The Science Behind Stance Caddy
A vast majority of golfers have heard of, or read, the book “Hogan, Ben. Five Lessons: The Modern Fundamentals of Golf. Simon & Shuster, Inc., 1957”. The book is a culmination of 5 articles published in a Sports Illustrated series in 1957 and continues to be revered as one of the most influential books in the history of golf instruction!
Stance Caddy is inspired by the illustration drawn by Anthony Ravielli which depicts where the feet are placed for each club in the bag, along with the ball position. That one image could be one of the most underrated, yet most used, golf training guides of all time. I have had instructors pull out a photocopy of that image and instruct me, “put the ball here, and your feet there”. You may recognize its likeness below.
The original image was not quite to scale, it was hand drawn and based on feel. At Stance Caddy, we looked into the geometry and scale to create a product to help people setup to the golf ball with confidence. Once measured against the golfer, when addressing the ball with the 5 iron, the heels will be directly under the shoulders and their stance is square. When addressing with a wedge, the outside their heels will be shoulder width apart and their stance is open. When addressing with the driver, the inside of the heels will be shoulder width apart and their stance is closed.
The physics and geometry represented by this one image is validated in the book “Kelly, Homer. The Golfing Machine., 1969”. There are essentially two ways to approach your stance, you move the ball forward and back in your stance, or you move your feet to an open or closed position depending on the club. This opening and closing of the stance actually changes the ball's position relative to your body, and provides a more consistent way to setup with your front foot always in the same spot no matter what club you are using. Stance Caddy was designed to support the latter.
There is a physics law called Conservation of Angular Momentum, which means the longer the club, the longer it takes for the clubhead to travel around your body and square up. Imagine an ice skater spinning, with their arms in, they rotate very quickly. When they extend their arms out increasing the diameter of the circle, they slow down.
Closing your stance (pulling your foot back to close your body to the target) positions the ball further ahead in your stance, relative to your body position, giving the club more time to come around and promote an inside out swing. With the driver, you also want to hit up on the ball. This stance allows you to bottom out your swing prior to reaching the ball and hit up on the ball with a better chance that the clubface is square at ball strike. This is known as the Divergence Plane.
Our best iron shots are made as we strike down on the ball to compress it. Inversing the principles above, a steeper decent, shorter club, the club face is going to be a bit open at ball strike on its way to the bottom of the arc of your swing. Opening your stance counteracts this and provides a great chance of starting the ball down the target line.
It is amazing this golf legend figured all of this out decades before TrackMan!
Online Resources
Ben Hogan's Five Lessons: The Modern Fundamentals of Golf
Homer Kelly's The Golfing Machine
Keep The Ball In One Place For Every Club - Butch Harmon, GolfDigest