Moment of Inertia (MOI) And Swing Weight

!±8± Moment of Inertia (MOI) And Swing Weight

Moment of Inertia (MOI) governs how a bat feels and is a more meaningful measure of how well it will swing for you than the actual weight of the bat. Bat speed, not bat size nor weight, is the main factor in driving a ball. Bat speed is affected by a number of variables including bat length, bat weight and bat Moment of Inertia (MOI) which is often referred to as swing weight or balance point.

The distinction between light or heavy swing weight really boils down to the location of the balance point (or center-of-mass) and the moment-of-inertia. The closer the bat's balance point is to the handle, the easier it is to swing. The basic concept is that it is not the total overall weight of the bat which determines how fast you can swing a bat, but the way that weight is distributed along the length of the bat. For example, a bat with a balanced point closer to the handle will feel lighter and swing faster than an end loaded bat. This is true even through both bats are the exact same weight on a scale. The higher the rating the higher the MOI and the heavier the swing weight.

As a general rule, most players can hit a ball further with lighter (really low MOI) bats. It is only the biggest homerun hitters, who can hit the ball further with a heavier (really higher MOI) bats. Also, lighter bats provide more bat control during the swing phase.

Good players who are strong tend to prefer bats with a heavy swing weight because they can swing the bat fast enough and the extra inertia of the bat makes for a more effective collision with the ball. Players who are not as strong, or who cannot swing a heavy bat quickly, tend to opt for bats with a lighter swing weight so that they can increase their bat-swing speed and obtain faster batted balls that way.

Easton is one of the few manufacturers that promote the MOI of their bats and is the basis of their Hit Matrix bat concept. Here is the MOI ratings for their 2009 bats:

Stealth IMX - 90 MOI Rating Synergy IMX - 80 MOI Rating SV12 - 70 MOI Rating V12 - 60 MOI Rating

Obviously MOI is only one factor to consider with material, handle flex, mass and design (1 or 2 piece) being the others. But, it is often ignored or misunderstood. You should take the time and effort to decide what MOI is best for you and what the ratings are for the bats you're considering.

You can visit The Baseball Bat Reviews Blog for reviews of all the 2009 baseball bats.