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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, 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, complexity 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, a 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 for the British army a folding version of his Pedersen bicycle that weighed 6.8 kg (15 lb) and had 610 mm (24 in) wheels. It included a rifle rack and was used in the Second Boer War. [4]
In 1941, during the Second World War, the British War Office called for a machine that weighed less than 10 kg (23 lb) (this was not achieved - the final weight was about 15 kg (32 lb)) and would withstand being dropped by parachute. In response, the Birmingham Small Arms Company (BSA) developed a folding bicycle small enough to be taken in small gliders or on parachute jumps from aircraft.
This British WWII Airborne BSA folding bicycle was rigged so that, when parachuted, the handlebars and seat were the first parts to hit the ground (as bent wheels would disable the bike). BSA abandoned the traditional diamond bicycle design as too weak for the shock and instead made an elliptical frame of twin parallel tubes, one forming the top tube and seat stays, and the other 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 peg pedals could be pushed in to avoid snagging and further reduce the space occupied during transit.
From 1942 to 1945, the British WWII Airborne BSA folding bicycle was used by British & Commonwealth airborne troops, Commandos, and some infantry regiments; some were also used as run-abouts on military bases. The bicycle was used by British paratroopers, Commandos, and second-wave infantry units on the D-Day landings and at the Battle of Arnhem. [6]
The 1970s saw increased interest in the folding bike, and the popular Raleigh Twenty and Bickerton Portable have become the iconic folders of their decade. It was, however, the early 1980s that can be said to have marked the birth of the modern, compact folding bicycle, with competing models from Brompton and Dahon. [7] Founded in 1982, by inventor and physicist Dr. David Hon and his brother Henry Hon, Dahon has grown to become the world's largest manufacturer of folding bikes, [8] with a two-thirds marketshare in 2006. [9]
Folding bikes generally come with a wider range of adjustments for accommodating various riders than do conventional bikes, because folding bike frames are usually only made in one size. However, seatposts and handlebar stems on folders extend as much as four times higher than conventional bikes, and still longer after-market posts and stems provide an even greater range of adjustment.
While folders are usually smaller in overall size than conventional bicycles, the distances among the center of bottom bracket, the top of the saddle, and the handlebars - the primary factors in determining whether or not a bicycle fits its rider - are usually similar to those 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 660 mm (26 in) wheels, e.g., Dahon, KHS, Montague, and Tern Bicycles. Advantages of smaller wheels include potential for more speed, quicker acceleration, greater maneuverability, and easier storage. [10] For example, the A-bike is similar to the Strida but has tiny wheels and folds a bit smaller. Bikes with smaller than 410 mm (16 in) wheels are often called portable bicycles. These forgo the performance and easy ride benefits of their larger counterparts, acquiring characteristics similar to those of an adult folding kick scooter. Nonetheless, regardless of how each bike folds, the result is easier to transport and store than a traditional bicycle. [11]
Folding mechanisms are highly variable.
Many folding frames follow the classic frame pattern of the safety bicycle's diamond frame, but feature a hinge point (with single or double hinges) allowing the bicycle to fold approximately in half. Quick-release clamps enable raising or lowering steering and seat columns. A similar swing hinge may be combined with a folding steering column. Fold designs may use larger wheels, even the same size as in non-folders, for users prioritizing ride over fold compactness. Bikes that use this kind of fold include, Dahon, Montague and Tern.
Instead of folding horizontally, this style of bike has one or two hinges along the main tube and/or chain and seat stays that allow the bike to fold vertically. The result leaves the two wheels side by side but is often more compact than a horizontally hinged design. The Brompton and Dahon Qix D8 both feature vertical folding.
A hinge in the frame may allow the rear triangle and wheel to be folded down and flipped forward, under the main frame tube, as in the Bike Friday, Brompton Mezzo Folder, and Swift Folder. Such a flip hinge may be combined with a folding front fork, as in the Birdy. Swing and flip hinges may be combined on the same frame, as in the Brompton Mezzo Folder and Dahon, which use a folding steering column. Folding mechanisms typically involve latches and quick releases, which affect the speed of the fold/unfold. Bike Friday offers a model, the Tikit, featuring a cable-activated folding mechanism requiring no quick releases or latches, for increased folding speed.
