A bobsled race takes place on a specially built track called a run. The IBSF has standards for all new bobsled runs, which must also be usable for luge and skeleton races. There are 18 bobsled runs in the world, and 16 have IBSF approval. IBSF standards regulate the length, curve construction, vertical drop and centrifugal force the bobsledders experience in curves. Whenever possible, new tracks follow the curves of the terrain to minimize environmental impact.
Of all of the bobsled runs in the world, only one, the St. Moritz-Celerina located in St. Mortiz, Switzerland, uses entirely natural snow and ice. The rest of the world's bobsled runs are made from metal and concrete. Before the race, people cover the concrete with snow, then soak the snow with water. The resulting ice forms the surface for the race.
Bobsledders begin the race in a push-off stretch. This is a straight stretch that's wide enough to allow the bobsledders to push the bob. The athletes have to run as fast as they can — this push and gravity are the bob's only sources of speed for the entire race. During the push-off, any ballast that the team has added to bring the bobsled up to the maximum weight is a liability. Even though there is very little friction, a heavier bob is harder to push.
The push-off takes about six seconds. A good start is crucial — a lead of a 1/10 of a second at this point can result in a lead of 3/10 of a second by the end of the race. After pushing off, the bobsledders jump from the track into the bob and crouch in an aerodynamic position. Usually, the driver gets in first, and the brakeman gets in last. The driver and crewmen, if there are any, fold their handlebars down.
At this point, the race is mostly up to the driver and gravity. Using very precise movements, the driver steers the bob down the run. Crewmen shift their weight when necessary in turns. The driver's aim is to find the line — the ideal path down the track. We'll look more at the line and how physics affect the bobsled's course next.