Recumbent bicycle

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). Recumbents hold the world speed record for a bicycle and were banned from international racing in 1934.

The back of the rider is supported, and the rider's legs extend forward to pedals that are at about the same height as the seat. Steering is either above- or over-seat steering (ASS or OSS) using a handlebar in front of the rider, or under-seat steering (USS) using a handlebar under the seat. The wheels are often smaller and/or further apart than on an upright bicycle.

Records of recumbent designs go back to the early days of cycling, however recumbent use was not widespread until the late 20th century. Recumbent riders hold world speed records for unpaced, human-powered vehicles. Tricycles form a substantial part of the recumbent market (far more so than they do for uprights); the generic term "bike" tends to be applied to these as well.

File:Gold-rush.jpg

The Gold Rush, a classic American long wheelbase bike

Description

Due to their variety, several ways are used to categorize recumbents. These include wheelbase, wheelsizes, steering system, faired or unfaired, and even front-wheel or rear-wheel drive.

Wheelbase

Recumbent bicycles may be classified according to their wheelbase: long wheelbase (LWB) models have the pedals located between the front and rear wheels; short wheelbase (SWB) models have the pedals in front of the front wheel; compact long wheelbase (CLWB) models have the pedals either very close to the front wheel or above it. Within these categories are variations, intermediate types, and even convertible designs (LWB to CLWB) - there is no "standard" recumbent.

Wheel sizes

The rear wheel of a recumbent is usually behind the rider and may be any size, from around 16 inches to the 700c of an upright racing cycle. The front wheel is commonly smaller than the rear, although a number of recumbents feature dual 26-inch (ISO 559), ISO 571 (650c), or ISO 622 (700c) wheels. Notable among these are "highracers", such as the Bacchetta Corsa and Strada or Volae Team. Larger wheels generally have lower rolling resistance; the trade-off is a higher profile with its accompanying air resistance. Highracer aficionados also claim that they are more stable, and although bicycle stability increases with the height of the centre of gravity above the ground, the wide variety of recumbent designs makes such generalizations unreliable.

The most common arrangement is probably an ISO 559 rear wheel and an ISO 406 (20-inch) front wheel. The small front wheel and large rear wheel combination is used to keep the pedals and front wheel clear of each other, avoiding the problem called "heel strike" (where the rider's heels catch the wheel in tight turns). A front-wheel drive configuration also overcomes heel strike since the pedals and front wheel turn together. Pivoting boom front-wheel drive (PBFWD) bikes may have dual 26-inch wheels or larger.

Steering

Steering for bikes is broadly over-seat (OSS) or under-seat (USS), and most trikes are USS. USS is usually indirect -- the bars link to the headset through a system of rods and pivots. OSS is generally direct -- the steerer acts on the front fork like a standard bicycle handlebar -- but the bars themselves may be well behind the wheel (more like a tiller); alternatively the bars might have long rearward extensions (sometimes known as Superman or Kingcycle bars). Chopper-style bars are sometimes seen on LWB bikes.

Drive

As with upright bicycles, most recumbents are rear wheel drive. However, due to the proximity of the crank to the front wheel, front wheel drive can be an option, and it allows for a much shorter chain. One style requires the chain to twist slightly to allow for steering.^[1]Another style has the crankset connected to and moving with the front fork.^[2]

Fairings

HPV's racing in Wonthaggi, Victoria. Many of these cycles are fully faired

Some riders fit their trikes with aerodynamic devices called fairings to reduce wind drag (fairings are also available for upright bikes, but are much less common). Fairings are available for the front and rear of the vehicle. Some riders also use a "sock," a fabric covering which connects the front fairing and the rear fairing, enclosing the rider for even less drag. Front and rear fairings have been shown to be beneficial for long wheelbase bikes, but front fairings are less beneficial for short wheelbase bikes.

