Recoil Weight

[saleem]

I added a text box for Recoil Wgt to the data input form I use for recording wgt, bal, and swg wgt in my database and have been watching it with interest especially for customers who have arm issues. One of my customers, a 3.0 female has an interesting history. She was using a Prince Ozone 7 when she first started stringing with me. She got it into her head that she needed something smaller and bought a Prince Exo3 White Lite 100. That gave her tennis elbow. We tried to modify it but she gave up on it and eventually playtested and bought a Pure Strike 100 which is what she is using now and her arm problem seems to be behind her.

The recoil weight on these racquets:
Ozone 7 = 146
White Lite = 144
Pure Strike = 145

The flex ratings of the 3 racquets:
Ozone 7 =74
White Lite = 65
Pure Strike = 65

I'm not sure what to conclude from this. I was surprised to see how close the recoil weights were considering how problematic the White Lite was for her.

it might have something to do with the balance
The balancet on these racquets:
Ozone 7 = 13.0 in / 33.0 cm HL even balance
White Lite = 4 points head heavy
Pure Strike = 5 pts HL

pure strike should be the most comfrotable with low RA and 5 points HL

 

[zalive]

I added a text box for Recoil Wgt to the data input form I use for recording wgt, bal, and swg wgt in my database and have been watching it with interest especially for customers who have arm issues. One of my customers, a 3.0 female has an interesting history. She was using a Prince Ozone 7 when she first started stringing with me. She got it into her head that she needed something smaller and bought a Prince Exo3 White Lite 100. That gave her tennis elbow. We tried to modify it but she gave up on it and eventually playtested and bought a Pure Strike 100 which is what she is using now and her arm problem seems to be behind her.

The recoil weight on these racquets:
Ozone 7 = 146
White Lite = 144
Pure Strike = 145

The flex ratings of the 3 racquets:
Ozone 7 =74
White Lite = 65
Pure Strike = 65

I'm not sure what to conclude from this. I was surprised to see how close the recoil weights were considering how problematic the White Lite was for her.

In the meantime from when this thread was created, I tried lately to as closely observe the hitting sensation which different racquets had on my arm, to try to determine what I feel differently.

So, for the sake of comparison, let's say that these racquets have lot of similar (I didn't check whether it's actually true): they have similar head size and they are strung with same strings at same tensions. So string bed stiffness should be about the same - this is important because string bed stiffness makes a difference, and head size, string type and tensions influence it (there's more but those are most important influences).

So let's say RW's on each is approximately the same - it seems it's really so from the numbers you have provided.

Where's then the difference? In the layup itself. And the difference is how a racquet layup reacts to a sudden collision with the ball - and it does not necessarily need to be the same as what RA tells, because it's a dynamic situation while flex measured in RA is a static measurement, hence different situation to a realistic collison. Where different layups may react differently (and they really do).

Anyway, my observation tells me that with really similar specs and with similar or identical string beds, some layups directly transfer a short, quick, harsh impulse of shock directly to your arm, while some else seem to make it milder by taking the shock on themselves - because you feel nothing similar harsh. Your arm directly tells you whether it received an unpleasant impulse of direct shock or not (and how much of it). You just have to observe it.

Anyway, conclusion was that with all other parameters being close - SW, RW, strings, tensions, head size - it's the layup itself that makes a pretty big, significant difference. And that certain layups, in combo with poly strings, are really best to avoid, even if you put a lot of mass on them, keep tensions low etc...just because of caution.

Any specs you might read won't tell you how good or bad a layup is for the arm. But it seems to be true that flexier racquets are generally better - though RA is not the true measurements. I play with Pro Kennex racquets occasionaly which have high RA, which have a stiff performance on the court, and which layup doesn't produce anything nearly as unpleasant as what I felt with some even much flexier racquets.

For me this became pretty important, I try to avoid any racquet with a layup that transfers shock more noticeably to the arm - I get rid of such. And while I find RW as important spec, for me it's not all that matters in a frame - I think layup is at least as much, if even not more important. But even when layup is fine, I still additionally customize the racquet to make it even more arm friendly. But usually I find if layup is good, then RW of 165-170 is tipically fine to me. I would perhaps gladly put even more but it's hard in respect to other important aspects for customization, such as MgR/I, or keeping the total static weight reasonable.

 

[zalive]

For me, good example of difference between good and a tricky layup is the difference in hitting sensation between Ti Radical MP and i.Radical MP.

Their specs are pretty much similar, even their RA flex is about the same or similar. But i.Radical transfers unpleasant impulse of shock to the arm and it does not feel quite harmless. While Ti Radical has completely nice and soft feeling sensaton when you hit with it. Comparison was done with their specs close and with the same string bed.

 

[10shoe]

I play with Pro Kennex racquets occasionaly which have high RH

I've been playing for about a year with a KI 15 PSE. I believe I felt exactly what you are describing from the first hit. A noticeable lack of harshness and shock. But what is "RH"?

 

[zalive]

I've been playing for about a year with a KI 15 PSE. I believe I felt exactly what you are describing from the first hit. A noticeable lack of harshness and shock. But what is "RH"?

