velomobile, velomobiel, velo, or bicycle car is a human-powered vehicle (HPV) enclosed for aerodynamic advantage and protection from weather and collisions. They are similar to recumbent bicycles and tricycles, but with a full fairing (aerodynamic shell). A fairing may be added to a non-faired cycle, or the fairing may be an integral part of the structure, monocoque like that of an airplane.

They are not to be confused with purpose-built for racing or speed records fully fared vehicles with two wheels, generally called streamliners. Streamliners have set many speed and distance records. Though fast in their own right, velomobiles are considered much more streetable machines. Using three or more wheels can have advantages for everyday use, including the ability to stop and start unaided, better stability, cross-wind handling, etc., though there are arguments made that the multiple track machines (three or more wheels) have aerodynamic disadvantages due to the drag of the extra wheels and the surface contact points.In practice though, velomobiles continue to be close to their two-wheel cousins in performance

There are a few velomobile manufacturers; some are home-built. Some models have the operator’s head exposed; some its covered.  The typical drive train of a velomobile is not unlike a bicycle or recumbent. It will consist of a front bottom bracket with one or more chainrings, and a rear derailleur. Depending on the configuration of the velomobile there may be any number of idler pulleys, and chaintubes along the drive train to manage and protect the chain. One of the defining characteristics of most velomobiles is that the chain and drivetrain components are protected from weather and the road.