Fernando H. Green Blog: XLabs: 7-Iron vs. 7-Iron

Introducing XLabs

At our primary test facility in Virginia and our secondary location in Upstate New York, we do a good bit of testing that we don't put in front of you. While we maintain the same standards in how we collect and analyze our data, we're often just testing concepts and ideas. For example, we sometimes experiment with ways to leverage launch monitor features. Sometimes we try out new testing protocols, or, in the case of this test, we kick the tires on a concept to see if a larger test could be of value.

The act of testing itself not only provides us with knowledge; the answers we find often come in the way of more questions. In that sense, testing often provides inspiration. We're hoping that by putting these XLabs in front of you, you'll have questions too.

To give you an example of what I'm talking about; upon completion of test detailed below, I found myself wondering two things:

To what extent is the relationship between loft and launch angle affected by swing speed?
Given the lower spin, and presumably, the lower launch of the modern game-improvement irons, would slower swing speed/senior golfers benefit from higher lofted irons?

So as you read through this XLab, think in terms of questions, not answers. Whatever questions you might have, feel free share to share them. They could help shape the next round of testing.

The 7-iron vs. 7-iron Backstory

Several weeks ago I hosted an informal demo day at McGregor Links Country Club in Saratoga, NY. The club wasn't pushing any specific product or selling much of anything at all. Instead, we wanted to provide an opportunity for the members to check out some new (and less new) gear while giving them a chance to see our Foresight GC2 in action so they could begin to get a sense of what a launch monitor is and what it does.

Asked and answered several times, "Is this thing accurate?"

Hell yes. And no, you don't actually hit your driver 250.

The Test

Once the foot traffic waned, I decided to conduct a simple experiment to look at the relationship between iron loft, launch angle, and distance. From the stuff I had in my demo bag, I pulled four clubs, each with the number 7 stamped in the sole. While there were obvious similarities (all golf clubs have a head, a grip, and a shaft), you probably won't be shocked to learn that all 7-irons aren't exactly created equal.

Here's what I hit.

Yonex's N1-MB Blade is about as close to a traditional blade as you'll find on the market today. It's a compact design with minimal offset, and a razor thin topline. A graphite insert provides the only hint of modernness. While it's not relevant to the test, I'd be remiss not to tell you that the N1-MB is absolutely the softest feeling iron I've hit in a considerable amount of time.

PING's iBlade is the epitome of a modern blade. It has the footprint of a player's cavityback. The topline is thinnish at best. It has some offset, though I wouldn't describe it as generous. A custom tuning port (CTP) provides vibration dampening as well as swing weighting capabilities.

Callaway's Apex CF16 is your textbook modern game-improvement club. It features a midsized blade, with moderate everything (topline, sole width, and offset). A multi-material forged design, Apex isn't the most distance-centric in Callaway lineup, but guys looking for a few more yards won't be disappointed either.

PXG's 0311XF is the big distance, big forgiveness iron in the PXG lineup - and within this test too. Of the included irons, it has the widest and deepest sole, the thickest topline, the most offset, and the largest overall footprint. While the PXG's signature big blade design provides some camouflage, the XF most definitely qualifies as a super game-improvement distance iron.

Tale of the Tape

As with some other tests we've done, this wasn't about creating a perfect apples to apples comparison. Instead, I took four obviously different irons that just happened to have the number 7 stamped into the sole, and without regard for much else, hit them side by side to find similarities and differences.

The above chart shows us what we'd more or less expect. Iron loft decreases (get stronger) as we move from the blades to the game-improvement designs. 5 degrees of loft separate the weakest (Yonex) from the strongest (PXG). It's fair to say there's some loft-jacking going on within this bunch. It's also important to note that shaft length differences are reasonably minimal. There's just a bit more than 1/4" between longest and shortest.

Stock shafts for each of irons are inline with what you'd probably expect. The CF16's shaft is lighter and has a softer profile, while the blades feature heavier lower launching shafts. The anomaly in the bunch is the C-Taper in the 0311XF. There's no such thing as stock in the PXG lineup. My sample was built to my specs - and that almost always means low launch/low spin.

Expectations

Before we get to the data, let's briefly talk about what we expected to find. Based on static specs, we would expect to see an across the board progression in performance. The blades should launch appreciably higher and spin considerably more. We'd also expect those launch conditions would come with diminished ball speed. We'd expect the game improvement clubs to fly lower and farther and ultimately create more distance. That's the point of distance irons, right? Finally, we'd also expect the larger irons to be more forgiving.

The Data

Observations:

The data suggests a clear and predictable progression in ball speed. The lower lofted 7-irons produced significantly more average ball speed.
You may find it surprising that despite significant differences in static loft, differences in launch angle were minimal (less than 1.5 degrees between the lowest and highest launching).
The greatest influence in narrowing the launch gaps likely comes from increased dynamic loft from the GI and SGI designs created by the lower and deeper centers of gravity in the Apex and the 0311XF.
As we would expect, the higher lofted (and also higher CG) designs produced significantly more spin. While not uncommon with average golfers, I believe most fitters would agree that ~5500 RPM produced by the GI/SGI irons is less than ideal for a 7-iron.
Somewhat surprisingly, the 0311 XF produced the highest peak (apex). So while it produced the lowest initial launch angle, it also produced the highest average ball flight - almost certainly due to the increased carry distance.
The Angle of Descent is similar for all four irons tested, but the higher spinning irons would produce less roll and offer greater green stopping power.
Differences in ball speed, launch, and spin rates created significant differences in carry yards. The PXG 0311XF was nearly 20 yards longer on average than the Yonex N1-MB, and 6.5 yards longer than the Callaway Apex CF16.
Standard Deviations in both Ball Speed and Carry Yards (the lower the value, the more consistent the data) can provide insight into what is generally referred to as forgiveness. The data suggests the forgiveness breakdown is what you'd expect. The larger (GI designs) are more forgiving than the blades. Conversely, though not tested, we would expect that better golfers would find it easier to shape shots and control trajectories (better workability) with the more compact designs.

Takeaway

It goes without saying that loft has an influence on distance, but perhaps not to the degree, or at least not in the way golfers tend to think. While it's true that the lower lofted clubs in this test produced more ball speed and ultimately more distance, the relationship between static loft and launch angle was disproportionate to the actual difference in lofts between clubs. In my case, A 5° difference in loft produced only a 1.37° difference in launch angles, and the lowest lofted club produced the highest peak ball flight.

This would seem to validate some of what the OEMs tell us about game-improvement irons, specifically CG locations and the resulting influence on launch (they launch higher). That said, despite mostly similar trajectories, the stronger lofted clubs produced significantly less spin than the blades. While that's great for distance, it's not the best recipe for holding greens. I still believe many golfers, particularly slower swing speed players, would benefit from weaker lofted irons.

The key thing to remember is that specifications almost never tell the complete story, and there's absolutely no such thing as an inherently good or a bad loft.

If I had hit these four irons with the intent to buy, I'd almost certainly eliminate the Yonex N1-MB (I LOVE them, but reality says they're not forgiving enough for daily use), and the PXG 0311XF (I might fall in love with the distance, but the low spin would be a concern based on how I prefer to play the game). That said, I might consider weakening the lofts by a degree or two.

From the remaining choices; if I'm focused on distance, I go Apex, but if I'm looking for control (at the expense of some forgiveness), I'd take the iBlades. Not to belabor the point, but the idea here is that you shouldn't get hung up on specifications. It should go without saying that individual results will vary based on a number of swing variables, but the goal should always be to find the iron that produces the best results within the dynamic realities of your golf game. The on-paper stuff...it doesn't matter much at all.