Sorry and thanks, typo, corrected, it was supposed to be RA

 

[travlerajm]

Two racquets can have very different mass distributions while still having identical RA rating, Mass, Balance, Swingweight, and Twistweight.

This will affect the feel quite a bit. You can tune the feel and vibration profile of a frame by adjusting the lead tape distribution without affecting the mass, balance, and swingweight.

For example, you can start with an 11-oz frame, then customize it to 13 oz by adding mass in two places (3-and-9 and at the butt, for example). You could also reach identical specs (mass, bal, SW, MgR/I, recoil, etc) by placing the same total combined added weight at a different pair of locations (12 o'clock and at top of handle).
Even though the measured specs are identical, the first weighting approach will feel more flexible than the second, because the added handle mass in the second case will be between the primary vibration nodes, which shifts the nodes closer together and reduces the vibration amplitude.

Also, how much vibration is felt at the hand depends mostly on the location of the handle vibration mode. If the node is under the hand, the racquet will feel vibration-free and comfortable, even if it is stiff in some cases. If the hand is located at a spot on the frame where the vibration amplitude is high, the impact won't feel very good. You can move the node location around by shifting the location of the added mass.

Bottom line is that variation in mass distribution is the main underlying cause of differences in feel.

 

[Irvin]

@travlerajm you can redistribute mass without changing mass, balance, or SW? Better rethink that.

EDIT: If you put 10 g at 32 cm (balance point) your I (SW at 0 cm) goes up 10.24 points. If you split the weight and put 5 g at 17.78 cm (7") and 46.22 cm (3&9) you I (Inertia at 0 cm) goes up 12.26. And if you split the weight and place it at the poles I (Inertia at 0 cm) will go up even more (20.48.) RW also changes and if the balance and mass are the same and RW changes so does SW. And if I changes so does MgR/I.

EDIT: if mass and balance remain the same and you move weight farther apart I goes up and MgR/I goes down. If the weight is moved closer together MgR/I goes up.

 

[travlerajm]

@travlerajm you can redistribute mass without changing mass, balance, or SW? Better rethink that.

Just knowing the mass, balance, and swingweight does not fully specify the mass distribution. There are infinite mass distributions that satisfy all three specs.

I sometimes use this added degree of freedom to tune the flex / vibration characteristics (i.e., the impact dynamics) of my racquet after first tuning the swingweight, balance, and MgR/I (i.e., the swing dynamics). In this way, I can decouple the swing dynamics and impact dynamics in order to tune each of these independently.

 

[Nicholas Kakatsis]

Two racquets can have very different mass distributions while still having identical RA rating, Mass, Balance, Swingweight, and Twistweight.

This will affect the feel quite a bit. You can tune the feel and vibration profile of a frame by adjusting the lead tape distribution without affecting the mass, balance, and swingweight.

For example, you can start with an 11-oz frame, then customize it to 13 oz by adding mass in two places (3-and-9 and at the butt, for example). You could also reach identical specs (mass, bal, SW, MgR/I, recoil, etc) by placing the same total combined added weight at a different pair of locations (12 o'clock and at top of handle).
Even though the measured specs are identical, the first weighting approach will feel more flexible than the second, because the added handle mass in the second case will be between the primary vibration nodes, which shifts the nodes closer together and reduces the vibration amplitude.

Also, how much vibration is felt at the hand depends mostly on the location of the handle vibration mode. If the node is under the hand, the racquet will feel vibration-free and comfortable, even if it is stiff in some cases. If the hand is located at a spot on the frame where the vibration amplitude is high, the impact won't feel very good. You can move the node location around by shifting the location of the added mass.

Bottom line is that variation in mass distribution is the main underlying cause of differences in feel.

The above analysis, is it fair to assume ti has an effect on trying to minimize probabilities of tennis/golfer elbow from stiff strings, setup etc?

Apologies if the question is wrong, moving the mass in butt and 3&9 will allow a more flex feel and therefore easier to the arm? And I mean truly easier for the arm and not just a perception of more flex

 

[10shoe]

Just knowing the mass, balance, and swingweight does not fully specify the mass distribution. There are infinite mass distributions that satisfy all three specs.

I sometimes use this added degree of freedom to tune the flex / vibration characteristics (i.e., the impact dynamics) of my racquet after first tuning the swingweight, balance, and MgR/I (i.e., the swing dynamics). In this way, I can decouple the swing dynamics and impact dynamics in order to tune each of these independently.

I notice you are playing with a 26.5" racquet. Did you reduce the length of the handle or is this what happens naturally when you string the mains 50 lbs tighter than the crosses?

 

[travlerajm]

The racquets I have been using for the last few years are mostly mid plus head size frames shortened by 1/4". The extreme differential tension stringing method shortens the frame up to an additional 3/16", but the hoop squashing effect is completely reversible, as the frame springs back when strings are removed.

