About a month ago, we unveiled the new 2018 EVNROLL models. The new models feature both traditional designs, like the Anser-style model 1.1, and more niche-market offerings, like center-shafted versions of their popular ER2 and ER7 models.

In addition to unveiling those models in that article, I hinted at the end that Guerin had one more model coming - the ER9 - and that you’d see and hear all about it at the PGA show. Well, the show starts today, and that means that we can finally unveil the EVNROLL ER9!

Today at the 2018 PGA Show, Guerin Rife, the mastermind behind the unbelievably accurate EVNROLL putters, will be unveiling a new putter model, the ER9. It’s a nearly unbelievable putter, and definitely deserving of a bit of PGA show fanfare.

Massive MOI

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The ER9 represents an exercise in extreme putter MOI. How extreme? Well, most putters are considered high MOI putters when the MOI reaches the 5,000 mark. The MOI value for the MOI is 10,000. Yes, 10,000 of anything is a lot (visualize 10,000 kittens), but

“What the heck is MOI?”

The short answer is that MOI stands for Moment of Inertia, and it is one of the quantifiable characteristics of an object that can affect both its rotational and angular momentum. Essentially, the higher the MOI value for an object, the more that object resists rotation when moving.

In physics class, I learned this concept through observing a figure skater. Envision an ice skater spinning with arms extended away from his or her body. When the arms are then pulled in to the body, the speed of the rotation increases. Simply put, the skater with arms extended has a higher MOI, and thus spins slower. Of course, MOI can also be discussed with fancy numbers and symbols, but thinking about the skater helps me to understand MOI in more practical terms. So how does all of this MOI stuff relate to putters? Here’s Guerin to help us out.

Can a putter be too stable?  Is there such thing as too much MOI?  And what the heck is MOI?  Short answer is… “an object’s resistance to twisting”.   For a putter, that translates to a rock steady swing path and an enlarged area of forgiveness off the face.  So all you have to do is aim.  This is achieved by moving weight away from the center of mass.

So in a way, the putter parallels the skater. When the mass is positioned toward the perimeter of the putter, like a skater with arms extended, rotation is decreased. Less putter head rotation means more stability, which should translate to a more stable stroke.

How did the ER9 get to 10K MOI?

Evnroll ER9 - 2

To achieve high MOI requires designing a big, really big putter head that resembles a frying pan on the end of shaft.  It needs to be a blend of aluminum and steel.  Steel is about 3 times heavier than aluminum so it’s the key to achieving the high MOI.  The ER9 has a milled 6061 aluminum body that has a hollow cylinder along the extreme heel and toe that runs the length of the head from face to rear to receive sizable steel weights.  This keeps the overall size down (somewhat) and achieves and incredible 10,000 MOI.

The ER9 is a multi-material design, reflecting a combination of light-weight aluminum and heavier stainless steel. The bulk of the putter is made from aluminum, allowing the relatively large putter body to be relatively light. The stainless steel perimeter weighting of the putter moves the overall relative weight of the putter to the edges, effectively “extending the skaters arms” weight-wise. Increasing the relative weight at edges of the putter boosts MOI, and leads to less rotation. You are going to be an MOI expert by the time we are done today...

Specifications: EVNROLL ER9-10K

  • Head Material – 6061 Aluminum
  • Hosel Material – 303 Stainless Steel
  • Cylinder Weights – 303 Stainless Steel
  • Shaft – FST Stepless, .370” Tip
  • Grip – Custom Evnroll Gravity Grip
  • Available in 3 Head Weights:
  • 33” @ 425 grams
  • 34” @ 410 grams
  • 35” @ 395 grams =
  • Hosels – Plumber Neck or Short Slant Neck

The ER9 is a Beefy Beast

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Maintaining pleasing aesthetics can be challenging when designing high MOI putters. Trying to get the weight to the edges will likely necessitate some visual compromises.

The ER9 gets around some of this by using the different metals, but the desire to position weight away from the middle and toward the edges mandates those edges be a good distance from the center of the putter. Again, you lose some of the aesthetic freedom when your goal is to boost MOI as high as you can. Figuring out how to make it not look like a “frying pan on the end of the shaft” can be challenging.

The ER9 is a big boxy beast. For comparison, I’ve included a shot of my EVNROLL ER5. I’ve never considered the ER5 a small head, but the ER9 just towers over it.

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Though its profile is rectangular, the ER9 is more than a brick on a stick. If you look closely, you will see areas where the aluminum material has been rounded or removed altogether. This improves the aesthetics and provides a means to remove weight from the center, thus boosting the proportion of weight on the edges and increasing the moment of inertia.

