Nunchuk Shaft

This keeps coming up, so let me put up an article I can point to when asked...

Around the beginning of 2011, NVentix introduced the Nunchuk shaft. Since then, the subject comes up on various golf forums about whether its rather radical claims and design are a good thing or bad. And I have been asked the question directly. Here are a few posts on the subject, which really constitute the bulk of my thinking about the Nunchuk.

Bear in mind that I have not used it myself, nor done any scientific measurements on the shaft or other golfers swinging it. This is just reasoning from their claims, through the lens of my experience with shaft analysis.

From the Secret In The Dirt forum about March 24, 2011, in response to a post by Mark Blake:

Dave Tutelman

Fresh Boarder

Posts: 17

Hi, guys!
Mark asked me to comment.
Mark Blake wrote:

Now what I would really like to know is what Dave Tutelman thinks of this shaft, considering he is probably the only person I could trust to be objective. :)

Objective? Perhaps.
Experienced? No.

I have never used the Nunchuk, nor have I had the opportunity to profile it. (At $250, I don't expect to have one to try or profile any time soon.) So I have to go by its specific claims and how they relate to my knowledge of science. Here goes...

New driver shaft on the market, the Nunchuk, as used by Johnny Vegas who just had a win.

OK, so we know it fits SOME golfer. Johnny Vegas likes it.

Read all about it here: www.nventix.com
but the basics are
- one size only, fits all, from Bubba Watson to my Aunty Dora

Every golfer? I kinda' doubt it. Read on.

- stiff tip and butt and soft mid section.
- weight is 104g
- cost $250

It's a very VERY tip-stiff shaft from their claims and what I could see from the video. That does make a few of their claims work, but not all. And it gives the lie to the notion that it will fit Aunty Dora, or even me. From my experience (and that of most clubfitters I know), the majority of golfers actually do better with a tip-flexible shaft. Not the majority of strong, big-hitting golfers, but the majority of the folks out there.

Normally, a super-tip-stiff shaft will feel like a telephone pole. They way the Nunchuk gets around this is to have a flexible area (almost a hinge, like a real nunchuk) in the middle of the shaft. Not a bad idea. Definitely not original!

Around 1990, I built a set of irons for myself with TrueTemper Flex-Flow shafts. They had a pinched "waist" to control where shaft bend occurred. The waist was at a different height for each club: high for the short irons and low for the long irons. It was not high for all the irons (as the Nunchuk would be), because most golfers need a more flexible tip on the longer clubs.
The Nicklaus clubs in the 1990s had a proprietary shaft called the Crankshaft. It did the same thing. In fact, it was made by TrueTemper. I'm pretty sure they were the Flex-Flow with a private label.
In the first half of the 2000s (perhaps still), Fujikura was known for a stiff tip and butt and a soft middle. That sure sounds like the Nunchuk.

My first reaction to that, is what a load of crap, goes against everything a clubmaker has ever told me, but reading the product info, it does make sense

Sorry, but my instincts still say "what a load of crap". Not that it is a bad shaft for some folks, but most of the claims are nonsense and I strongly suspect most golfers would hate it.

First the good news
One claim that I buy is that the leading bend is reduced. Tip-stiff does that. It is not for everybody, but if it is for you then that is a good thing.

For the same reason -- tip stiffness -- it does limit toe droop. That is almost certainly a good thing. (But you may have to be re-fitted for lie, if you use it on a club where lie matters. You probably won't.)

The claim that it increases ball speed because the clubhead does not lose as much speed during impact is marginal. But let's give them that. There may be a little more shaft mass involved in impact (because the tip of the shaft is stiffer and the shaft is heavier). This could raise the momentum transferred infinitesimally. Let's assume that this combination adds an effective 20g to the clubhead for purposes of momentum transfer. (Probably not that much, but let's be optimistic.) A big hitter with a 120mph clubhead speed (that is BIG) would see an extra six yards or so. Not a huge amount, but certainly not to be sneezed at.

That's sorta' the max. More realistic assumptions or a more "normal" golfer would not see nearly as much gain. For instance, 10 grams and a 100mph swing speed would see a little over two extra yards. Hardly enough to get a consistent experimental verification without a robot.

Now the bad news
One size fits all? I don't think so! If the Nunchuk theory were correct, all proper custom fittings (before the Nunchuk was available) would result in the most tip-stiff shaft money can buy. But they don't. Except for big hitters, the good clubfitter and his launch monitor just as often fits a tip-flexible shaft. I won't go into the reasons here -- too much to say and too little time -- but the Nunchuk does not negate these reasons.

How about clubhead lead and "energy loss". That's a red herring. Sounds good, but really not much to it. Energy is the product of distance and force. If you reduce the lead by making the shaft stiffer, you are increasing the force. So, if lead represents energy loss, then both shafts are the same. (I won't discuss here whether lead is energy lost. That is a controversial statement anyway. But the energy represented by the lead is the same for the Nunchuk -- less lead but more force.)

Then, there's the issue of spin. Sidespin is not reduced by tightening the torque of the shaft. Gear effect here is not reduced at all. No advantage to Nunchuk. But let's talk about backspin and vertical gear effect.