 

[Doppelganger]

The magic happens from the moment of impact to the moment that the ball takes off the strings. Maximum speed for minimum effort at the ball impact... and then NO accelaration through the contact... with the "right" stick (which means that the stick hits the ball... and not you... which means that the stick has to plow in a way that its inertia is optimum for your game)... This is what we call (or should) call pocketing, and practically this is the art of Federer, Cilic, etc... they hit the ball faster, but the ball stays in the strings longer... and the maths reveal clearly that you can not optimize it by accelarating through! Cheers

Interesting information here. It is my understanding that strings and tension can also affect this "pocketing" to a degree. I had a HEAD racquet that had great pocketing, but ultimately I moved on from that to a couple of Donnay's that also feature good pocketing, but perhaps not quite as nice as the HEAD. I have noticed that with lower string tension, I get a bit more of that sensation and I've been toying around with it. Right now I'm in a hybrid with 54 on the mains and 57 on the cross, but I was thinking of going lower...

 

[Shroud]

The magic happens from the moment of impact to the moment that the ball takes off the strings. Maximum speed for minimum effort at the ball impact... and then NO accelaration through the contact... with the "right" stick (which means that the stick hits the ball... and not you... which means that the stick has to plow in a way that its inertia is optimum for your game)... This is what we call (or should) call pocketing, and practically this is the art of Federer, Cilic, etc... they hit the ball faster, but the ball stays in the strings longer... and the maths reveal clearly that you can not optimize it by accelarating through! Cheers

Hmm. Not sure what you are saying. Ball pocketing is a product of the stringbed stiffness and the swing weight mostly. Not sure i see the relation to MgR/I. What proof do you have that balls stay on the strings longer and by how much?

Personally at my tensions with my kev/poly set up and stiff racquets i dont get much if any pocketing and like it that way.

 

[Shroud]

Interesting information here. It is my understanding that strings and tension can also affect this "pocketing" to a degree. I had a HEAD racquet that had great pocketing, but ultimately I moved on from that to a couple of Donnay's that also feature good pocketing, but perhaps not quite as nice as the HEAD. I have noticed that with lower string tension, I get a bit more of that sensation and I've been toying around with it. Right now I'm in a hybrid with 57 on the mains and 54 on the cross, but I was thinking of going lower...

Best pocketing ever is open pattern at 15 lbs.

 

[Doppelganger]

^ lol. Well at 16x19 all I have to do is string up my racquet by hand and I'll probably be around that number

 

[Shroud]

Doppelganger and Shroud

Ball pocketing is primarily a result of "how" you hit the ball, and it can happen even with with a padel racket!

The strings affect, the tension affects (although there is an optimum, lower is not necessarily better, too many factors affect), but it is you and your game that creates it, not the racket.

All I can say is that it practically works simply because is winning grand slams (this way of hitting among other things)...
The maths are really simple, just applying them where it matters, and then theory explains the beauty of the optimum shot. And the magic is revealed, it is so simple that it blows your mind, and it took me few years to understand it!

Read my sentence again, and go apply it on court
Just do not try accelarating through the contatc...
Obviously you should not de-accelarating!

After all what is "wrist lag"? What is effortless swing? What is exhaling at the impact? They all serve this amazing 1 purpose...

You sound like collotennis. He was a poster that claimed one could absorb the ball and influence dwell time by acting on the ball DURING impact. Guy was delusional!

Imho you cant affect dwell time with technique. And if you could why would you? Its a big variable and an ever changing one so it just adds more difficulty.

And how can you NOT accellerate through contact? Ex. Every fh vid i use to post had feed back along the lines of "you are accelerating too fast in the beginning" or "start your swing slowly and accellerate later", etc.

And what about other shots? Not all shots have wrist lag.

And fwiw i had lessons with a world renown coach on my fh and he never talked about maximizing dwell time and afaik doesnt think you can. So i have the hardest of times with this notion. And certainly cant pull it off. And even if i could do the technique (funny how no one can explain it) my stringbed has little ball pocketing...

 

[zalive]

@Admaris
To be able to not accelerate through the contact, one must do the job prior to contact. Players who don't accelerate through the contact reached huge RHS prior to contact, so they don't need to accelerate through the contact. Isn't this the secret of pocketing, huge RHS, rather than not accelerating through the contact?

 

[zalive]

And since this is a thread about Recoil Weight I have a question:

We measure the Recoil Weight by assuming that the racket is static, assuming that it is hold STATICALLY from the grip, and there is coolition with an incoming ball. Or no?

But when the racket swings quick is this the case? Does this static RW number really works THE SAME WAY when our fast moving racket has a coalition with the ball, relevant or irrelevant to if we hold our racket strong or soft?

RW is inertia of racquet rotating around its COM. If anyone wanted to measure it, the way for this would be to measure the COM (balance point), then tighten (or hang) the racquet at its COM and then perform SW measurement. But it is calculated from SW (and the rest of measured specs) rather than measured directly.

The relevance of RW is in the fact that whenever ball and racquet collide, a tendency to rotate the racquet around its COM is created. RW being an inertia relevant to (tendency for) rotation of racquet around its COM is opposing the forces which try to rotate it.

 

[Irvin]

RW is inertia of racquet rotating around its COM. If anyone wanted to measure it, the way for this would be to measure the COM (balance point), then tighten (or hang) the racquet at its COM and then perform SW measurement. But it is calculated from SW (and the rest of measured specs) rather than measured directly.

