Recumbent bicycle

From Academic Kids

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Tandem recumbent bicycle manufactured by BikeE

A recumbent bicycle is a variety of bicycle which places the rider in a seated or supine position (rarely, in a prone position). The back of the rider is supported, and the rider's legs are extended forward to pedals that are about the same height as the seat. Steering is either above seat steering (ASS), which uses a handlebar that is located in front of the rider, or under seat steering (USS), which uses a handlebar located under the seat. The wheels are often smaller and/or further apart than on an ordinary bicycle.

Contents

General description

Recumbent bicycles are often classified according to their wheelbase. Long wheelbase (LWB) models have the pedals located between the front and rear wheel. Short wheelbase (SWB) models have the pedals in front of the front wheel. There are variations and intermediate types. Compact long wheelbase (CLWB) models have the pedals either very close to the front wheel or above it.

The rear wheel of a recumbent is usually behind the back of the rider and is the size of a normal bicycle wheel or smaller. The front wheel is usually smaller than conventional bicycle wheel. A new trend for performance recumbents is the hi-racer which has dual 26" (ISO 559), ISO 650, or ISO 622 (700c) wheels. Many feel that the larger wheels are faster. Most recumbents have an ISO 559 rear wheel and an ISO 406 (20") front wheel.

The small front and large rear wheel combination comes about because the pedals and front wheel must be kept clear of each other. A further configuration that overcomes this constraint is a front wheel drive arrangement where the pedals and front wheel move together. The pivoting boom front wheel drive (PBFWD) often has dual 26" wheels or larger.

Advantages of recumbent bicycles include a more comfortable seating position without pressure on the genital area and without neck and back strain, sometimes better aerodynamics, safer braking and, particularly with trikes, greater stability. A disadvantage of recumbent bicycles is that they are often more expensive than comparable upright bicycles.

On the flat, recumbent bicycles are often substantially faster than upright bicycles for the same level of effort because the aerodynamic profile of the rider reduces wind resistance. Many owners prefer a "'bent" because it reduces the strain on the hands, arms, shoulders, and buttocks. A perceived disadvantage of the recumbent cycling position is that the rider is unable to stand on ascents and so tends to be slower going uphill than on an upright bicycle. This is most noticeable during the initial period of riding a recumbent when the muscles are not yet trained for the different exertion. Some riders who switch styles find that they are slower in hilly terrain but they are able to keep riding longer because they experience much less discomfort. Others (especially those who would otherwise NOT stand up to climb a hill) find that the ability to brace against the seat-back gives them the perception of being faster uphill than they were on an upright bike. Experienced recumbent riders learn to pedal at a higher cadence than they would on an upright, or "diamond-frame" bicycle. This reduces leg strain and fatigue in strenuous situations.

Some recumbent bicycles and tricycles utilize aerodynamic devices called fairings which reduce wind drag. Fairings are available for the front as well as the rear of the vehicle. Some recumbents also use a "sock" which is a fabric covering which connects the front fairing and the rear fairing, enclosing the rider for even more aero benefit. Front and rear fairings have been shown to be beneficial for long wheelbase bikes whereas front fairings are not beneficial for short wheelbase bikes.

Recumbent tricycles

Recumbent tricycles or "trikes" are closely related to recumbent bicycles, although they have three wheels instead of two and are therefore not technically bicycles. Trikes come in two varieties, the delta, with two rear wheels, and the tadpole, with two front wheels. Most recent high-performance trikes are of the tadpole variety. There are three remarkable characteristics of recumbent trikes: the rider does not need to disengage from the pedals when stopped; the trike can be geared very low to enable mountain climbing while heavily loaded and at a slow speed without losing stability and becoming wobbly; and trikes are capable of turning sharply without leaning, producing lateral "g forces" similar to a sports car. Recumbent trikes are very suitable for anyone with a balance or limb disability.

Some riders of very low recumbent bikes (low-racers or trikes) attach a flag to the rear of the bicycle to give themselves greater visibility in traffic. However, the unusual appearance of a recumbent often means it is readily spotted anyway.

History

Bicycle designs that put the rider in a reclined position date back to the middle of the 19th century. A couple of recumbent designs were patented around 1900 but the early designs weren't successful.

The predecessor of first successful recumbent bicycle was not a bicycle. It was a four-wheeled pedal-car called the 'Velocar' built in the early 1930s by French inventor Charles Mochet who had previously built very light automobiles. Due to a poor economy in France just after World War I, Velocars sold well to buyers who couldn't afford a real car. The four-wheeled Velocars were fast but they didn't corner well at high speed, so Mochet experimented with a three-wheel design and then finally settled on a two wheel design, a bicycle.

Looking for a way demonstrate the speed of his recumbent bicycle, Mochet convinced cyclist Francis Faure, who was not one of the top cyclists, to ride the two-wheeled Velocar in races. Faure was highly successful, defeating many of Europe's top cyclists both on the track and in road races, and setting new world records at short distances. Another cyclist, Paul Morand, won the Paris-Limoges race in 1933 on one of Mochet's recumbents.

Then on 7 July 1933 at a Paris velodrome, Faure rode a Velocar 45.055 km (27.9 miles) in one hour, smashing an almost 20 year old record held by Oscar Egg. Since the one hour record was one of the most important in all of cycling, that accomplishment attracted a great deal of attention. Less than two months later, on 29 August 1933, Maurice Richard, riding an upright bicycle, also bettered Egg's one hour record.

When the Union Cycliste Internationale (UCI) met in February, 1934, manufacturers of upright bicycles lobbied to have Faure's one hour record declared invalid. On 1 April 1934, the UCI published a new definition of a racing bicycle that specified how high the bottom bracket could be above the ground, how far it could be in front of the seat and how close it could be to the front wheel. The new definition effectively banned recumbents from UCI events and guaranteed that upright bicycles would not have to compete against recumbents. For all intents and purposes the ban is still in effect.

After the decision Faure continued to race, and consistently beat, upright bicycles with the 'illegal' (according to the UCI) Velocar.

In 1938 Faure and Charles Mochet's son, Georges, began adding fairings to the Velocar in hopes of bettering the world record for one hour for a bicycle with aerodynamic components. On 5 March 1938, Faure rode a faired Velocar 50.537 kilometers in an hour and became the first cyclist to travel more than 50 kilometers in an hour without the aid of a pace vehicle.

Performance

Official speed records for recumbents are governed by the rules of the International Human Powered Vehicle Association. Records are set over a distance of 200 meters on level ground from a flying start with a maximum allowable tailwind of 1.66 m/s. The world record for any human powered vehicle is 130.36 km/h (81.00 mph), set by Sam Whittingham of Canada on a low racer recumbent bicycle with front wheel drive and a highly aerodynamic body. The official record for an upright bicycle under somewhat similar conditions is 72.98 km/h (45.36 mph) set by Curt Harnett in 1995.

The hour record on a recumbent bicycle is 84.215 km (52.32 miles), set by Sam Whittingham on July 31, 2004. The equivalent record for an upright bicycle is 49.441 km (30.723 miles), set by Chris Boardman in October 2000. The UCI no longer considers the bike Boardman rode for his 1996 record to be in compliance with its definition of an upright bicycle.

External links

de:Liegerad eo:Kuŝbiciklo fr:Vlo couch ja:リカンベント nl:Ligfiets pl:Rower poziomy

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