would like to know my serve speed

FranzS

Rookie
Hi, from my videos of me serving I can calculate my average speed, starting from racquet/ball impact to ball landing into the service box. Does anyone know how much the ball speed decreases from impact to landing, knowing the distance covered? In other words, if a know my average speed from impact to landing (and I also know the distance covered), can I know (approximately) the ball speed a radar would measure right after the impact?
 

Raul_SJ

G.O.A.T.
So the serve speed immediately after the bounce is dependent on the distance covered? I i.e. a 100mph serve landing in the middle of the box will be slower (speed measured immediately after the bounce) than a 100mph landing on the service line?

See also http://www.popularmechanics.com/adventure/sports/a2072/4221210/

Velocity
The serve speeds you see on courtside digital displays are measured just as the ball leaves the racquet. Fortunately for returners, by the time the ball reaches them, air resistance and the friction of the court surface have diminished its speed by roughly 50 percent. Tennis instructor and analyst John Yandell has found that, on average, a 120-mph serve slows to 82 mph before the bounce, then to 65 mph after the bounce, and finally to 55 mph at the opponent's racket.
 
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FranzS

Rookie
I mean the racquet/ball impact. And I mean that the longer the ball travels, the more its speed is reduced by air friction.
 

LeeD

Bionic Poster
Video is one tool to figure serve speed.
Another is how high the ball bounces on the backfence/backwall, after landing IN. Around 80 is enough to hit the backfence after the initial bounce, but of course, low on the backfence.
Warmer air and Wilson balls generally mean higher bounces. New abrasive courts also cause higher bounces, while slick painted cement courts and grass courts cause the lowest bounces.
Another consideration is how your serve compares to your buds at the courts. If your serves are average, don't expect much more than 80 mph. If you have the fastest of anyone's, including most 4.5 level players, you're probably exceeding 105 mph.
Hit some hard serves IN, see where they land on the backfencing.
Also, see where your opponent's are standing. If they generally stand 6' behind the baseline to return your serves, you can bet on 110+.
If they stand near the baseline, maybe under 105.
If they stand in deep NML, you better work on your serves, they're only 75 max.
 

LeeD

Bionic Poster
Interesting, no doubt.
Was your radar calibrated correctly?
Topspin serves can go slower, yet still bounce to the backfence. Flat serves might need 80 mph.
I can't believe you only hit sub 70 mph?
How high up the backfence?
Today, I was hitting flat serves to Miquel Loo and Papa Mango, both posters on here. Both stood about 5' behind the baseline, every serve they didn't get their racket on hit about waist high on the backwall. Since they both post on here, you can verify with them. Penn balls, 70 degrees, side wind.
 

shindemac

Hall of Fame
I bought a radar gun last year. One of the most useful tools if you're trying to improve your serve speed. You really can't see the 1-2 mph improvements from week to week, but it's there and keeps you really motivated. Small changes in technique show up on the radar. Also, my biggest serves are what I think would be my slowest because it felt effortless. Also reverse is true. What I think should be a big serve, and those turn out real slow. Faster serves help you quickly figure out what went right so you can repeat it. IOW, continuous self-improvement.
 

LeeD

Bionic Poster
True, effortless POP results in the fastest serves.
But it's not really "effortless". You still need leg drive forwards and slightly upwards. You need a full turn and fast swing. You need a loose wrist joint and full pronation. You need to hit center with pop.
None of those things work without the other's.
Shindemac, do you ever want to hit with a low 4.0? I'm in the Berkeley area mostly, I think you're in the City. I have a big serve for a 4.0.
 
A

Attila_the_gorilla

Guest
Interesting, no doubt.
Was your radar calibrated correctly?
Topspin serves can go slower, yet still bounce to the backfence. Flat serves might need 80 mph.
I can't believe you only hit sub 70 mph?
How high up the backfence?
Today, I was hitting flat serves to Miquel Loo and Papa Mango, both posters on here. Both stood about 5' behind the baseline, every serve they didn't get their racket on hit about waist high on the backwall. Since they both post on here, you can verify with them. Penn balls, 70 degrees, side wind.
That radar gun doesn't need calibrating, should work out of the box. Supposed to be very accurate.

Hmm my fastest serves tend to hit the fence somewhere between knee and waist height. But I can't really serve flat, my serves always have some slice on them and bounce off the court a bit sideways.
 

LeeD

Bionic Poster
Are you playing on clay? Clay's abrasive surface accounts for the high bounce.
I play on cement courts, with a layer of paint atop. The 4.0's I play against, Shroud, Papa Mango, Miquel Loo, all serve their fastest serves close to 100, but I have an edge, because they need to stand back 5' behind the baseline to return mine, while I stand atop the baseline and usually return theirs with no problem.
Of course, they can return my second serves from inside the baseline, if they choose to. It goes maybe 75 mph, doesn't reach the backfencing after it's first bounce, and is eatable material for any decent player.
I'm pretty sure that "out of the box" need calibration.
Matt Lin was timed at 111 two weeks after we played. My first flat serves, which I didn't hit any of, is not quite there, but close.
 

LeeD

Bionic Poster
Unless you are a dog, you cannot hit a serve that bounces near the top of a door.
How high is your backfence? At San Pablo Park, it's 10' of fencing, with an 11' wall between the two sets of courts.
 

jaxadam

Rookie
I haven't seen many dogs hit much of anything with a racquet.

I don't know how high, prob 10 feet or so, almost in the middle, near the top of the gate where you walk in. Lucky shot.
 

LeeD

Bionic Poster
Oh, 70 mph is the first serve speed of a weak hitting 3.5 level player, maybe even a 3.5 level woman.
That is about my second serve speed, with tons of spin.
No way, Attila can serve that slow, unless he's not a very good player.
EVERY 4.0 I know can flatten out a first serve into the low 90's, or at least the highest '80's. Well not every. That dude that spent 26 hours in the water in Baja Cortez side can't, but he's 5'3" tall and likes to irritate oppoent's by serving and having the bounce still inside the service line, around 30 mph or less.
 

LeeD

Bionic Poster
Door height for HUMANS is 6'6".
You do not hit any serves that go IN, and bounce higher than halfway up the height of a door.
You might be able to, if you're taller than 6'3", can serve into the 130's, but I seriously doubt that.
 

jaxadam

Rookie
Well, that one went in and hit higher than the middle of the fence, almost to the top of the gate where you walk in, and the pro said he was going to get the radar gun out again.
 

steve s

Professional
Judging the speed of a serve by where it hits the back fence --- is not MIT like science. Do you make this stuff up. Without a speed gun your just making up a numbers.

I hit the fence at four feet three inches---- that 121 mph.
 

LeeD

Bionic Poster
Carpet WOULD be synthetic.
I"ve heard some guys here say carpet is slick and fast.
The only carpet I played on was at the TransAm Pro tourney in SF, in the Cow Palace. Even my serves kicked up over 5' at the baseline, and they weren't kick or twist serves, just standard top/slice second serves.
 

Alien

Hall of Fame
@LeeD I believe you are assuming backfences are set at same distance to the deep line. At least where I play, they differ significantly.
 

LeeD

Bionic Poster
Where I play, they are exactly 21' behind the baseline. It's called regulation courts.
Clarendon Courts, in SF, not where I play, they are 50', and nobody can hit that on one bounce, as on the other side, it's closer to 70'.
 

Chas Tennis

G.O.A.T.
The most basic way to measure velocity in to measure distance traveled in a known time. Here is a demonstration using a video camera with known frame rate. The velocity off the racket can be measured.

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Here is a more direct and simpler way to measure serve speed. It also measures closer to the speed off the racket.

