Single Length vs. Variable Length Irons: The Ultimate Test

Single Length vs. Variable Length Irons: The Ultimate Test

How do single length irons compare to variable length? Equipment editor James Savage has put them head-to-head in an extensive long-term test.

So I had been using the Cobra Forged One irons pretty much for all of the 2018 season.

Towards the end I made a switch into their Forged Tec Black One irons so see if they offered me a little bit more forgiveness.

But I’m a big fan of Mizuno irons and recently got fitted into a set of JPX919 Forged following a visit to their new Tour Performance Centre at Bearwood Lakes.

And I was fitted into the exact same shaft (True Temper AMT White S300) as I have been using in the Cobra Forged Tec so it gave me the opportunity to put together a detailed comparison.

I was primarily focussed on gapping so gathered a lot of data on the SkyTrak launch monitor hitting the 9, 7 and 5-iron.

Ideally I would get a nice, consistent 20-yard gap between those three clubs.

Single length vs. variable length irons: The technology

So the Cobra One Length irons all have a shaft the length of a 7-iron.

But the heads are weighted accordingly to get the right swing weights and add a bit of ball speed in the longer irons.

The theory though is largely based on getting a more consistent strike.

If you are able to strike your 5-iron out of the middle more often, you will see a better average carry compared to a variable length 5-iron where you may hit, say, one in four shots out of the middle.

With each shaft the length of a 7-iron Cobra say you can take the same set-up and make the same swing for each of your irons – again to improve consistency of strike.

The theory with variable length irons is that the shafts are shorter in the short irons and longer in the long irons.

Longer irons have less loft therefore you need more swing speed to launch the ball in the air properly.

You want to be able to hit your long irons further than your short irons and a bit more swing speed will obviously help you do that.

With short irons being more about precision and accuracy, rather than distance, the shorter shaft can help add a bit more control.

The shaft I was using for this test has something called ascending mass technology (AMT) which means the shafts are heavier in the shorter irons and lighter in the long irons.

Again, this is to help add a bit more speed to help launch those longer irons.

Single length vs. variable length irons: Pre-conceived ideas

Everyone thinks that the problem with the single length irons is that the short irons will go to far and the long irons won’t go far enough.

This is a reasonable assumption to make because there’s a good chance you will swing your shorter irons faster when using One Length irons.

This could result in a bit of added and unwanted distance.

And you would also expect to swing your longer irons slower which could result in a loss of distance.

Single length vs. variable length irons: The results

Let’s take a look at the SkyTrak launch monitor data first.

As I said, this was gathered hitting a 9-, 7- and 5-iron with the Cobra Forged Tec Black One and the Mizuno JPX919 Forged.

This data was gathered during multiple visits to Leeds Golf Centre to try and get a picture of how these irons might perform over a sustained period of time rather than on just one visit the the driving range.
I still always take launch monitor data with a pinch of salt because when I collect data, it bears very little resemblance to actually playing golf out on the course.
You’ve got a perfect lie every time and there’s no pressure of hitting it to a target or bunkers to carry or playing partners looking on.
That’s why on-course testing and using things like Toptracer’s nearest the pin and simulator games all gave me more valuable information.
But you can see the launch monitor numbers below and I will explain them in more detail.
What did surprise me was the swing speed with the single length irons.
With all shafts being the same length, you’d expect to see the swing speeds being a lot closer together.
But I think the combination of the different weights in the shafts and the fact your subconscious tells you to hit a 5-iron harder than a 7-iron accounts for much of that.
There’s hardly anything to split the single length and variable from a ball speed point of view.
Slightly more with the variable length but I suspect that may be due to the Mizuno JPX919 being slightly faster off the face than the Cobra Forged Tec.
I did notice the 9-iron in the One Length launched incredibly high. This could be due to having the ball a bit more forward in the stance than where I would have it for a variable length 9-iron.
From a gapping point of view, I noticed a 25-yard gap between the variable 9- and 7-iron and an 18-yard gap between the single length 9- and 7-iron.
A 17-yard gap between the variable 7- and 5-iron and an 18-yard gap between the single length 7 and 5-iron.
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