Physics and Technology of Tennis" and "Technical Tennis." Lindsey is also known as the "TW Professor" and in just a couple years he has created an absolutely first class collection of articles, databases and scientific papers on racquets and strings. All of it is free, and all of it is excellent. If more people took the time to read this stuff about half the threads on the racquet forum would not exist because everyone would already know the answers.

Check it out by clicking "TW UNIVERSITY" at the top of the page.

Click to expand...

I tried all the different variables on the shot speed calculator, and it seems like overall no matter what the speed of the stroke, the racquet does not make a huge difference...plug in a serve returned by a 15 mph volley, and the difference between a pure drive and an EX03 tour is 1 or 2 MPH.

marosmith said:

So does anyone disagree with chicagojacks (even if it is recycled) information or conclusions? And if so can they provide research which would contradict it?

Click to expand...

Hi marosmith,

1. Cool man, I invite you to hang onto that healthy skepticism. On any any given day, the volume of baseless assumptions, contradicting player experience, and questionable sources is pretty high around this ranch.

2. Having said that, what you are calling "recycled information", I would simply describe as "widely available published research" I'm just trying to explain the basics here, which ought to be no big whups. As it turns out, the truth is often stranger than fiction, not very intuitive at times, not widely known, and is often not accepted and derided by even the most avid racquet junkies.

3. It has been also been implied (by someone else a few posts ago) I'm procuring information from a single book. That's not the case. That's actually kind of funny, as I often take a fair amount of heat for providing too many sources and links, which I'm happy to provide here. Lots of good reading in there, feel free to fact check and cross reference. It's all good.



The Really, Really, Short Version, Basics Of Racquet Power, ACOR:
(More Detail, Screen Grab Photos On My Posts #12, 13, 24, 34)

1. Ball velocity is the only measurable indicator of racquet power. On the court, ball velocity is typically measured with a radar gun and expressed as MPH or KPH. In laboratory conditions we might also measure film frames or measure bounce heights. However, recreational players don't often play with radar guns court side, so we often are using visual cues such as depth, trajectory, and height over the net to make guesses about ball speed. The problem is that all of these visual cues are highly sensitive to changes in string pattern, string tension, string type, and technique. Here are a just few examples: An open pattern and or slippery strings creates a higher arc, than a denser patterns or sticky strings, given the same stroke. If the player does not adjust to the additional height over the net, the ball might land deeper in the court, not because the ball is traveling faster, but because it is simply launching at a higher angle. However, if the player adjusts to the high arc by closing the racquet face, the result will be more spin. If the player now sees the ball diving into the court with more spin, and several feet to spare, this might create yet another stroke adjustment, wherein the player begins to open up his technique, will swing faster and with more confidence. The result of that 2nd adjustment would be even more spin and more ball speed.

2. All things being equal : A higher swingweight frame has more power. This assumes the swingspeed does not drop, which is easier said than done. [1][2][3][5][6]

3. Racquet power is almost directly related to swingweight. It is the single most predictable indicator of racquet power when attempting to distinguish inherent power levels between different types of racquets. [2][5][6]

4. In general : a stiffer frame is slightly more powerful than a flexible one. However, a flexible frame is just as powerful as a stiff frame when you hit the center of the strings. Stiffer frames have slightly more power when the ball is struck hit near the tip of the racquet. [1][2][5][6]

5. All things being equal : A racquet with a bigger head has more power. If the string tension remains constant, the longer strings creates a softer string bed overall. A softer string bed creates a more powerful racquet. There are limits to this however, as you cannot play tennis with a butterfly net. [1][6]

6. All things being equal: A racquet with a wider head will have more twistweight. This creates more power on balls that miss the sweet spot near the sides of the frame.[5][6] For additional insight on wide heads and spin, see link [4]

7. If you add length to an existing frame, swingweight increases dramatically. If two frames are equal SW, and one is longer, then the longer frame has less mass in the head, and the balance point is lower. So while the leverage is greater with the longer frame, it is harder to swing, and there will be less mass in the head per every SW unit.[1][2][6]

