respectable pace in competitions. Handcycles have also been used for touring, though few designers incorporate mudguards or luggage racks. Also, the gear ratios of standard handcycles tend to be less useful for long steep climbs. Hand-and-foot recumbent tricycles Recumbent cycles offer the possibility of combined hand and foot power inputs, and thus the potential for a full-body workout, and the option for persons with a weak or missing leg(s) to power a cycle. In one recumbent tricycle design the user makes the two front wheels change direction by shifting his center of weight, and moves forward by rotating the rear wheel. There are also hybrids between a handcycle, a recumbent bike and a tricycle; these bikes enable cycling by use of legs, despite a spinal cord injury Recumbent quadracycles Recumbent four-wheel cycles have the same general advantages of tricycles. For quadracycles with only one seat the stability improvements of the fourth wheel offer only a marginal advantage over a tadpole recumbent tricycle. More wheels introduce more weight and more complexity. The fourth wheel is only of the most benefit to the single-seat rider when going off-road. When two and sometimes four riders want to ride together in a sociable configuration the four-wheel recumbent cycle is a viable option. Homebuilts As with upright bikes, there is a subculture of recumbent builders who design and build home-built recumbents. Often 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, or 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. Folding Several manufacturers offer folding recumbents to facilitate packing and travelling. Couplers It is possible to add couplers either during manufacturing or as a retrofit so that the frame can be disassembled into smaller pieces to facilitate packing and travel. Stationary recumbents As well as road-going recumbent 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. Compared to uprights There are striking differences between recumbents and upright bikes. Since recumbents vary widely, the advantages and disadvantages listed below may apply to different types to different degrees or not at all. (For example, balance is not a concern with tricycles.) History Recumbent bicycle designs date back to the middle of the 19th century. Several designs were patented around 1900, but these 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 10 September 1893. This year also saw what is considered the first genuine recumbent, the Fautenil Vélociped. Patent applications for a number of recumbent