Discussion in 'Tennis Tips/Instruction' started by boramiNYC, May 1, 2012.
Yes, minus coefficient of restitution.
With all respect, i'll ask again... do you play tennis?
Because if you did you would know that heavier racquets hit more powerful shots (within reasonable limits). It's not even debatable. It's extremely obvious to anyone who's put lead on their racquet.
Yes you cherry pick outliers and say a child can swing faster with a 10oz stick vs a 17oz stick therefore blah blah blah etc etc... but those of us who've actually played with more than one racquet know the deal.
And Jack was probably speaking about light metal racquets in relation to the wood racquets at the time.
I play tennis. Do you know physics? Last time I checked tennis still observes every physical law in the universe, including conservation of momentum.
Your argument may have been satisfactory in Middle Ages, but we have advanced a bit since then.
If we are just talking about what it "feels" to you, then it is a moot point since everyone is correct, including Jack.
But physically and mathmatically, what Jack is saying is true. You can deny it all you want, but it does not change the facts or how this world works.
(With regard to the mass of the ball being too large to ignore):
Some analyses of the influence of mass on the racket-ball impact, along with discussion of the effect on racket speed by decreasing mass, are carried out in:
Cross, R. (2001), Customising a tennis racket by adding weights. Sports Engineering, 4: 1–14.
Cross, R. and Bower, R (2006), Effects of swing-weight on swing speed and racket power. Journal of Sports Sciences, 24(1): 23–30.
You must be living in some alternate universe then. In the universe I'm from, even if I hold the racquet as tightly as I can facing up, and simply drop a ball onto it, the racquet is going to move backwards.
If in your universe the ball will not be able to move the racquet back a single millimeter, then I grant that you are correct, and I'd be playing tennis with a badminton racquet in a cartoon world.
Guys, his whole model is based on the assumption that the ball is insingnificantly light, and that it cannot move the racquet a single millimeter due to our massive body holding on to it. A flawed premise leading to a flawed model.
Every book on the physics of tennis shows a freely suspended racquet, not one clamped to death.
I have 2 pure drives. One a Roddick and one a standard plus. after some slight mods, the Roddick weighs 345 and the Standard weighs 325.
Having spent 9 hours using both I clearly hit a bigger ball with the heavier one, since I wanted to choose between the 2 in terms of what works for me. The 325 gram stick still hits pretty big, but I wanted more depth and heaviness.
So without dropping math and science, I will just use a real world tennis example. Heavier stick hits a heavier ball.
Also, did gameboy really say 1 ounce does not make a difference??"?
Conservation of momentum holds only when there are no non-conserving forces (e.g. friction) in action.
Stiffness is as important as mass. Lighter stiff could be > heavier flexible.
You are right about stiffness.
I think that is why the PDR hits such a massive ball. It is right at 12ozs, which is a nice weight, but it also is stiff AND has the thick beam.
So there are many factors. Very stiff racquets at a lighter weight can hit bigger than their specs, but the lighter you go the less shock is absorbed so you have to be more careful.
FYI, your experience seems logical. But, according to TWU's power comparison tool, the PD+ is more powerful than any of the PD, PDR and PDR+. You can check it out here: http://twu.tennis-warehouse.com/cgi-bin/poweruniverse.cgi
PS: I am referring to the PD GT's, not the latest 2012 models which are not all available on the comparison tool.
Thats why I never can use those tools. I use my own personal experience, and I can assure you that is not the case.
The PD+ is powerful though.
Here is the thing..a standard racquet comes through the air very fast compared to a plus. So even though the PDR is heavier, I can swing it faster..so fast that I added lead at 3 and 9.
So while maybe the PD+ reacts better if you shoot a ball off it's strings or whatever they do..if you are a power hitter and take both of those sticks out to the courts, you will experience what I did. More racquet head speed with the PDR, plus the weight will equal a more powerful ball with more spin and heaviness to it as well.
Yes, it is well-known that when a light body hits a massive body which does not move, it reflects back with the same speed.
