Best of our tests : The science of the game - golf equipment testing

Golf Digest, Dec, 2000 by John Strege, Peter Farricker

Springing eternal

Trampoline effect (heretofore known as spring-like effect) entered golf's lexicon in 1998, creating an enduring controversy. In 1999, Golf Digest developed its own titanium driver that failed the USGA's conformance test. The nonconforming driver generated on average 2 percent more ball speed than the conforming club, translating to one or two yards on 220-yard shots but escalating to four to six yards on 270-yard shots. The greater the swing speed, the greater the increase in ball speed and carry distance.

A caveat: The advantage occurred only when the ball was struck on an exact impact location.

These balls are hot

You see them advertised, "hot balls" that do not conform to USGA regulations (and aren't allowed in tournament play governed by USGA rules). Is it hype or is it real? Our robotic testing earlier this year showed these so-called hot balls average five to 15 yards longer off the driver than a conforming distance-type ball. Most of the difference was generated in carry. The balls, incidentally, are smaller and heavier than conforming balls.

Does size matter?

In 1991, oversize drivers--Callaway Golf's Big Bertha and Yonex' A.D.X. among them--transformed the equipment industry. Is bigger really better, we asked? To find out, we tested the Big Bertha against a previous Callaway entry, the S2H2. Note the lower center of gravity (red dot) on the Big Bertha.

The Big Bertha produced a greater average carry, whether the clubhead speed was 85, 95 or 108 miles per hour, on center hits, high toe hits or low heel hits, with a two-piece ball or a three-piece wound balata. In each case, the difference in average carry was greater on off-center hits than center hits, proving, at least, that oversize drivers are more forgiving.

Tests of time

How do today's balls and clubs compare with those of yesteryear? We asked the question in 1994 and pitted a Wilson Staff Dynapower 5-iron from 1973 against a Wilson Staff Ultra 45 5-iron from 1993, a '73 model Wilson Staff 11 driver versus a Wilson Killer Whale, and a 1970-model Titleist K-2 Acushnet ball against a '93 Titleist Tour Balata. The overall conclusions: The new equipment outperformed the old equipment, but to a lesser degree than some claimed. Also, the old ball hit with the old clubs went as far as the new balls hit with the new clubs.

What flex?

It was a given that big hitters required stiffer shafts than short hitters, a notion we set out to prove--or disprove--in 1994. For our test, we employed 19 golfers--men and women, high handicappers and low handicappers, hard swingers and easy swingers--and had them swing four drivers, each with a different flex: L (weakest flex), R (medium), S (stiff), and X (extra stiff). The results were not what you might have expected. For instance, a longer hitter does not necessarily bend the shaft more during the swing than a short hitter. Acceleration, not final clubhead speed, may be the key to choosing your shaft flex.

The J's have it

Long before the USGA expressed concern over thin-faced metal woods, Bridgestone introduced the controversial J's Professional Weapon, brought to the fore at the 1990 Masters by Jumbo Ozaki. "Thirty yards longer," Jack Nicklaus said. Fact or fiction? We conducted three tests pitting a J's versus a Precept, a conventional metal driver from Bridgestone. First test: drivers with 8.5 degrees of loft, swung at a speed of 108 m.p.h., hitting three-piece balata-covered balls. Advantage: J's. Its carry and roll averaged 272.8 yards to the Precept's 254 yards. Second test: drivers with 9.5 degrees of loft, swung at 92 m.p.h., hitting three-piece Surlyn-covered balls. Advantage: Precept, 234.4 yards to 231.3 yards. Final test: drivers with 10.5 degrees of loft, swung at 80 m.p.h., hitting two-piece Surlyn-covered balls. Precept won again, averaging 206.3 yards to 196 yards.

Steel or graphite?

We tested identical 5-irons, one equipped with a steel shaft, one with a graphite shaft, in 1998. The graphite-shafted 5-iron hit the ball farther by about five yards, probably due to its lighter weight, resulting in greater swing speed. The steel-shafted 5-iron, meanwhile, maintained more consistent distance control. The steel-shafted iron averaged 50 percent less variation in distance and dispersion.

Hit the sweet spot

In 1998, we used a typical graphite-shafted titanium driver and hit balls on the center of the face as well as off the center in both heel and toe directions. Half-inch mis-hits lost up to 3 percent (seven to eight yards) from the 250 yards achieved with center hits. Three-quarter-inch mis-hits averaged a loss of 5 percent (12 to 13 yards). Missing the center by a full inch produced a 9 percent reduction (22 to 23 yards).

If your current shoes look like this, you have pronated feet

Pronator

Clues: Shoe upper extends outside of heel on big-toe side of foot. Low arch, lower-leg pain (e.g., shin splints).

Problem: Foot tends to roll in excessively in heel area.

Best shoes for you: Firm cushioning. Semi-flexible.