To most tennis fans, it's common knowledge that the French Open clay has the slowest playing surface among the Grand Slam tournaments. Other than that piece of information though, facts about courts and their speeds are not widely known. This is perhaps one of the greater oversights in the understanding of tennis as the speed of court surfaces have a huge impact on the effectivity with which the different styles of playing tennis can be used.
What Court Pace Is and How It's Measured
Court pace, referring to how slow or fast a particular tennis court plays, is measured by the International Tennis Federation (ITF) using a system called the Court Pace Rating (CPR). CPR is determined by measuring the effect that the surface has on a tennis ball. Doing so requires taking many factors into consideration and plugging the measurements of these factors into an equation, both quite complicated and technical. The bottom line, though, is that CPR takes into account the surface's friction and temperature, and how these affect the bounce of the ball.
Various devices are used to determine CPR. One of them is a cannon that fires out a tennis ball at a particular speed. Another is the Sestée, which uses laser technology to take various measurements on the movement of the ball before and after it hits the surface being tested.
The CPR of a court is then used to classify its speed into one of the following categories: Slow, Medium-Slow, Medium, Medium-Fast, and Fast. Looking at the CPR of the various Grand Slam courts paints a clearer picture.
Australian Open: Medium-Fast
French Open: Slow
Wimbledon - Medium
US Open - Fast
Why Courts Have Gotten Slower
In recent years, the courts on the professional tennis tours for men and women have gotten slower, with many of the tournaments opting to use surfaces with lower CPR's than they previously used. The ATP has denied that they gave a directive for courts to be slowed down, but regardless, tournament directors have been choosing to do so.
For example, the ABN AMRO World Tennis Championships in Rotterdam saw a change in the surface it used, resulting in the CPR of courts there to move from "fast hardcourt 38" to "fast hardcourt 25". When their representative, Dimitri Bonthuis, was asked why the change was made, he explained that it was because the courts played too quickly the previous year. He also shared that most players were happy with the change the tournament made, with only a few saying the courts played too slowly.
Furthermore, in 2009, carpet, one of the fastest surfaces to play on, was removed as a featured surface in ATP matches, thus forcing the Rotterdam and Bercy tournaments to change their surfaces into much slower ones. This decision was one voted on by the Top 50 players on the ATP Tour at that time.