Kick serve, or topspin serve?

[myke232]

Let’s confuse the OP more. There are those who call all high-bouncing topspin serves as kick serves. There are others who call it a kick serve only if it moves sideways in the opposite direction of a slice serve. Never the twain shall meet!

Exactly why I like the older terminology, 'twist serve" (from the old American Twist), to refer to a serve that changes direction. Whereas "kick serve" is a broader, somewhat ambiguous, class of high-bouncing serves.

These are actually the least confusing concepts!!

 

[myke232]

By the way guys, I’m surprised no one pointed there’s no pure topspin serve actually hit in tennis…
If this is contact for (close to) pure sidespin serve, guess what? Pure topspin should be 90 degree tilted arm and racquet from this. Isn’t used by current pro players

True...

 

[SystemicAnomaly]

These are actually the least confusing concepts!!

The problem is that all people don't use these terms in the same manner. Some will tell you that twist serves and kick serves are synonymous terms. That is, if the ball doesn't change its direction after the bounce then it's not a kick serve. They might say that twist serve (or American twist) is just the older name for kick serves.

Others I'll tell you that any high bouncing serve is a kick serve, regardless of which direction. They may or may not include a lob kick as a type of kick serve.

And then there are some who use the term, topspin serve, to mean the same thing as kick serve. But they may (or may not) include a twist serve as a topspin serve. OTOH, some may say that not all topspin serves will bounce high so those are not kick serves .

Also as @Dragy has mentioned, there are probably no pure topspin serve anyway. So that probably means that a topspin serve is a topspin-slice serve that has somewhat less sidespin or more topspin than other topspin-slice serves.

Still not confused? It's just best to realize that not everyone uses these terms the same.

 

[Dragy]

a topspin-slice serve that has somewhat less sidespin or more topspin than other topspin-slice serves.

Or maybe people see topspin to add arc to natural gravity arc (and more with lower ball speed), while side curve is only due to sidespin (if no wind is present). So for many relatively fast top-slice serves with 50:50 side/top ratio we'll notice mostly downward arc and consider it more as topspin serve.

 

[Chas Tennis]

@Dragy regarding post #50 comments.

Forget "pure" top spin.

Look at the ball diagram.

It helps when looking at the ball spin vector picture, if you print it and extend and draw the kick serve spin axis through the bottom of the ball. Think about the spinning ball and the felt on the bottom where it first contacts the court, that felt motion direction indicates the direction of the bounce.

The kick serve has a side spin component, AVz that is larger than its top spin component, AVy, AVz>AVy. The top spin serve will have the same kind of ratio between side spin and top spin components as a kick serve, but it will have little or no spiral spin component, AVx.

Note - The components spiral spin, top spin, and side spin change during flight and are only similar just after impact to the ball diagram's AVx, AVy and AVz which are based on vertical and the court lines.

I believe that occurs for the TS serve because the racket is not tilted closed by 13-15 degrees just before impact as for the kick serve. The TS serve is hit more directly on the back of the ball - see the red dot below - and not on its top half like the arrow. In other words, I believe that it is more difficult to create spiral spin with the racket strings first contacting the ball on the red dot. The bounce direction is related to the direction of the moving felt.

Technical Tennis, Rod Cross and

Figure 3. Average angular velocity vector (AV x , AV y , and AV z ) of...

Download scientific diagram | Average angular velocity vector (AV x , AV y , and AV z ) of ball spin for each type of tennis serve. from publication: Ball spin in the tennis serve: Spin rate and axis of rotation | The purpose of this study was to describe three-dimensional ball kinematics...

www.researchgate.net

The difference in racket work for kick and top spin serves obviously can be resolved with a high speed video camera and a tennis player with a strong kick serve.

 

[Chas Tennis]

Just found this Googling.

TennisOne - The Serve: Spin Axis, Body Position, and Swing Path

tennisone.tennisplayer.net

The views I have differ from some of those in this article.

 

[Chas Tennis]

Vector Analysis

The basic idea of vector analysis is that, if a coordinate system is defined, then any vector in 3D space can be described by 3 measurable components. One component is often chosen in the direction of gravity (Z upward). The components are perpendicular to each other (orthogonal).

This ball diagram involves vector analysis using a coordinate system based on vertical and the "forward" and "leftward" directions of the tennis court lines. It can describe any spin vector for a tennis ball and it does not change with the ball's trajectory. See publication in post #55 for more information on the coordinate system for the ball diagram measurements.