Empirical results indicate that a faired tailbox can increase speed on a low short wheelbase bike by around 5-10%, but this has not been validated formally. The design of the fairing is important: a long, sealed fairing gives best compensation for the added weight; for road riding a tailbox may well not repay the weight penalty. The most exotic machines have lightweight full-body fairings, tested in wind tunnels, but these are not practical for street use. Indeed the pilots of many of these bikes must be taped in, and the bike launched by handlers on the outside.

For the ultimate in all-weather riding, a velomobile has a fully enclosed body, is usually a three-wheeled design, and keeps the rider warm and dry in all weather.

Seats

The seats themselves are either of mesh stretched tightly over a frame (as in the Gold Rush pictured) or hard shells like the Stinger pictured, which might be moulded (as here) or assembled from sheet materials. Hard-shell seats predominate in Europe, mesh seats in the USA.

Variations

Lowracers

Lowracers are a type of recumbent more common in Europe among racing enthusiasts. The extreme reclined position, and the fact that the rider is not sitting atop the wheels, but is in line with them, makes this the fastest type of bicycle that can be used on roads.

Tandem recumbents

Just as with upright bicycles, recumbents are built and marketed with more than one seat, thus combining all the advantages of recumbents with those of tandem bicycles. In order to keep the wheelbase from being any longer than absolutely necessary, tandem recumbents often place the stoker's crankset under the captain's seat.

A tadpole recumbent tricycle made by ICE with a transparent front fairing

Recumbent tricycles

Recumbent tricycles (trikes) are closely related to recumbent bicycles, but have three wheels instead of two. 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.

Three remarkable characteristics of recumbent trikes include: 1) the fact that the rider does not need to disengage from the pedals when stopped; 2) the trike can be geared very low to enable mountain climbing while heavily loaded and at a slow speed, without losing stability; and 3) trikes are capable of turning sharply without leaning, producing lateral "g forces" similar to sports cars. Recumbent trikes may also be more suitable for people with balance or limb disabilities.

The Windcheetah, designed by Mike Burrows and one of the first commercial tadpole designs, is often credited with kicking off the recumbent tricycle boom. In addition to having a long association with Giant (for whom he designed the OCR series), Burrows designs and builds two- and three-wheeled recumbent racers, as well as load bikes. The Windcheetah is still in production and is an iconic design much appreciated by enthusiasts.

At present, the tadpole trike market is represented by companies such as Inspired Cycle Engineering (ICE), Greenspeed and HP Velotechnik, with touring being a strong market but sporting use also being common. ICE has produced a sub-20lb trike - all the more remarkable for being steel framed and fitted with a hard-shell seat, full mudguards, and luggage rack. As the market expands, costs continue to drop. Stein has launched a range of budget recumbent trikes made in Eastern Europe, the KMX Kart stunt trike, and others.

File:Handcycle.jpg

A competition handcycle

Handcycles

In order to accommodate paraplegics and other individuals with little or no use of their legs, many manufacturers have designed and released hand-powered recumbent trikes, or handcycles. Handcycles are a regular sight at HPV meets and are beginning to be seen on the streets. These usually follow a delta design with front wheels driven by standard derailleur gearing powered by hand cranks. Brake levers are usually mounted on the hand holds, which are usually set with no offset rather than the 180° of pedal cranks. The entire crank assembly and the front wheel turn together, allowing the rider to steer and crank simultaneously.

Although arms are less strong than legs, many hand cyclists are able to make use of the power of the whole upper body. A good hand cyclist can still achieve a respectable pace in competitions. Georgiev's Varna bikes have been well represented over the years (see also Records below) and in 1995 Jacob Heilveil achieved 52.47 km/h (32.60 mph) in the flying 200 m.

Handcycles have also been used for touring, though few designers incorporate mudguards or luggage racks. Additionally, the gear ratios of standard handcycles tend to be less useful for long steep climbs.

Homebuilts

Unlike upright bikes, there is a subculture of recumbent builders who design and build home-built recumbents. Many times these are assembled of parts from other bikes, particularly mountain bikes. The frame designs may be as simple as a long steel tube bent into the appropriate shape to as elaborate as hand-built carbon fiber frames. For many builders, the engineering and construction of the bikes is as much of a challenge as riding them.