What people need to understand is that you have reached your limit how fast you can swing the racquet. But, there are other people who can generate more rhs with your lighter racquet and to them lighter racquet will have more power.
what is the definition of power here? it seems power = velocity from discussions. i also see the word "heavy ball" in a couple posts as well. a faster ball need not be heavy.
for the physics "experts":
why do you limit analysis only to racquet? doesn't the whole arm swing? there is no collision between point masses a la classical physics in a forehand.
fyi, average mass of human arm is 3.2 kgs with 0.4 kg standard deviation. that is 10x a racquet weight. i would think a tennis player's arm is on the heavier side.
now if you think about adding 20-30 gms to racquets (1/100th of the mass of the full apparatus), how much of a difference does it make to the rotator cuff (or/and other joints involved) to produce the difference in velocity we are talking about that presumably comes out of a lighter racquet?
If they swing faster with the lighter racquet, and then I said my PDR swings even faster than that, how would they not generate more power with the 12 oz stick?
I have already said that it is a not a perfectly rigid body.
Let's go the other way. Just hang a racquet by a string and throw a ball at it. Then do the same thing while you are holding the racquet. Tell me which moves more.
Just because it is not a perfectly rigid body does not negate the fact that your body weight factors into the equation, and even if fraction of your weight is a factor, it is much larger than a 2 oz tennis ball.
I just went out and hit balls with Pure Drive and Pure Drive Lite. I hit bigger balls with Pure Drive Lite. Hence, light racquet produces heavier ball.
We can do this all day, if you want to just go by anecdotal evidence...
There is no way to refute your contention or mine if we are just going by feel. If you feel more powerful with heavier racquets, then well, good for you. The conservation of momentum does not care about how you feel.
The difference in stock power potential is only 41.5% vs 40.4%, whereas Power Player has also stated that he modified the Roddick with about 10 g extra weight over stock (without indicating where the lead was placed), which could increase the swing weight by more than 10%. So, there is actually nothing inconsistent between the TWU tool and his experience playing with the racquets.
Thank you Olliess! I don't know how I missed the last one.
The last paper you cite lays it out pretty clearly:
When swinging with maximum effort, swing speed (V) was found to decrease as swing-weight (Io) increased
He also found out that weight does not matter that much when it comes to impacting power (once you go above 200 gram swing weight).
The elementary calculations presented above show that changes in racket mass or bat mass have only a small effect on the power of these implements.
If you combine these conclusions, for the maximum power, you want racquet with lighter swing weight where you can generate maximum swing speed.
There is a caveat, however, as they also find that swing speed doesn't increase in exact proportion to decreases in swing weight.
is "lighter racquet -> higher swing speed" a proven result or an assumption?
sorry, with all the higher math i did, i always get such silly questions in my mind.
what i have observed is that (note the "I") with heavier raquet it is not so much about compromise in swing speed as sloppy footwork because cumulative tiredness. i can swing my kps as fast as i can swing my apd in the tail end of a second set. but i am swinging usually at the wrong place in the case of former. my shanks ricochet at phenomenal speeds, so there is no question of loss of power (so i can perceive the swing speed).
which is greater limiting factor : your rotator cuff or the racquet mass?
the pointmass collision math is useful but is only a half truth.
In that case, I refer you back to your formula,
(m1 * v1) + (m2 * v2) = (m1 * u1<speed after collision>) + (m2 * u2)
Since you agree the racquet does move back, it moves back with a speed.
You cannot then pretend that v1 =u1. Every model in Rod Cross's book shows the racquet slowing down after impact. I refer you to page 106, chapter 10 in The Physics and Technology of Tennis. If you do not have access to the book I'll see if I can scan the diagrams.
If we do your own equation properly with your own admission now that the racquet does move back on impact, then a lighter racquet moves back faster on impact, leading to a slower ball.
(m1 * 0 <stationary racquet>) + (m2 * v2) = (m1 * u1) + (m2 * u2)
=> m2 * v2 = (m1 * u1) + (m2 * u2)
The larger m1 is, the closer u2 approximates v2 in the opposite direction.
