Clay Court 101

In 2005, 1,435 aces were hit at Roland Garros, versus 2,080 at Wimbledon. It is no surprise that clay proves to be the most difficult surface for heavy hitting Americans. Dr. Stuart Miller, the chief technical ‘wizard’ for the International Tennis Federation gave ESPN Magazine a tennis insider’s look into the physics which makes Roland Garros so challenging.

In the June issue, Miller comes to the conclusion that for the most part Americans are “just too powerful.” Miller has analyzed the earthy mix of clay surfaces (a combo of rocks, pebbles, clay, mud and brick) to determine something called “frictional coefficients, numbers that indicate the resistance between court surface and ball. Clay, the slowest surface has a rating of about 20, where as Wimbledon grass courts are in the low 40’s.

A neutral spin 120 mph serve on clay (which absorbs a serve’s power) takes .101 seconds longer to reach the baseline than a serve hit on grass. Players are well aware of this and don’t waste energy trying to kill the ball. In fact, the average speed for the 20 top servers at the French is 134 mph, 4 mph slower than at Flushing Meadow and Wimbledon.

In addition, serves on clay also bounce higher than on other surfaces. The same 120 mph serve rebounds 17.32 inches higher than on grass, giving receives more time to set up, resulting in fewer aces. It is these scientific certainties that force most players to change their strategies significantly.

Check out the June issue of ESPN the Magazine for more dirt on the tricky clay courts.