A bicycle trailer is a motorless wheeled frame with a hitch system for transporting cargo by bicycle. It can greatly increase a bike's cargo capacity, allowing point-to-point haulage of objects up to 4 cubic yards (3 cubic metres) in volume that weigh as much as half a ton. Types Different types of trailer are designed for various purposes, cargo requirements and riding conditions: By number of wheels Single-wheel: a single rear-mounted wheel. Though of limited towing capacity, this design tends to be more stable (when moving) than trailers with two or more wheels. The single wheel can tilt from side to side when cornering (as the bicycle itself does,) allowing for coordinated turns at relatively high speed. The connection to the bicycle is simpler than a two-wheeled trailer since only two degrees of freedom are required- the trailer tilts with the towing bicycle. Two-wheel: A two-wheel design makes possible much greater load carrying capacity and a wider cargo bed. Though not suitable for high speed, they are ideal for everyday cycling (very much like towing a trailer behind a car). Two-wheel trailers tend to be as wide or wider than the handlebars of the bicycle, therefore care needs to be taken when riding through narrow spaces. Three-wheel: Similar to two-wheel trailers with wheels on either side of the cargo area, but also equipped with a fork-mounted front wheel to remove practically all tongue weight from the lead vehicle. This trailer is usually connected via a fork-mounted tow bar and allows for the greatest weight capacity out of all types of bicycle trailers, in some instances even equipped with its own overrun brakes and electric motor assist. By intended cargo General cargo: for transporting cargo of all kinds. The load capacity of commercially available cargo trailers ranges from 30 to 300 pounds (14 to 140 kg), but much larger loads have been transported by custom-built trailers or by multi-trailer "trains" attached to a single bicycle. Human passenger (as cargo): constructed to enhance the comfort and safety of one or more human passengers. These usually have a low centre of gravity and widely spaced wheels to increase stability when cornering, and often have integrated rain-proof covers, seat padding, and safety belts. A lot of the trailers designed for transporting children can also be converted to strollers. Trailers have also been used as pedicabs. Child passenger (as rider): trailer bikes and pedal trailer,