Sensor Says Flat. Correct, or Just Varying Degrees of Topspin and Slice?

Roger Federer preparing to hit a topspin forehand. How much spin depends on what he's trying to achieve with the shot.Three of the four tennis sensors available on the market today measure three types of spin when a player hits a ball. The Zepp, Qlipp and Play sensors all measure topspin, slice and flat. The Sony Smart Tennis Sensor only measures the first two. There’s never a mention of a flat ball.

Does a Flat Shot Exist?

The problem with labelling a shot as “flat” is that it implies the ball was hit with no spin. I like to call it a “maker’s name” shot. As a coach, if I can read the name Head or Wilson on the ball as it travels towards or past me, I know the player with whom I’m hitting hasn’t used topspin or slice. More to the point, they’ve achieved an undesirable result.

As a player, I’m never looking to play a flat shot ie a shot with no spin. First of all remember, spin and ball speed have an inverse relationship. The more speed the less spin and the more spin the less speed. There may well be times when I’m looking to “flatten” my forehand out a bit. Say, on a mid-court ball that’s above the level of the net at the point of contact that I’m trying to put away. But flattening my forehand and hitting a flat forehand are two very different things.

It’s the same for slice. On approach to the net, I might want a more attacking, or slightly flatter slice that skids through off the surface at my opponent’s end. A defensive slice from the back of the court may have more or less revolutions depending on what I’m trying to achieve.

What About the Pros?

Now, there are those who would argue that even Rafa has a flat forehand in his arsenal of heavy weapons. To that I say, “show me one”. I’d defy anyone to show me a forehand that Rafa hit intentionally flat, with no spin. You might find one from Jimmy Connors 35 years ago, but not a modern day player. Today, there’s just varying degrees of spin.
Zepp App showing flat, topspin and slice shots for a session. Flat, or just less spin?Moreover, to hit a flat ball would require a player to have a flat racket face on approach to the ball and/or no angle of approach to the ball. That is, to hit with topspin requires a player to swing up at the ball with a brushing motion at point of contact, perhaps with a slightly closed racket face. To achieve any sort of slice would require the opposite approach and/or racket angle. Again, I defy anyone to show me an example of a pro hitting a flat ball any more than once in a match (except maybe a defensive lob!).

Bottom line. A flat shot is an undesirable result. There will almost always be varying degrees of spin.

Should Sensors Provide a Reading for a Shot with no Spin?

Now back to the sensors. If, as suggested, there’s rarely such a thing as a shot hit with no spin, then the three sensors reading shots as flat (and on a significant number of occasions) could actually be mixing up slice and topspin. That is, I may have played two backhands in my session. One was a topspin backhand that I flattened out a little to get more power. The other was an attacking slice approach to the net. Two vastly different shots read as “flat”, yet one had topspin and the other slice.

Is it possible that the three sensors with flat readings may be defaulting to “flat” when the device is unable to get a good enough reading on the amount of slice or topspin used? Not sure. Either way, the use of “flat” as a spin measurement is only distorting the data. Varying degrees of spin (whether topspin or slice) would do nicely thank you.

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