The relevance of RW is in the fact that whenever ball and racquet collide, a tendency to rotate the racquet around its COM is created. RW being an inertia relevant to (tendency for) rotation of racquet around its COM is opposing the forces which try to rotate it.

That cannot be done if the racket is hung from the center of mass it will not spin. You're going to have to use a bi-polar or tri-polar pendulum to measure the inertia around the center of mass. But if you wanted to calculate SW you could hang the racket from any point other than the COM and then use the parallel axis theorem to calculate the inertia at the center of mass.

 

[zalive]

That cannot be done if the racket is hung from the center of mass it will not spin. You're going to have to use a bi-polar or tri-polar pendulum to measure the inertia around the center of mass. But if you wanted to calculate SW you could hang the racket from any point other than the COM and then use the parallel axis theorem to calculate the inertia at the center of mass.

You're absolutely right Irvin, as usual

 

[Outliar]

I never completely understood recoil weight tbh, something just didnt sit right with the equation that the higher the SW the higher the recoil weight and therefore the higher the comfort. So would it be more comfortable then to wield a 400SW racquet compared to a 350SW racquet? And likewise a 450SW racquet compared to a 400SW racquet?

Doesn't make sense to me.

 

[zalive]

The idea beneath higher RW is following: if you crashed against the car, would you fare better if you were driving another car, or a truck?
There's a collision of a racquet and a ball, through the string bed. Any you want racquet to feel the collision least possible.
RW in a rotational physics is nothing but equivalent of a mass. Mass is inertia in linear movement. RW is relevant inertia in rotational movement.
But to really reach absolutely better comfort, one prerequisite must be met: you must not lose RHS to a degree where momentum of a racquet decreases.
If momentum increases, comfort gets better, with everything else being the same.
To ensure you don't lose too much on RHS, MgR/I physics is important, and understanding that certain values of MgR/I allow easier and faster RHS than the others, with the same given SW.
In a practical sense this means that racquets can be customized to swing with least effort and allowing the best possible RHS for their given SW.

 

[zalive]

Actually my opinion is that in a stroke and collision with the ball both RW and SW play the role together with the RHS, with the double (if not triple) pendulum significance (for which SW and RHS are important), as well as the tendency to rotate around the COM (for which RW is important). If this is true then SW has a double role and significance, both as a generator of kinetic energy and as a contributor to a higher RW.

 

[zalive]

Yes, but RW as measured does not provide realistic enough info (?), simply because the racket is not static when the incoming ball colliding to the ball, but there is a moving object (racket) with "huge" momentum (and much bigger momentum than this of the ball - which affects the collition result) and this racket does not even has constant distribution of mass, and does not even moving with the string pattern perpedincular to the direction of the ball.

As a result the tendency for rotation of racquet around its COM is different in theory according to how we define RW in comparison to reality (how we hit the ball) ?


This is why if for example we have
Shot A squizing at 100% and
Shot B squizing at 0.1%

RW would mean a lot (regarding the ball outcome) if our racket speed has 0 velocity (just holding the racket static)
but does not explain much when our racket has huge velocity (primarily to ball outcome, but also - in some degree - to ball income > feeling)?

You must understand that when rotational movement is considered, RW is nothing but a mass. Static as static can be.
You keep telling that RW is 'as measured', but it's not measured in reality. It's calculated by using measured values of SW, weight (mass) and balance point.
Yet since it's calculated by using the exact physics formula and measured values, it's as good as measured.

Now. You mention the relevance of RW when hitting the ball with certain RHS. There's nevertheless a tendency to rotate the racquet around its COM after the collision.
If there was no such tendency, there would be no the (recoil) shock which pulls the arm and causes arm injuries.

 

[zalive]

Thank you for your answer, and clarifications. Also many thanks for your patience (because I have to use google translator).

I agree about calculated instead of measured, and since SW is within the formula it has a role as contributor to RW, too.

You have actually replied to my post, and my "concern" with your #377 post which I did not read while posting my previous one. For the reasons that you explain in 337, I also practically praise the role of SW during each shot (and I see a multi pendulum - not double) and not that much of the RW (exception volleys).

No problem Admaris, translate works pretty well
Observe. Put some significant mass at the butt (easiest way: stick a chunk of putty at the butt cap), hit the ball, then observe that you actually gained noticeably on power, while SW was practically intact.
Then you'll understand the role of RW when you do swing the racquet.
Don't believe or not believe. Observe.

 

[zalive]

and not that much of the RW (exception volleys).

Rotation of a racquet is complex. This is why a double pendulum model is used to describe the swing.
But what happens at the moment and after the collision with the ball?
Racquet will slow down. It's inevitable.
What causes the injury? After the collision, racquet handle side will tend to pull your arm in front of you, because collision created the tendency for the head side to go back. Naturally the other pole of the racquet will follow (more or less - it depends on dynamic flex as it changes the geometry of a racquet).

