Xander Schauffele and the Curse of the Non-Conforming Driver

Sounds like a new Harry Potter novel, doesn't it?  Rest assured, this harrowing golf tale isn't anything new, but it is rare.  Not as rare as getting the golden snitch in your first tournament... but less fun.

The Xander Schauffele Driver Snafu: what made it non-conforming?

The simple answer is "extra springy-ness".  But it's a good conversation to have about COR and CT.

What's COR?

COR, or Coefficient of Restitution, is the springlike effect of a golf club's face.  It has a direct effect on the smash factor of your golf club.  Your swing speed dictates how much it helps (and there are other myths about stuff like this), though.

Let's look at what happens when a driver has the legal limit of COR:

Driver distance with conforming driver

With a driver right at the conforming limit for COR, our golfer gets respectable distance for their swing speed.

What does a non-conforming driver's numbers look like?

Not Xander Schauffele driver numbers, but still an increase over a conforming driver

With all else equal, a 0.03 bump up in COR gives this non-conforming driver an extra five yards.

It's really not much of a difference, is it?  This is a bare-bones "in a vacuum" look at it, though.  

In his book, Just Hit It, former USGA Tech Director discussed what happened when the original fight over COR took place.   He and the USGA curtailed the PGA Tour to the 0.83 limit, while the R&A allowed "hotter" drivers.

According to Thomas, the European Tour players didn't make it a full season before switching back to conforming drivers.

The reason is because the faster you can make the ball go, the farther it flies... but the more offline you are, the hotter-faced drivers will make things worse.  A lot worse.  The EPGA guys didn't like hitting longer drives farther into the woods, so they went willingly back to something they could control better.

For COR, the basic test is to fire a ball at 100-mph at a driver's face.  The balls should not rebound off the face more than 83-mph.  It's an impractical test, which is why Characteristic Time was substituted.

What's CT?

Characteristic Time is measured in milliseconds.  The test for it is a not-so-simple pendulum device.  It looks like this: 

A Characteristic Test Machine

Diagram of a Characteristic Time measuring device, from the USGA (view the PDF here)

You insert the driver/club in the clamp, so the face is pointing at the "hammer".  The hammer is raised, then allowed to drop.  The legal limit is 239 microseconds; the absolute fastest it can measure, which includes tolerance, is 257-ms.

Yes, even at 258-ms, it's deemed "non-conforming".

The problem with non-conforming golf clubs is bigger than just one guy

This Xander Schauffele driver dilemma was just part of a bigger whole.  His wasn't the only driver to be deemed non-conforming.  His has become the most public, though.

Normally, this stuff is kept under wraps.  Kinda like their drug testing program was, at least until 2018.  The public was deemed in the know with drug testing... maybe they're getting more open-door with non-conforming clubs, too?

The kicker is, Ping, Callaway, and Taylormade had issues with conformance at Royal Portrush.  But that part of the story doesn't seen to be getting much traction.  

Personally, I don't believe player's knowingly play with non-conforming drivers.  Or gear in general.  But both the OEMs and the players have a responsibility to make sure their gear is in the clear.

The OEMs have a hand in this because they know the limit, and yet they push their gear to be right at it.  You get a driver right at the edge and who knows?  

With player testing, it usually only happened because one player thought another player had a "hot" driver, and asked the USGA to step in and test it.  In all fairness, why would a player think they're not getting a conforming driver?  But on the other hand, shouldn't they be more involved with the stuff they use?

What's this mean for the rest of us?

You and me, we could get a driver from the same brand that's 238ms, one that's 246ms, or even 260ms.  We don't have any way of testing them, right?  How do we know exactly what we're getting?  Hell, I've been a club fitter for a while now, and even I don't have one of those expensive machines! 

Unless you're playing, or plan to play, a USGA or R&A sponsored event, I wouldn't sweat it.  As you could see in the pictures above, a golfer that had good club head speed for an amateur with a high angle of attack only gained an extra five yards from using a non-conforming driver.

Most of what they sell us is marketing, anyway.  That small, tiny, miniscule probability we're using a non-conforming driver is the least of our worries.