- Track bicycle
A track bicycle or track bike is a bicycle designed for racing at a
velodrome . Unlikeroad bicycle s, they have a single gear, nofreewheel , and no brakes. Tires are narrow and at high pressure to reducerolling resistance .Tubular tires are often used.Frame design
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
International Cycling Union (UCI), sets limits on design and dimensions as well as the shape and diameter of the tubes used to construct the frame.Geometry
A track bicycle differs from one used on the road by having:
*higherbottom bracket so the pedals do not touch a steeply banked trackFact|date=August 2008
*steeper seat tube for a more aerodynamic position,
*steeperhead tube for more responsive steering,
*less fork rake.Typical track frames use 120mm spacing for the rear hub. The dropouts or "track ends" face backwards to facilitate chain tension adjustment.
Material
Frames can be made of
steel ,aluminium , carbon fiber, ortitanium . 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 sustain speed easier, important in
pursuit ,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 practise fast pedalling as a compromise.Long-distance attempts such as the
hour record 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 chain s: 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. All bicycles withderailleur gears use bushingless chains which flex, making gear changing possible.External links
* [http://www.chainedrevolution.com/discuss/default.aspx Discussions and Photos of track cycling topics at Chained Revolution]
* [http://velospace.org/taxonomy/term/1+2+3 Photos of track bikes at velospace.org]
* [http://www.veloroutes.org/photos/fixedgear.html More photos of track bikes at veloroutes.org]
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