Now you can say, how's this possible, this is not happening, racquet head still goes forward/to the side, it didn't stop, it never went back.
This is because motion of a racquet is complex. Rotation around COM is superponed to racquet's movement dictated by the swing. Racquet can simultaneously rotate around more than one center of rotation.
Besides, rotation around COM may even not happen. Because hand/arm holding the handle stopped rotation around the COM to happen. But arm suffered the moment of force which caused shock to the arm, because arm stops the rotation of racquet around its COM.

COM is here racquet's center of mass, I reckon you understand this abbreviation?

 

[zalive]

I believe because I have observed it. But it is not the RW that has created the power (primarily). It is the increased mass, which means increased momentum, which means increased power, which means increased damage to the ball! Or no?

Mass directly is completely meaningless in a rotational movement.
And when racquet is concerned, everything is rotational. Because whatever happens during the swing, prior to colision and after it, is rotation. No linear movement!
Even if swing was completely linear (which is not), what happens after racquet collides with the string bed is again rotational movement (or tendency to rotational movement if something holds it from happening).
Mass has no direct meaning in rotation...but rotational inertias cannot happen without a mass

 

[Irvin]

I never completely understood recoil weight tbh, something just didnt sit right with the equation that the higher the SW the higher the recoil weight and therefore the higher the comfort. So would it be more comfortable then to wield a 400SW racquet compared to a 350SW racquet? And likewise a 450SW racquet compared to a 400SW racquet?

Doesn't make sense to me.

Welcome to the club I think 85% is BS. But let me see if I can try to explain. Imagine if you can a 10' pvc pipe and you're trying to swing it like a tennis racket. It would be very hard to swing because the center of mass is 5' from your hand and in addition to that some points are 5' from the center of mass creating a large inertia value. Now imagine another pvc pipe with the same weight but only 1' long. It will be much easier to swing because the COM is only a few inches from your hand and the inertia is much lower because all points (except for those at the COM) are much closer to the COM.

Now let's compare 2 rackets, one with a 320 mm balance point RW of 160 and mass of 341 g. The other has a balance of 320 mm, SW of 325 and mass of 341. Which one is easier to swing? They are both the same.

SW = RW + (mass x distance x distance) where the distance is the measure from 10 cm SW pivot to COM

325 = 160 + (.341 x 22 x 22)

RW is the inertia around the center of mass. SW is inertia around some other pivot point. You can convert from the COM inertia to any other point by using the Parallel axis theorm.

So your question how can a SW of 400 or 450 be more comfortable? Try swinging one for a couple of hours and ask me that. But on the other hand if you swing a stick like that when it hits the ball due to it massive inertia there will be less shock to your arm.

 

[zalive]

I understand you 100%. And what happens if at the point of contact you release the racket from your arm?

If you release the arm racquet handle will fall out of your hand, we've seen videos of this happening. Handle tends to go forward upon the impact of the ball. This is a pure demonstration of rotation around racquet's COM.

You will get no injury. The RW will be there. It is not the RW that created damage to the ball. It is the momentum of the racket (even if you do not hold it). I highlight the ball outcome, you highlight what happens to the racket.

I guess you want to say that with a looser grip and loosening of your arm you actually feel less shock. Which is I believe true. You actually let racquet pull set your arm in motion instead of putting force to stop this rotation motion. But shock still happens to a degree. We see some of best ATP players (like Novak or Kei currently) suffer shock arm traumas no matter what racquet they use.

Nevertheless, if we squiz the racket the collition effect, including the recoil of the racket will create a frequency that will travel through our nerves, etc etc. But it is still the high momentum of the racket that primarily protected us, and less the RW (which also contributes).

From observation standpoint of view, I personally feel better comfort with my custom setups. But crucial for me was learning how to customize them to make them fully beneficial for the comfort.
And neverheless when I sense a certain layup is made bade, I discard that platform. Because sticks which are especially harsh, while you can make them better, what you can't is make them equally comfortable as some better layup platform. Dynamic stiffness play its role too.

From physics point of view, more inert racquet will recoil less. And the part of rotating aroud COM is the most important for the arm health from all rotations happening in this complex racquet movement.

 

[zalive]

Collision is collision, and mass is not meaningless either it is coming from a linear or centrifugal movement.

I said directly. Mass creates rotational inertias as well, so indirectly of course mass matters! But directly it matters only if there's linear movement. If there's no linear movement, there's no direct significance of a mass. Only through directional inertias. Anyway, I think what really counts is SW, RW, TW, balance point and MgR/I. Weight not directly. But those specs will depend on weight because mass distribution has to be somewhere, and it will increase some of inertias. So it's complex.

Anyway, the concept of polarizing setups, I say it acqnowledges that mass in the middle of the racquet is least useful and that you can get basically everything and even more with least static weight if you ensure there's least mass in the middle of the racquet. But this is not working if setup is not fine tuning by a skillful (or luckily hit lol) customization!

Let's say we have an open stance forehand, and yes we have 2 rotations (no linear movement). The one rotational inertia is thanks to our body rotation, and the degrees of freedom from ancles to wait to shoulder etc which is kind of parallel to the ground, and the point of impact ALLIGNS with our target to the other side of the court, and there is another rotational inertia (more or less - depending the tecnique - I will not analyse in this thread) which is let's call it 45 degrees for a top spin forehand.