A magnet combined with a rear shock absorber forms the folding mechanism. The magnet connects and locks the back wheel section to the frame. To fold the bike in half, the magnet disconnects with one movement and in a second, and without having to use one's hands, the rear wheel rotates forward, and the bike folds vertically. This mechanism also enables one to roll the half-folded bike on its rear wheel. [12]
Bikes may partly fold and partly disassemble for packing into a standard or custom sized suitcase for air travel (e.g., Airnimal and Bike Friday). Other variations include: Bicycle Torque Coupling, a proprietary connector system that can be retrofitted to a standard frame; the Gekko, which folds from the seat tube like an upside down umbrella; the Giatex, which folds and retracts, adjusting to the size of the rider; the iXi, which literally breaks into two-halves; and the Strida, which has a triangular frame and folds to resemble a unicycle.
Folding mechanisms may incur more cost and weight, allow folding smaller, and they tend to use smaller wheels. 610 mm (24 in) wheels are the largest for which flip hinges are generally used, but smaller wheels, typically 410 or 510 mm (16 or 20 in), are more common.
Smaller size does not mean lighter weight, as most of these designs forgo the bracing benefits of the diamond frame and must compensate as a step-through frame does, with thicker metal. The step-through design is a boon to a wider range of rider size, age, and physical ability.
Another system found on folders, such as Montague Bikes, utilizes the seat tube as a pivot point for the frame to fold. This system uses a tube within a tube design to give the bike more torsional stiffness. It allows the user to fold the bike without "breaking" any vital tubes down, thus preserving the structural integrity of the diamond frame. This system is operated by a single quick release found along the top tube of the bike.
The primary purpose of folding a bike is to increase its portability. This is so that it may be more easily transported and stored, and thus allow greater flexibility in getting from A to B. [13] Many public transportation systems ban or restrict unfolded bicycles, but allow folded bikes all or some of the time. For example, Transport for London allows folding bikes at all times on the Underground, but on buses it is down to the driver's discretion. [14] Some transport operators only allow folding bicycles if they are enclosed in a bag or cover. Airline baggage regulations often permit folding bikes as ordinary luggage, without extra cost. [15] Singapore has also implemented new laws to allow folding bicycles in its rail and bus transportation system, with certain size and time limitations. [16]
The first folding electric bike was the Honda Step Compo in 2000. Many more were introduced in the next 20 years. [17]
Notable folding bicycles include:
A tandem bicycle or twin is a form of bicycle designed to be ridden by more than one person. The term tandem refers to the seating arrangement, not the number of riders. Patents related to tandem bicycles date from the mid 1880s. Tandems can reach higher speeds than the same riders on single bicycles, and tandem bicycle racing exists. As with bicycles for single riders, there are many variations that have been developed over the years.
A bicycle frame is the main component of a bicycle, onto which wheels and other components are fitted. The modern and most common frame design for an upright bicycle is based on the safety bicycle, and consists of two triangles: a main triangle and a paired rear triangle. This is known as the diamond frame. Frames are required to be strong, stiff and light, which they do by combining different materials and shapes.
A bicycle wheel is a wheel, most commonly a wire wheel, designed for a bicycle. A pair is often called a wheelset, especially in the context of ready built "off the shelf" performance-oriented wheels.
A hub gear, internal-gear hub, internally geared hub or just gear hub is a gear ratio changing system commonly used on bicycles that is implemented with planetary or epicyclic gears. The gears and lubricants are sealed within the shell of the hub gear, in contrast with derailleur gears where the gears and mechanism are exposed to the elements. Changing the gear ratio was traditionally accomplished by a shift lever connected to the hub with a Bowden cable, and twist-grip style shifters have become common.
Moulton is an English bicycle manufacturer based in Bradford-on-Avon, Wiltshire. The company was founded in 1962 by Alex Moulton (1920–2012) who had designed the "Hydrolastic" and rubber cone suspension systems for the BMC Mini motorcar. Moulton bicycles are noted for unconventional frame design, small wheels, and front and rear suspension.