Quote 3: "Racquet stiffness has no effect on power when the ball is struck in the middle of the strings, but stiff racquets are more powerful when the ball is struck nearer the tip of the racquet"
-- Rod Cross, Chapter 14, Racquet Power, The Physics And Technology Of Tennis. Link [6]



References, Links, Suggested Reading:

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/articles/2006/02/raw_racquet_power.html

Link [3] Racquet Handle Weighting And Maneuverablility, by Rod Cross
http://www.racquetsportsindustry.com/articles/2006/04/racquet_handle_weighting_and_m.html

Link [4] The Inch That Changed Tennis Forever, By Rod Cross
http://www.racquetsportsindustry.com/articles/2006/01/the_inch_that_changed_tennis_f.html

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

Link [6] The Physics And Technology Of Tennis
http://www.tennis-warehouse.com/The_Physics_and_Technology_of_Tennis/descpage-PHYSICS.html

Link [7] Mark Philippoussis Service Speed Testing:
Averages 124 MPH with a Wood Racquet, and 126 with his Graphite Racquet,
Time Magazine, June 2009
http://www.time.com/time/magazine/article/0,9171,1899876,00.html

Link [8] Power Potential, The Total Performance Measurement
http://twu.tennis-warehouse.com/learning_center/totalperformance.php

Link [9] The Ingredients Of Maximum Shot Speed
http://twu.tennis-warehouse.com/learning_center/maxspeedeasy.php

Link [10] Maximum Shot Speed, Where to Hit on the Racquet
http://twu.tennis-warehouse.com/learning_center/maxshotspeed.php

Link [11] Why Is Maximum Power In the Throat and Maximum Shot Speed Toward The Tip?
http://twu.tennis-warehouse.com/learning_center/PPandspeed.php

Link [12] Compare Racquet Shot Speeds (Mph)
http://twu.tennis-warehouse.com/cgi-bin/comparespeed.cgi

Link [13] Compare Racquet Trajectories
http://twu.tennis-warehouse.com/cgi-bin/trajectory_compare.cgi

Link [14] More Tennis Physics, Rod Cross
http://www.physics.usyd.edu.au/~cross/presentations.html

Link [15] Power, Does the Racquet Matter?
http://twu.tennis-warehouse.com/learning_center/racquetcontribution.php

Link [16] Power Potential Test Procedure
http://twu.tennis-warehouse.com/learning_center/test_method.php

PS - Corners, thanks for chiming in.. I was hoping you might swing by and contribute.

- Jack

As a former user of stiff frames and now an Exo Tour user, I can't believe the difference between a Pure Drive and the Exo with exactly the same string at the same tension is only 1-2 MPH. I'd say it is a few more MPH than that just based upon my own observations (no hard measurements).

jimbo333 said:

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?

Click to expand...

jimbo333 said:

Am still hoping ChicagoJack returns to answer my questions from post56 on page 3, he is probably very busy, I will try to be more patient.

Click to expand...

Hi Jimbo

1. Sorry for the long delay. Been pinned to the mat with work for a few days. As an abstract concept, that's mostly correct. For stationary racquets, or racquets not moving very quickly, the area of the stringbed that has the most power is called the best bounce, and it's down low near the dampener. See photo provided. But the point of max power rises once the racquet accelerates. That's because on a groundstroke, and especially during the serve, the tip of the racquet is moving faster than the center, so the added velocity creates more power. In the service motion on a 100 mph serve, the tip of the frame is moving around 100 mph, and the center of the strings is moving at around 72 mph. However, in practice, I really cant advocate aiming for the vibration dampener on a volley. I think aiming for the middle of the strings is a much better idea, as it might not be the "most powerful volley" but it will be a clean volley. It does explain however, why you can mishit the ball near the tip of the frame, and still get a decent result. But if you impact up high blocking back a serve, or a volley, the result is often a ball in the bottom of the net. I've also posted, just a few moments ago, quite a few more links and articles, many of which adress this specific issue.

