Racing bicycle
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An aluminum racing bicycle made by Raleigh and built using Shimano components. It uses a semi-aerodynamic wheelset with low spoke count. |
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A racing bicycle made by Cyfac using shaped aluminum and dual carbon fiber chain- and seat-stays. It uses Campagnolo components. |
A
racing bicycle is a
bicycle designed for
road cycling according to the rules of the
Union Cycliste Internationale (UCI). The UCI rules were altered in 1934 to exclude
recumbent bicycles.
The two most important things about a racing bicycle are its weight and the
aerodynamic efficiency of the rider's position. Drop
handlebars and optional handlebar extensions are combined with a raised seat in order to put the rider in a more aerodynamic posture. The front and back wheels are close together so the bicycle can turn very quickly. The
derailleur gear ratios are closely-spaced so that the rider can pedal at his or her optimum
cadence.
Bicycles for racing on
velodromes are
track bicycles; bicycles for racing offroad are
mountain bicycles,
cyclo-cross bicycles or
cycle speedway bicycles; bicycles that race according to the rules of the
International Human Powered Vehicle Association include
recumbent bicycles which are the fastest bicycles in the world. Recumbents were excluded from the definition of a bicycle on
1 April 1934.
Time trial bicycles are a subset of racing bicycles that are designed for
time trial events.
The
wheels greatly affect the performance of a racing bike. The wheels rotate at high speeds; consequently their
moment of inertia matters a lot. The rim of the wheel can be shaped for greater aerodynamic efficiency making a triangular cross-section to form a teardrop with the tire. For hillclimbs, however, effects from weight overcome those from aerodynamics, and the traditional box-sectioned rim is often used.
For aerodynamics and rotating weight, it is generally better to reduce the number of
spokes in the wheel. For high-end wheelsets, the spokes can be shaped to have a bladed cross-section, further reducing wind resistance.
The most common material for a wheel rim is
aluminium alloy. Using a molded
carbon fiber rim reduces weight compared to a metal rim. Using exotic materials, race-grade wheelsets are very expensive. Riders who race often choose to own at least two pairs of wheels. A heavier, more durable, and cheaper wheelset for training, and a lighter, more aerodynamic wheelset for racing.
To reduce both air resistance and
rolling resistance on the road, tires or tyres are lightweight, narrow, and have a thin, smooth tread. They are inflated to a high pressure, typically around 8
bar (820
kPa/120
psi); track racing tires can be inflated up to c.14 bar. Until recently, most racing bikes used "tubular/single/sew-up" tires which have no beads: they are sewn around the tube and glued to the rim. These tires provide an advantage in weight (lacking the relatively heavy wire bead), rolling resistance and grip, but their greatest advantage lies in the ability to use a very lightweight simple box-section rim, rather than the U-shaped clincher rim. A U-shaped clincher rim must use relatively heavier gauge to prevent the tire pressure from spreading the inherently weak U shape and allowing the tire to come off the rim. Advances in tire technology, however, have seen the far more practical clincher (beaded) tire close the gap. Some manufacturers create Tubular-Clincher tires, where the tires are sewn around the tubes and have a bead, there is some debate as to the effectiveness of a tubular-clincher tire. Some say that it has all the advantages of a Tubular tire made to fit a clincher rim. Other would argue that you have all the disadvantages to both systems---the rim weight is still high, the tire is more expensive than a standard clincher tire, and repairing a puncture on a tubular clincher is as inconvenient as it is with a standard tubular tire. The one benefit of a tubular-clincher is that the risk of pinch flats is very low (like the tubular tire) and one would get to use the more popular clincher style wheels.