Compared to uprights

The striking difference in appearance between recumbents and upright bikes begs comparison. Note that recumbents come in a very wide variety of concepts (prone recumbents, front wheel drive, tricycles...). This means the (dis-)advantages listed below don't apply to all types, and when they do, then to different, type- or even model-dependant degrees. (For example, balance is not an issue on tricycles.)

The Optima Stinger short-wheelbase bike with disc brakes, rear suspension and over seat (tiller) steering; ETRTO 406 wheels front and rear - a fairly representative European recumbent bike

Riding position

A study by Bussolari and Nadel (1989) led them to pick a recumbent riding position for the Daedalus flight even though the English Channel crossing was accomplished in the Gossamer Albatross with an upright position. Drela in 1998 confirmed "that there was no significant difference in power output between recumbent and conventional bicycling."^[3]

Advantages

Recumbents have several advantages over traditional upright bicycles.

Variety. A specific recumbent can be purchased that best meets the physical needs and aesthetic preferences of the rider. Models can range from semi-upright to a full reclined position, short wheelbase to long wheelbase, fairings for rain/wind protection, suspension, and many others. (This could be considered a disadvantage; see below).

Safety. The recumbent bicycle's low center-of-gravity and low distance from the ground significantly reduce the consequences of a fall for the rider, although the probability of a fall is greater.^{[citation needed]} (A fall is far more critical to a fairing, however.) It's also possible to cycle right beside the curb without risking a pedal-curb collision. A fall from a recumbent may be less harmful than from an upright bike due to the feet-first orientation.

Comfort. The recumbent riding position reduces strain on the body, making it particularly suitable for long rides and touring. It is very easy on the neck, wrists, hands, arms, shoulders, lower back, and ischial tuberosities ("sit bones"). Riders who suffer back pain or genito-urinary trouble often find that recumbents allow them to make significant rides without pain.

Riding Position. The recumbent riding position enables the rider to face forward, at a comfortable angle, and view the passing scenery. An upright bike, particularly a road bike, on the other hand, has a riding position in which the natural angle is to stare down at the pavement below. In order to see the scenery, you have to crane your neck upward.

Health. Many riders switch to recumbents to alleviate the chronic back or neck pain they got from riding upright bikes. And on tricycles (or trikes), the inherent stability of three wheels allows very low gearing to be used, so that hills can be climbed without strain on joints. Also, on some recumbents, the rider's legs are nearly at the same height as the heart. This reduces the rider's hydrostatic pressure, thus allowing venous blood to more easily return to the heart. This physiological effect of improved circulation suggests an increase in rider endurance and/or increased power output on long rides.

Speed. On declines, on the flat, or on shallow inclines, recumbent bicycles are generally faster than upright bicycles for the same level of effort because the aerodynamic profile of the rider reduces wind resistance. It is this feature which led to the Union Cycliste International (UCI) banning them in the 1930s (see History).

Disadvantages

Balance. Balance is easier to effect with a higher centre of gravity, because of the "pendulum effect" (it is easier to minutely change the angle at which ordinary bicycles lean).^[4] The lower center of gravity makes two-wheeled recumbents harder to balance, especially when moving slowly or on unstable surfaces. If a wheel slides, the bike will typically go down very fast. Where one can change one's weight from the seat to the pedals on an ordinary bicycle, one's weight is only on the seat while riding a recumbent. This ability to shift one's weight and place weight on one's feet is an important part of the difference in balancing an ordinary bicycle and balancing a recumbent.

Maneuverability. Recumbents have usually a larger turning radius. Also, it's impossible to jerk the front wheel up curbs. Since the front wheel is usually small, driving up unlowered curbs is very risky even with suspension.

