The Truth About Spin

1. Golf Ball Construction. Golf balls come in two, three, four and even five pieces. The two-piece ball has a thin outer layer around a large, solid core (Top, Flight, Titleist, DT Solo). Spin is minimized, distance maximized. Two, three, four and even five-piece balls have a soft cover, one or two intermediate pieces and a solid, sometimes liquid core (Pro V1, TaylorMade TP5). Spin is maximized, distance is less (although not much these days). Your club head speed should determine what golf ball you might consider. 

2. Friction is the force between two surfaces when rubbing together. Two smooth surfaces create little friction, while two rough surfaces create a lot of friction. That is why golf clubs have grooves and golf balls have dimples (the grooves provide the necessary friction that is created as the golf ball slides up the club face and the dimples create the aerodynamics that lift the golf ball). Any matter (dirt, water, grass) that comes between the golf ball and club reduces friction and therefore spin. This is why you will seldom see a professional spin the ball out of tall grass.

3. Dynamic Loft is the actual loft of the club at impact, which is much different than what the club reads on the bottom. The reduction in loft is due to the fact that in order for a golfer to strike down on the ball, he or she must create some forward shaft lean at impact, which reduces loft. A typical 6 iron with around 31 degrees of loft will have as little as 19/20 degrees of dynamic loft when hit by an elite level player; yet I have seen readings as high as 40 degrees from some amateurs with poor impact positions! Example of de-loft:  If you attend a PGA Tour event, you’ll be struck by how LOW their wedges actually fly!

4. Contact point on the face: Even though there is less loft at the bottom of a club face and more loft at the top (a 10-degree driver can have as much as 13-degrees at the top and seven-degrees at the bottom), a principle called vertical gear effect causes shots that are hit low on the face to have more spin than shots hit higher on the face. It seems counterintuitive but think about how much more roll you get on tee shots you hit high on the face compared to the ones you hit low on the face.

5. Speed: All things being equal, faster club head speed creates more spin and slower club head speeds create less spin.

Now let’s take a look at the swing, both with the driver and the irons. There is a big difference between the driver and the irons. 

Attack Angle: First we need to consider what is called the “attack angle.” In order to get the golf ball airborne, the club must be traveling up with most golf balls teed up, down for any ball hit from the turf. Most top players will hit DOWN four-degrees with a 6-iron, and UP one-degree with the driver. Note, however, hitting up or down does not necessarily increase or decrease spin. We also have to consider where the ball is struck on the face, as noted earlier, as well as the construction of the golf club. When the driver is struck near the top, we get a high launch and low spin which is optimal for carry. When the driver is struck nearer the bottom we get low launch, high spin - terrible for a driver. 

Swing Arc: Remember that a golf club is always traveling on an arc and on an incline. The earlier the ball is met in the arc, the less loft and spin it will have. The later it is struck in the arc, the more loft and spin it will have. So, if a lower launch and spin is desired, play the ball back, and of course vice versa for a higher launch and spin (all things being equal). 

Compression: The chart below explains collision (impact). It can be quite involved but let’s break it down: The red line is the face of the club AT IMPACT. The blue line is direction (both horizontal and vertical) of the club AT IMPACT. Now the angle between face and direction is something called spin loft, (black line). The golf ball will always be launched between the two. Consider a wedge as compared to a driver. Wedge needs a downward attack angle with a very lofted face; that creates a very a WIDE gap (difference between red and blue lines); but a driver with very little loft and an ascending attack angle has a very narrow gap. In other words, the golf ball is struck more directly or compressed more. Elite players will get 2,500 RPMs on a driver, and 10,000 RPMs on a wedge.

NOTE: The latest scientific evidence shows that there is not an increase in loft per se when golfers hit more down on the golf ball. Here’s the reason — in order to hit down more a golfer has to lower the dynamic loft of the club, which causes the ball to be launched lower. 

Final checklist for spin

• Clean your grooves and keep the surface area between the grooves roughened.
• Play a premium golf ball, one that allows for spin to happen.
• Do not expect spin off any lie where contact with the golf ball first is impossible; example — a shot from the rough, especially ones that are into the grain, as they limit friction with the ball.
• While hitting down can cause more spin, the launch may not be higher because of spin-loft (dynamic loft minus attack angle=spin loft!)