Callaway's I-Mix driver system
David Walberg/SI
Tuesday, March 23, 2010

Callaway's Adjustable Drivers
Do-it-yourself assembly lets you switch shafts as often as you like I-Mix fitting system

FT-5 FT-i Tour Low CG)

I-Mix is an intriguing complement to Callaway's popular Opti-Fit driver fitting system. The I-Mix has a more durable locking mechanism (an aluminum sleeve and titanium screw) that's designed to hold up round after round.

Clubheads: FT-5, $435; FT-i Tour Low CG), $500 Shafts: Start at $185.

Get Fit
Our reader gets 5 more yards — and greater consistency — with Miura Tournament Blades

Reader: Dontae Farmer
Age: 22
Handicap: +2
Height: 6'2"
Weight: 170 lbs.
Residence: Tucson, Ariz.

• Old irons: Forged muscleback blade, 3-PW, True Temper Dynamic Gold S300 steel shaft, midsize grip.
6-iron: 37" shaft length, 32° loft, 62° lie angle.

• New irons: Miura Tournament Blade, 3-PW, FST KB Tour steel shaft (5.4 frequency), midsize grip.
6-iron: 37.5" shaft length, 31° loft, 62.5° lie angle.

"Dontae is a great ballstriker. But his iron shafts were a little short, causing a consistent pull. Giving Dontae extra length allows him to maintain better posture throughout his swing and virtually eliminates the pull. Our fitting matrix shows that he also needs stiffer shafts. Switching to the KB Tour shaft, at the proper frequency, brings down the backspin to create a more penetrating ball flight. In addition, we bent the [lie angle of the] Miura clubheads 2° upright from their stock spec to better suit his hand position." —Matt Phelps, Clubfitter, Hot Stix Golf

Ask Dr. Tom
Dr. Tom Mase, EVP of R&D and Innovation for Hot Stix Golf and Bently Endowed Professor, Cal Poly State Univ., answers your questions.
Q. What effect do grooves have on a driver face?

A. Beyond cosmetics, grooves really aren't necessary for drivers today. Grooves can limit "flyers" from rough, where the ball "hydroplanes" up the clubface, launches high with diminished spin, and travels too far. But drivers are teed up, so there's no concern over flyers. Some companies etch lines on the driver face to emulate grooves for visual purposes. Removing grooves from the center of the face allows designers to make a thin, energetic face to withstand the 2,000-plus pounds of impact.

Send Dr. Tom questions to

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