The Driver and Accuracy (Part 2)

We all want to hit the ball straight and far of the tee don't we? In more technical terms our goals with the driver are to achieve the highest ball speed possible (distance), along with the desired flight pattern (accuracy). We want cake and we want to eat it too!  Here's a run down on what club manufacturers have been working on to help us keep the ball in the fairway...

The primary factors directed towards accuracy are bulge and gear effect, center of gravity placement, adjustable heads or weights, a preset face angle and the clubhead design.

  • The most interesting element built into each driver that serves to increase accuracy is the one two punch of bulge and horizontal gear effect.  The face of every driver (all clubs requiring a headcover for that matter) has roll and bulge while irons do not.  Bulge is the curvature of the face from its heel to its toe, while roll is the curvature of the face from the crown to the sole.  Bulge starts the ball farther to the right on toe shots and farther to the left on heel shots and is a correction for the clubhead’s center of gravity (CoG) that causes hooking or slicing (gear effect) on off center shots. In other words, manufacturers have built bulge into the face to counter the negative results of gear effect.  Here is an explanation (BTW Irons do display gear effect just far less than drivers):

Here's a definition of gear effect from Dave Tutelman (who has an excellent site for the scientist golfers out there):

Gear effect causes a ball to  have sidespin which is the result of an off-center hit with a club whose center of gravity is well back from the clubface.

Without an off center hit and a CoG that is well behind the face gear effect cannot happen.  In the picture above, we have a toe impact with an iron and a driver.  The center of gravity (CoG) is indicated by the black and white circle.  The collision between the clubface and the ball on the toe creates a torque that causes the club to twist - the club twists around the clubs' CoG which is indicated by the red arrow.

The CoG on the iron is virtually on the face and this type of strike causes the face to rotate open.  This invariably causes the ball to fly weakly to the right as there is no gear effect on the spin imparted on the ball.

The driver is very different.  With the CoG being further back from the face a toe impact causes the entire face to rotate around the CoG.  As the ball compresses and grips on the face the red arrow causes the ball to actually rotate to the left (blue arrow) - the ball and the face actually work like two gears!  Thus the term gear effect.  And the reason why a toe hit with a driver tends to hook and a a heel hit tends to fade.  Bulge helps out by launching a toe hit to the right of the target - a good thing if the ball has draw spin.

  • The design and shape of the clubhead is something that we have seen much tinkering with in recent years.  From the triangular Titleist 907 D1 (how could you forget that!) to the onslaught of ugly square heads - these designs all strive to do one thing - re-position the CoG to stabilize the head during off center hits.  The longer (from face to back) the clubhead is, the further back the center of gravity is from the face which also increases gear effect.  If you can deal with the aesthetics of these scientifically upgraded clubs by all means have at it.
  • Another modern trend that has been proven to straighten wayward tee balls is the advent of adjustable weights or screws on the clubhead.  Originally introduced by TaylorMade in their R7 line, tests have shown that the higher the swing speed the more a golfer is able to curve a ball by changing the weights in the clubhead.  A golfer with a swing speed of 115mph (PGATour average is 112mph) will experience 35 yards of curve while a golfer with an average type speed of 85 mph will only experience 6 yards of corrective curve.
  • Along similar lines are the adjustable heads where the shaft rotates in order to adjust the loft or lie. While changing the loft will not do much to improve your accuracy, altering the lie angle can help you make subtle changes.  Moving the shaft to a more upright position will promote a draw, while flattening will promote a fade.
  • There is also the preset face angle. For those golfers out there who struggle with slicing this has been a tremendous help.  If you feel like you could benefit from this just look for on offset driver or one that says draw somewhere on the head.

There are also rumors that there are certain shafts (Nunchuk) that make the ball go straighter, but I have not read anything or seen any convincing evidence to support this.

Thanks for reading and I hope that now you have a better understanding of what your driver can do for you....

Weight Transfer and Positioning

Having the use of the Swing Catalyst system has almost been like being able to look behind the curtain to see what truly happens to a golfers' weight when they swing the club. Guesswork and perception are taken out of the equation and the information you read in the following post is based purely on fact. 

