Other Heft Issues

Backweighting

• One of the better tests of backweighting that I have seen was done by Jeff Summitt, Technical Director of Hireko Golf, in the summer of 2009. It used to be available on their blog site; a copy can now be found here. The point of the test was "to see what happens to ball speed when length and swingweight changes." Summitt found that, even for the same golfer, a 27g backweight could add 7mph of ball speed or subtract 4mph of ball speed, depending on the club. He saw nothing in his sixteen-driver one-golfer data to hint at whether backweighting would help or hurt for any particular driver. Here is a table of the two drivers he tested with and without counterweight. (With counterweight is shaded in blue. If you understand the tutorial so far, you should have figured that out from the higher total weight but lower swingweight.)
  

  #	Length	Shaft	Freq	Head weight	Total weight	Swing- weight	MOI	Ball speed	Comments
  11	45¾	Golf Gear CT-58	234	196	305	C8	2918	143	Long, high
  11C					332	C1		150 (+7)	Longest of CT-58, but inconsistent
  12	45	Aldila NV-65	252	201	321	D2	2918	156	Longest and straightest by far
  12C					348	C5		152 (-4)	Straight, but shorter with the counterbalance

  
  
• Tim Hewitt of MyOstrich Golf, one of the more experienced people at fitting for backweight, has posted to SpineTalkers his experiences and methods. His conclusion: "I don't know of ANY science that has been able to predict which clubs will benefit which player, or been able to find the commonality in finished clubs that can predict the combination for the next club. I have even had single length iron customers benefit in odd clubs throughout a set - with clubs that were virtually IDENTICAL club to club."

• Doesn't affect MOI -- We know that weight at the butt of the club is not going to affect the moment of inertia. So that isn't what is going on.
• Computer simulations -- I investigated the effect of backweight, using Max Dupilka's "SwingPerfect" program. It showed only a tiny effect from backweighting -- even with backweights as high as 100 grams -- and less than a 0.1% effect from the sort of backweights that are normally used. So there is nothing in the physics to support backweighting a club.
• Wristwatch analogy -- If there were any physical validity to backweighting, then a wristwatch or weighted bracelet should have the same effect. A metal men's wristwatch weighs between 50 and 80 grams, quite a bit more than most backweights. And a wristwatch has just about the same effect on the equations of motion that a butt weight would. Both would show up as extra mass very close to the hinge; which side of the hinge it was on would make almost no difference in the equations of motion that govern the swing. (That's true for any physical model of the swing, not just Jorgensen's model.)
  But, in fact, informal experiments have shown no effect due to the weight of a wristwatch on the wrist.
• More wisdom from Jeff Summitt -- In an email discussion with Jeff, I mentioned that robot testing does not show any effect from backweighting. He responded, "You are right, a robot will not tell any difference in counterbalancing, but a human can (well at least some will). While at Dynacraft, we had a very special test club that was counterbalanced by 30g (±2g), can't remember exactly since it was so long ago. It was a heavy club, but not when you picked it up and tried to waggle it. There was an identical club sans counterbalance as a control. Inevitably the students would swing the counterbalanced club faster and change their swing from outside-in to inside-out. It was truly amazing how it would work on some people but not all. "

