A folding bicycle is a bicycle designed to fold into a compact form, facilitating transport and storage. When folded, the bikes can be more easily carried into buildings and workplaces or on public transportation (facilitating mixed-mode commuting and bicycle commuting), and more easily stored in compact living quarters or aboard a car, boat or plane. Folding mechanisms vary, with each offering a distinct combination of folding speed, folding ease, compactness, ride, weight, durability and price. Distinguished by the complexities of their folding mechanism, more demanding structural requirements, greater number of parts, and more specialized market appeal, folding bikes may be more expensive than comparable non-folding models. The choice of model, apart from cost considerations, is a matter of resolving the various practical requirements: a quick easy fold, compact folded size, or a faster but less compact model.[1] There are also bicycles that provide similar advantages by separating into pieces rather than folding.[2] Military interest in bicycles arose in the 1890s, and the French army and others deployed folding bikes for bicycle infantry use.[3] In 1900, Mikael Pedersen developed a folding version of his Pedersen bicycle for the British army that weighed 15 pounds and had 24 inch wheels. It included a rifle rack and was used in the Second Boer War.[4] The British WWII Airborne BSA folding bicycle was used from 1939-1945 in the Second World War by British paratroopers. A folding bicycle was developed as a small size was needed to enable it to be taken on parachute jump from aircraft. The War Office in 1941 called for a machine that weighed less than 23lb and which would withstand being dropped without protection by parachute. BSA abandoned the traditional diamond design as too weak for the shock and made an elliptical frame of twin parallel tubes, one forming the top tube and seat stays and the other for the chainstay and down tube.[5] The hinges were in front of the bottom bracket and in the corresponding position in front of the saddle, fastened by wing nuts. The pedals could be reversed to avoid snagging. The frame weighed 4?lb.[6] The bicycle was used by British paratroopers at the D-Day landings and at the Battle of Arnhem.[7] Folding bikes generally come with a wider range of adjustments than conventional bikes for accommodating different riders, because the frames are usually only made in one size. Seatposts and handlebar stems on folders extend as much as four times higher than conventional bikes. For even greater range of adjustment, longer after-market posts and stems are available. While folding bicycles are usually smaller in overall size than conventional bicycles, the distances between center of bottom bracket, the top of the saddle and the handlebars, the primary factors in determining whether a bicycle fits its rider, are usually similar to that of conventional bikes. The wheelbase of many folding designs is also very similar to that of conventional, non-folding, bicycles. Some manufacturers are producing folding bikes designed around folding systems that allow them to use 26" wheels, e.g. Montague, KHS and Dahon Bicycles.