I believe that Rod Cross, as a physicist working in tennis research, originally used two familiar tennis terms - 'side spin' and 'top spin' - to rename the Z and Y axes, respectively, for tennis readers.

There is no problem for the tennis serve just after impact
X axis direction "forward" corresponds to spiral spin axis direction forward
Y axis direction "leftward" corresponds to top spin axis direction horizontal
Z axis direction "upward" corresponds to side spin axis direction upward

But after impact -

Coordinate System Based on Ball Trajectory. But spiral spin changes direction with the ball's trajectory. Also, as the ball moves across the court its trajectory curves and changes and Cross's terms "top spin" and "side spin" no longer apply and lead to confusion using this coordinate system. In addition, who knows what the trajectory direction is as the ball flies and curves? What are these 'spiral spin', 'top spin' and 'side spin' components at bounce as the ball dives onto the court surface?

Coordinate System Based on Vertical and Tennis Court Lines. But the coordinates shown in the ball diagram are based on vertical and the court lines, they do not change and can always be used to describe the spin vector of a spinning ball is 3D space. A video camera can be used to measure the components of the spin vector in this coordinate system, at any location, for example, at the bounce.

Introductory comments about 2D and 3D vector analysis.

 

[HuusHould]

Thank you for playing but, NO, the answer we were looking for is African. Before they immigrated to either China or Japan, H Sapiens first came from Northern or Eastern Africa.

The video clearly illustrates the confusion caused as a result of giving an unspecified response.

 

[Chas Tennis]

Here is a doctorial thesis on the ball bounce. Too much detail for me so far, but a good reference.

https://etheses.whiterose.ac.uk/14607/1/576971.pdf

I have been searching for measurements of the bounce of the kick serve, especially the bounce to the right for a right handed server viewing it. Videos with any quantitative information on the spin rates and angles would be a great beginning.

 

[myke232]

I gotta say, this pretty much nails it...

 

[mrmarble]

Topspin serve= top spin only
Kick serve= top spin + side spin

a true topspin serve much harder to hit as it takes a lot of strength and flexibility to swing 6 to 12 o’clock overhead. 7-8 to 1-2 o’clock much less

 

[SystemicAnomaly]

Topspin serve= top spin only
Kick serve= top spin + side spin

a true topspin serve much harder to hit as it takes a lot of strength and flexibility to swing 6 to 12 o’clock overhead. 7-8 to 1-2 o’clock much less

A pure topspin serve is not just much harder to hit, it is probably impossible. It would require a perfect brush ankle from 6:00 up to 12:00 but, because of our anatomy, there would always be an angle and a swing arc in such an attempt. We may very well visualize a 6 to 12 brush but here are the way that top spin serves are actually hit:

 

[SystemicAnomaly]

I gotta say, this pretty much nails it...

Very formative. Important to note that not everyone uses the terminology the way that Nikola does here. Quite a few don't.

A very interesting distinction he makes between the American Twist that was developed in the late 19th century and the twist / kick serve that servers developed as they started to jump higher in the 80s / 90s. Racket & string technology may have played a part too.

He indicates that the older implementation of the (American) twist serve had more of a lateral swing and did not bounce as high as a modern kick serve. This is undoubtedly due a smaller topspin component &/or a shallower approach (incident) angle on the bounce.

 

[Chas Tennis]

Post with Topspin Tennis Youtube. Supports the closed racket angle for the kick serve impact.

Found this kick serve impact caught with the camera angle to show one racket edge behind the other racket edge. Go to impact frame to see the racket tilt at impact, 11 sec. Measures 12.5 degrees closed when the ball is squished and cupped in the strings, about 2 milliseconds after first contact. Topspin Tennis places blue marks to indicate the racket tilt during impact. See 6:09.

See frame at 11 sec & tilt marked at 6:09.

Place line of protractor along the racket shaft and protractor center at the top of one of the fences as a reference to the horizontal. This measures about 12.5 degrees closed tilt.

Impact frame at 11 sec. One racket edge behind the other to observe the closed racket shaft tilt.

Topspin Tennis Youtube.

Starts at 6:17. It shows the closed tilt of the racket at impact. This is the point that I would like to confirm and also video along its bounce. Without the tilt the top spin serve should result.

Ideally, we would like to capture the racket strings or shaft tilt just before impact. That avoids collision effects.

If anyone finds clear videos showing kick serve impacts from this particular camera side view, please post them in this thread.

