Cobra KING F9 ONE Length Irons Review: Hit Me Baby ONE More Time

When Cobra Golf signed Bryson DeChambeau three years ago to its Tour Staff, their first generation of one length irons was a solid effort.  The F7 ONE accounted for almost 50-percent of Cobra's iron sales, but I think even Cobra would admit there was still room for improvement.  Tweaks were made and the next generation of one length, the F8 ONE, was better.  Still, subtle issues that generally plague one length irons remained. 

 

With a few years of development and empirical testing under their belts, and experimenting with all the components of one length iron design, this year Cobra absolutely nailed it with one length. The KING F9 ONE length irons are not only their finest one length irons so far, but also irons that actually unlock one length potential with consistent gapping, easy distance, and exceptional accuracy. 

I've been playing and testing the F9 ONE since early this year, and what's most impressive is how much better overall gapping and trajectories are through the entire set compared to previous ONE versions. 

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The new @cobragolf F9 SPEEDBACK ONE Length irons unlock one length potential with consistent accuracy & easy distance. @fujikuragolf Atmos shafts are incredibly stable. _____ Progressive sole widths and lie angles improve gapping and optimize trajectories through the set (something that plagued previous models). _____ The love is 💯 real. _____ #cobragolf #alwaysbegolfing @brysondechambeau #cobraonelength #pgatour #golfer #golf #golfers #cobraf9 #pgapappas #golfing #golfshot #golfpro #golfswing #golfaddict #golfporn #pga #golfirons #lovegolf #golflife #golfreview #golfislife #golfclubs #golfequipment #golfgods #golfswag #golfballs #golfcourse #golfcoursephotos #teetime #kingofspeed

A post shared by Pete Pappas (@pgapappas) on Feb 19, 2019 at 12:09pm PST

I saw consistent 12 to 15 yard gaps between each iron, and trajectories were nearly uniform for all clubs (with slightly more roll-out with the 5 iron and my ONE Length 4 Hybrid).  I also got more distance with the ONE Length irons than I usually have, particularly with my long and mid irons (5-iron 189, 7-iron 164). 

 

 

Some will say 15 yards seems like a larger gap than ideal, and that does have some merit.  However it's a consistent 12 to 15 yard gap between clubs, and quite frankly that's just as easy to get used to and dial in your shots as a more traditional 8 to 12 yard gap range.  

It's especially impressive when you consider that one of the issues with one length irons in general is too large a gap in the short irons and too small a gap in the long irons.  The F9 ONE irons don't create any confusion wondering what club to hit, and don't give you any unexpected surprises when distance control is especially crucial. 

 

The purpose of one-length irons of course is to create a simplified, repeatable swing for all shots you take with every iron you hit.  And that's always meant the using same length shaft for all your clubs.  There's also been a conventional (and ironic) thinking in one length design that requires the same 7-iron shaft be used for all the clubs in the set.  The reasoning was to duplicate the same feel for all the irons.  However, the F9 ONE irons prove that there's not just one way to accomplish that feel goal. 

 

 

Cobra F9 irons are indeed all the same length, but you still have a 4-iron shaft in your 4-iron, a 9-iron shaft in your 9-iron, etc.  And combined with progressive lie angles and sole widths, as well as strategic head weighting, feel barriers are for the most part eliminated.  I would dare say even Bryson wouldn't be able to decipher any significant feel difference between one length clubs with the same shafts and those like the F9 ONE using different shafts in the the short, mid, and long irons. 

 

No matter what irons you play, you want a little more launch in the long irons, and feel and control in the short irons.  So the F9 ONE long irons have longer and more upright blades, and the short irons have shorter and flatter blades.  And this makes perfect sense when you consider that the CG is out further in long irons (which normally droop more) and in closer in short irons (which droop less).  Tweaking lie angles gives the F9 ONE better performance and just make it easier to make perfect contact with any club. 

 

Progressive sole widths eliminate another challenge with one length irons of getting enough carry in the long irons and keeping the short irons from ballooning.  Having different sole widths in the F9 ONE lets Cobra put the CG back a little further in the long irons so you get the distance you expect, and closer to the face in the short irons for more control when you need it. 

 

 

 

The soles also feature an ingenious design (as you can see in the pictures) that essentially still gives you a traditional sole width that makes them playable and versatile from a variety of lies. 

I had my F9 ONE irons out with me on the famous and difficult Lake Course at The Olympic Club last month, and this is a course that's going to give you some tricky down-hill and side-hill second lies.  As intimidating as these kinds of shots can be, turf interaction and control was spectacular with the F9 ONE. 

 

 

One thing that's been most surprising about the F9 ONE all season is how much better my dispersion is in the short game.  The shot consistency is great throughout the set, but with the short, and even mid-irons, the performance results are particularly impressive.  You'd think longer shafts (than traditional variable length) in the short irons would mean less feel and consistency, but it's the exact opposite. 

 

 

If you're wondering about forgiveness, the F9 ONE are one of the most forgiving game-improvement irons I hit all year.  Cobra uses a variable thickness face, and tungsten weights in the heel and toe of the 4 to 7 irons for truly substantial forgiveness.  Check out the video below.  Even on shots hit out towards the toe, directional and distance loss is minimal. 

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The @cobragolf Golf SPEEDBACK F9 ONE Length irons are very long and easy to hit, but also extremely forgiving. _____ You can see I hit this one out near the toe, and ball still pretty much stays on line. _____ #cobragolf #cobraspeedback #cobraf9 #cobrakingf9 #pgatour #golfer #golf #golfers #golfing #golfshot #golfpro #golfswing #golfaddict #golfporn #golfequipment #golfirons #lovegolf #golflife #golfreview #golfislife #golfclubs #golfdriver #golfgods #golfswag #golfballs #golfcourse #golfcoursephotos #teetime #golfequipmentreviews

A post shared by Pete Pappas (@pgapappas) on Mar 9, 2019 at 4:59pm PST

And again showing why they're one of the most innovative companies in the industry, Cobra also designed the long, mid, and short irons with different grooves (V-grooves, U-grooves, and Wedge-grooves), so forgiveness doesn't come at the expense of overall performance. 

 

 

I don't know the nuances of Cobra's design process, or a whole lot about physics or club design for that matter.  But it seems to me that this year with the F9 ONE, Cobra just decided to dump all the pieces of the jigsaw puzzle (that would be one length design) on the table, and not rest until the puzzle was complete.  

 

 

If you've been curious about one length irons in the past, or even played other one length irons but didn't find them to be as simple to hit and consistent in results as you like, these will give you reason to believe.  The F9 ONE length irons deliver consistent performance too obvious to ignore, and that also makes them legitimate alternatives to variable length irons. 

PROS: 
Makes hitting efficient and consistent shots easier 
No gapping or trajectory issues 
Incredibly forgiving, but even a low-handicap player will benefit 
The best single length irons Cobra has made to date 

CONS: 
Players preferring more traditional lofts or head shape should check out the TOUR ONE irons instead 
First time one length players will still need to get past the mental hurdle of hitting irons all the same length 

 

 

 

 

As always, if you have any questions about the Cobra KING F9 ONE Length irons, or anything else you've seen on my blog or social media,  feel free to shoot me an email or DM on twitter or Instagram.