The Importance of the Strike Point on the Club Face

What causes a golf ball to curve in the air?

Generally speaking if there's a difference between the club path and club face aim at impact then the ball will curve in the air. For example if the club face is open to the path the ball curves from left to right and if the face is closed to the path the ball curves from right to left.

The starting point of the shot is determined by the both the face aim at impact and the club path, with the face aim having a greater influence (approx 70/30 face aim/club path). The curvature is then determined by the difference in the face aim and club path as well as the difference between the angle of attack and the launch angle(spin loft).

However there is one impact factor that can skew the expect results i.e. centeredness of strike.

Let's look at two similar shots recorded on TrackMan last year to see what can happen with two different strike points on a driver.

Shot	Club Speed (mph)	Angle of Attack	Club Path	Face to Path	Ball Speed (mph)	Launch Angle	Spin Rate (rpm)	Carry (yards)	Distance to Target (feet)	Spin Axis
A	102.5	1.8	-2.1	-1.1	152.4	13.9	2437	253.2	103.5 L	-9.1
B	102.7	-0.3	-2.2	-0.5	153.2	14.2	3075	268.2	34.8 R	7.3

So looking at the club path and the face to the path in both shot A and B, both values are negative meaning both are going to the left of the target. As a result we would expect both shots to start left of the target and to curve right to left away from the target but shot B finishes right of the target (34.8 feet right) and shot A finishes a long way left of the target (103.5 L). We would also expect that the curvature wouldn't be that much as the difference between the face and the path isn't great (1.1 and 0.5 degrees). So both shots should start left of target and curve just a slight bit more.

So what happened? The factor that gives us an idea is Spin Axis, if the spin axis is minus the ball is moving right to left and positive moving left to right. Shot A has a spin axis of -9.1, much higher than the path and face to path would suggest. Shot B has a spin axis of 7.3, higher and is positive when expecting a negative value.

So what caused this to happen? The strike point on shot A was on the toe and the strike point on shot B was on the heel. There is a gear effect with the driver, toe shots curve right to left and heel shots curve left to right. This is caused by the clubface rotating around it's center of gravity on off center strikes.

Here's a link to Brian Manzella's forum with a discussion on gear effect.

http://www.brianmanzella.com/golfing-discussions/14569-off-center-gear-effect-driver-impact-affects-d-plane.html

Also note that there is little gear effect in irons.

What does this mean for you?

Just be wary of your strike point before analysing your swing. These two swings were quite similar but gave wildly different results (138.3 feet apart!!). Also, as we see in shot B an out to in path with a closed clubface can still lead to a left to right shot. Generally some would suggest closing the clubface to cure a slice but this wouldn't work in shot B.

Also a swing and strike that would cause a result like shot B with a driver would end up left with an iron.

High Launch, Low Spin - How to lower the spin

One of the main mantras that is seen for extra distance is High Launch, Low Spin. So for extra distance we should look to increase the launch of the drives while also lowering the spin. This is true for a lot of golfers but not all, some need to increase spin, while others would be better served by lowering launch. A better mantra would be 'Optimise',  i.e. seek out the optimal launch and spin for each player. For a player with 100 mph club head speed, optimal is around 14 degrees launch and 2500 rpms spin. For lower swing speeds these figures are slightly higher and for higher swing speeds these figures are slightly lower.

However for the purpose of this blog post, let's look at ways of reducing spin.

Change Ball

The easiest and cheapest way of reducing spin is to use a different type of golf ball. For example the Titleist ProV1X in general spins less off the Driver than the ProV1, the NXT Tour and Velocity spin even less and solid two piece balls such as the Pinnacle even less again.


Club Head Design

The next way to lower spin is to use a different club head. Clubs with less loft spin less. Also clubs with higher and closer to the face center of gravity reduce spin. These type of clubs normally have a deeper face. A good illustration of these points is the difference between the Titleist 913D3 and D2. The D3 has a deeper face with the center of gravity higher up and closer to the face, this promotes a lower launch with less spin, D2 is shallower and also has the center of gravity lower and further back in the head, promoting a higher launch with higher spin.

