Gear: Mizuno ST-Z 230, ST-X 230, ST-X PLTNM 230 drivers
Price: $499.95 for the ST-Z 230 and ST-X 230 with Project X HZRDUS Smoke Green shaft, Mitsubishi Kai’Li Blue shaft or UST Mamiya LINQ Red shaft and Lamkin Hybrid ST grip. $549.95 for the ST-X PLTNM 230
Specs: Forged SAT 2041 Beta Ti face with titanium chassis, internal steel weight with TPU coating, carbon fiber crown and adjustable hosel. Lofts – 9.5, 10.5 degrees for the ST-Z 230; 9.5, 10.5, 12 degrees for the ST-X 230, 10.5, 12 degrees for the ST-X PLTNM 230
Available: February
Who They’re For: Golfers who want a stable, low-spin, neutral-bias driver (ST-Z 230); players who want a draw-biased driver (ST-X 230); golfers who want a lightweight club to generate more swing speed (ST-X PLTNM 230)
The Skinny: The addition of an internal steel weight helps the ST-230 drivers generate more ball speed and lower spin rates, while the three club configurations give fitters a chance to help more golfers find a head that suits their needs best.
The Deep Dive: Four years ago the engineers and designers at Mizuno set out to do something hard. They were tasked with bringing the brand’s woods up to speed with Mizuno’s irons, which have been loved for years by discerning golfers for their distinctive looks and feel.
In each of the previous three seasons, Mizuno has released a new driver, starting with the ST-190, followed by the ST-200 and last season’s ST-220 drivers. (ST stands for speed technology.) Now the brand is releasing three ST-230 drivers, and Mizuno feels good enough about them to plan to move to two-year product cycles.
What they have in common
The ST-Z 230, ST-X 230 and ST-X PLTNM 230 all have carbon fiber crowns that weigh about 12 grams, saving weight on the top of the club, along with carbon fiber panels in the sole. They also have been made with very thin Forged SAT 2041 Beta Ti faces designed to flex efficiently at impact.
The ST-Z, ST-X 230 and ST-X PLTNM drivers also each have an adjustable hosel that allows players and fitters to increase or decrease the loft by as many as 2 degrees.
What's new: CorTech Chamber
What sets the ST-230 drivers apart from their predecessors is the addition of a CorTech Chamber. Mizuno used to add a Wave Sole behind the leading edge of its drivers to allow the lower portion of the hitting area to flex more and broaden the sweet spot, and the new CorTech Chamber takes things a step further. It is a channel cut into the sole of each driver that is filled with a special blue thermoplastic polyurethane that has stainless steel in it.
The cut-through design lets the lower portion of the hitting area flex more efficiently, but the steel floating in the TPU weighs more than the titanium it replaces. So it works with the carbon fiber top to drive down the center of gravity and pull it forward. Mizuno engineers learned that a low and forward center of gravity helps reduce spin and increase ball speed, so the CorTech Chamber’s effect should be increased distance with a more solid feel.
The CorTech Chamber does such a good job of allowing the lower part of the face to flex that it reduces strain on the seam where the hitting area and sole meet, allowing Mizuno to make the lower part of the face even thinner. The company also made the three internal ribs that help improve the sound of impact smaller and lighter.
ST-Z 230
The ST-Z 230 driver was designed with the center of gravity on what engineers call the z-axis, which is the center line of the head. Doing this creates a neutral weight distribution that can help golfers who like to hit draws and fades shape shots more easily.
The ST-Z 230 also has a 14-gram weight in the back of the head to boost the moment of inertia and increase stability.
ST-X 230
The ST-X 230 driver also has a 14-gram weight in the back, but it is positioned slightly toward the heel side, and its carbon fiber sole goes less deeply into the heel area than the ST-Z’s composite sole. This creates a draw bias to go along with the stability.
Compared to the ST-Z 230, it is slightly larger front to back in the address position.
ST-X PLTNM 230
ST-X PLTNM 230 was designed for slower-swinging golfers who want a lightweight option to create more clubhead speed. It has all the technologies found in the ST-Z and ST-X, like the Forged SAT 2041 Beta Ti face, carbon fiber crown and sole panel, and the CorTech Chamber, but it has a 7-gram weight in the back. It is about 45.75 inches in length (instead of 45 inches) and comes standard with a lighter shaft and grip.
