# John Yandell - Service Speed Loss % and Depth ...

#### cervelo

##### Rookie
I read the information on your website and it sparked a line of thinking which was explained to me some time ago - I'll try to summarize:

As a general rule, I was told that a ball served at 120 mph reaches the returner at about one-half of its maximum speed --- I was also told that this same serve at 120 mph, if it lacks depth in the service box and bounces several feet inside the line, can lose an additional 10-15 mph or more by the time the receiver gets a crack at it ... Accordingly, it might be better to serve a deeper ball at 100mph or even 90mph as the ball will be traveling faster when it reaches the returner due to the service path angle and the effect of friction, etc.

Finally, if we examine the elapsed time from bounce to returner, the "slower" serve actually reaches the returner in less time because the angle and depth give the returner LESS time to react to the ball after the bounce. Point is, there is less friction to counteract pace and there is less distance to travel from bounce to returner ...

Does any of this make sense or did I totally butcher it?

If you can make sense of this, at what point or how far inside the box do you consider a serve to lack depth that it will nullify the power on a serve?

#### NoBadMojo

##### G.O.A.T.
i'm not john, but what you said sounds right to me. you want to hit as deep in the boxes for both serves as you can unless you are Y serving and can hit short angles. if you hit your spots with a 100mph serve it can be alot more effective than a poorly placed serve with more pace. as far as what depth nullifies your serve that depends on some factors like type of serve that was hit, spin rate, mph, and how good your opponent is, and location he/she decides to take the serve

#### cervelo

##### Rookie
Yeah, I understand that spin can upset my equation ...

Importantly, I brought up this topic because I see a lot of players trying to "amp" up their serves but they seem to trade some depth to do it ...

I wonder if many players don't understand some basic concepts underlying the power they're trying to harness ... they work diligently to get more service power but suddenly, they're looking across the net and see a returner who is able to get that serve back - and they assume that the returner is simply blocking back the return and using the server's pace against him/her ...

I see a different analysis- I see a returner who has more time to work over and hit out against this "faster" serve ... I just don't know where the trade-off begins and where a server is actually losing time/pace to hit harder against the returner ... maybe it's a foot inside the line - maybe two feet ...

Anyway, I'm glad my explanation was (somewhat) understandable ...

#### mucat

##### Hall of Fame
It is not just serve, ground strokes too, the deeper it is the better. IMO, speed of the ball is not as important as depth of the ball, depth make your shot unattackable, even a relatively slow shot. Heavy topspin bounce at the middle of the court is easier to handle than flat shot hitting close to the baseline, same reason.

#### kevhen

##### Hall of Fame
I agree with what you say, although it's very difficult to hit a 120 mph serve and have it land short in the box, but if you could, then I agree that a deeper slightly slower serve hit would likely reach the returner sooner if they could get their racquet on it.

The bounce slows the ball down quite a bit. Air resistance slows it down too but is more gradual. The bounce immediately takes air out of the ball.

#### cervelo

##### Rookie
kevhen said:
I agree with what you say, although it's very difficult to hit a 120 mph serve and have it land short in the box, but if you could, then I agree that a deeper slightly slower serve hit would likely reach the returner sooner if they could get their racquet on it.

The bounce slows the ball down quite a bit. Air resistance slows it down too but is more gradual. The bounce immediately takes air out of the ball.

This is why I'm wondering how much of a difference is measured ... It is hard to hit a 120 mph flat serve two feet short of the service line ... but if the numbers change, or specifically, the serves are slower - the percentages will change also. Then, I would guess even inches could make a difference - but I don't really know ...

#### Bungalo Bill

##### G.O.A.T.
cervelo said:
This is why I'm wondering how much of a difference is measured ... It is hard to hit a 120 mph flat serve two feet short of the service line ... but if the numbers change, or specifically, the serves are slower - the percentages will change also. Then, I would guess even inches could make a difference - but I don't really know ...
I dont know how exact this will ever get. It seems so many variables can be mixed around and get slightly different results.

Heck, even how close you are to sea level would have something to do with it.

I think this is a general study of the ball slowing down and the approximate rate and speed it slows down. Lots of variations from there.

What you can take from this study is to not get caught up in the speed of the ball from the windup and initial hit and focus on the bounce. Use a timing mechanism when receiving serve to help you determine the speed between the hit and the bounce.

#### kevhen

##### Hall of Fame
This is another reason why placement of your shot (especially groundstrokes that can land by your feet) is better than power, since placement can make your shots seem more powerful.