Therefore, the heavier the racquet, the more powerful it is as the velocity of the racquet approximates zero.
Enough physics for you?
Ok well this thread is ridiculous at this point. If you want to think that way, go for it. I don't care because I know what works for me and I know heavier racquets hit bigger. you also said one ounce does not make a difference at all, and that is just silliness.
Also, I modified both the standard and the roddick with lead. One was 325 and one was 345. the + actually has a bigger SW in the 330s, while the roddick's is 328.
This is why all this discussion and theory is ridiculous. If I hit a heavier, harder ball with the +, I never would have tried the Roddick. It is subjective, but I assure you I hit bigger with the roddick, or I would have no reason to go with that racquet.
I also modded the + with the same amount of weight.
That is called the intrinsic power of the racket and comes from its mass. It is the power at low speeds. The extrinsic power comes from the stiffness of the racket and the head size (larger head size produces more amplitude of vibration of the string bed). These are basically the 2 sources of power inherent to the frame -i.e., without considering the actual movement of the racket by the player (swingspeed).
When people say that a light stiff big-headed frame gave me a lot of power, they mean that the extrinsic power is greater plus they swung it faster. When people disagree and say that a small-headed heavy flexy frame provides more power, they mean that even though they swing slower, they are benefiting from the intrinsic power. This is the source of many arguments on this forum.
Of course, if everyone could play with a stiff heavy big-head frame and swing it very fast, everyone would have enormous power. But they can't.
There are some very counter-intuitive results - e.g., I believe it was shown once from TWU power diagrams that the K90 has more power than the PD. It is due to the mass overpowering the effect of stiffness and larger head. The Sampras K88 is probably the most powerful frame around. Yet even Sampras does not use it any more.
We are all different!
Maybe for most of TW's posters, heavier rackets hit harder.
Maybe for GameBoy and maybe me, lighter rackets hit harder.
Maybe for most male pros, higher 11's to low 13 hits harder.
Maybe for most rec players, we never face hard balls nor hit hard.
Maybe for most rec players, we should use what we feel confident with and have FUN with......
Maybe for most players, tennis is much more than just hitting hard!
This kind of advice has been given many times and actually means very little. A rec player cannot know what he has fun with and gives him confidence unless he demos a whole lot of frames with identical string setups. A pro player already has a very good idea of what suits him, and he can tinker a little from there - read the thread on Kevin Anderson's frame tinkering for 2 weeks with a little lead here and there.
Rec players have very little idea of what suits them, since they don't play every day or try different frames. They also don't know what fun means. Does it mean that you win? Does it mean that the frame feels good? Can a frame feel good with dead strings? What is confidence? Staying at the same level? Moving up a level?
That is why this advice does not help any rec player.
This is the main thing. A very light racquet that requires a 100% swing at all times is not that practical for many players.
I like to be able to block shots back as well. The heavier racquets have always been much better for this. Why the TWU tool says the + would be better at this, I do not know. even modded with lead the + did not block shots back with the same depth or pace as the Roddick.
Anway..these types of threads pop up all the time with 1 guy saying idiotic stuff about how an ounce does not matter, then people get trolled into it like myself, someone posts a complex math formula and nothing is ever resolved.
You don't have to argue with me, go argue with Prof Cross. He actually did experiments and has data to prove his conclusions (which just happens to be in line with physics - go figure).
If you want to disprove it, you can conduct a scientific experiment yourself. But arguing against actual experimental results with personal belief is not going to get you very far. You might as well argue if God really exists.
Go read the paper yourself:
The conclusion clearly states:
When swinging with maximum effort, swing speed (V) was found to decrease as swing-weight (Io) increased
You don't have to believe it if you choose not to. But it does not change the facts.
I think there is a definite limit of weight of racquet how one's body can handle swing speed. Past that limit the extra weight will slow down the swing speed. If you can generate the same swing speed with a heavier racquet, it means you still haven't reached that limit. You can go heavier and heavier until your body can comfortably handle swing speed and then you can stop. That would be your sweet spot.