Hills. A perceived disadvantage of the recumbent position is that the rider is unable to stand on ascents. This is most noticeable during the initial period of riding a recumbent when the muscles are not yet trained for the different muscle recruitment. Offset against this, the rider can push against the seat to generate more pedal force than is possible on an upright bike ^{[citation needed]} because on an upright, top pedalling force also derives from a pulling action on the handlebars and not just the legs. As with upright bikes, higher cadence reduces leg strain and fatigue when climbing. A few designers have attempted to build bikes which convert from recumbent to upright for climbs. In practice the biggest difference is probably the additional weight of the recumbent layout combined with the difficulty of balancing a bike with a low centre of gravity at speeds below about 5mph; the idea that recumbents inherently cannot climb is regarded by recumbent riders as a myth as recumbents have won hill-climb challenges and races with substantial ascents against uprights in mixed fields, and have been ridden over the mountain stage routes of the Tour de France.^{[citation needed]}

Riding position. The riding position, while comfortable and removing stress from the arms, cannot easily be varied during a ride (as upright riders might stand for a hill), and some find that bottom brackets at or near hip level produces problems with cold or numb feet. Some riders suffer "recumbent butt", a pain in the gluteal muscles caused by their working harder while being compressed. This can usually be addressed by adjusting the seat angle and pedal position. In a more reclined position, the weight is spread evenly between the back and "butt". Another disadvantage is the eye offset: the distance between the eyes and the front end is quite a bit larger, and in addition, you don't have the option of leaning forward. This leads to a bad insight angle at sharp corners. (Car drivers have the same problem, though less acute since they are closer to the middle of the street.) It's also a bit more difficult to glance back.

Price. Recumbents are generally more expensive than upright bikes. Most are hand-built in comparatively small runs by independent manufacturers, usually with high specification components. A typical recumbent costs 10% to 15% more than an equivalently specified (i.e. generally high-end) upright bike.

Nonstandard design. Recumbents often have radically different shapes than diamond frame bikes, so that conventional bike racks, automobile carriers, accessories and locks don't fit in the usual ways.

Other

Some recumbents with small wheels generally have higher rolling resistance, although this is counteracted by the fact that they also have lower wind resistance (since they have a smaller profile)^{[citation needed]}.

Some models, especially those with a short wheel base (SWB), carry a risk of heel strike where the heel of either foot overlaps the front wheel during turns. This is only evident during tight turns, and is easily avoided by lifting the heel. Another injury phenomenon called "leg suck" occurs when a foot touches the ground and the bike runs forward over the contact point, causing ligament damage and in some cases ankle fractures.

There is some debate as to whether or not it is advisable to use clipless pedals with recumbents. While clipless pedals greatly increase a rider's power since he can "push" and "pull" with both legs during each stroke, there is a tendency to "dab" with a foot to avoid falling just as with an upright bicyle. A clipped-in foot is not as available to respond to this reflexive action. Resulting soft tissue injuries from falling over while clipped in are typically not severe. Alternately, remaining clipped in during a front tire or wheel failure at high speeds can result in the recumbent rolling over the rider and taking his/her clipped in leg(s) with it. This scenario, although very rare, can create severe spiral fractures of the femur. These injury classes notwithstanding, recumbents are generally considered safer than upright bicycles. Many upright bicycle accidents involve the rider going over the handlebars with the resultant risk of head injuries. Recumbent riders are less prone to these types of injuries.

File:Radius-peergynt.gif

The Peer Gynt, a classic long wheelbase bike with under-seat steering and mesh seat

History

Recumbent bicycle designs date back to the middle of the 19th century. A couple were patented around 1900 but the early designs were unsuccessful.

Early recumbents

Recumbent designs of both prone and supine varieties can be traced back to the earliest days of the bicycle. Before the shape of the bicycle settled down following Starley's safety bicycle, there was a good deal of experimentation with various arrangements, and this included designs which might be considered recumbent. Although these dated back to the 1860s the first recorded illustration of a recumbent considered as a separate class of bicycle is considered to be in the magazine Fliegende Blätter of September 10 1893. This year also saw what is considered the first genuine recumbent, the Fautenil Vélociped. Patent applications for a number of recumbent designs exist in the late years of the 19th Century, and there were discussions in the cycling press of the relative merits of different layouts. The Challand designs of 1897 and the American Brown of 1901 are both recognisable as forerunners of today's recumbents.