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A racing bicycle with carbon frames and cranks. It has a drop handlebar and components made by Campagnolo, except for the cranks. |
Race bike components (excluding frame, fork, wheelset, bars, stem, pedals, saddle and seatpost) are collectively referred to as the
groupset. The quality of the groupset determines how refined the bike feels, how much maintenance it requires, and contributes to the performance of the bike. The two major groupset manufacturers of complete groupsets for racing bicycles are
Shimano and
Campagnolo. The companies have different design philosophies, and some cyclists have great brand loyalty for one or the other. Other companies that produce individual components, but not whole groupsets include
Full Speed Ahead (FSA) and
SRAM. However, SRAM has recently announced that they will be introducing a full road groupset in
2006.
In the early 1990s,
Shimano introduced dual-control a system called
Shimano Total Integration (STI). STI is characterized by its combined brake and
shift levers, or "brifters". Previously, the shifters were mounted on the stem or the down tube of the frame. Dual control addressed the problem of having to reposition a hand to change gears. STI was followed by the competing
Campagnolo/Sachs
Ergolever. Other than this, the general design of a racing bicycle has changed little since the development of derailleurs.
In the mid 1990s
Mavic, known for their wheelsets, introduced an electronic shifting system which was pioneered in the
Tour de France by American
Greg LeMond and later on by Brit
Chris Boardman, who liked that the system allows him to shift from his
aerobars and his brake levers. The system did not catch on due to technological hurdles, but it has been rumored that Campagnolo has been developing an electronic groupset and has been field tested as recently as the 2005
Giro d'Italia. In early March of 2006, some pro riders were seen riding with Shimano electronic shifting groupsets as well.
Carbon-fibre has also become more popular for components. Campagnolo has introduced carbon-fibre for their high-end shifters and brake levers, cranks, and parts of their
derailleurs. Carbon-fibre stems, handlebars, shoe soles, forks and seatposts are also more commonplace, including integrated stem/handlebar combinations. The advantages of carbon fiber are low weight as well as increased vibration dampening leading to a more comfortable ride.
For
recreational cycling, the racing bicycle is less popular than the mountain bike. Mountain bikes, through mass production and popularity, are less expensive. A new entry-level mountain bike starts around half the price of an entry-level racing bike.
Racing bikes are less durable and less strong than mountain bikes. But unless a rider intends riding on rough tracks a racing bike is more efficient for everyday use.
Cyclo-cross bikes, which are ridden off-road, are closer to racing bikes than to mountain bikes. They have wider, treaded tires and cantilever brakes instead of caliper brakes but are still less efficient than racing bikes for use on the roads. Cyclo-cross bikes, because of their more rugged frame construction, can make very dependable and durable road racing bikes for a beginner with only limited modification -- usually just a change of tires.
The UCI rules (rewritten in 1934 to exclude recumbent bikes which had recently captured the world speed record) specify[
1] that a racing bicycle have the following characteristics, :
* be a vehicle with a front wheel steered by a
handlebar and a rear wheel driven by a system comprising
pedals and a
chain by the legs moving in a circular movement
* wheels must be of equal diameter, between 70 cm and 55 cm, and must have minimum 12 spokes
* maximum length 185 cm
* maximum width 50 cm
* the peak of the saddle must be at least 5 cm behind a vertical plane passing through the
bottom bracket spindle
* the saddle must be between 24 cm and 30 cm in length
* the distance between the bottom bracket spindle and the ground must be between 24 cm and 30 cm
* the distance between the vertical passing through the lower bracket spindle and the front wheel spindle must be between 54 cm and 65 cm
* the distance between the vertical passing through the bottom bracket spindle and the rear wheel spindle must be between 35 cm and 50 cm
* the maximum internal distance between the front
fork ends is 10.5 cm, and of the rear stays 13.5 cm
* minimum weight 6.8 kg (~15 lbs)
*
frame must be built around a main triangle, constructed of tubular elements (that may have non-circular cross-sections) such that the form of each encloses a straight line
Note that the regulations regarding the dimensions of the bike are allowed exception, given that the rider can demonstrate a morphological need for the exception based on limb size or other factors.
*
Bicycle*
Bicycle frame*
Road cycling*
Bicycle racing
