E. Michael Johnson of Golf World has published an article which says that the USGA sent a memo yesterday to manufacturers announcing a proposal to limit the moment of inertia (MOI) in drivers. If adopted, the proposal will go into effect March 1, 2006.
Moment of Inertia has been a hot selling item lately… on putters, but its use in drivers has taken a back-seat to two other existing limitations - head size (460cc) and Coefficient of Restitution (or CoR, capped at 0.830). MOI is a measure of a clubhead's ability to resist twisting on off-center hits. High MOI = more forgiving clubs. In March of this year, the USGA said that MOI had tripled in drivers since 1990 (yes, since the persimmon days). The March notice also mentioned three other areas would be looked at: spin generation, MOI, and the adjustability of woods and irons (see: TaylorMade r7 Quad).