The reason you want to hit the ball above the center of the driver's face is that vertical gear effect will reduce backspin for a high-face hit and increase backspin for a low-face hit. But, if you manage to get a really REALLY tip-stiff shaft, vertical gear effect might be limited. Let's assume that the Nunchuk is sufficiently tip-stiff to limit vertical gear effect significantly. I don't know that it is, but let's assume. In that case:

If you hit the middle of the clubface or below, the Nunchuk will limit the increase in backspin. That's good.
If you hit high on the clubface, the Nunchuk will limit the decrease in backspin. That's bad.
Either way, you probably need a driver with less face roll than most commercial drivers have. E.g.- something like the Wishon GRT.

Bottom line: the Nunchuk will be more "forgiving" of low-face hits, at the expense of potential gain in high-face hits. If you're skilled enough to make high-face hits, that's a disadvantage. If you hit all over the face, the Nunchuk may be able to limit the distance dispersion.

That's all I can think of for now. There were other things that occurred to me as I watched their video and read their web site. But I've hit the high points.

DaveT

Dave Tutelman

Fresh Boarder

Posts: 18

Dave Tutelman wrote:

That's all I can think of for now. There were other things that occurred to me as I watched their video and read their web site...

I just recalled one other point, and it is sort of important.

They slammed the current trend in driver design, which is to use ever lighter shafts to build ever longer clubs. Nunchuk is a heavy shaft. So a driver with the proper swingweight/MOI for the golfer is going to be shorter with a Nunchuk.

They are right about that! Long clubs are harder to control. I won't go into the details here, but my own drivers are about 44.5", an inch or more shorter than the typical commercial driver. And I start beginners with a driver of 43.5". (Just built one for a second-year golfer, and played with him yesterday the first time he used it. He hit more good drives yesterday than the previous three rounds I played with him. So the principle works.)

That said, we have to look at how we get the club shorter. Going with a heavier shaft is not silly at all, but it is not the best way. Adding weight to the clubhead turns out to be better. You don't have to add as much weight to keep the club's heft the same. So heavy head and light shaft is always my preferred method, if I can. If not, a heavier shaft is still preferable to a too-long driver.

I have analyzed this before; see the article on my web site. The gains from light shaft and heavy head are comparable to the gains from my most optimistic assumption for the Nunchuk from my previous post.

DaveT

From the TrajectoWare forum on April 4, 2011, in response to a post by David Bahr:

dtutelman

Posted: Mon Apr 04, 2011 10:25am Post subject: Re: Nventix Nunchuk Shaft

Site Admin

Joined: 09 Apr 2007

Posts: 80

Location: New Jersey,

USA

Hi, David!

NYKnuckleballer wrote:
One shaft fits all, from A flex to XXX flex, from hybrid to driver. Smells gimmicky. But I have heard some glowing reviews.

Same here. Smells gimmicky. Heard some glowing reviews.

I did a quick-and-dirty assessment based on analysis. I've never actually hit one myself. It was at the SecretInTheDirt (http://www.secretinthedirt.com/index.php/forum/133-driver-golf-shafts-group-forum/10941-nunchuk-driver-shaft-unique-concept) forum. I guess an article on my web site wouldn't hurt -- when I get around to it.

Quote:
The same head, 9* loft, was used in all testings, as well as the same golfer, who by all accounts is very, very solid. The machine was the Flightscope Kudu.

Below are the numbers in a nutshell:

Ball speed for all three shafts is basically 157 mph across the board.

LA numbers in order (Kyoshi shaft, Kai'li shaft, Nunchuk shaft):
12.3 Vertical, 1.3 Horizontal Right
11.9 Vertical, 1.7 Horizontal Right
10.6 Vertical, 0.9 Horizontal Right

Backspin Numbers (same order):
2,428
2,304
2,855

The Nunchuk is living up to it's billing of low launcher or launches true to loft. What I don't get is how?

I find it curious that the lowest launcher would have the highest spin. I guess this means the dynamic loft was highest at impact but that would also imply the AoA was lowest with this shaft. Why would someone launch 2+ degrees higher with two softer tipped shafts? Wouldn't a softer tipped shaft bending forward at impact, create a greater dynamic loft? I just can't picture how this shaft is doing it's thing.

Actually, David, it makes a bunch of sense. The lower launch angle with the super-tip-stiff Nunchuk isn't surprising. Apparently it's not surprising to you either. The increased spin is the issue, and it should be. Here's my take:

Let's assume that, as you noted in the overall description of the test, the golfer making the swings is very solid and repeatable.

Point #1: The difference ain't gonna be the angle of attack! A 2-degree difference of AoA is a big swing change for a repeatable golfer. And the combination of effective loft and AoA doesn't sound like anything a shaft would do on its own.

Point #2: If the guy is repeatable, he probably hits the ball in the same spot on the face nearly every time. And if he is solid -- a good driver of the ball -- that spot is high-middle on the face. So he is getting backspin reduction from vertical gear effect. (See http://www.tutelman.com/golf/ballflight/gearEffect2.php)

What does all this tell me? It is possible that a very tip-stiff shaft will limit the vertical gear effect, and the result would be more backspin. Dana Upshaw has observed this effect years ago, with less radical shafts than the Nunchuk. My own analysis (http://www.tutelman.com/golf/ballflight/gearEffect4.php) suggests that the effect should be a lot less than he observed. But a super-tip-stiff shaft like the Nunchuk might emphasize the effect that Dana observed, and that could explain the spin results.

Hope this helps,
DaveT

Quick Guesses about the Nunchuk Shaft

Empirical evidence: