The Stability Shaft – how good for your game is a high-tech, multi-material putter shaft?

As I mentioned in my previous post – Putting is hard – but you already knew that, right? –  I bring years of experience as a mechanical engineer, and a naturally skeptical nature, to the task of reviewing and evaluating golf equipment. I am very critical of the performance claims that equipment manufacturers make for their latest design innovation, and I subject them to close scrutiny. Putters seem to be the worst offenders when it come to gibberish tech-speak, but many golfers still seem to eat it up.

Because of the difficulty of putting and the irrecoverable nature of poor performance on the greens, club manufacturers seem to be constantly introducing some new high-tech innovation that will help golfers improve their putting. Sometimes it’s a training aid, sometimes it’s a design tweak to the putter itself, but it seems as though there is always something new coming down the pike when it comes to putters.

The latest high-tech innovation to come to putters is the Stability Shaft, from Breakthrough Golf Technology, with the involvement of well-known golf club pioneer Barney Adams, the inventor of metal fairway “woods” – the original Tight Lies clubs. While I will admit that this is a fairly new approach – little has been done with putter shafts over the years – the needle of my skepticism meter started twitching as soon as I read the ad copy on their website.

Wait, it does what?

The four-part, multi-material Stability Shaft is made up of a carbon-fiber composite tube, which forms the grip end and most of the length of the shaft; an aluminum insert placed inside the carbon-fiber tube at its lower end to “reinforce flexural rigidity”; and a 7075 aluminum alloy connector which adapts the upper end of the shaft to the conventional stainless steel tube which mates with the putter head.

The main structure of the shaft is described as “Eight layers of high-modulus carbon fiber specifically layered, wrapped and widened, with a no-taper design to greatly reduce torque.” This statement makes little or no sense in terms of mechanical attributes of the structure, or the functional requirements of this portion of the putter shaft. The little loading, either in bending or in torque, that a putter shaft experiences is concentrated at the other end of the shaft, where it is joined to the putter head.

Regarding the aluminum insert, their ad copy says, “Through finite element analysis a light-weight, 22-gram aluminum insert was developed and precisely located to reinforce flexural rigidity.” (“Flexural rigidity” is an oxymoron, by the way.) If the high-tech “high-modulus carbon-fiber” main body of the shaft is so precisely designed to resist deformation due to torque loading (which is what they really mean by “…a no-taper design to greatly reduce torque”), why are they adding half the weight of a golf ball near the middle of the shaft to increase rigidity?

Another claim for the Stability Shaft is that it “…delivers the face squarer at impact for improved accuracy and solid feel…”. The forces acting on a putter are low at impact, even lower during the swing. The rigidity and stability of a putter shaft is concerned with forces that are substantially less than those encountered in a full swing club, so what forces do the designers of this shaft feel are acting to deform the shaft of a putter during the swing? The only rotation experienced by the putter face will be the result of rotation of the entire club, caused by variability in the player’s grip, and arm and hand movement.

Fancy data says what?

The website for Breakthrough Golf Technology offers a pair of graphs which are said to show the velocity of the heel and toe of a putter with a standard steel shaft and with the Stability Shaft. Represented as showing toe and heel velocity at a data rate of 2,500 frames per second, based on the “Frame Number” scale along the bottom of the graph, they depict a little over 1/10th of a second in the motion of the putter, about 3/4ths of which is before impact. The lines for toe and heel are fairly uniform preceding impact (though apparently offset, which must be for clarity, to differentiate between the two, because unless the putter is moving through an arc, they should be moving at the same rate), but after impact the graph for a “Standard Steel Shaft” shows significant deviation of the two lines from each other, represented as a difference in velocity between the heel and toe. The graph for the putter with the Stability Shaft shows much more uniform velocities for the heel and toe, ramping up again evenly after the expected drop at impact.

