Track bicycle

File:RIH Sport track bike.jpg

A track bicycle

A track bicycle or track bike is a bicycle optimized for racing at a velodrome or outdoor track. Unlike road bicycles, the track bike is a fixed-gear bicycle; thus, it has only a single gear and has neither a freewheel nor brakes. Tires are narrow and inflated to high pressure to reduce rolling resistance. Tubular tires are most often used in track racing and training, though advances in clincher tire design have seen them being used somewhat more often.

Frame design

See also: Bicycle frame

A track frame is specific to its use. Rigidity is more important than lightness. Frames for sprinting are as rigid as possible, while those for general racing as aerodynamic as possible.

Rules

The governing body, the Union Cycliste Internationale (UCI), sets limits on design and dimensions as well as the shape and diameter of the tubes used to construct the frame.

Geometry

File:Bicyclemeasurements.svg

Bicycle frame measurements

A track bicycle differs from one used on the road by having:

• higher bottom bracket so the pedals do not touch a steeply banked track
• steeper seat tube for a more aerodynamic position and a shorter wheelbase
• steeper head tube for more responsive steering,
• less fork rake.

Typical track frames use 120mm spacing for the rear hub. The dropouts or track ends face rearwards to facilitate chain tension adjustment.

Material

Frames can be made of steel, aluminium, carbon fiber, or titanium. Carbon fiber is most common at the professional level.

Gears

Track bicycles have only one gear so its size is important. A lower gear allows quicker acceleration or 'jump.' But a bigger gear makes sustained speed easier, important in pursuit racing, time trial and bunched races such as points or scratch events. Without a good jump, the rider risks opponents accelerating away; without good sustained speed, he will be unable to keep up with a fast race. Track cyclists practice fast pedalling (cadence) as a compromise.

Long-distance attempts such as the hour record sometimes use high gear combinations such as 52x12 or 55x14. Ondřej Sosenka used 54x13 with 190mm cranks to set the 2005 record.

Chain

There are two common widths of single speed and fixed gear bicycle chains: 1/8 inch and 3/32 inch. The chainring, sprocket and chain should all be the same width. Although an 1/8-inch chain will work on a 3/32-inch chainring or sprocket, it is not ideal. A 3/32-inch chain will not work on a 1/8-inch chainring or sprocket. Because they do not need to shift from sprocket to sprocket, track chains use a full bushing to allow little flex and to be stronger. Newer bicycles with derailleur gears use bushingless chains which flex, making gear changing possible.

See also

• List of cycling topics
• Path racer