#### Bungalo Bill

##### G.O.A.T.
kevhen said:
This is another reason why placement of your shot (especially groundstrokes that can land by your feet) is better than power, since placement can make your shots seem more powerful.
Yes, very good point. Placement makes people work harder to beat you.

T

#### TwistServe

##### Guest
Thats also why an effective kickserve must land deep in the box or on the corner.. if it lands short by the time it hits the baseline it'll be in strike zone.. if you land it deep, it'll be shoulder or head height at the baseline..

#### kevhen

##### Hall of Fame
Yep and it's harder to place a kick serve than a flat serve, but a deep kick serve comes in faster and higher and is much more difficult to return when it's not hit with as much depth. That is why my kick is not so good since I can't always keep it deep.

#### Bungalo Bill

##### G.O.A.T.
TwistServe said:
Thats also why an effective kickserve must land deep in the box or on the corner.. if it lands short by the time it hits the baseline it'll be in strike zone.. if you land it deep, it'll be shoulder or head height at the baseline..
If you mix in a short kicker every now and then wide or down the T, you would be surprised at how you catch someone sleeping. Also, many times they overhit it!

So remember, if you want to have a certain serve speed by the time it reaches the server it is important to know how fast you need to swing to achieve that. You got to practice and learn this.

Mix up the speeds, placement, and your stance position to constantly make the returner have to think about his timing.

If he nails a ball at a certain speed, take note of where he hit it, backhand or forehand, and how fast the ball ended up being when he hit it. Many times, having it arrive in the exact same spot, to the same side, but slightly slower causes him to have fits.

#### JohnYandell

##### Hall of Fame
You guys have pretty much covered it all before I even logged in.

To tell you the truth we didn't look at it in terms of where the serve lands. In general though it's going to be hard to hit a flatter, faster serve and have it land in the box consisently short. So I'm not sure the deeper slower thing makes sense. We still have a long, long way to go to understand how spin fits into the whole equation and the complex relationships between speed, spin, trajectory, and court surface.

The one thing we did seem to find, that I need to write about on Tennisplayer, is that all things being equal, a little more topspin component seems to make the ball heavier at the time of the return--but probably not at the expense of much speed. That was the Sampras deal. 120mph and 2500rpm with a heavier topspin component.

By the way, we have begun looking at other servers, and you guys will probably be interested to know Roddick is serving about 130mph on average with about 2400rpm of spin, but slightly more sidespin than Pete. He probably does have more pure racket head speed than Pete...not sure what that really means but think it's interesting.

I guess the way to look at it from the player's point of view has more to do with your serve than the physics of the bounce. This sounds like a cliche, but you wnat to develop your serve so that you can hit 60% first serves plus, and move it around the box. How much speed and spin to do that is a function of you.

Same on the second serve. I just think it's too tough to think "I'll hit two feet deeper with 20% more spin and than will get to this guy.10 seconds sooner." You want confidence in the delivery and that is more of a feeling than an equation.

#### cervelo

##### Rookie
I'm working with a bunch of different service "types" to try to get a handle on the most effective placement for the best results- which is why I posed the question - I guess I'm looking for a general rule for service depth (e.g. - A service depth guideline like, "anything consistently more than one foot inside the line is not gonna get it done" ... type of rule). I understand that mixing it up may call for a shorter offering, from time to time.

What's interesting for me is that I serve both righty and lefty - I favor topspin-ish delivery on the right side - more of a natural slice on the left -

The righty is fairly powerful and heavy (when my body allows me to loosen it up - an injured hand caused me to switch in the first place - bad hand makes it tough some days). Before my injury, my righty serve was a decent weapon- now I see some lack of depth and shorter deliveries.

The lefty stays lower, nowhere near as powerful or quite as well placed - but 10x more effective at producing return errors or setting up my forehand. Initially, I "chalked it up" to the lefty spin - but my usual hitting partners have been around the tennis block enough to have played their share of lefty's.

Ultimately, I've decided that my lefty serve is consistently deeper - despite having a pace and racquet head speed which is leagues below the righty - it gets the job done and even seems to rush the returner's strokes. Of course, I hafta know why this is so and I must torture myself with the specific "why's" and "how's." I'm guessing that, without the consideration of many serving variables, it's tough to create a straight-line rule for every server.

(correct that, torture YOU GUYS!!! ... sorry!)