This was taken at 30 fps with the automatic exposure control selecting the shutter speed. In bright sunlight, the motion blur is workable - use the front or back of the ball or the center of the blur. Also, this was a somewhat telephoto lens not a wide angle lens as all smartphones have.





The camera views approximately perpendicular to the ball's trajectory where the intended measurement will be, here about 10 feet in front of the server.

The time between frames at 30 fps is 1/30 sec or 0.0333 seconds.

The problem is now simply to calibrate the distance along the trajectory. I could not do that here.

For your serve, you could just video a taught rope with black tape every 6" or 10 cm. Video a PVC pipe with tape every 6", etc. If no scale, just place your racket approximately on the ball's trajectory and video yourself as you walk along the trajectory. A little off, say, the racket is tilted 5 degrees to the trajectory, it does not make a big difference to the accuracy of your serve speed measurement.

If done with reasonable care this method can be more accurate than a radar gun.
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Example measurement using the ball as a scale.

If I use the ball itself as a crude scale on my computer screen I measure the ball blur to be about 3 mm across, in the direction perpendicular to the trajectory. Assuming the ball is 2.7" in diameter. Then a mm on my screen is 0.9" on the trajectory. If he had held his racket vertically or along the trajectory we could have used that as a more accurate scale.

In the first frame, on my computer screen, the back surface of the ball measures 88 mm from the pole.

In the second frame, it measures 5 mm from the pole.

(Since the camera was hand held and might have been moving the pole is used as a reference.)

The ball moved 88-5 = 83 mms from frame #1 to frame #2.

Converting 83 mm using the scale of 1 mm on the screen = 0.9" inches in real space.

The ball moved
83 mm X 0.9"/mm = 74.7 inches between frames.

74.7"/fr X 30 fr/sec = 2241"/sec

1 MPH = 17.6"/ sec

Video measured serve speed
2241/17.6 = 127 MPH

The radar gun measured 130 MPH.

The scale based on measuring the ball diameter is not accurate. The measurements just happened to come out close. I picked 2.7" as a ball diameter to demonstrate how to do a video measurement, not to evaluate the accuracy.

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Same principle but applying an interlaced video camera for timing. Not so many cameras have interlaced video anymore.
 
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kandelin16

New User
OP, perhaps this page will give you some insight on calculating your serve speed:

http://donthireddy.us/tennis/speed.html

Note: Donthi appears to indicate that 30 fps is really 29.97 fps
There is an app on the ios app store that uses this equation to determine your serve speed based on the frame where the ball is hit, the frame where the ball hits the ground, where the ball hit, your height, and your position on the court.
 

Tight Lines

Professional
There is an app on the ios app store that uses this equation to determine your serve speed based on the frame where the ball is hit, the frame where the ball hits the ground, where the ball hit, your height, and your position on the court.
Yep, I have this app called Servespeed. It works really well.

Harry
 

LeeD

Bionic Poster
I'm with you on the need for 80mph to hit the backfence, 21' behind the baseline, on one bounce, after going IN.
 

shindemac

Hall of Fame
Some of those radar things from Amazon are very inaccurate.. I don't think you can hit fence on one bounce below 80.. If its normal distance back there. Actually if you try to nail the back fence on zero bounces while standing pretty far back its harder then you think.. But I digress.

film is pretty decent..
Every ball and every person is going to be a little different. Different heights, amount of spin (slice), etc., so there isn't one number you can say that will hit the back fence. For a rec player (3.0 to 3.5), if you can hit the back fence in one bounce, that would be considered fast. Low end 4.0 can tag the back fence, and I've seen USTA rated 4.0 players hit up to 3 feet on the back fence. In general, as my mph started to go up, I would hit consistently higher and higher up the fence. There's two big differences with my fastest serves : Sound and force at impact is bigger, and ball is still rising on impact. Point is, at least for me, there's lots of little clues that can gauge my serve speed, but feel is not one of them.

