A racing bicycle, commonly known as a road bike, 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 most important things about a racing bicycle are its light weight and the aerodynamic efficiency and ergonomics of the rider's position. To this effect racing bicycles may sacrifice comfort for speed. The drop handlebars are positioned lower than the saddle in order to put the rider in a more aerodynamic posture. The front and back wheels are close together so the bicycle has quick handling. The derailleur gear ratios are closely-spaced so that the rider can pedal at his or her optimum cadence.
Distinction between racing bicycles and others Edit
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 faired recumbent bicycles which, on flat ground, are the fastest bicycles in the world. Recumbents were excluded from the UCI 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 UCI rules for these bikes are slightly less prescriptive than those for "massed start road races". (See rules 1.3.020 to 1.3.023)
Racing wheels and tires Edit
The wheels greatly affect the performance of a racing bike. 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 hill climbs, however, energy losses due to the higher weight of most aerodynamic rims are greater than the aerodynamic drag reduction that they offer, so a traditional lighter box-sectioned rim is often used.
Wheel moment of inertia is a controversial subject. In this article: wheel theory, the author does some calculations on wheel effects. Moment of inertia changes result in a decrease in watts of between .004 and .022%, while lower mass provided between .2 and .46%, and better aerodynamics provided between .6 and 1.8% decrease in wattage. Therefore, wheel moment of inertia effects are neither noticeable nor important. At the same time, a product launched in 2008 to dynamically alter the rotating inertia of bicycle wheels claims to have "outperformed the standard, equivalent wheel by 5.6sec/mile."
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 aluminum 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 are lightweight, narrow, and have a thin, smooth tread. They are inflated to a high pressure, typically around 8 bar (820kPa/120psi); track racing tires can be inflated up to circa 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, grip and pinch flat protection, 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 (due to greater ease of changeability) clincher (beaded) tire close the gap. Some manufacturers create tubular-clincher tires, where the tires are sewn around the tubes and have a bead, but there is some debate as to the effectiveness of a tubular-clincher tire. ProponentsTemplate:Weasel-inline believe that it has all the advantages of a tubular tire made to fit a clincher rim, but criticsTemplate:Weasel-inline argue that the design includes disadvantages inherent 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. However, a particular benefit of the tubular-clincher design is that the risk of pinch flats is very low (like the tubular tire), yet it allows the use of the more popular clincher wheel.
Template:RoadBikeComponentsRace 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. In 2006 SRAM introduced their Force and Rival racing groupsets . The companies have different design philosophies, and some cyclists have great brand loyalty for one or the other. In the early 1990s, Shimano introduced dual-control with 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, handlebar ends 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.
The road groupset levels that these companies offer are as follows, from highest to lowest level. The number in the brackets indicates the number of cogs on the freewheel. Shimano: Dura-Ace (10s), Ultegra SL (10s), Ultegra (10s), 105 (10s), Tiagra (9s), SORA (9s), 2300 (8s). Campagnolo: Super Record (11s), Record (11s), Chorus (11s), Centaur (10s), Veloce (10s), Mirage (10s), Xenon (10s). SRAM: Red (10s), Force (10s), Rival (10s).
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 Briton Chris Boardman, who liked the fact that the system allowed 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 2006, some pro riders were seen riding with Shimano electronic shifting groupsets; further testing in the pro-ranks continued during the next 2 years. Recently, Shimano have announced that their 2009 Dura-Ace groupset will include both manual and electronic shifting options.
Carbon fiber has also become more popular for components. Campagnolo and SRAM have introduced carbon fiber for their high-end shifters and brake levers, cranks, and parts of their derailleurs. Carbon fiber 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 road cycling, the racing bicycle is less popular than the sports bike (aka training bike, a slightly heavier and less expensive version of the road racing bike), or the sport/touring bike (a road-only bike with more relaxed frame geometry for general recreation and day touring). Such bicycles, having drop handlebars and other superficial resemblences, are sometimes colloquially called "racing bikes".
Mountain bikes also work on roads, and in their mass produced basic entry-level form tend to be less expensive than road racing bikes, though this is not true of more esoteric dual-suspension models. An entry-level mountain bike starts around half the price of an entry-level road racing bike.
Road bicycles including racing bikes are more efficient for use on smooth roads. Cyclo-cross bicycles, which are used for racing on off-road circuits, 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 larger clearances, can make very dependable and durable general use bikes with only limited modification—usually just a change of tires and gearing.
The UCI rules currently specify 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
- that the only points of support are the following: the feet on the pedals, the hands on the handlebars and the seat on the saddle
- wheels must be of equal diameter, between 70 cm and 55 cm, and must have minimum 12 spokes; spokes can be round, flattened or oval, as far as no dimension of their sections exceeds 10 mm
- 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 mass 6.8 kg (15 lb)
- 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
- The maximum height of the frame elements shall be 8 cm and the minimum thickness 2.5 cm. The minimum thickness shall be reduced to 1 cm for the chain stays and the seat stays. The minimum thickness of the elements of the front fork shall be 1 cm; these may be straight or curved. The top tube may slope, provided that this element fits within a horizontal template defined by a maximum height of 16 cm and a minimum thickness of 2.5 cm
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.
See also Edit
|Search Wikimedia Commons||Wikimedia Commons has media related to: Racing bicycle|
Template:Cb start Template:Road bicycle racing Template:Cb endde:Rennrad hu:Versenykerékpár it:Bicicletta da corsa he:אופני כביש nl:Racefiets ja:ロードバイク pl:Rower szosowy pt:Speed (ciclismo) ru:Шоссейный велосипед sv:Racercykel tr:Yarış bisikleti vls:Koersvelo yi:רעיסינג ביציקל