Four Numbers That Matter More Than a Launch Angle Alone
Four terms we use in nearly every session — and none of them can be read off a box or guessed from how a shot feels off the face.
Spin Axis
The tilt of the ball's spin relative to the target line, expressed in degrees. A tilted axis is what actually produces a slice or a hook — sidespin isn't a separate thing from backspin, it's the same spin viewed from a different angle.
Spin Rate
How fast the ball is spinning at separation, in revolutions per minute. Too much spin balloons a shot and costs distance; too little spin lets it drop out of the air early. The right number changes by club and by swing.
Spin Loft
The gap between attack angle and dynamic loft at contact. It's the single biggest driver of spin rate on full shots, and it's why two golfers with the same clubhead speed can produce very different spin numbers with the same club.
Spin Decay
How much spin a club loses as grooves wear down. A wedge that spun the ball well when new can lose meaningful stopping power after a season of use, often before it looks worn to the eye.
Reading Spin at the Source, Explained
Every shot has a spin signature the instant it leaves the face — axis, rate, and launch angle together. Most fitting tools estimate that signature from where the ball ends up after a few seconds of flight, which works reasonably well outdoors but gets noisy indoors, in wind, or on a mishit.
Reading it directly at separation removes that guesswork. When we say a driver produced a spin axis of six degrees, that's what the cameras measured at contact, not a number backed into from a landing spot on a simulated fairway.
Want the Deeper Explanations?
Release Notes covers each of these topics in more depth, or bring your own questions straight to a session.