## Thursday, June 20, 2013

### The Road to Golf Club Fitting Nirvana - Part IX

I am returning to this series after a bit of a layoff. Most of it was due to me getting my Sand Wedge grinded by Joe Kwok (www.joekwokgolf.com). The other part was to me installing a new driver head (still the same Wishon 919THI model) along with studying Monte Doherty’s worksheet some more.

One thing I figured out is a bit of a better way to understand MOI Balance Index (MBI). Here’s a chart showing each of my irons that are MBI matched. It shows the weight of the clubhead versus the weight of the shaft+grip. And then the percentage of shaft+grip weight to the clubhead weight.

(Click to Enlarge)

There is some significance to this:

1. We can see that the percentages are roughly at 58% to 62%. My target MBI is 38.0 to 42.0.

2. If we understand the ratio of shaft+grip to head weight, we can then get a better idea of how much the shaft will have to weigh given the weight of our club head and grip. For example, let’s say we have a driver head that weighs 208 grams. And we have a grip (w/grip tape included) that weighs 50 grams. If we want out shaft+grip to weigh 50% of the head weight, we know that our shaft (trimmed) will need to weigh *roughly* 54 grams:

50 g (grip) + 54 g (shaft) / 208 g (head) = 50%

Now, I say it is a ROUGH estimate because as you can see some of my irons stray from the 58%-62% shaft+grip versus clubhead ratio. This is the reason for Doherty’s spreadsheet as it factors in the balance point of the club along with the type of head design to calculate the rest.

The other part is that we STILL have to match the MOI of the clubs. So, in the driver example if we have a 208 gram driver head and a 50 gram grip, we could put a 54 gram shaft in there and get the percentage at 50%. But, if the MOI comes out to 2,700 and we need the MOI at 2,750; we need to add weight to the head and/or the shaft in order to match the MOI.

We’ll want to keep the percentage roughly at 50% still as we add weight so we match the MOI. In the end, the knowledge of the percentage of weight between the shaft+grip versus the clubhead gives us a START as to rough amount of shaft weight. And we can always add weight to either the head or the shaft. But, removing weight from the shaft or the head is a different story.

***

When I originally started this series, I had determined that I did not want to fool around with my Lob Wedge since I hit that very well. But, as I started to MOI and MBI match my irons and I liked the process, I decided to alter all of my clubs. In the end, I figured that if I started hitting my Lob Wedge worse with MBI matching, I could always go back to the old specs of the club.

Ironically, the Edel wedges were the clubs that initially got me into MOI Balance Index. When I first started hitting them, I was not hitting them as well as I did in the fitting. The heft of the clubs didn’t quite feel the same. I then measured the static weight of the clubs and noticed they were quite heavy despite being MOI matched. Later, I disassembled the clubs and noticed that Edel uses heads that are quite heavy. The Gap Wedge came in at 305.3 grams, the Sand Wedge at 307.4 grams and the Lob Wedge at 309.5 grams. The Sand Wedge and Lob Wedges are much heavier than any raw OEM wedge head that I’ve found. That is not a bad thing, but for optimal fitting there needs to be the right amount of head weight versus shaft weight and the right MOI.

My solution at the time was to try to match the MOI, but to lower the overall static weight. I did this by using a much lighter shaft in the Dynamic Gold SL model which is roughly 12 grams lighter than the originally installed KBS Tour C-Taper shafts. I started to hit the clubs a little better. But in conclusion, I had always been hitting the Lob Wedge well and I just struggled with the Sand Wedge.

Here is a look at the Sand Wedge specs BEFORE I sent it to Joe Kwok:

As we can see, the MOI matched. But, the Balance Index was WELL off (50.12 with a target of 38.0 to 42.0) and the % of the shaft+grip weight vs. Head weight was also well off (48.43% vs. 58% to 62%). Essentially, the Balance of the Club is well off for my swing and head was too heavy with relation to the shaft.

Often times with MBI matching, the solution is simple. Get a heavier shaft. So I tried to install my old KBS C-Taper shaft and found the following results (again, this is BEFORE I sent to wedge to Joe Kwok):

What we see is that the heavier KBS C-Taper shaft helped get the Balance Index down more towards the target (38.0 to 42.0). The problem was that the maximum weight I could add to the shaft in order to lower the Balance Index was 3 grams. Any more lead tape added to the shaft would cause the MOI to not match.

That’s when I started to determine that the weight of the head had to be lighter. And the only way to achieve that was thru having a professional club grinder to properly grind the head and take some of the weight off. Thankfully, with Doherty’s sheet I could determine roughly how much weight I should take off.

Here’s a picture of the head grind as Joe ground some off the head. The grind made a little indentation which is what I asked for:

And here are the new specs:

Joe was able to shave off about 5 grams off the head. I then added a little extra lead tape to get the head weight just right. This allowed me to add a lot of weight to the shaft and the end result was a MOI and MBI that matched. And in turn, I hit the Sand Wedge much better and it’s a full-time club in my bag.

One question I am sure that will arise is ‘why didn’t you just get a heavier shaft?’

Remember, we have 2 things that take precedent over MOI Balance Index matching:

- Matching the MOI of the entire club
- Getting the correct shaft bend profile for your swing

Without those two, Balance Index matching is virtually worthless. I just simply could not find a substantially heavier shaft that would allow me to match both the MOI and the Bend Profile.

With that said, Wishon’s new Shaft Bend Profile software was updated. And we found that his Wishon Stepless Steel (stiff) shafts have virtually an identical bend profile to the KBS C-Taper R+ shaft model. The Stiff flex model has a much stiffer tip section.

(CLICK TO ENLARGE)

I know when I tried the C-Tapers out in my irons with a Stiff flex, I was losing about 1-club of distance. I also know that as far as the flex labels go, Wishon’s shafts tend to play quite a bit stiffer than most OEM shafts. So, if the KBS C-Tapers play stiffer than the Wishon shafts, you’re really dealing with a very stiff shaft.

Anyway, while I’m pleased with the wedges and the changes made by Joe Kwok. I plan on installing the KBS C-Taper R+ shafts soon and I think then we have found the ultimate fit for these wedges.

3JACK