At speeds approaching 90 mph, two-man and four-man sleds race down an icy, curved track. The competition is determined in four heats against time. The final time is the combined total of four runs. The bobsled must be push started, and each heat has to be completed by the same crew.
Watch for an explosive start. Standing 50 meters behind the starting line, the driver and his brakeman (and two pushers in the four-man) rock their bodies and the sled back and forth in unison, then throw the sled forward. A tenth of a second saved pushing can translate into a third of a second off the run time.
Speed is affected by three factors: weight, air resistance and friction. Only technical aspects - length, weight, etc. - are regulated. Sleds can be any shape.
Allows front of sled flexibility to react independently of the rear.
THE CREW AND SLED
BRAKEMAN: Once over the finish line, pulls metal arms that lower a saw-toothed brake. Braking during a run is an immedite disqualification.
CREWMAN: Push the sled at start, jump in and mostly stay still, although they will bob forward with brakeman and driver on the straightaways to help the sled jump forward.
DRIVER: Looks for and steers the fastest route, using a rope pulley system. The ropes barely have to be moved to affect the direction of the sled. Best results are when the crew remains still and the driver lets the sled do the work for him.
Work as bumpers. Sleds can lose a tremendous amount of speed by hitting the ice wall.
Design varies depending on the weather. Shape is flat for warmer weather and curved for colder.
Source: Associated Press