Part 3 In Response To The Customer Driver Design Campaign
In Hireko’s “We want YOU to be a part of the design process for our new 2010 driver” campaign, we showed you one rendition based upon your comments. We need your driver to first start with a solid foundation therefore we would like to take this opportunity to tell you the pros and cons on each shape or geometry so you will have a more informed understanding on why manufactures select the different shapes.
If you haven’t paid attention lately, you might have noticed drivers, fairways and utility clubs are now available in a plethora of geometric shapes. This wasn’t always the case. For a very long time, wood head shaped changed very little. One of the reasons was the wording in the Rules of Golf, the official set of rules and regulations that the golf club designs must abide by. There was and still is a small passage called the “Plain in Shape” rule:
In fear of having a head deemed “non-traditional”, manufacturers made relatively little change. But as heads transformed from wood to steel and then to titanium and other exotic materials, manufacturers started to push the envelope to help differentiate their products. But is there is a rhyme and reason behind these geometric shapes? And if so, which one may be best for you?
Moment of Inertia
One of the hot topics in golf is the term Moment of Inertia or MOI for short. Moment of inertia is a measurement of the clubheads ability to resist twisting about a known axis. A higher MOI is supposed to be a strong indicator as to the forgiveness of a clubhead. At impact, the golf ball is not always struck in line with the center of gravity, resulting in the head twisting and consequently consuming energy that could be imparted to the ball. A club with a higher MOI will resist the twisting more so than a lower MOI value.
Drivers went from being solid and made out of persimmon or laminated maple to metal in the early 1980’s. Even though the size of the heads is approximately the same, the metal woods increased their MOI over their wooden predecessor by about 25%. This is because the metal heads were not solid, but a hollow shell with a very lightweight density foam injected to dampen sound. All the weight that would have been in the center of the head was distributed to the perimeter, thus the term “perimeter weighting”. Since the advent of the petite size metal drivers of the early 1980’s, the MOI has increased nearly three-fold in modern drivers.
Golf clubs (drivers in particular) have limits on size (or volume) as well (460cc). If we want to have the largest possible club, then the maximum the dimensions would be a 5” (12.7cm) from heel to toe and 5” (12.7cm) from front to back. However, if you looked at the first 460cc driver heads, they were no where close to filling the 5” x 5” box.
Because the volume or size of the club is tied directly to the MOI, it will have limits as well. But there are a couple of other things that can be done to increase the MOI. One is to better utilize the shape, like in the direction of the new “geometric-shaped” clubheads.
Pear or Traditional
Before we get to those shapes, let’s first take a look at the benefits of the pear or traditional shaped clubheads. These are the narrowest from front to back, have a more forward and perhaps higher center of gravity than any of the other categories. When you look at the crown, it will most likely have a nice rounded top. However, their beauty is often compromised as these will possess the lowest MOI value for more workability, which is preferred by better players. Make no mistake. The modern 460cc “pear” shaped driver is still considerably more forgiving than their smaller predecessors. Examples of the traditional shape in our current product line would be the Acer XP905 and iBella Obsession.
One of the first unique shapes to become commercially available was square – after all, square justifies plain in shape, but perhaps not the interpretation of traditional that the founding fathers of golf had envisioned. The square shaped help to push more weight to the rear two corners represented by the black shaded areas. This pushes the MOI about 12% higher given the same volume and front to back dimensions as pear shaped driver.
The obvious benefit is to increase the MOI of the head for maximum forgiveness, which is recommended for golfer with more mid or higher handicaps to hit the ball straighter. To some, the downside of the square shape is its unconventional and sometimes bulky appearance. Examples of the square profile are the Acer Mantara and Power Play System Q2 series.
The triangular shape pushes weight further rearward in producing a more “pointy” shape. This shape promotes a higher MOI than the traditional shape, but not quite as high as the square. The triangular shape produces a unique appearance at address. Traditionalists who have played for many, many years might be taken aback by the shape, but golfers new to the game have had no problems with the appearance at all. Although the face height are not much, if at all different than the “pear” shaped heads, often times they may have the appearance of being shallower. This is partially due to the fact they are broader from front to back and slope down quickly in rear part of the head as they are nearly absent of any skirt. Examples of the triangular shape are the Acer XK and Power Play Caiman (use you imagination a little).
The bullet shape is more full-bodied than the triangular. These are not only broader from face-to-back than the traditional shape to move the center of gravity rearward for added stability, but also more material is pushed to the corners. The purpose of the bullet is to produce a higher moment of inertia closer to that of a square shape, but with a more traditional appearance to appeal to a wider range of players. Examples of the bullet shape are the Dynacraft Avatar XMOI and the iBella Bellisima.
The down side to some of the geometric designs is in order to achieve the 460cc volume some of the dimensions need to be modified. By making the clubhead broader from front to back, the club is generally made shallower. Therefore some golfers may have to tee the ball down slightly lower compared to a deeper faced club they might have owned. The shallower face does lower the center of gravity as well and lends itself to creating a more rearward CG to help launch the ball higher (and sometimes with less spin as well).
We hope that helps explain the differences aside from the obvious appearance at address and allows you to make a more informed decision on what you would like to see in YOUR new design.