2. Yeah that's a really good point. That Flex Infinity Machine thingamajiggy is something I'd like to have in my Christmas stocking for sure! I think there are a few possibilites explaining why the Donnay Pro One tests as more powerful up high than a stiffer (rdc) frame. The first is your idea that it has a stiffer hoop, but is flexier in the throat. The second might be that it is solid core. Donnay suggestss that the traditional ACOR forumla is valid for hollow frames, but not for solid core frames. I'm not sure how I feel about that assertion, nor can I find the link for the formula they suggest is more correct, but I recall they provided a wikipedia reference (so it must be true lol).



- Jack

mikeler said:

As a former user of stiff frames and now an Exo Tour user, I can't believe the difference between a Pure Drive and the Exo with exactly the same string at the same tension is only 1-2 MPH. I'd say it is a few more MPH than that just based upon my own observations (no hard measurements).

Click to expand...

I sometimes think the same thing, but after reading ChicagoJack's and Corners' posts, the only way that I can think about squaring these conflicting ideas is: spin production.

Some of the lighter weight, stiffer frames with open string patterns can produce a lot of spin. that extra spin allows you to take bigger cuts at the ball and still keep the ball in play. Therefore, since you are swinging faster, the ball is traveling faster.

But with smaller/flexier/heavier/denser string pattern frames, some people like to slow down their swing speed in order to keep the ball in play, since they don't produce as much spin. Therefore, you're swinging slower and producing a lower velocity shot.

but that's just an assumption on my part.

anubis said:

I sometimes think the same thing, but after reading ChicagoJack's and Corners' posts, the only way that I can think about squaring these conflicting ideas is: spin production.

Some of the lighter weight, stiffer frames with open string patterns can produce a lot of spin. that extra spin allows you to take bigger cuts at the ball and still keep the ball in play. Therefore, since you are swinging faster, the ball is traveling faster.

But with smaller/flexier/heavier/denser string pattern frames, some people like to slow down their swing speed in order to keep the ball in play, since they don't produce as much spin. Therefore, you're swinging slower and producing a lower velocity shot.

but that's just an assumption on my part.

Click to expand...

Hi Anubis -

I think you might have just answered your own question you had for me on post #29. I was thinking the exact same thing. Your older generation black and yellow APD has a sw of 316, 16x19, and 100sq. Your IG Rad Mp is 320 sw, 16x19 and the Head 98's are closer to 95 square inches.

The Radical has slight more inherent power, which might have the ball landing a bit deeper. It's also a bit harder to swing, so perhaps, along with the tighter pattern, its more difficult to get the racquet going fast enough to produce spin. Perhaps the adjustment you are then making with the Radical is a shorter, slower, more tentative stroke. But you are able to swing more freely, and with more confidence, with the lighter SW more open pattern APD.

Since you've expressed some discomfort with the APD, I'd consider switching a racquet with the same SW, head size, and pattern, but which is more headlight and flexible. Just shop in that SW 316 area, and play with something that feels good to hit with. Easy Peasy. It's also possible that that the Higher SW of the Rad isn't good for your wrist either, so in switching back and forth from a too heavy frame, to a too stiff one, your wrist is letting you know it's not happy with either frame.

-Jack

ChicagoJack said:

Hi Anubis -

I think you might have just answered your own question you had for me on post #29. I was thinking the exact same thing. Your older generation black and yellow APD has a sw of 316, 16x19, and 100sq. Your IG Rad Mp is 320 sw, 16x19 and the Head 98's are closer to 95 square inches.

The Radical has slight more inherent power, which might have the ball landing a bit deeper. It's also a bit harder to swing, so perhaps, along with the tighter pattern, its more difficult to get the racquet going fast enough to produce spin. Perhaps the adjustment you are then making with the Radical is a shorter, slower, more tentative stroke. But you are able to swing more freely, and with more confidence, with the lighter SW more open pattern APD.