PP, you are also changing what started this whole thread - Jack Kramer saying lighter racquet = more power.
That is like saying lighter car = more speed.
But you want to argue about how tire grip, stiffer shocks, and better handling will provide lower lap times. But that is not the question at hand.
Kudos, this statement is accurate I believe.
I think Jack's statement is not the whole truth. It's only true if one was using a racquet weight that's heavier than his optimum. The weight below that optimum, swing speed should be almost the same (by the limit of body) but the power will decrease.
But I think it's important to point out it's also easy to stop improving swing speed when you use the optimum weight. With a lighter than optimum racquet there's a room for improvement in increasing swing speed.
Thus, when there's no need or desire to improve but just enjoy game at the level, optimum racquet would be wise, but when one is looking for improvement in their physical ability to swing faster, a lighter than optimum is better.
Not all rec players are beginners who have played tennis for only a few years.
Some of us are beginners who have played for over 37 years! After 37 years, I tend to know whether a racket is too light or too heavy. It's called the lesson of EXPERIENCE!
And not every tennis player, rec or otherwise, is in RafaelNadal's shape, and conditioning....or inclination.
...I do a lot of postings in the Epic Ski forum, and I see a lot of the same kind of stuff, where somebody tries to make Platonic form for some aspect of skiing, and a bunch of people support it, and a bunch of people argue with it, and it sort of goes nowhere.
I haven't seen the ad referenced in the original post, but I'd kind of like to see the context of that. I wouldn't be at all surprised if what he said, or was thinking, was something along the lines of "We used to play with heavy wood rackets, and we thought they had a ton of power, until this innovator Lacoste came along with his steel racket, and Connors picked it up, and wuddenya know it? Connors started generating more power?"
Forgetting about whether "lighter" actually equates to "more power" for a minute, one thing this thread got into, again as a tennis Platonic form, is "With lighter rackets, of course everyone can swing faster." Not necessarily true, at least effectively so. If someone is really weak, "swinging faster" might actually happen, but the increase in racket speed might be so negligible that it doesn't make any real difference in ball speed, heaviness, whatever.
We should also realize that not everyone actually "swings" at the ball. There's a whole world of 3.0/3.5 players who either take a huge backswing, or no backswing...but as soon as they contact the ball, game over. There is no follow-through, they don't complete the stroke, there is no real "swinging", so all they are doing is "paddling" the ball, so lighter isn't going to make any difference in ball speed or heaviness.
The racket manufacturers know this, and they (the racket manufacturers) aren't stupid. They know that their target market is the 3.0/3.5 crowd, which is why you have seen rackets getting lighter and the technology (head size, and so forth) doing what it can to produce more power. Lighter means easier to manipulate, which is great for players who are perpetually late with their preparation and/or have less than ideal swing paths. And you can see all the claims that racket makers make for more power. Whether or not any of these claims are true, they sell rackets.
It's very similar for "heavy rackets produce more power." Sure, if you can swing the racket, you're likely to get more power. If you can't, as above, then heavier is going to make a negligible difference, if any.
As LeeD points out, even if your stroke mechanics are decent, there probably isn't any Platonic form for racket weight, because, as he points out, if there were, we'd all be playing with the same weight racket, and that's not the case. Even among the pros, it's not consistent. Just to take one aspect of rackets that may or may not affect power, head size, Del Potro, Djokovich, and Nadal were fairly early adopters of bigger head size, while Federer was not. They all play pretty well, and, despite what some people might believe, they're all pretty competitive with each other and with the rest of the crowd...
Provided you have tried many rackets. Many rec players do not try many rackets, nor do they try any for an extended period of time with the same string setup. Nor do they try them in a small enough period to be able to remember the results from one to the other in an accurate manner.
There are many rec players who play horribly even after 40 years, so time does not equate to experience or skill in their case. Heck, that is true in most jobs too. Younger people fresh out of school are often far better than the experienced ones.
Yes. I have a degree in physics and I'm an engineer. As i said earlier it obvious to anyone who's added lead to their racquet. and no it's not 'feel'.
