Bobsledding

I

Introduction

Bobsledding, winter sport in which teams of two or four steer a sled down an ice-covered track, reaching speeds of more than 135 km/h (84 mph). The fastest sled wins, often by mere hundredths of a second. The sport’s name comes from its early days, when sledders bobbed their bodies back and forth on straightaways to help the sled along. Bobbing was never proved to work and was soon discontinued, but it remained a part of the sport’s name.

II

Strategy and Technique

The most critical part of a bobsled run is its start. Teams focus on explosive starts because momentum at that point strongly affects the sled’s speed throughout the course. Saving one-tenth of a second during the start often translates to saving one-third of a second on the run as a whole.

To set the bobsled in motion, team members sprint while pushing the sled forward. They run for about 50 m (164 ft) and then leap into the sled just before the first turn, assuming streamlined positions for the remainder of the run. The driver occupies the front position and steers the sled. The brakeman, in the rear position, operates the brake. On a four-man bobsled the two middle sledders contribute mostly during the start, although they also shift their weight during turns.

On the course, drivers try to steer through the turns smoothly and to prevent the sled from skidding into the walls. The greatest challenge is to maintain a tight line on the banked curves, not allowing the sled to drift high up the turn. After the finish, the brakeman pulls up on the brake to stop the sled.

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The basic techniques used in two-man and four-man bobsledding are the same, but because four-man sleds have two extra sledders, they are faster. They gain power from the extra push provided by the middle sledders at the start, the sledders’ additional weight, and the increased weight of a larger sled. The increased speed and weight make four-man sleds harder to steer than two-man sleds.

Bobsled competitions involve training runs and two or four heats, with the lowest combined time winning. Racers often use the training runs to experiment with different strategies.

III

Course and Rules

Bobsled runs look like tunnels without roofs, and they twist and wind down hillsides or artificial slopes. Most have a base of concrete or stone, which is covered with snow and iced over. Courses measure from 1200 to 1600 m (0.75 to 1 mi) in length. Over that distance most courses drop 110 to 125 m (360 to 410 ft) in elevation. They feature straightaways that are barely wider than the sleds and curves that range from slight deviations to 360° turns that are banked 6 m (20 ft) high. In these banked curves, racers can experience the pressure of four times the force of gravity.

Bobsledding’s international governing body, the Fédération Internationale de Bobsleigh et de Tobogganing (FIBT), sets guidelines for equipment, course design, and competition. These guidelines reduce the sport’s risk, but the weight of sleds and their fast speeds make bobsledding hazardous, and some bobsledders have lost their lives during competition. The accidents that occur mostly involve overturned sleds.

Electronic timers at the start and finish lines record the times of the sleds, which often finish only a few hundredths of a second apart. At the end of each run, officials select the top finishers and several other teams for weight and specification checks to ensure that all competitors abide by the rules. Officials also inspect sled runners to check that they are not illegally warmed or coated with silicone for better glide.

IV

Equipment

To provide traction during the start, bobsledders wear spiked shoes that grip the ice. These spikes may not exceed 4 mm (.16 in). Bobsledders also wear skintight uniforms and gloves that make them more aerodynamic. All competitors must wear helmets. Drivers must wear goggles.

Bobsleds are made of aluminum and steel, although synthetic materials such as kevlar and carbon are becoming increasingly popular. All sleds must fit international specifications. The maximum length for two-man sleds, sometimes called boblets, is 2.7 m (8 ft 10 in). Four-man sleds can be 3.8 m (12 ft 6 in) long. Maximum weights, including crew, are 390 kg (860 lb) for two-man sleds and 630 kg (1389 lb) for four-man sleds.

The sled slides on four runners, two on the front axle and two on the rear. The front axle is connected to a steering mechanism of pulleys and ropes that the driver handles. The back axle is bolted to the sled and does not move. The sled also has a brake, a saw-toothed bar that comes down between the back runners. An aerodynamic hood, or cowl, covers the front of the sled. The back is open, which allows the brakeman to jump in easily at the start (the other sledders jump over the side). Handles extend from the back, where the brakeman pushes at the start. The other sledders use handles along the sides; these handles retract once the sledders jump into the sled.