Since you've expressed some discomfort with the APD, I'd consider switching a racquet with the same SW, head size, and pattern, but which is more headlight and flexible. Just shop in that SW 316 area, and play with something that feels good to hit with. Easy Peasy. It's also possible that that the Higher SW of the Rad isn't good for your wrist either, so in switching back and forth from a too heavy frame, to a too stiff one, your wrist is letting you know it's not happy with either frame.

-Jack

Click to expand...

Thank you very much I appreciate the time and dedication you put into the science behind tennis.

Little known fact :

Jack's posts were the inspiration for the track "She blinded me with science".

They added an S to He to make it more accessible to the kids.

It's just seems like some of the science with rackets and strings correlates well with my on court experience while other data does not. Could it just be my perception is wrong? Perhaps.

anubis said:

Thank you very much I appreciate the time and dedication you put into the science behind tennis.

Click to expand...

No worries, anubis. I'm happy to help. I know that 4 SW digits, and 10 digit spread in stiffness doesn't seem like much, but when you've got some pain that can be a really big deal. I've got a few Pro One's in my stable that are under spec for balance, mass, SW and flex by a just a smidge. when I was nursing my TE, those slightly easier swinging frames were my favorites for sure.

The relationship of spin to power you mentioned is a big fat piece of the overall puzzle. After all, we still have to keep the ball in the court right? For extra credit reading you might you might check out the article I linked called "The Inch That Changed Tennis Forever", by Rod Cross. The basic premise is that the real revolution from small headed wood frames to larger headed graphite frames wasn't power, but spin. The SW of wood frames is typically in excess of 360
SW. That's power o' plenty right there. It is suggested that the wider head creates the opportunity for more spin. ALOT more spin, about five times more. Couple that with slick co-poly string, and you've got some game changing innovation.

The transition from wood to graphite happened in the late 70's, but it's only been in the last 10-15 years on the tour that players have taken full advantage of that innovation. When muscle mass, fitness, and racquet head speed finally crashed the party, that's when we started to see the game really change. Yes, frames have gotten stiffer, moving in perfect tandem with the dramatic shift. Perhaps this goes along way to explain the common mis-perception, that a super stiff racquet is a super powerful racquet.

-Jack

W/out a doubt and I know this from experience.

I was hitting with a western grip and heavy spin as a wee lad in the late 80s and 90s and for a while was using a Prince 90 with a rather narrow headshape.

Can't say how many times I clipped the frame coming over the ball while developing my forehand. It felt like 1 million.

corners said:

I don't know of any published research that contradicts the view he presented. Bottom line: "power", and the role stiffness plays in power, has been grossly oversold by racquet manufacturers. I've posted this before, but in a paper published last year and financed by Prince, an analysis using a finite element computer model found that if you had two racquets, identical in all respects except that one was twice as stiff, say 65 RDC vs. 130 RDC, the stiffer frame would give you about 5 extra miles per hour on a hard groundstroke. But the frames on the market today differ by only 10-15 RDC points, not 65! The difference in power between a flexy (60 RDC) frame and stiff one (70 RDC) is really not that great.

Consider this comparison. 2012 Babolat Pure Drive Roddick vs. 2012 Head Youtek IG Radical Pro. This is a really good comparison because the frames that TW University tested both had the same swingweights (328 ) and nearly identical twistweights.

The Pure Drive Roddick had stiffness of 72 and the IG Rad Pro 64. And yet they pretty much have the same power. The PDR has slightly greater power potential at the three locations 2 inches above the center, and just a little bit greater power to either side of center. But look what this actually means to a player in terms of shot speed:

An extra MPH 2 inches above center, a couple extra MPH if you want to hit right below the tip. You can see from the second graphic that hitting in the center of the strings is where you get your fastest shots. And that is exactly where stiff frames help you the least. Basically, stiff racquets give you a tiny power boost near the tip and toward 3&9. This effectively expands the "sweetzone", in so far as your shots will be slightly faster if you miss the center of the strings. A better way than "powerful" to describe this would be "forgiving".