Maybe you should change to a 7 ounce racquet (200 grams). With all the power you'd get you could turn pro.
"some of us beginners have played 37 years".....
With the racket section showing some players of 5 years have tried over 30 rackets, you'd think......
Some people change their car every 6 months on a whim. Doesn't mean they are F1 or Nascar drivers. It is just something they do if they have money. Some people try a new restaurant every week. Some people get married 8 times.
Hey, I try a new restaurant about every week!
Talking CHEAP restaurant, but still......
My first 3 years of tennis, went from StanSmiths to Kramers, to ProStaffs, a brief flirt with MaxPlys, then to HeadPro and finally to YonexGreens.
oh boy, another lite vs heavy thread. These are always so civil.
I took my stock 11 oz racket with SW 313 and customized with lead tape to make it 12.1 oz racket with SW 334. TW University show the power rating for the center area improved 5.1% and power rating off-center (3 and 9 o'clock) improved 12.2%. There's the scientific proof.
Of course, I play test too. And the heavier racket is a way better for power and stability. It is a no brainer to me. Power zone is bigger according to TW University tools and according to my play test too. I added over an oz of static weight and 20 grams of SW and it did not slow my swing down. The final result with the heavy racket is way way way improved - not even close decision.
So, by adding weight; I have a more powerful, more stable racket with a bigger power zone (sweet zone).
To those that think really lite rackets have more power; then why don't pros play with lite rackets? ATP and WTA players play racket 10-30% phatter than the stock stuff most of us play with. Granted, they are in better shape but they also know that phat is good when it comes to hitting a tennis ball.
My only hesitation is there is a heavy threshold where if we go over the threshold, then it will negatively impact swing speed and the players endurance. I am 55 yo but in reasonably good shape. I have no problem with swing speed or fratigue and have been playing rackets in the 12 - 12.5 oz range and SW 330-340 for many years now.
My personal belief is even if your swing speed begins to slow a little as you age, a heavy racket is a better choice because as long as you accel thru the contact zone a heavy racket will have pop.
Of course, it takes all types to make a world and have debate. Some players don't care about improving and playing better and just want to have fun playing tennis. In that case, play a light racket if it feels good to you. Juniors, very senior, and very small adults may want to go lighter too.
But, my forecast tennis rackets at the high levels will continue to have swing weight between 330-400 grams even 30 years into the future unless they change the dimensions of the courts or the weight/size of the ball. Phat = good for rackets. In fact, if athletes continue to get bigger and stronger, I predict average pro SW will go up and not down.
Can't extrapolate that easily. Nadal plays with a lighter racket than you (though it has a higher SW). Who do you think hits a heavier ball?
Pros also need a heavier frame for the return of serve. In fact, I would say that their racket weight is strongly biased by that. Rec players don't face such serves.
So much complicated physics.
This is how it just works in the real world..
Depending on a players strength and heft - they can swing various weight racquets at various speeds. Quite obviously you can swing a lighter racquet faster then a heavier one.
However there is racquet weight where for an individual you can swing it almost as fast as a significantly lighter one. This racquet will produce more power.
This is why IMHO big guys should often use heavier racquets. They can swing them nearly as fast as lighter ones and will generate more power..
FWIW it should be fairly obvious - no physics degree required that you get to a point where lighter racquets impart significantly less power - like when the racquet weighs the same amount as the ball....haha.
In short - find the heaviest racquet you can swing fast. I will add though that for bad players a very light racquet can allow them to generate some swingspeed being set up poorly.. So these people won't want to switch even if they are strong enough..
This doesn't add up...