Putter with a standard steel shaft

Putter with the Stability Shaft

Leaving aside the other questions which these graphs raise (the unlabeled velocity scale, for example, and the lack of information about how the data was gathered), what value is there in uniform velocity between heel and toe, if indeed that is what is actually being depicted, AFTER impact? If the ball is no longer in contact with the club face, no movement that the club face undergoes has any effect on the motion of the ball.

The amount of time represented in the graphs after impact, again, based on the frame number scale along the bottom, is approximately 4/100ths of a second. The changes in velocity depicted on the graph – which are not quantified – occur in a very short timeframe, and there is no information offered as to the magnitude of the displacement which these “velocity changes” represent. If the concern is the squareness of the club face, it is obvious that the relative displacement, therefore the relative positions, of the heel and toe of the club would be of concern.

You keep using that word. I do not think it means what you think it means

The more I looked at and thought about the data that these graphs are supposed to represent, the more I came to be convinced that these graphs must depict vibration in the club head measured at the heel and toe ends, not the velocity of the heel and toe of the club head.

The graph for the steel shaft before impact shows tight, consistent data for the heel and toe, with after-impact data that is consistent with undamped vibration in a rigid material, such as a high-strength stainless steel shaft. The graph for the Stability Shaft depicts slightly less-regular behavior before impact compared to the steel shaft data, and a well-damped behavior afterwards. The latter is consistent with a system which contains a vibration-damping component such as a wound carbon-fiber tube.

How I evaluated the Stability Shaft

My experience with the Stability Shaft is based on the conversion of my Odyssey Tank Cruiser blade putter. Before sending it off to the people at Breakthrough Golf Technology, I swapped out the counterweighted original shaft (because I would not be getting it back) for the plain steel shaft from (ironically…) an old Tight Lies stainless steel blade putter. The Tight Lies received the counter-weighted shaft from the Odyssey.

Needless to say, when I got the Odyssey back with the Stability Shaft installed, it felt much different. Not bad, necessarily, but different. The balance was off, for instance, without the counterweight, and I noticed that the head was a bit wobbly in the take-away as a result. In order to make this as complete a test I could, after a few weeks of using the club as-is I decided to remedy that situation.

A trip to a local golf shop netted me a 50-gram counterweight kit for Super Stroke putter grips. Even though I don’t use that type of grip, I was able to install it securely in the grip end of the re-shafted Odyssey – and it transformed the putter’s performance.

Counter-weighting increases the inertial moment of the putter (its resistance to rotation) along the long axis from grip to club head, stabilizing the club during the takeaway and the down swing (such as it is with a putter.) I had noticed the difference with the Odyssey when I first got it, installing the grip counterweight after having used the club for over a year with no weight in the grip, and I noticed it in the Odyssey Mk II (as I am referring to it) with the Stability Shaft. I now own two counter-weighted putters – the Odyssey Tank Cruiser with the Stability Shaft, and the old Tight Lies which inherited the Odyssey’s original shaft – and frankly, it has become a toss-up which one I put into the bag when I play.

In conclusion

Unlike the folks at BGT, I don’t have high-speed video, or sophisticated data-gathering equipment of any kind, at my disposal with which to evaluate clubs – only my eyes, ears, and hands. What they told me over a few weeks of using my re-shafted Odyssey putter is that the Stability Shaft is not a miracle solution to anyone’s putting woes, whatever they may be.

My knowledge and engineering experience told me that the claims that are made in their advertising copy are suspect, and the time I spent with the re-shafted putter showed that, at best, after becoming accustomed to the altered swing weight of the putter, I was no worse off than I had been before. Further modifying the club with the grip end counter-weight improved the swing stability of the “Odyssey Mk II” – which reinforces what I had previously learned about counter-weighting, but did not substantiate any of BGT’s claims.

So – if you have the spare cash to drop $200 on a putter shaft, and really want to explore the option, you may find that the Stability Shaft feels right in your hands, and with your swing; but if a putter with the Stability Shaft works better for you, it’s more about balance and feel that works with your particular stroke than it is about any of the performance claims that Barney Adams and the people at Breakthrough Golf Technology are making.