It should be clear to anyone looking at the above graphs, and even more clear to anyone looking through the TWU Power Potential database, that the key to power is swingweight. But manufacturers won't try to sell you racquets based on swingweight because swingweight is a double edged sword. High swingweight means a racquet is inherently powerful, but it also means that it is harder to swing fast. So if you get a high-swingweight stick in your quest for power you might find your swingspeed to be slower and your shots to end up being the same speed as before. So, in terms of power, there is no free lunch. Well, there is natural gut, but you'll lose a couple lunches to pay for it.

Click to expand...

Absolutely superb post, brilliant info thanks!

ChicagoJack said:

Hi Jimbo

1. Sorry for the long delay. Been pinned to the mat with work for a few days. As an abstract concept, that's mostly correct. For stationary racquets, or racquets not moving very quickly, the area of the stringbed that has the most power is called the best bounce, and it's down low near the dampener. See photo provided. But the point of max power rises once the racquet accelerates. That's because on a groundstroke, and especially during the serve, the tip of the racquet is moving faster than the center, so the added velocity creates more power. In the service motion on a 100 mph serve, the tip of the frame is moving around 100 mph, and the center of the strings is moving at around 72 mph. However, in practice, I really cant advocate aiming for the vibration dampener on a volley. I think aiming for the middle of the strings is a much better idea, as it might not be the "most powerful volley" but it will be a clean volley. It does explain however, why you can mishit the ball near the tip of the frame, and still get a decent result. But if you impact up high blocking back a serve, or a volley, the result is often a ball in the bottom of the net. I've also posted, just a few moments ago, quite a few more links and articles, many of which adress this specific issue.

2. Yeah that's a really good point. That Flex Infinity Machine thingamajiggy is something I'd like to have in my Christmas stocking for sure! I think there are a few possibilites explaining why the Donnay Pro One tests as more powerful up high than a stiffer (rdc) frame. The first is your idea that it has a stiffer hoop, but is flexier in the throat. The second might be that it is solid core. Donnay suggestss that the traditional ACOR forumla is valid for hollow frames, but not for solid core frames. I'm not sure how I feel about that assertion, nor can I find the link for the formula they suggest is more correct, but I recall they provided a wikipedia reference (so it must be true lol).

- Jack

Click to expand...

Excellent, thanks very much for the answer Jack!

1. Yes, i wasn't suggesting actually aiming for the dampner on the volleys (I'm certainly not that good), but now I know that for punched volleys at least the most powerful volleys will always be lower in the hoop.

2. I've been thinking about this theory about certain rackets having stiffer hoops (generating more power) for a while, and would really like to see some more examples on the flexinfinity machine. I've said this elsewhere, but would really like to see the Head PT57A compared to the Angell (Vantage) Custom 63RA, because I think they would be completely different (one relatively stiff hoop with flexy throat, one relatively flexy hoop with stiffer throat), and yet both are superb rackets for me to play with, yet feel very different!

Anyway I've learnt so much from this thread, at least more technical info than ever before, thanks especially to ChicagoJack and Corners

ChicagoJack, I'm not skeptical but since I'm a lemming and can't read I wanted to see if there we actual real, tangible, scientific arguments which would support the use of stiff rackets as a primary means of generating power.

I think it's pretty safe to say that head shape, weight, swing weight and string type and string bed tension are the primary determining factors contributing to power in a racket. That's what I said a few pages back but it seemed to create lots of controversy.

Why don't you try a PDR vs a Microgel, then you would know.

For what it's worth Marosmith, I agree with you. I think the problem was, that Zed guy then came along and made it all about Babs instead of the OT. Loving the info from ChicagoJack and Corners. Seriously, in my case, I'll only be looking at flexi racquets from now on. Just my take on it all.

I always thought it was a KNOWN fact that players with good strokes almost always hit harder with more flexible rackets, because when they use stiff rackets like PureDrives, the ball goes OUT OUT OUT, so they add more spin or swing more controlled, giving them LESS power.
On a flexi racket, the ball stays IN, so they can swing hard, and the ball goes faster.

LeeD said:

Why don't you try a PDR vs a Microgel, then you would know.

Click to expand...

If modded to the same static and swing weight, and string to the same string bed tension and type my guess is probably about 1-2mph difference on off center hits and a different launch angle.

LeeD said:

I always thought it was a KNOWN fact that players with good strokes almost always hit harder with more flexible rackets, because when they use stiff rackets like PureDrives, the ball goes OUT OUT OUT, so they add more spin or swing more controlled, giving them LESS power.
On a flexi racket, the ball stays IN, so they can swing hard, and the ball goes faster.

Click to expand...

I thought that too, but it appears we thought that incorrectly. It's now been shown the flexibility of the racquet makes little difference in terms of power, appart from some minor exceptions, just to drive the point home again.

Let's see....
Mr.Roddick...
Biggest serves, then and now.
Groundies then..powerful.
Groundies the past 4 years, spinny and weak.
Why?
Because I TOLD YOU SO.

Read the Phillipoussis serving study that Chicago Jack posted LeeD.

While the pursuit of knowledge is often a worthwhile endeavor......
In this case, it's pure esoteric.
Fact... Pros hit hard.
Fact... Few pros use the siffest rackets.
KISS

LeeD said:

While the pursuit of knowledge is often a worthwhile endeavor......
In this case, it's pure esoteric.
Fact... Pros hit hard.
Fact... Few pros use the siffest rackets.
KISS

Click to expand...

Ok then, so wouldn't the logical conclusion then be that flexibility doesn't necessarily have much to do with power?

Says someone who can't figure what racket to use, or how to play with his racket......
Yes, it's really really really important to know exactly why and how a flexi racket can be more powerful...
Or, maybe use nature as an example. Look at tennis player's playing tennis.
NO, of course, that would not be something you would consider....
Who cares about reality? This is a theory class, and to heck with reality.

LeeD said:

Says someone who can't figure what racket to use, or how to play with his racket......
Yes, it's really really really important to know exactly why and how a flexi racket can be more powerful...
Or, maybe use nature as an example. Look at tennis player's playing tennis.
NO, of course, that would not be something you would consider....
Who cares about reality? This is a theory class, and to heck with reality.

Click to expand...

Don't make me post those videos of your serve again, lol! We all know your playing level. There's no point trying to use reason or logic with you LeeD as you don't possess any. Have a nice life.

Or rather, you should post them, and compare them with videos of your serve again.

LeeD said:

Or rather, you should post them, and compare them with videos of your serve again.

Click to expand...

I don't remember ever claiming my serve to be better than yours. I do, however, remember being surprised at the gross discrepancy between your written description of your own serve and the visual evidence of that same serve.

LeeD said:

Let's see....
Mr.Roddick...
Biggest serves, then and now.
Groundies then..powerful.
Groundies the past 4 years, spinny and weak.
Why?
Because I TOLD YOU SO.

Click to expand...

Roddick hasn't changed a bit. His competition on the other hand has gotten much better and more diverse. His forehand is still the same as it once was, as is his slice bh.

Pros hit with so much spin from high rhs because they are so fit. Depending on how their strokes have developed over time, they choose a racket that compliments their game. Not one that tames it.

Ashley D said:

I'm a bit interested in the BLX Blade Team or the Donnay Pro One Oversize Extended. Both of these racquets are much more powerful than my current stick, the Rebel 95 (2009). However, the BLX has a flex in the mid to low 50s. How is it that a soft racquet can be that powerful? I understand swingweight and headsize make a difference, but the swingweight of the blx is pretty low too. Is it just the bigger head? Is it beam width?

Click to expand...

I think rating a racquet flexible or stiff is of little use. There are so many variables that it mitigates any generalizations about how a racquet will play based on stiffness rating. Demo until you find the one that feels right is my advice.

