SPOTTED: What we know about Mizuno’s new ST-X and ST-Z drivers

Product launch season is just around the corner, which means equipment manufacturers will slowly start to release images of their upcoming designs in the coming months. With the USGA’s conforming list acting as a glorified spoiler alert, it’s possible to get a general idea of what’s going on from a design standpoint.

This brings us to Mizuno’s upcoming ST-X and ST-Z drivers that recently surfaced on the USGA’s list of conforming driver heads. The addition of both drivers on the list means Tour pros are at least contemplating the idea of putting them in play.

All drivers have to be given the green light by golf’s governing body before they can see action, and based on the release date of the current 2021 version, it hints the 2022 models should be coming to retail in January or February.

Mizuno ST-X driver

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While the conforming list only provides black-and-white photos of the sole, it’s clear from the images that Mizuno designers are retaining some technologies while making noticeable weighting modifications. With the ST-Z, Mizuno appears to be doubling down on the stable profile with a more substantial sole weight that’s positioned low and deep along the perimeter of the Z axis (front-to-back). The weight position should improve MOI (Moment of Inertia) and ensure a neutral shot shape.

The weight port on the upcoming ST-Z is also positioned along the extreme perimeter with a slight heel location to induce a draw shot shape. It should be noted that Mizuno designers chose to shift the center of gravity closer to the shaft axis by inboarding the hosel and concentrating more composite in the heel with the third-generation ST-Z driver head. The fourth-generation design looks to have more composite in the heel than the toe to move the center of gravity even closer to the shaft.

Mizuno’s Wave sole design is still found in both drivers — a carryover from previous iterations — along with the carbon fiber panels. And while we can’t see the crown, it’s a good bet Mizuno is once again adding carbon composite to capture as much discretionary weight as possible.

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