A touring bicycle is a bicycle designed or modified to handle bicycle touring. To make the bikes sufficiently robust, comfortable and capable of carrying heavy loads, special features may include a long wheelbase, frame materials that favor flexibility over rigidity, heavy duty wheels, and multiple mounting points.
A bicycle fork is the part of a bicycle that holds the front wheel.
The Birdy is a folding bicycle designed by Riese und Müller in Germany and produced by Pacific Cycles in Taiwan. As of 2010 over 100,000 had been sold. Three distinct models have been marketed, in addition to some specialist variations, with the third (Mk3) introduced in July 2015.
Brompton Bicycle is a British manufacturer of folding bicycles based in Greenford, London.
The A-bike is a folding bicycle released by Sir Clive Sinclair in the United Kingdom on 12 July 2006. It was designed by Hong Kong design agency Daka, in collaboration with Sinclair Research, over a 5-year period. It was announced to the public in 2004. Clive Sinclair envisioned the A-bike, and Alex Kalogroulis was the main designer. It weighs 5.7 kilograms (13 lb) and folds to 67×30×16 centimetres (26.4×11.8×6.3 in), small enough to fit in a rucksack. The first version had 6-inch (15 cm) wheels, which was increased to 8 inches (20 cm) in later models. In 2015, an electric version, the A-Bike Electric, was introduced to the public as part of a Kickstarter campaign.
Strida is a portable belt-driven folding bicycle with a distinctive 'A'-shaped collapsible frame, designed by British engineer and designer Mark Sanders. The first model, Strida 1, was released in 1987 and the latest, Strida 5.2, in 2009.
A portable bicycle is a bicycle that has been designed to be small and light enough for easy carrying. It is usually dismantled to make a convenient bundle and the frame often has a folding action to facilitate this. The design of a portable bicycle involves a trade-off between ease of carrying and ease of riding.
The Bickerton, also called the Bickerton Portable, was a portable aluminium folding bicycle designed by Harry Bickerton and manufactured in the UK and Australia between 1971 and 1989. Bickerton, an accomplished engineer, suffered a three year driving ban in 1970 following a car crash, and invented the bike for himself, to be carried onto public transport or stored in the trunk of a car as small as an Austin Mini.
The Swift Folder is a folding bicycle, designed by Peter Reich of Design Mobility Inc. of Brooklyn, New York, in collaboration with Jan VanderTuin of the Center for Appropriate Transport in Eugene, Oregon.
Dahon is the world's largest manufacturer of folding bicycles with a two-thirds marketshare in 2006. The company was founded in 1982 by David T. Hon, a former laser physicist, and is headquartered in Los Angeles, California, with assembly factories in China, Macau and Bulgaria. Dahon markets bicycles under its own name as well as other brand names, including the affiliated Yeah and Biceco Brands, and Novara for REI in the U.S. The company is a member of the Global Alliance for EcoMobility. Dahon holds over 200 patents, some having become industry standards.
Montague Corporation is an American company that designs, manufactures, and sells full-size folding bicycles. It is headquartered in Cambridge, Massachusetts.
Small-wheel bicycles are adult bicycles that have wheels of 510 mm (20 in) nominal diameter or less, which is smaller than the 700c (522 mm), 660, 700, 740 mm (26, 27.5, 29 in) sizes common on most full-sized adult bikes. While many folding bicycles are small-wheel bicycles, not all small-wheel bicycles can fold. Some small-wheel bicycles neither fold nor separate, such as the Moulton, which comes in both fixed-frame and separable-frame versions. While BMX bikes also have 510 mm (20 in) wheels, they are not normally categorised as "small-wheel bikes".
Melon Bicycles was a folding bicycle manufacturer based in Chapel Hill, North Carolina. Many cyclists refer to the company as Melon Bikes, Melon Bicycles, or simply Melon. Melon Bicycles went out of business in 2014.
The Bootie Folding Cycle, or 'Bootie', is a rare folding bicycle produced in West Yorkshire UK from 1965 to 1973.