...meaning I don't see how "Nadal plays with a lighter racket than you" fits with "Pros also need a heavier frame for the return of serve." See what I said in post #83. You can go through all the discussions you want, and all the physics having to do with swing weights, swing speeds, and so forth, and none of it will ever be able to produce a universal rule, or even a set of rules, for racket weight. Players succeed...or fail...with all kinds of combinations of rackets, strings, and so forth. The racket you pick matters to you; the racket I pick matters to me. Maybe I pick the wrong one, maybe you pick the right one, maybe we both lose. But I get to pick mine, and you get to pick yours, and there isn't any real reason why we might choose differently. My hitting partner and I both hit pretty heavy, in terms of shot weight. He uses a leaded up Head Youtek IG Speed, Djokovich's racket, which is pretty weighty to start with. I use a Head IG Speed Lite, which is pretty light, with just a little lead at the bottom of the frame. Which of us is right? Answer: we both are, which is something the racket manufacturers know. Go out and look at Head's lineup, for example. You can get any weight, any balance, different constructions, anything you want.
The racket manufacturers know this, and they also know that a specific racket can work well for a multitude of levels of players, stroke paths, and so forth. Djokovich is what, according to NTRP? A 7.0? So a racket that's appropriate for him shouldn't work at all for anyone else, but it works just fine for my hitting partner, who ain't even close to being a 7.0...
I doubt that there is an ATP pro below 12 oz or 330 SW, so I don't think everything works for them.
Your hitting partner is not hitting with Djokovic's frame, BTW. His is a custom layout.
...I'm just trying to point out that 2 plus 2 doesn't equal 5. I'm not the one who said "Nadal plays with a lighter racket than you", you did.
Okay, so my hitting partner isn't playing with Djoko's racket, exactly. That wasn't really my point. He plays with a heavy stick, I play with a relatively light one. We both hit a heavy ball. Who's right? Answer: We both are...
Finally we're on the same page. I have Rod Cross's book and I even referred to a chapter from it earlier. Here you say it yourself:
When swinging with maximum effort, swing speed (V) was found to decrease as swing-weight (Io) increased
Now I ask you, do you swing at maximum effort for every single stroke when you play tennis? This is why I kept talking about volleys. You want to talk physics, then be specific and quantify your statement.
Lighter racquets are more powerful when swinging at maximum effort.
Heavier/lighter racquets are sometimes (this is when you pull out your equations and check the racquet head speed to mass ratio) more powerful when not swinging at maximum effort.
Heavier racquets are more powerful on strokes with low racquet head speeds.
I believe everyone (or at least, most of us) would be in agreement with this yes?
Why stir the pot with a vague "Lighter racquets are more powerful, period" kind of statement. That's simply not what Rod Cross, who you just quoted, said.
And to end the debate right now, pros rarely swing with maximum effort during a match at all. Ideally they are at 70-80%.
I would play with a badminton racquet if I thought it would help...
there is an ideal weight that combines sufficient mass to be able to return serve or volley with a sufficiently low swing weight to allow a 'maximum effort' groundstroke.
not everyone plays the same, or faces the same opposition. I could not return serves at my level with a 10 oz racquet any more than I could serve myself with a 14oz racquet, hence my use of a 12 oz racquet.
your mileage may vary.
Because it is true. When you compare a car and see which car is more powerful, you don't measure that when the gas pedal is half way down. You measure it when it is at maximum output. And that is exactly what Prof Cross states as well.
The OP that started this whole thread was about whether or not what Jack Kramer said is correct. And it is because you can swing the racquet faster with a lighter racquet (with maximum effort).
Sure, Prof Cross' table shows that heavier racquet can produce more ball velocity when swinging at the same speed as the lighter racquet (because you are spending more total energy), but it is not a given (it peaks around 350 gram swingweight then decreases from there).
But that was not what Jack was saying.
"Lighter racquet is more powerful. Period." is not vague. It is the truth. Just like a lighter car is going to have a higher top end speed than a heavier car (with all other things being equal). It is certainly less vague than saying "heavier racquet is more powerful".
I agree with gameboy, but I don't think Kramer was thinking this much. I think he meant what most old timers say when they say that modern rackets are lighter and more powerful - the extrinsic power due to stiffness and larger head. They are not comparing apples to apples, but a PS85 to a PD, and noticing that if they feed the ball casually with each one, the PD will send the ball further. In the rackets section, you will repeatedly hear that someone switched from a heavy frame to a lighter one, and the ball flew out. They are not really talking about how heavy the resulting ball is.
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