Mochet's Velocar

A crucial story in the history of recumbent cycling began with the design of a four-wheeled pedal-propelled car called the 'Velocar' (or 'Vélo couché') built in the early 1930s by French inventor and light car builder Charles Mochet. Velocars sold well to French buyers who could not afford a motor car, possibly because of a poor economy just after World War I. The four-wheeled Velocars were fast but didn't corner well at high speed. Mochet then experimented with a three-wheel design and finally settled on a two-wheel design.

To demonstrate the speed of his recumbent bicycle, Mochet convinced cyclist Francis Faure, a Category 2 racer, to ride it 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 hour 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 Mochet's son, Georges, began adding fairings to the Velocar in hopes of bettering the world record of 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.

The UCI ban on recumbent bicycles and other aerodynamic improvements virtually stopped development of recumbents for four decades. Although recumbent designs continued to crop up over the years they were mainly the work of lone enthusiasts and numbers remained insignificant until the 1970s.

1970s resurgence

While developments had been made in this fallow period by Paul Rinkowski and others, the fathers of the modern recumbent movement are usually said to be Chester Kyle and particularly David Gordon Wilson of MIT, two engineers working in the USA. Kyle and his students had been experimenting with fairings for upright bicycles, also banned by the UCI, leading in 1974 to the International Human Power speed Championship, from which the IHPVA grew.

The Avatar 2000, a LWB bike very much like the current Easy Racers products, arrived in 1979, and is often considered the first modern production recumbent. It was featured in the 1983 film Brainstorm, ridden by Christopher Walken, and in the popular cycling reference Richard's Bicycle Book by Richard Ballantine. The oil crises of the 1970s sparked a resurgence in cycling coincident with the arrival of these "new" designs. Since competition was not a driving force, the UCI ruling did not hinder the commercial development of recumbent designs. The influence of Kyle and Wilson and their students probably also had a lot to do with the strength of this renaissance. This era also spawned an adaptation of the recumbent called the Rowbike. Created by Rollerblades inventor Scott Olson, the Rowbike is a hybrid of a recumbent bicycle and an indoor rowing machine.

A parallel but somewhat separate scene grew up in Europe, with the first European human power championships being held in 1983. The European scene was more dominated by competition than was the US, with the result that European bikes are more likely to be low SWB machines, while LWB are much more popular in the US (although there have been some notable European LWB bikes, such as the Peer Gynt).

Recumbents in the 1980s

In 1984 Linear recumbents (of Iowa) began producing what was at the time arguably one of the most comfortable and relaxing bicycles available. Their stability, handling, comfortable seat and natural arm position made them a relaxing form of transportation, recreation and exercise. One rider, returning from their first test ride said, "If my butt had wheels this is what it would be like!"

Linear ownership has changed hands since the 80’s. And in 2002 Linear Manufacturing's assets were bought by Bicycle Man LLCand moved to New York. Since then owner Peter Stull has been working with senior engineering students at Alfred University Alfred University, local engineers and machinists utilizing available technology including computer FEA testing to improve their Recumbent Bikes and bring an old favorite into the new century.

Two short-wheelbase recumbents in an amateur HPV race

In the UK in the 1980s the most publicised recumbent cycle in the UK was the delta configuration, sometime electrically powered Sinclair C5. Although sold as an "electric car", the C5 would be more accurately characterised as a recumbent tricycle with electrical assistance, with all the associated advantages and disadvantages.

Recumbents in the 2000s

A number of recumbent manufacturers went out of business after the 1990s, including BikeE and Vision.

Popular models in the 2000s include recumbents by Challenge Bikes, Bacchetta, RANS, Easy Racers, Lightning, Linear recumbents, HP Velotechnik, and Volae.

