USGA rules on MOI

[Gxgolfer]

By Mike Stachura

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WHEN the USGA informed equipment manufacturers last week it will be implementing a rule on clubhead moment of inertia in woods (in essence, MOI is a clubhead's resistance to twisting on off-center hits) but at a less stringent limit than previously proposed, clubmakers breathed a sigh of relief.

Less clear in the wake of the April 12 e-mail, a copy of which was obtained by Golf World and Golf Digest, is what the increase could actually mean from a performance standpoint. For although the raised limit, which takes effect May 1, was hailed by most manufacturers as a potential boon for average players who miss the center of the clubface by a lot (while having little to no impact on elite players whose mis-hits are confined to a smaller area), Dick Rugge, senior technical director for the USGA, said the increase from the originally proposed 4,750 grams-centimeters squared to 5,900 grams-centimeters squared (plus a test tolerance of 100 gm-cm2) would mean little for golfers across the board.


"At that level [of MOI], there's not any appreciable difference," said Rugge. "It really doesn't mean anything. If you were talking about going from 2,000 to 3,000, then yes, but not at this level. We thought this was an appropriate place for us to set a limit to protect the game from any future unknown developments."

Most large-headed drivers currently on the market are in the 4,000 to 4,300 MOI range. However, the move is consistent with the USGA's desire in recent years to be proactive with equipment regulations.

When the USGA announced in March 2005 that MOI was one area (along with spin generation and adjustability of clubs) it was looking at, the governing body said it was "concerned that any further increases in clubhead moment of inertia may reduce the challenge of the game." And when the original proposal was put forth last August, Rugge made it known it was being done with an eye toward the future.

"This is based on our own research and modeling of what could happen," Rugge said. "And that showed that manufacturers could respect the head-size limit but produce clubs with a significantly higher MOI, and we felt it better to act well prior [to] than after the fact."