LeeD said:

I always thought it was a KNOWN fact that players with good strokes almost always hit harder with more flexible rackets, because when they use stiff rackets like PureDrives, the ball goes OUT OUT OUT, so they add more spin or swing more controlled, giving them LESS power.
On a flexi racket, the ball stays IN, so they can swing hard, and the ball goes faster.

Click to expand...

I think one of the reasons that high-level, hardhitting players use flexible racquets is dwell time. The faster the incoming ball and the faster the racquet-head speed the shorter the time the ball is in contact with the strings. Some people find brief dwell time to be good for control, others feel that long dwell time allows them to cradle the ball on the strings and fling it where they want it to go. In order to have long dwell time with really fast swings and incoming balls you either need a flexible racquet, flexible strings, or loose strings, or some combination of those things. I look at a guy like Berdych and it makes sense that he uses a stick with sub-60 flex. If he used a stiff frame he would have little dwell time and might not be able to control his shots.

Of course, he probably grew up playing flexible racquets and developed his technique, timing and feel for the ball with them. If he had grown up with stiff frames he might be comfortable with briefer dwell time and might still be using stiff racquets.

Relinquis said:

nope. chicagojack's posts seem legit.

i don't know what el zed is on about though. i can't see how a properly weighted up APD can magically provide more spin unless it was attributable to one of it's physical characteristics that relates to launch angle or spin, i.e. string pattern, or such.

i don't see how it's comparative stiffness is what allows it more spin or power compared to a more flexible stick (apart from an incremental amount of power at the tip, after adding weight to the stock babolat stick to get it's swing weight in line).

Click to expand...

You might want to check out this thread, which talks about the effect of frame stiffness in varying planes on spin generation: http://tt.tennis-warehouse.com/showthread.php?p=7196196#post7196196

If the hypothesis proposed by travlerajm is correct - that stiffness in the plane of the stringbed is conducive to spin generation - then we would expect the APD, with it's very wide-beamed throat, to be spin-friendly.

I think we, as consumers, don't really understand frame stiffness very well. Racquet manufacturers are looking at stiffness in many planes while all we have is the RDC measurement to go by, which looks only at global stiffness in the plane perpendicular to the stringbed. The manufacturers don't bother to explain to us what they're doing, probably because most of us don't really care. It also may be that all their contrivances with beam stiffness don't add up to much in terms of measurable performance differences. Who knows?

MikeHitsHard93 said:

Roddick hasn't changed a bit. His competition on the other hand has gotten much better and more diverse. His forehand is still the same as it once was, as is his slice bh.

Pros hit with so much spin from high rhs because they are so fit. Depending on how their strokes have developed over time, they choose a racket that compliments their game. Not one that tames it.

Click to expand...

Well, in a recent interview (within the past month) Roddick revealed that he had lost RHS on his serve due to shoulder injuries, which was one of the reasons he chose to retire. If his shoulder affected his serve it definitely affected his forehand too. I think this actually solves the mystery of why Roddick's forehand lost sting from early to late in his career. From these recent comments, I suspect that Roddick may have developed something of a "dead arm." The dreaded dead arm happens to baseball pitchers and usually is a result of damage to the labrum of the shoulder joint. Damage here causes muscular inhibition, and the shoulder muscles are no longer able to contract as forcefully as they once did, resulting in a loss of "snap" and speed.

corners said:

Well, in a recent interview (within the past month) Roddick revealed that he had lost RHS on his serve due to shoulder injuries, which was one of the reasons he chose to retire. If his shoulder affected his serve it definitely affected his forehand too. I think this actually solves the mystery of why Roddick's forehand lost sting from early to late in his career. From these recent comments, I suspect that Roddick may have developed something of a "dead arm." The dreaded dead arm happens to baseball pitchers and usually is a result of damage to the labrum of the shoulder joint. Damage here causes muscular inhibition, and the shoulder muscles are no longer able to contract as forcefully as they once did, resulting in a loss of "snap" and speed.

Click to expand...

I stand corrected. However he DID still stay in the top 20 he will always be my tennis idol.