This will go beyond our discussion, but there's even more centres of rotations prior to collision, the way I see it:
- centre of the body - originating from the body/core rotation
- shoulder - arm speed is mostly done through the shoulder - this is a centre of rotation different to body rotation, but still existing, right?
- racquet head lag-release rotation - which is done by any modern or even efficient traditional technique; centre of this rotation is I guess somewhere in the hand?

So in all honesty, double pendulum model is not enough even to describe the swing motion prior to collision, as there's in reality a triple pendulum (three centres of rotation).

After the collision you get as well the mentioned tendency of a racquet around the COM, which is the fourth centre of rotation. OK; as hand holds the racquet, it's yet more complex than that. But since wrist is not firm, this tendency will happen. As I said, if it never existed we would be lucky when it comes to arm injuries

I believe because I have observed it. But it is not the RW that has created the power (primarily). It is the increased mass, which means increased momentum, which means increased power, which means increased damage to the ball! Or no?

Then we have 180 degrees opposite observations. But I trust mine. And why I trust them? Because I noticed influence on tailweighting to the power of racquets before I knew anything about RW, and when all I could read on this board was that if customization doesn't influence significantly SW, it doesn't influence the power as well. Yet my observations told me opposite to my beliefs at the moment. When your observation tells you opposite to your believes you can trust it much more than when it confirms your beliefs, because in latter you cannot know if your current beliefs influenced the objectivity of your observation.

Anyway, if tendency for the racquet to rotate around its COM happens then RW must have it's significance. And this is the point when I stop with further discussion about this, because I fired about everything I know and understand about the subject.

 

[zalive]

It depends! It depends on mass distribution of the racket, and on so many other factors. There is an optimum scenario than the racket will be almost unaffected!

It does not really depend. Open your fingers on impact to let the handle slips from your hand forward, and see what happens

What really matters is velocity multiplied by mass, the end result thanks to the body ergonomics.

Angular velocity multiplied by relevant rotational inertia (moment of inertia), actually.

angular momentum L is proportional to moment of inertia I and angular speed omega
L=I*omega

Source:
https://en.wikipedia.org/wiki/Angular_momentum

It depends on the type of the stroke, on the personal physiology, on the body ergonomics (or bio mechanics)!

I overall agree with you, I wish we could be on court, and explain in 5 minutes time my point, and concerns! I also have to stop here. Thank you for clearing up my mind in so many occasions.

We both know it's complex really, but there's no need to force irrelevance of RW on each stroke, still.
But I insist on relevance of recoil weight because doctors specialists found that recoil is the main source of elbow and wrist injuries. If racquet just rotated in your hand there would be no significant recoil. If you understand this, you'll understand that recoil will occur at any stroke. But! Higher the RHS, more energy goes to the ball, less energy goes to recoil. This is what makes a difference. Difference in distribution of kinetic energy, related to RHS. One more things make a difference. Higher RHS creates more pocketing. More pocketing means less recoil, as ball sinks in the string bed and because of this it jerks it less.

 

[Shroud]

It does not really depend. Open your fingers on impact to let the handle slips from your hand forward, and see what happens



Angular velocity multiplied by relevant rotational inertia (moment of inertia), actually.

angular momentum L is proportional to moment of inertia I and angular speed omega
L=I*omega

Source:
https://en.wikipedia.org/wiki/Angular_momentum



We both know it's complex really, but there's no need to force irrelevance of RW on each stroke, still.
But I insist on relevance of recoil weight because doctors specialists found that recoil is the main source of elbow and wrist injuries. If racquet just rotated in your hand there would be no significant recoil. If you understand this, you'll understand that recoil will occur at any stroke. But! Higher the RHS, more energy goes to the ball, less energy goes to recoil. This is what makes a difference. Difference in distribution of kinetic energy, related to RHS. One more things make a difference. Higher RHS creates more pocketing. More pocketing means less recoil, as ball sinks in the string bed and because of this it jerks it less.

Whenever i go light on the racquet and increase RHS its never as comfy as a much heavier racquet

 

[zalive]

Whenever i go light on the racquet and increase RHS its never as comfy as a much heavier racquet

Weight will show somewhere, if not as SW then as RW. Only middle of the racquet is pretty much insignificant except it changes how racquet swings, which again can be very significant

 

[George Whitelaw]

It's the first of those that i have coming to me. So it's very head heavy (i won't mention SW...). Is the sensible thing to add weight in the handle? I'm thinking 20-30 grams of blue tack in the handle. What do you recommend?

how can you fit that much blu tack in the handle

 

[George Whitelaw]

That is true for the most part but it is possible you can increase either SW or RW and not have much effect on the other. I played around with a racket of mine yesterday. Took it and added 50 grams of plumbers putty in the handle. Here are the specs before and after:

BEFORE:
Weight 347 grams
Balance 30.9 cm
Swing Weight (@ 9.75 cm) 331 Kg cm^2
Recoil Weight (@ COM) 179 Kg cm^2