The widebody cavity and its three associated sight lines break up the blockiness a bit and should help you to square the putter to the target line at address. The characteristic EVNROLL double sight dots on the top edge also aids with alignment.

An alignment scheme that helps you aim correctly, paired with the stable swing from the staggering MOI, should be a solid recipe for making putts. The ER9 has some other features that should also help your putting.

Roll Technology

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Like all Evnroll putters the ER9-10K features Sweet Face Technology that produces consistent distance and eliminates dispersion.  However because of the extreme stability created by the 10,000 MOI the parabolic grooves have been dialed back to produce the same energy transfer and gearing effect for off-center hits.

The grooves have been tweaked a bit, but they are still the Sweet Face Technology grooves that make the EVNROLL putters so user-friendly. To refresh your memories, these are the grooves that can help correct not only for distance with off-center strikes, but also accuracy as heel and toe strikes will track back toward the target line rather than away from it. They didn’t twist the face to do this, just made it groovier. Dibs on the twisted face putter patent...

Feel Balanced

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I think the word is “serendipity”.   It when you head out into unknown territory and fate delivers you and unexpected bonus.  The ultra light aluminum body with long heavy steel weights running along the length of the heel and toe allows for 15% more head weight.  Yet ER9 swings effortlessly along the swing plane and “feels” like a much lighter swing weight.  Having the lighter feel with the heavy head weight delivers excellent distance control and deadly accuracy.

Counterweighting putters have been a huge help for many golfers. The heavier than normal head, coupled with a heavy grip, or weighted shaft tip, promotes a smoother stroke. It’s been a few years since the (IMHO silly) anchored putter ban, and many formerly anchored player are now using counterbalanced models. It’s not the answer for all golfers, but for quite a few, it is the answer to putting woes. Many golfers have found the counterbalance putter to be the only thing that cures the yips.

Gravity Grip

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Even the grip on the ER9 has high MOI.  The patent pending Gravity Grip is made buy Evnroll and features a 70 gram, 10” steel rod that travels the full length of the deep V underside of the grip.  This places 85% of the grips total weight in the fingers below the shaft promoting a toe-up square face to the swing plan.  At total weight of 120 grams the Gravity Grip also acts as a counter weight for additional head weight and even more overall stability.

This new EVNROLL grip was a fun little surprise when I opened the ER9 box. It is a weighted grip, helping to counterbalance the 400g ER9 head, but it’s more than that.

The shape is unique. It’s much more wedge-shaped than a traditional putter grip. When your fingers curve around the bottom of the grip, your palms end up sitting reasonably flat against the sides. It takes some getting used to, but this grip allowed me to place my palms and back of hands much more parallel to the target line. It’s less of a “grip” action, and more of a “hold” if that makes sense.

Although it is a weighted grip, that too is a bit unusual as the weight in the fingers feels different than it does in more butt-weighted grips. You feel it in your fingers as opposed to the back end of the club, or inside of your clenched hand.

I’m not sure what my opinion is about the gravity grip. It feels nothing like my usual grip, and that’s a bit disconcerting, but not necessarily bad. After a bit more acclimation, it’s possible that what I now feel as different could transform into a feeling of better. Maybe not, but I’m not comfortable making a final decision on this one just yet. If nothing else, the unique design definitely merits more exploration.

Slant Neck Option

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You may have missed in the list of specs, but you can also get the ER9 in a slant neck configuration. I played around with swapping the necks back and forth, and I do prefer the slant neck. Not totally surprising since most of my current gamers feature the same design. Fingers crossed that EVNROLL makes that neck an option on the ER1.1 or ER2.

The Beast is Released

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The ER9 will not appeal to every  golfer especially the traditionalist.  But for those who absolutely, positively want to make every pressure putt the ER9-10K will deliver.

EVNROLL knows that the ER9 will not be everyone’s must have new putter, but there will be a segment of the golfing public that will wonder how they ever putted at all before bagging the ER9.

It’s a big thing, with the MOI numbers to match its hulking profile. I’ve talked to some other putter makers who believe that above a certain point, boosted MOI is a diminishing returns investment, particularly for looks and even for forgiveness. Time (and testing) will tell if the 10,000 MOI hits the stability sweet spot, or if it is just too darn huge.

I don’t know if the ER9 is immediately going to become my new gamer, but I love that it exists. I like to see putter makers push the design envelope here and there. Even if the ER9 ends up being just an exercise in engineering, it’s a hugely valuable exercise as I'm sure some interesting new design concepts will emerge because of it.

We all win in this story. Some win this season as they bag the ER9 and putt better than ever before, others may end up gaming some upcoming EVNROLL putter specifically because of what was learned and incorporated from the ER9's development.

Call it a brick on a stick if you need to, but we all benefit from these boundary-pushing, bold adventures in gear design.