Wiki article on this topic: A velodrome is an arena for track cycling. Modern velodromes feature steeply banked oval tracks, consisting of two 180-degree circular bends connected by two straights. The straights transition to the circular turn through a moderate easement curve.
The first velodromes were constructed during the mid-late 19th century. Some were purpose-built just for cycling, and others were built as part of facilities for other sports; many were built around athletics tracks or other grounds and any banking was shallow. Reflecting the then-lack of international standards, sizes varied and not all were built as ovals: for example, the oldest velodrome in the world, at Preston Park, Brighton , is 579 m long and features four straights linked by banked curves, while the 536 m Portsmouth velodrome, in Portsmouth, has a single straight linked by one long curve. Early surfaces included cinders or shale, though concrete, asphalt and tarmac later became more common.
Indoor velodromes were also common particularly in the late 19th and early 20th century. For example, the Vélodrome d'hiver was built in Paris in 1909 and featured a 250 m indoor track with a wooden surface.
International competitions such as the Olympic Games led to more standardisation: two-straight oval tracks quickly became the norm, and gradually lap lengths reduced. The Vélodrome de Vincennes, used for the 1896 Games was 500 m per lap, while Antwerp's Vélodrome d'Anvers Zuremborg, used in 1920, and Helsinki Velodrome, used in 1952, were both 400 m. By the 1960s, tracks of 333.33 m length were commonly used for international competitions. Since 1990, such events are usually held on velodromes with 250 m laps. London's 2012 Olympic velodrome and a new velodrome in Turkmenistan's capital city Ashgabat both have a 250 m track and a 6,000-seat spectator capacity.
Banking in the turns, called superelevation, allows riders to keep their bikes relatively perpendicular to the surface while riding at speed. When travelling through the turns at racing speed, which may exceed 85 km/h , the banking attempts to match the natural lean of a bicycle moving through that curve. At the ideal speed, the net force of the centrifugal force and gravity is angled down through the bicycle, perpendicular to the riding surface.