Just found this kick serve impact caught with the camera angle to show one racket edge behind the other racket edge. Go to impact frame to see the racket tilt at impact, 11 sec. Measures 12.5 degrees closed when the ball is squished and cupped in the strings, about 2 milliseconds after first contact. Topspin Tennis places blue marks to indicate the racket tilt during impact. See 6:09.

Place line of protractor along the racket shaft and protractor center at the top of one of the fences as a reference to the horizontal. This measures about 12.5 degrees closed tilt.

Impact frame at 11 sec.

Topspin Tennis Youtube.

Ideally, we would like to capture the racket strings or shaft tilt just before impact. That avoids collision effects.

If anyone finds clear videos showing kick serve impacts from this particular camera side view, please post them in this thread.

 

[Chas Tennis]

Topspin serve= top spin only

No, you cannot find a pro serve with only top spin.

Kick serve= top spin + side spin

Ball diagram of spin vectors measurements by researchers show
Kick Serve = side spin + top spin + spiral spin components just after impact where side spin is greater than top spin for a kick serve.

a true topspin serve much harder to hit as it takes a lot of strength and flexibility to swing 6 to 12 o’clock overhead.

There is no serve technique that swings 6 to 12 o'clock. Some instructors demonstrate that racket motion on the ball, but no high speed videos of high level serves ever show 6 to 12.

I've posted the racket motion for a kick serve as viewed from behind.

 

[mrmarble]

No, you cannot find a pro serve with only top spin.


Ball diagram of spin vectors measurements by researchers show
Kick Serve = side spin + top spin + spiral spin components just after impact where side spin is greater than top spin for a kick serve.


There is no serve technique that swings 6 to 12 o'clock. Some instructors demonstrate that racket motion on the ball, but no high speed videos of high level serves ever show 6 to 12.

I've posted the racket motion for a kick serve as viewed from behind.

Correct
its about percentages of top spin and slice
I doubt there’s pure top spin

 

[myke232]

Very formative. Important to note that not everyone uses the terminology the way that Nikola does here. Quite a few don't.

A very interesting distinction he makes between the American Twist that was developed in the late 19th century and the twist / kick serve that servers developed as they started to jump higher in the 80s / 90s. Racket & string technology may have played a part too.

He indicates that the older implementation of the (American) twist serve had more of a lateral swing and did not bounce as high as a modern kick serve. This is undoubtedly due a smaller topspin component &/or a shallower approach (incident) angle on the bounce.

May not be universal, but I like the way he distinguishes and categorizes them, it makes sense to me and seems to be pretty straightforward.

Yeah when he demos the old american twist he actually finishes with the raquet on the right side of his body.

 

[SystemicAnomaly]

May not be universal, but I like the way he distinguishes and categorizes them, it makes sense to me and seems to be pretty straightforward.

Yeah when he demos the old american twist he actually finishes with the raquet on the right side of his body.

That was a more common finish sometime back -- prior to the evolution of the modern kick in the 80s or 90s. Fabrice Santoro, "The Magician", was one of the last players that I regularly saw using ye olde American Twist finish

 

[HuusHould]

"The Magician", was one of the last players that I regularly saw using ye olde American Twist finish

Sam Stosur has the same finish. Her singles prowess may have declined, but she still has one of the best kickers/American twist serves (whatever you prefer to call it) on the WTA tour.

 

[Chas Tennis]

Here is Rod Cross's TW University article on the kick serve.

The Physics of the Kick Serve, Rod Cross
http://twu.tennis-warehouse.com/learning_center/kickserve.php
(Information is mentioned here and there throughout this article, if you find something interesting, make a record of where it is.)

1) Closed Tilt on the Kick Serve Racket Face Tilt. In the abstract Cross states
" In addition, it helps to strike the ball with the racquet head tilted forward slightly. "

I measured one Stosur serve at 13 degrees closed just before impact. The usual flat and slices are racket face tilt around 0 degrees at impact. I posted the Topspin Tennis video in post #64 showing Federer's kick and I have posted another video of Federer's kick serve with closed racket tilt.

I have seen enough video evidence myself to believe that the racket face is closed by around 13-15 degrees just before impact. I'll continue to find video evidence on the closed tilt of the racket face for the kick serve. The only video evidence that has been presented has shown the racket face closed at impact much more than for the slice and flat serves.

The question is - if you do not have this closed racket face can you ever hit a high level kick serve?