Shaft 

One of the common ways to look to reduce spin is to put a low spin shaft in the driver. Interestingly Tom Wishon states, from his testing, that the difference between the highest spinning shafts and the lowest spinning shafts is only 700 rpms. Some golfers look for exotic expensive shafts to reduce spin but a similar reduction can be achieved by changing ball.

Sometimes, changing the ball isn't enough so some of the shafts that will reduce spin are slightly heavier (75 grams and up), overall flex is stiffer, and the bend profile of the shaft has a stiffer tip.

Some examples of these type of shafts are:

Oban Kiyoshi Black
Fujikura Speeder VC 7.2
Fujikura Rombax 7Z08
Graphite Design Tour AD Di7
Mitsubishi Diamana 'aHina
Matrix 7M3, F7M2 LTD
Aildila RIP

Some golfers tip the shafts by 0.5 or 1 inch to stiffen the tip even more.

Strike Point on Club face

With the gear effect on a driver head, striking the ball higher up then the center of the club will both increase launch and lower spin. A quick explanation of gear effect is; on off center strikes the club head rotates around it's center of gravity, on woods toe strikes will try to move right to left, heel strikes left to right, bottom strikes launch lower with more spin and top strikes launch higher with less spin.

Swing Technique

The impact conditions which cause spin are spin loft times club head speed. Spin loft is the difference between angle of attack and dynamic loft. When spin loft or club head speed is increased spin is increased. We're not looking to decrease club head speed, as we would like to hit the ball further. So we would look to decrease spin loft to decrease spin. The easiest way to decrease spin loft is to change the angle of attack. For example if we go from hitting down to hitting up on the driver we generally see a decrease in spin loft.

Some ways to hit up on the ball include teeing the ball higher (also might help to strike higher on the face), moving the ball further forward in the stance and keeping the head behind the ball.

 If you have any questions or comments, please ask or post.

Under Competition, Your Brain Reverts to the Familiar

Last weekend, I attended a coaching seminar given by Dr. Rick Jensen and Henry Brunton. If you ever get a chance to attend a talk by Henry or Rick, please do, you won't regret it. They have a lot of knowledge to pass on.

This story comes courtesy of Dr. Rick Jensen.

Imagine attending a five day running school. The first day, your running is evaluated, your times are recorded, technique looked at etc.. The second day, a new running technique is introduced, running backwards. This technique will turn out to be more efficient, use less energy, put less stress on your joints, give you a better posture and eventually you will run a lot faster and longer backwards.

For the rest of the school you learn this new technique and practice it. At the start it's a bit awkward but towards the end of the week, you're getting the hang of it, starting to enjoy it and are running better and faster backwards. You go away happy and think this will be great for your running.

The following weekend, you head off on a long awaiting hiking trip to the Yellowstone National Park. You're having a great time with your family, the scenery is fantastic, the hiking is challenging but very rewarding when late on the first day you come across this

 

So what do you do? You run as fast as you can away from the bear. Would you run backwards? Unlikely. You would run forwards because that's what your brain is most familiar with. It takes a lot longer than a running school of 5 days to master a new running skill.

What does this have to do with golf?

A player's weakest skill tends to break down under pressure. What does it break down to?  It reverts to the familiar, the player's most common prior ball flight for example. Under competition, the body will revert back to what it knows best, and if a player hasn't developed or trained a new skill effectively enough, the old pattern will often show up.

How is a Skill mastered?

There are four steps to mastery.

1) Understanding Cause and Effect

2) Supervised Practice

3) Transfer Training

4) Play

It takes time to go through all these steps. When you're out playing and a new swing change isn't quite working, it just means that you haven't gone through all the steps required to master it. It doesn't mean you're choking or the swing change isn't right for you. There's no need to go back to step 1 and look for another swing fix. Consider that Tiger Woods has gone through numerous swing changes in his career and it has roughly taken him 18 months to get comfortable with the changes. If Tiger takes 18 months, practicing numerous hours a week, don't be too harsh on yourself if it's taking a couple of months for you to fix your slice.

If you would like some more information on the Four Steps to Mastery, read Dr. Rick Jensen's book 'Easier Said then Done' or contact us here at Drive Golf Performance to find out how we coach to mastery.