Weight shift is a poor term.  Similar to the term "takeaway" it does not convey the appropriate sensation.  My research has shown that the term "weight transfer" would be far better.  And here's why: When I think of shifting my weight I make a conscious move to get my body over to my back foot for example.  Not good!  The weight transfers in the swing purely due to the motion in the arms hands and club as they travel away from the target.  Think of it this way - if I swing my arms, which each weigh 15 lbs, and a club  in my backswing you can be sure that I am transferring weight onto my back foot. There is however no conscious shifting or body move that gets the weight over there. This is exactly why the 84 degree  rule (as illustrated below) holds true.

There should be no lateral body move in the backswing, yet many players often wrote or spoke about a sense of weight transfer. The body stays centered while the weight is transferred by the motion in the arms and the club. Video HERE

I found that very good golfers (college and touring professionals) had a maximum percentage of 80% of their weight on their back foot slightly beyond halfway back.  This was achieved with almost no lateral movement in the upper body.

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In the screen shot above notice how the center of gravity indicator between my feet (top right) is almost as far to the right as it goes. This should be the furthest point to the right the weight moves and from here it starts moving back to the front foot.

I did find that a reverse weight shift (reverse pivot) was almost impossible for me to achieve. With the arms and club swinging to the right it made it very difficult to get the weight to favor the front foot in the backswing.

In the screen shot below I have positioned my weight 70/30 on the front foot (with the 84 line as a reference) at the top of my swing as advocated by some teachers. While the numbers may be difficult to achieve I did find that for many people the idea of keeping their body left and sensing the weight being 70/30 in favor of the front foot proved to be very helpful. This helped me to seperate the difference between what a student felt and what was real.  Many times it was better for a student to work towards a feeling than the actual reality.

Click to Enlarge

At the start of the downswing, when the left arm (for right handers) gets parallel to the ground the majority of top tour professionals displayed a weight distribution of 50/50.  Sam Snead illustrated this beautifully!

I did notice that with single figure handicap golfers there seemed to be a tendency to get their weight too far forward (75/25) at this point. This led to a situation where, when they got to the delivery point (shaft parallel to the ground), they very often had more than 90% of their weight on their front foot and had to back up through impact.  This seemed to be a contributing factor to hooks and blocks - the better golfers most common malady!

All the best ball strikers studied displayed a tendency to transfer the weight to the front foot in a smooth and continuous flow with no backing up or slowing of the transfer. The more straight and direct the CoG trace moved the better. This meant that they arrived at impact with an 80/20 split favoring the front foot and the weight continued to move smoothly over to the front side beyond impact.

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Notice the continuous and smooth CoG trace into the front foot here by Billy Hurley.  His weight was more than likely 85% on the front foot at impact.

The tendency with higher handicap golfers (above 18) was for the weight to get too far back and then remain there all the way through impact. It was not unusual to see one of these golfers have a split of 70/30 favoring the back foot at impact.

In summary:

  • The weight should start at 50/50
  • Somewhere between halfway back and the top of the backswing the player should max out weight on the back foot at 80/20
  • At halfway down (arm parallel to the ground) the weight should once again be 50/50
  • The weight should make a continuous tranfer to the front foot in the downswing with an 80/20 split occuring at impact. 

A few more screen shots:

Geoff Ogilvy passing through impact (shaft bend is due to camera lens)

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Peter Uihlein at impact

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Please keep two things in mind as you process the above information: due to the relative newness of this technology there is not a huge sample group of golfers to study and that all percentages are a mean or "ballpark" number.

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The New Driver Terminology...MoI, CoR and CoG

As players on the PGA Tour started using 20 year old Ping Eye2 Wedges I started thinking about how much (or little) technology has effected equipment in the last two decades. The facts are: Other than changes in the golfball, driver and the invention of hybrids very, very little has changed. Excluding the advent of perimeter weighting (which is very similar to toe/heel weighting) when it comes to irons there have been no groundbreaking upgrades. Wedges are the same and fairway woods are just like they used to be - in fact, the better ones look just like the really old ones. The driver has been the primary club in the bag for technological advancement. And with this progress has come an entirely new language. What does MoI mean? What is Cor? Whaaat....? Here is a brief primer, compliments of my friend Ian Hayes, on some new driver terminology:

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