For video evidence and discussions
Search forum - racket face closed tilt kick serve Chas

2) Does the Spin Vector Direction Stay the Same as the Ball Flies to the Bounce? Below is a quote of Cross's on the spin vector direction as the ball approaches the net. In videos, I have seen the print on the ball appear not to change spin orientations over 3-4 rotations. This is an extremely important point for the spin vector during the ball's flight to the serve bounce. It gives you the spin vector for the bounce in the coordinate system using vertical and the court line directions, as discussed in earlier posts.

I found Cross's comment on the spin direction of the kick serve as it approaches the net. From Physics of the Kick Serve.

"4. INTERPRETATION OF SPIN
Measurement of spin rates from high speed video film is relatively easy. The spin axis remains fixed while the ball travels toward the net, so the time for one revolution can be measured in terms of the number of video frames required for a particular mark or pattern on the ball to re-appear in the same orientation."

I accept that by Cross as the most creditable information that the forum has on the spin vector direction during flight. Anyone one of us with two video cameras could video the spin vector direction after racket impact and then again on the other side of the court and determine what is true. (Maybe it requires high speed video cameras.) Probably some of us have seen top spin forehand drives and the ball print reappearing as it flies. A sharpie could be used to make a larger and more visible mark on the ball.

It tells us the direction of the spin vector at bounce.

The Principle of Gyroscopic Rotation and the Football Pass. We would like to have a similar video for the spin vector of a tennis ball, we are already certain the tennis ball has a Gyroscopic effect because it is spinning.

3) Racket Rise.

from Physics of the Kick Serve -

"One of the mysteries concerning the kick serve is how the server manages to generate topspin in the first place. In order to achieve a good kick serve, the racquet head needs to rise up the back of the ball, as it does in a topspin groundstroke. To return a groundstroke with topspin, players normally swing the racquet upwards at an angle of about 30 degrees to the horizontal. That way, an upwards friction force is exerted on the back of the ball, causing the ball to rotate with topspin if the racquet is swung fast enough. The incoming ball bounces off the court with topspin, so the spin direction needs to be reversed in order to return the ball with topspin. In a serve the racquet head is almost at the top of its trajectory when it strikes the ball, so the racquet is rising at an angle of only a few degrees just before it strikes the ball. Therein lies the mystery. If the racquet needs to rise at 30 degrees to hit a good topspin forehand, how can anyone serve a ball with a significant amount of topspin when the racquet head is rising at only a few degrees?"

To single frame on Vimeo hold down the SHIFT KEY and use the ARROW KEYS. The top video may skip frames when the arrow key is used.

240 fps

For this kick serve technique, during impact there does not appear to be any racket head upward motion due to jumping.

A better confirmation of the kick serve bounce, with a second video camera is needed in future experiments.

There may also be more than one kick serve technique out there. ?

Observe current ATP player's kick serves.


@SystemicAnomaly and @Dragy
Do you have a true or false opinion on any of the above three issues?

 

[SystemicAnomaly]

Sam Stosur has the same finish. Her singles prowess may have declined, but she still has one of the best kickers/American twist serves (whatever you prefer to call it) on the WTA tour.

Had forgotten about Sam

 

[Shroud]

I would say last two could be called kick. But the first, the top slice, could not.

So I think from a righties serving perspective, if it bounces straight up, or to the right it's a kick, but if it bounces at all to the left, even with substantial topspin, it's not a kick, but a top slice...

Top slice, kick and twist is more specific IMHO. but its like 2021 and no one has any tolerance for nuance so kick serves all...

 

[ZPTennis]

This video is a definition of a kick serve.

It's always good to imagine the highest level of knowledge in a field. I'm guessing that many college & pro coaches and other knowledgeable tennis experts, such as biomechanics researchers, would agree that this is a kick serve.

If this video were in slow motion, we would see more of the racket work. A side camera view, from the particular camera angle that I have described and shown, would show the racket closed by, say, 13-15 degrees just before impact.

Does anyone recognize this server?

Less effective bounces to the right would also be kick serves, but they would need clear video evidence showing enough right bounce. Enough right bounce to define it as a kick serve is not yet defined.

Tennis terms such as 'kick serve' or 'pronation'(for serve) are often named when first noticed, but not yet well understood. Then in later decades, we argue over each poster's personal meaning of the poorly defined and understood tennis terms.

He looks familiar

 

[ballmachineguy]

I suggest that everyone drill a hole through the center of a tennis ball and insert a pencil.

Can I please be excluded? I already have a hole in my palm from trying to remove an avocado pit with a fork. I don’t need any more trouble.