Racket Speed or Ball Speed – Which One Is More Important?

Novak Djokovic BackhandThe four tennis sensors (Sony, Qlipp, Zepp and Babolat Play) have rather different outputs for “Speed”. So, as a player and/or coach, is racket speed more valuable or more important than ball speed, or vice versa?

It should be stated at the outset that all you will ever get from Zepp and Babolat Play are session or overall averages. Neither provides shot by shot data. That’s a major analytics draw-back in itself. A player needs to play for a heap of sessions before having anything useable for comparison purposes. On the other side of this coin, Sony and Qlipp provide their speed data shot-by shot, both during the session and after the fact.

Speed Outputs of Tennis Sensors

We still find it quite incredible that there’s no common ground on the output of each of the four sensors. Not one is the same as another.

Zepp: Shows session averages of racket speed for forehands, backhands and serves. No ball speed is shown.

Qlipp: Shows shot by shot and session averages for ball speed. The Qlipp developers say they derive ball speed from racket speed, but for some reason they only show the former.

Babolat PlayRichard Gasquet generates enormous racket speed on his backhand: Shows ball speed for serves only and only as a session average, not shot-by-shot. No ball speed data is shown for other shots and no racket speed for any shots.

Sony: Shows racket and ball speed for all shots both as session averages and shot-by shot.

Now, scientists we’re not. But if there’s one thing that a sensor that’s attached to a racket can plainly show, it’s racket speed. All these devices have their little accelerometers and gyroscopes to measure it. And yet only two of them have the output for it and only one has the ability to show it shot by shot.

So it begs the question, is racket speed important? You bet!

But we’ll come back to that.

Ball speed, as measured by a racket sensor, is a little more difficult to measure. Each sensor uses its own algorithm to measure it. It’s based on a number of factors, including racket speed, spin, player profile etc. Qlipp and Sony give it a go while Babolat Play only shows it for serves (maximum and session average only).

So, Which One? Racket Speed or Ball Speed?

In isolation, both racket speed and ball speed have a place in game improvement. A player wants a consistent racket speed with only subtle changes depending on the circumstances.

The speed at which the ball travels is also worth knowing. Too slow may be a result of deceleration. Too high and a player may be finding it difficult to keep the ball in play if there’s not enough spin.

It’s only when you put the two together and combine them a value for spin that a player or coach gets the full picture. The three together complete a triangle of data that’s invaluable, for a shot, a session and over time.

In our article “Developing a Second Serve with Sony Smart Sensor“, we provide a great case for why having racket speed, ball speed plus a value for spin can improve your game.


They’re as valuable as each other. There’s benefit in having one or the other. But both together exponentially increases the value of your analytics. Sony is the only sensor displaying it at the moment. Qlipp says on its website that its device measures racket speed. Why they don’t display it as part of the analytics output is unknown.

This is definitely a case where the whole is worth more than the sum of the parts.

Lastly, why “racket speed” and not “racket head speed”? Only the Qlipp measures from the head of the racket. The other sensors are in, or on, the butt cap. The drawback of racket head data is that the Qlipp’s 8g does effect racket performance (sorry guys, it does). The massive positive is surely that their device can actually measure the speed of the racket head, wrist lag/snap and all! Watch this space.

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