## Tuesday, November 16, 2010

### Updated Shaft Spine Alignment Thoughts

I was asked the other day by a blog reader if I thought spine alignment of the shafts are important.

First, let’s take a look at a video showing what spine alignment is and how it is executed.

Spine alignment is mostly there to take out the shaft droop (aka toe droop or toe down) that happens at impact.

Here’s a pic of what shaft droop looks like.

And here’s a photo of a club that has been spine aligned.

According to studies, shaft droop alone can cause a golfer’s lie angle to change by 0.58 to 2.0*. And from what we know about Trackman, if you miss the sweetspot by ONE DIMPLE with an iron that is hit 170 yards…that will knock the ball off-line by about 3 yards. And if you miss by ONE DIMPLE with a driver hit 250 yards…that will knock the ball off-line by 10 yards. And one dimple off the sweetspot is such a marginal amount that the golfer will not actually feel that off center strike. Instead it will feel like a sweetspot hit, but will have actually missed the sweetspot and move the ball flight off-line.

Here’s also some research from Professor Sasho Mackenzie

SASHO MACKENZIE RESEARCH

SASHO MACKENZIE THESIS

(note: I paraphrased what MacKenzie has written for the sake of brevity)
For an optimized swing that generated a clubhead speed of 45 m/s (95 mph clubhead speed), with a shaft of regular stiffness, toe-down shaft deflection was 2.27 cm at impact. Toe-down shaft deflection had relatively no influence on dynamic loft. For every centimeter increase in toe-down shaft deflection, dynamic closing of the clubface decreased by approximately 0.5 degrees
First, let’s understand that MacKenzie is not saying that every golfer with a swing speed of 95 mph will generate 2.27 cm of toe droop. It’s a model that he used and that’s the measurements he got. Still though, for every 1 cm of toe droop, it will close the clubface by 0.5*. So with this model:

2.27 cm of toe droop x 0.5* clubface close = 1.13 closed clubface

While I like Steve Elkington’s demonstration of the ‘line test’ to test lie angles, I’m surprised that he has forgone getting his shafts spine aligned. The ‘line test’ helps with the change in the lie angles as the shaft droops at impact. But, it doesn’t account for the clubface closing.

Let’s say you have typically a very good golf swing with a path that ranges in the 0 to +1.0* range (inside-to-out) and a face that goes from the -0.5* (closed) to +0.5* (open) range. Let’s say that you take two swings. The first swing with a spine aligned shaft and the clubface is at -0.5* (closed) and +1.0* path (inside-to-out). That would probably result in a draw that misses slightly left of the target. But let’s say you take the same swing with a shaft droop of 2.27 cm, now the face gets more closed. Instead of being -0.5* closed, it would now be -1.6* closed and your path is still at +1.0*. That would result in a bigger miss left (and that doesn’t account for the possible mis-hit off the toe). And if you’re Elkington, that could result in a shot that falls in a bunker instead of being on the green and 1 shot could be a major difference between winning a tournament and finishing in 2nd place.

The ‘rub’ is that typically steel shafts and iron shafts have less shaft droop. And the cost of spine alignment can be expensive. So for a PGA Tour professional, it should be a no-brainer. For the semi-serious amateur, it’s an issue of cost and whether it’s worth it or no. I would highly recommend getting your driver shaft and your 3-wood and if you carry a hybrid, spine aligned.

I’ve discussed the effects of a driver and toe droop, but often times we will use a 3-wood or a hybrid off the tee on a tighter par-4. So you don’t want to miss those off-line either.

3JACK

Anonymous said...

2nd picture looks like address, no?

Rich H. said...

Looks like it, but isn't. I've seen plenty of golfers who have very similar address and impact positions. But that's not what we want :)

3JACK

Nick said...

I got my 3 wood SST Pured a couple of weeks ago (r9 with Diamana Blue 83x). What a difference. 3 wood has always been a tough club for me, but this is like a completely different animal.

I love it. I'm putting together a matching 3 wood and having the club maker spine it for me. I'm curious to see what's different. I will also probably have him do the same for my driver too.

It's just too big of a difference to ignore.

I know that for my next set of irons, all shafts will be spined. It just makes too big of a difference not to have it done.

Matt D said...