AFTER:
Weight 397 grams
Balance 27.7 cm
Swing Weight (@ 9.75 cm) 336 Kg cm^2
Recoil Weight (@ COM) 212 Kg cm^2

Now that is a big difference in balance and Recoil Weight 212 is extremely high but the racket was not more powerful, still easy to swing, and a bit more comfortable. The OP showed a video with the author uses this formula for computing Recoil Weight. R = SW - m^ He said as mass goes down Recoil weight goes up, and that is just one of the many errors in that video. As mass goes up y has got to change (the distance between the COM and SW axis.) The author of the video is adding mass above the the COM. This will raise the COM decreasing the distance between the COM and the SW axis and SW goes way up as does RW. But if I add mass below the COM the distance between the COM and the SW axis lengthens and RW goes way up with little change in SW as can be seen in the before and after figures above.

It is impossible to add mass to a racket and not change the SW, TW, and RW. Depending on where the weight is added make a big difference in which parameter changes the most but they will all change to some degree.

EDIT: Had I added that 50 grams to the head of the racket the SW would have went up to about 500 and the Recoil Weight would have went way up at the same time. @zalive and the video author are confusing the results of SW and RW and they don't even know it.

EDIT: If you're really talking about increasing SW why would one feel the need to discuss recoil weight and add more confusion?

how did you fit som much plumbers putty in the handle

 

[Irvin]

how did you fit som much plumbers putty in the handle

LOL getting it out was the hard part. To get it in I used a dowel as a ram rod to smash it in. Put a little in and push it up to the top of the handle. Then keep repeating. I would never do it again.

 

[Alberges]

Placing mass at the butt and at 12 o'clock will have most effect on increasing RW, thus reducing recoil. The farthest points from the balance point.



At the butt, you get most RW increase without a significant SW increase.

So should I strive for a racquet with the most HL balance possible? Namely 0 cm instead of the common 32-33 cm. At least in theory.

 

[Alberges]

What do you think about achieving a high recoil weight (>175) with a light racquet (270 g)? Is it possible? What about its effects?

 

[Irvin]

What do you think about achieving a high recoil weight (>175) with a light racquet (270 g)? Is it possible? What about its effects?

What are your specific specs? Need balance, SW, and weight to begin with.

 

[aaron_h27]

Just to bump this thread, I've been tinkering with racket mods for about 2 years now and I've noticed a few things regarding SW. I don't think high SW is necessary for everyone as evidenced by many newer pros using lighter specs.

So you have one side of the spectrum where SW > Static Weight (aka polarized set-up) this would include players like Gasquet, Serena, Venus, Henin, Zverev, Nadal. This set-up works for many great players on many surfaces, maybe with a slight disadvantage on faster courts. A lot of people with this set-up also play with extended frames since you get the SW boost without static weight increase.

Then you have the other side where Static weight > SW (aka depolarized set-up) this would include players like Osaka, Kyrgios, Tiafoe, Nishioka, Giron, Federer. Lot's of great players also using this spec, good for fast hard courts/grass, or hard courts in general. Not ideal for slow hard courts or clay courts. Open string pattern, stiffness & static weight can make up for the lost SW. I don't know of any players using 18x20 and low SW. This is probably best for the rec player as we mostly play on hard courts and it's easier to use.

So you can see both specs clearly work on tour, the only thing they both have in common is a similar recoil weight. The recoil weight for both set-ups is around 170 (for professionals), and I think maybe that might be a better way to approach customization rather than only talking about SW, Static Weight, MGR/I.

hope this helps someone or would love to hear more thoughts on it.

 

[Wheelz]

Just to bump this thread, I've been tinkering with racket mods for about 2 years now and I've noticed a few things regarding SW. I don't think high SW is necessary for everyone as evidenced by many newer pros using lighter specs.

So you have one side of the spectrum where SW > Static Weight (aka polarized set-up) this would include players like Gasquet, Serena, Venus, Henin, Zverev, Nadal. This set-up works for many great players on many surfaces, maybe with a slight disadvantage on faster courts. A lot of people with this set-up also play with extended frames since you get the SW boost without static weight increase.

Then you have the other side where Static weight > SW (aka depolarized set-up) this would include players like Osaka, Kyrgios, Tiafoe, Nishioka, Giron, Federer. Lot's of great players also using this spec, good for fast hard courts/grass, or hard courts in general. Not ideal for slow hard courts or clay courts. Open string pattern, stiffness & static weight can make up for the lost SW. I don't know of any players using 18x20 and low SW. This is probably best for the rec player as we mostly play on hard courts and it's easier to use.

So you can see both specs clearly work on tour, the only thing they both have in common is a similar recoil weight. The recoil weight for both set-ups is around 170 (for professionals), and I think maybe that might be a better way to approach customization rather than only talking about SW, Static Weight, MGR/I.

hope this helps someone or would love to hear more thoughts on it.

I like that type of discussion and analysis. Specs like Kyrgios are kind of low recoil weight. I do like your comparaison of surface versus specs. As I move from different type of outdoor surface to super fast indoors. Some specs work super good on slow and kicking surfaces and then I go inside against a good hitter and it’s just not the same. I also like to experiment with weight and see how different specs feel.

