Recumbent

Sheldon Brown's Bicycle Glossary · letter R
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A vehicle in which the rider assumes a more-or-less horizontal position, usually reclining with the feet forward. Recumbent bicycles are potentially more aerodynamic than conventional "upright" bicycles, but tend to be more complicated mechanically. They are very comfortable, and are often quite well adapted for long-distance riding. Most recumbent bicycles have smaller-than-usual front wheels.

There are many different designs of recumbents. They fall into several classes which are known by arcane abbreviations:

Wheelbase categories:

• L.W.B. (Long Wheel Base) recumbents have the front wheel located in front of the "bottom bracket". LWB recumbents have straight, efficient chain runs. The downsides of the LWB design include poor weight distribution (too little on the front wheel), and general unwieldiness due to the greater overall length.
• C.L.W.B. (Compact Long Wheel Base) recumbents are a variation which usually uses small 406 mm (20") wheels front and rear, with the rear tucked somewhat under the seat to reduce the wheelbase.
• S.W.B. (Short Wheel Base) recumbents have the front wheel behind the bottom bracket. SWB machines are more maneuverable, and generally more compact. The downsides of the SWB design relate to interference between the front wheel and the drive chain. SWBs generally have to run the chain over an idler pulley or two, which causes a significant loss in efficiency. An SWB recumbent also can pitch forward, and in this way it is less safe than an LWB or CLB recumbent.

Steering Categories:

• A.S.S. (Above Seat Steering) recumbents have tall handlebars, with the grips typically located just in front of the rider's shoulders.
• U.S.S. (Under Seat Steering) recumbents have the handlebars located below the seat, so the rider's arms hang down at his or her sides. This is a very comfortable position, and makes for easier mounting and dismounting. USS machines almost always use an indirect steering linkage, with a tie rod connecting the handlebars to the fork crown.

Recumbent Pros & Cons
Pro	Con
Recumbents are generally more comfortable for the butt. Recumbents are generally more comfortable for the hands/wrists. Recumbents are generally more comfortable for the neck. Recumbents are more aerodynamic, potentially faster. If you crash a recumbent, you hit feet first (though maybe not with an SWB recumbent, and particularly not if it has above-the-seat steering.).	Recumbents are generally heavier. Recumbents have more complicated drivetrains, often with convoluted chain runs, due to the need to avoid interference between the pedals and the front wheel. Upright bikes are generally less expensive, partly due to simpler design, partly due to economies of scale in manufacture. Recumbents are usually more awkward to store or transport, due to their greater length. Recumbents are a bit harder to balance, due to their lower center of gravity.This is more of a problem with SWB recumbents. Some LWB recumbents can be ridden no-hands.

This site also has an old article of mine from 1992: "Recumbents in Four Flavors."

Copyright © 1996, 2008 Sheldon Brown

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