About the process. There is some natural improvement that can be had from just practicing. But then it levels off, and I needed to make specific changes in my technique. I blogged about it extensively last year so you can look at the details if you want. But in general, each week I had to focus and make very minor changes. After a few months time, it added up to quite a bit. My philosophy on serve is very different from most here and I don't concentrate on the trophy too much. To recap quickly:
0. Ball toss
1. Loose arm
2. Balance
3. Kinetic chain

Ball toss is listed as zero because it's that important.
 

onehandbh

Legend
Hi, from my videos of me serving I can calculate my average speed, starting from racquet/ball impact to ball landing into the service box. Does anyone know how much the ball speed decreases from impact to landing, knowing the distance covered? In other words, if a know my average speed from impact to landing (and I also know the distance covered), can I know (approximately) the ball speed a radar would measure right after the impact?
I have a way to estimate it fairly accurate if you have a video of your serve. Upoad it to youtube and send it to me via dropbox.
 

BMC9670

Hall of Fame
How can where the ball bounces on the back fence determine serve speed? Too many variables:

1. Distance from the baseline to fence varies by court. Of the courts I frequent, they vary quite substantially. If you measure this, the time it takes to hit the fence would be better, although timing accurately would probably be difficult. Could do it with video, but that would calculate speed at the fence. Not very useful.
2. The amount of spin imparted can make create an inconsistent relationship between height on fence and speed. Factoring this into a speed calculation accurately would be quite the science experiment.
3. The surface the ball bounces off can also create an inconsistent relationship between height on fence and speed. Factoring this into a speed calculation accurately would add another complicated variable to the above science experiment.

So, at the end of the day, using where the ball bounces on the back fence, unless many complicated mathematical calculations are met, is just a guess. And probably not a very accurate one.

Video analysis with known frame rate inside the known dimensions of the court and/or a good radar gun is better.
 
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onehandbh

Legend
Most people prefer using a radar to measure ball speeds.

Some approximate it using an app or video frame counting.

Some use visual estimation.

Others use than rec player friends. (e.g. "Dang! That was fast. I think it was like 120!")

Myself, I use a LeeDar. Backfence virtual speed estimator.
 

GuyClinch

Legend
How can where the ball bounces on the back fence determine serve speed? Too many variables:
It's called margin of error - assuming that you hit the back fence - serve goes in and its at least regulation distance to the back fence - its going to be around 80mph or more.

Yes you cannot get it down to an exact number with this method - but its close enough. And its easy to check this.. Go film yourself serving - use the frame rate method to estimate your speed. Then see if your serve hit the back fence. You will find LeeD's theory that around 80mph hits back fence to be pretty good..

You see serves bouncing way up and sticking into the fence - that's a over 100mph serve. Again film test it if you don't believe me.
 

BMC9670

Hall of Fame
It's called margin of error - assuming that you hit the back fence - serve goes in and its at least regulation distance to the back fence - its going to be around 80mph or more.
Margin of error? LOL. I have 13 year old kids that can hit kick serves that hit the fence at a decent height and there is nooo waaaay they are going 80mph.
 

LeeD

Bionic Poster
I don't think you have 13 year olds, or 16 year olds, who hit kick serves that hit the backfencing, located TWENTY ONE feet behind the baseline.
Even Stosur kick's don't most of the time.
Fed's can, as can Isner's, but they are not 13.
 

GuyClinch

Legend
Margin of error? LOL. I have 13 year old kids that can hit kick serves that hit the fence at a decent height and there is nooo waaaay they are going 80mph.
Most confusing humblebrag ever.. HS kids can hit 80mph serves no problem. Grats on having kids that can hit nice kickers though... I guess.
 

LeeD

Bionic Poster
Plenty of high school boys can hit 110+ flat serves.
A handful in the nation can hit kick serves IN and still bounce to the backfence, TWENTY ONE feet behind the baseline. That would require 75+ mph, nothing a 13 year old can do.
 
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