• Wisdom from Leith Anderson -- Leith Anderson probably has more experience fitting backweights than almost anybody. He says that they are almost universally helpful, but at different weights for different golfers. Also, bear in mind that he focuses just about exclusively on good golfers who are willing to work and practice to get better. That puts his clientele in a small minority to begin with. Anyway, Leith told me, "I have done that hundreds of times. I use the Achiever. I set the benchmark with no weight. Then, I swap 5g, 10g, 15g, and 20g weights and look for improved patterns in swing path, face angle at contact and launch angle. The Achiever has one terrific report that shows all that on one page with the average deviation numbers. I have literally sold hundreds of customers counterweights. They stay installed. I have taken out two or three sets of counterweights and an occasional one with a driver. I'm not saying it's 'pure science' because I slip in a little swing advice - most players don't know what they ought to be trying to do." So Leith's approach is organized trial and error, augmented by a lesson while he fits.
• How about negative backweight? Since the helpfulness of backweight varies from golfer to golfer, it is reasonable to ask if some golfers need negative backweight -- that is, less weight in the butt of the club. It would be a huge coincidence if only positive backweights help, given that the best weight varies markedly, and many golfers are not helped at all (at least if we believe Jeff Summitt's testing). And apparently there are a lot of golfers who prefer a negative backweight. How do we know? Winn grips makes a lot of money selling lightweight grips, maybe 10-25 grams lighter than normal. But that is exactly the opposite of adding 10-25 grams of backweighting.
• The TaylorMade Bubble -- In fact, negative backweighting predates the popularity of backweighting by several years. When TaylorMade came out with their Bubble shaft in the mid-1990s, there was a lot of mystery and "magic" about what it did. Those clubfitters who did their homework figured it out fairly quickly, and it was both simple and surprising. By far the biggest difference the Bubble shaft introduced was the ability to add a very light grip. Very light! In fact, it was 30-35 grams lighter than a standard grip. This suited a large number of golfers, and the clubs were popular for years. And their unique feature is a negative backweight of 30-35 grams. (Note that a positive 30-35 grams is the very high end of conventional backweighting.)
• The Heavy Club -- Steve Boccieri of Boccieri Golf pioneered a club named the Heavy Putter in 2004. He came up with a putter head that was by far the heaviest on the market, then countered the extremely head-heavy feel with a huge backweight (over 200 grams). Since then, he has concluded that the same approach (albeit less extreme) works for full-swing clubs, too. His company now makes the Heavy Driver, Heavy Wedges, Heavy Irons, etc. He goes with a heavier head (to make the golfer hit with the body rather than the hands) and a slightly shorter overall length of club, then counters the extremely head-heavy feel with a much bigger backweight than you would expect from a typical Balance Certified fitting. For instance, the Heavy Driver has a standard backweight of 50 grams. The trick in all the Boccieri clubs is to add enough backweight so the balance point of the club is actually significantly higher than the balance point of a "normal" club of the same designation. For instance, the modern driver has a balance point of about 12", while the Heavy Driver's balance point is closer to 15".

Total weight

• Tom is completely committed to the importance of MOI as opposed to swingweight. I also believe that MOI is fundamental, and swingweight is not -- and I went to some pains to make the case for that belief earlier in this chapter. So let's just assume for this argument that MOI matters and swingweight does not.
• The only ways to make a large difference in overall weight are the shaft weight (e.g.- ultralight graphite to standard-weight steel), or backweighting (see above).
• Changing the shaft weight also affects the MOI of the club, so it has other effects besides just changing the total weight.
• Changing the grip weight or adding butt weight does not affect the MOI, so only the total weight is affected. But, as we saw above, butt weight has no effect on clubhead speed by itself. It may have an effect for some golfers, but that is a feel issue that causes the golfer to change his swing.
  

1. We'll include ball speed.
2. We'll sort the rows in order of total weight.
   

And here it is plotted as a graph. This shows very clearly that Wishon is right. While the clubhead speed jumps around as we vary total weight, the ball speed progresses smoothly, almost proportionally. In fact, it is nearly a straight line, with a slope of 1mph of ball speed for every 10 grams of weight saved. As an example of what is possible, look at the two yellow rows of the chart. Each has the same MOI (the same basic heft feel) as the base club. But one is 40g lighter than the other, and gives 4mph more ball speed. That translates into six to ten extra yards of distance. No, it's not going to turn you into a "big hitter". But it's a pretty sizeable increase, among those things that just club design can do. Of course, there are practical limits to how much you can do by reducing total weight. Here are some of the more important considerations.