 

[aaron_h27]

I like that type of discussion and analysis. Specs like Kyrgios are kind of low recoil weight. I do like your comparaison of surface versus specs. As I move from different type of outdoor surface to super fast indoors. Some specs work super good on slow and kicking surfaces and then I go inside against a good hitter and it’s just not the same. I also like to experiment with weight and see how different specs feel.

Kyrgios spec is on the lower side but it's still near 170 RW. IIRC his specs are 343g, 325 SW, 8 pts HL I believe. Which comes out to 163 RW. If you're somewhere around 170, I think that's good.

 

[Wheelz]

Kyrgios spec is on the lower side but it's still near 170 RW. IIRC his specs are 343g, 325 SW, 8 pts HL I believe. Which comes out to 163 RW. If you're somewhere around 170, I think that's good.

Ah ok it’s such a small range that it’s hard to gauge what’s low and high.

 

[movdqa]

Just to bump this thread, I've been tinkering with racket mods for about 2 years now and I've noticed a few things regarding SW. I don't think high SW is necessary for everyone as evidenced by many newer pros using lighter specs.

So you have one side of the spectrum where SW > Static Weight (aka polarized set-up) this would include players like Gasquet, Serena, Venus, Henin, Zverev, Nadal. This set-up works for many great players on many surfaces, maybe with a slight disadvantage on faster courts. A lot of people with this set-up also play with extended frames since you get the SW boost without static weight increase.

Then you have the other side where Static weight > SW (aka depolarized set-up) this would include players like Osaka, Kyrgios, Tiafoe, Nishioka, Giron, Federer. Lot's of great players also using this spec, good for fast hard courts/grass, or hard courts in general. Not ideal for slow hard courts or clay courts. Open string pattern, stiffness & static weight can make up for the lost SW. I don't know of any players using 18x20 and low SW. This is probably best for the rec player as we mostly play on hard courts and it's easier to use.

So you can see both specs clearly work on tour, the only thing they both have in common is a similar recoil weight. The recoil weight for both set-ups is around 170 (for professionals), and I think maybe that might be a better way to approach customization rather than only talking about SW, Static Weight, MGR/I.

hope this helps someone or would love to hear more thoughts on it.

I saw one person post something on young pros that can manage low twistweight racquets, particularly since they can see the ball so well and decrease mishits. They may have genetic factors where they can recover faster from shock and twist. I had a set of frames like this but had to add lead at 3/9 as I needed the stability. I use high SW because I had an injury a decade ago and need sufficient twistweight for stability and SW for power.

 

[aaron_h27]

I saw one person post something on young pros that can manage low twistweight racquets, particularly since they can see the ball so well and decrease mishits. They may have genetic factors where they can recover faster from shock and twist. I had a set of frames like this but had to add lead at 3/9 as I needed the stability. I use high SW because I had an injury a decade ago and need sufficient twistweight for stability and SW for power.

Thanks for responding.

High TW and High SW are not mutually exclusive and are two separate things.

For example Osaka, Giron, Tiafoe all use lead at 3 & 9, but still have lower SW.

Nadal has a high SW and low TW.

Low TW is good for spin players who's dominant wing is the forehand, players who play far behind the baseline, clay court specs. Low TW means off-center hits go short in the court and you need time to run down those mistakes.

Higher TW is good for playing closer to the baseline, flatter hitting, playing on the rise.

Basically the closer you play to the baseline the higher you would want your TW to be without making the racket unmanageable.

 

[Wheelz]

Not a big fan of high TW but maybe it's just about getting used to it. I feel even more able to hit the sweet spot with low TW then higher TW, just easier to put into place (I'm talking mostly on the forehand).

Question for recoilweight ... Why don't companies do more like Clash specs ? I did that with my ezone 98 and it played good. 330 to 335g total, mid 320 SW but get the balance between 31.5-32. What would be the minus of doing that ? It's rare to see a light (305ish gram) racquet with low balance. You'd get the high recoilweight ( near 170) package in a lighter frame. I think Prince might have a few models like that. Seems companies will go towards that same static weight and spec but balance always between 32.5-33.

 

[movdqa]

Not a big fan of high TW but maybe it's just about getting used to it. I feel even more able to hit the sweet spot with low TW then higher TW, just easier to put into place (I'm talking mostly on the forehand).

Question for recoilweight ... Why don't companies do more like Clash specs ? I did that with my ezone 98 and it played good. 330 to 335g total, mid 320 SW but get the balance between 31.5-32. What would be the minus of doing that ? It's rare to see a light (305ish gram) racquet with low balance. You'd get the high recoilweight ( near 170) package in a lighter frame.

I have moderate TW. I cannot play regularly with low TW. I have a couple of low TW racquets which I use when my regular frames are all unstrung and I can use them for a couple of days before my arm starts complaining. I don't have any high TW racquets. I think that the highest I have is the RF97 which is around 15.4. That twistweight is the reason I can use a racquet that stiff. Everything else I have is 63 flex or lower.

I really hate looking for new racquets.