Velodrome

The Dunc Gray Velodrome located in City of Bankstown

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.

Technical aspects

Banking in the turns, called superelevation, allows riders to keep their bikes relatively perpendicular to the surface while riding at speed. When traveling through the turns at racing speed, which may exceed 60 kmh (about 37 mph), the banking attempts to match the natural lean of a bicycle moving through that curve. Therefore, the centripetal acceleration of the combined inertia of bicycle and rider moving in the curved path balances the tangential acceleration pulling them outwards. There is no centrifugal force 'trying' to tilt the bicycle outward, a net normal force is acting on the tires through the riding surface.

Riders are not always traveling at full speed or at a specific radius. Most events have riders all over the track. Team races (like the madison) have some riders at speed and others riding more slowly. In match sprints riders may stop. For these reasons, the banking tends to be 10 to 15 degrees less than physics predicts. Also, the straights are banked 10 to 15 degrees more than physics would predict. These compromises make the track ridable at a range of speeds.

From the straight, the curve of the track increases gradually into the circular turn. This section of decreasing radius is called the easement spiral or transition. It allows bicycles to follow the track around the corner at a constant radial position. Thus riders can concentrate on tactics rather than steering.

Bicycles and track design

Bicycle racing on an outdoor velodrome.

Bicycles on velodromes have no multiple gears or brakes. They employ a fixed rear gear, or cog, that does not freewheel. This helps maximize speed, reduces weight, avoids sudden braking while nevertheless allowing the rider to slow by pushing back against his pedals.

Modern velodromes are constructed by specialised designers. The Schuermann architects in Germany have built more than 125 tracks worldwide. Most of Schuermann's wooden outdoor tracks are made of wood trusswork with a surface of strips of the rare rain-forest wood Afzelia. Indoor velodromes are built with less expensive pine surfaces. Other designers have been moving away from traditional materials. The 1996 Atlanta Olympics saw the introduction of synthetic surfaces supported by steel frames.

The track is measured along a line 20 cm up from the bottom. Olympic standard velodromes may only measure between 250 m and 400 m, and the length must be such that a whole or half number of laps give a distance of 1 km. Others range from 133 m to 500 m, although 250m is the most popular and the length used in major events. The velodrome at Calshot Spit, Hampshire, UK is only 142 m because it was built to fit inside an aircraft hangar. It has especially steep banking. Forest City Velodrome in London, Ontario, Canada, is the world's shortest at 138 m. It was built to fit a hockey arena. Like Calshot, it has steep banking.

Many old tracks were built around athletics tracks or other grounds and any banking was shallow. The smaller the track, the steeper the banking. A 250 m track banks around 45°, while a 333 m track banks around 32°.

Velodrome tracks can be surfaced with different materials, including wood, synthetics and concrete. Shorter, newer, and Olympic quality tracks tend to be wood or synthetics; longer, older, or inexpensive tracks are concrete, macadam, or even cinder, as in the Little 500.

Track markings

Track markings

All tracks must have standard markings. Between the infield (sometimes referred to as an apron) and the actual track is the blue band (called "côte d'azur") that is typically 10% of the surface. The blue band is not a part of the track. Although it is not illegal to ride there, moving into it to shortcut another rider will result in disqualification. During time trials, pursuits or other timed events, the blue band is obstructed with sponges or other objects. The blue band is a warning to cyclists that they may scrape their pedal along the infield when in a curve. This can easily result in a crash, so this is why it is ill-advised to ride on the blue band.

20 cm above the blue band is the black line. The inner edge of this 5 cm line defines the length of the track. 90 cm above the inside of the track is the outside of the 5 cm wide red sprinter's line. The zone between black and red lines is the optimum route around the track. A rider leading in this zone cannot be passed on the inside; other riders must pass on the longer outside route.

Minimum 250 cm (or half the track width) above the inside of the track is the blue stayers' line. This line serves in races behind motorbikes as a separation line. Stayers below the blue line may not be overtaken on the inside. In Madison races (named after six-day races at Madison Square Garden in New York City, New York and known as the American), the team's relief rider rests above the Stayer’s line by riding slowly until his or her teammate comes around the track and throws him or her back into the race.

The finish line is black on white and towards the end of the home straight. Red lines are marked in the middle of each straight as start and finish line for pursuit races. A white 200 m line marks 200 m before the finish.

Track construction

Velodromes may be indoors or outdoors. In the heyday of velodrome racing (1890-1920), indoor tracks were common. When hosting six-day races, they were popular for revelers and urban sophisticates to congregate in the early hours after the bars had closed. Indoor tracks are not affected by weather and are more comfortable for spectators. They ride smoother and last longer. Despite the advantages of indoor tracks, outdoor velodromes are more common, as an outdoor venue does not require a building, making it more affordable, especially when new. Today, although many classic indoor tracks have been torn out of buildings and replaced by venues for more popular sports, velodromes are still sometimes built into indoor venues, particularly where track racing can generate enough to cover the expense of dedicating a building to it.

A velodrome will usually be among facilities constructed for events such as the Olympics or Commonwealth Games.

External links

• Greek olympic velodrome
• List of velodromes