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 twoman sleds, sometimes called boblets, is 2.7 m (8 ft 10 in). Fourman sleds can be 3.8 m (12 ft 6 in) long. Maximum weights, including crew, are 390 kg (860 lb) for twoman sleds and 630 kg (1389 lb) for fourman 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 sawtoothed 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.