The high racer designs of Bacchetta and Volae have become particularly popular^{[citation needed]}, since they combine the safety of being highly visible in traffic^{[citation needed]} with the performance of a nearly fully reclined position and ultra light and performant components.

In 2006, Cruzbike became the first manufacturer to commercialise the Tom Traylor originated configuration for front wheel drive moving bottom bracket with a product that provided a seat height similar to a high racer but with a lower crank height. This approach erased many of the riding difficulties of the center-steered variations^{[citation needed]} produced by European Flevobike company in the 1980s.

Performance

Over distances recumbent bicycles outperform upright bicycles as evident by dominace in ultra-distance events like 24 hours at Sebring (http://www.ultracycling.com/results/sebring2006.html) Official speed records for recumbents are governed by the rules of the International Human Powered Vehicle Association. A number of records are recognised, the fastest of which is the "flying 200m", a distance of 200 m on level ground from a flying start with a maximum allowable tailwind of 1.66 m/s. The current record is 130.36 km/h (81.00 mph), set by Sam Whittingham of Canada on a fully faired Varna Diablo front-wheel-drive recumbent lowracer bicycle designed by George Georgiev. The official record for an upright bicycle under somewhat similar conditions is 82.53 km/h (51.29 mph) set by Jim Glover in 1986 with an English-made Moulton bicycle with a hardshell fairing around him and the bike.

The IHPVA hour record is 85.991 km (53.432 miles), set by Fred Markham on July 2, 2006. The equivalent record for an upright bicycle is 49.700 km (30.882 miles), set by Ondřej Sosenka in 2005. The UCI no longer considers the bike Chris Boardman rode for his 1996 record to be in compliance with its definition of an upright bicycle. Boardman's Monocoque bike was designed by Mike Burrows, whose Windcheetah recumbent trike (see above) also holds the record from Land's End to John o' Groats, 861 miles in 41 h 4 min 22 s with Andy Wilkinson riding.

In 2003, Rob English took on and beat the UK 4-man pursuit champions VC St Raphael in a 4000 m challenge race at Reading, beating them by a margin of 4 min 55.5 s to 5 min 6.87 s - and dropping one of the St Raphael riders along the way.

Stationary recumbents

As well as road-going recumbents bicycles with wheels, stationary versions also exist. These are often found in gyms but are also available for home use. Like a regular stationary exercise bike, these stay in one place and the user pedals against some kind of resistance mechanism such as a fan or alternator but in a recumbent position. These have the same comfort advantages as road-going recumbents. Stationary recumbents almost always have a fairly upright seat and the pedal crank is lower than the level of the seat. The seat is normally adjustable and is adjusted by sliding it along a rail. The heads-up position also makes it easier to watch TV.

Recumbent culture

Recumbent riders tend to be enthusiasts for the type, often referring to upright bikes as "wedgies" or "upwrongs".

Notes

^ "Toxy TT Race Recumbent". Retrieved 2007-02-03.
^ "Front Wheel Drive - Is it practical?". Retrieved 2007-02-03.
^ Wilson, David Gordon (2004). Bicycling Science (Third edition ed.). Massachusetts Institute of Technology. pp. 72, 86. ISBN 0-262-73154-1. {{cite book}}: |edition= has extra text (help); Cite has empty unknown parameter: |coauthors= (help)
^ Fajans, Joel. "Email Questions and Answers: Robot Bicycles". Retrieved 2006-08-07.

External links

[Toxy-1] "Toxy TT Race Recumbent". Retrieved 2007-02-03.

[traylor-2] "Front Wheel Drive - Is it practical?". Retrieved 2007-02-03.

[wilson-3] Wilson, David Gordon (2004). Bicycling Science (Third edition ed.). Massachusetts Institute of Technology. pp. 72, 86. ISBN 0-262-73154-1. {{cite book}}: |edition= has extra text (help); Cite has empty unknown parameter: |coauthors= (help)

[4] Fajans, Joel. "Email Questions and Answers: Robot Bicycles". Retrieved 2006-08-07.

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