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A bicycle is a two wheeled vehicle driven by the riders feet pushing on cranks or pedals. A common misconception is that the earliest form of bicycle was the dandy-horse, which was pushed along by the rider's feet. However, while both the dandy-horse and the later bicycle are both velocipedes, the dandy-horse is not propelled by cranks.
The first bicycle was introduced to England from France in 1868, and comprised two solid wheels of equal size fitted to a frame, much like a modern bicycle in appearance, with a saddle fitted in the centre and propelled by cranks attached to the front wheel. This vehicle provided such a bumpy ride to the rider that it became popularly known as 'the bone-shaker'. Later came the Penny-Farthing with pedals fixed to the large front wheel which was made large to achieve high speeds. Later still, around 1895, came the safety bicycle with pedals driving the rear wheel by way of a chain, and the rider sitting upon a saddle set back from the front wheel so as to reduce the chances of falling forwards over the handlebars, from this developed the Raleigh bicycle design of 1900 which forms the basis of the modern bicycle. In 1888 the two-person tandem bicycle was invented.
In 1906 it was reported that speeds of 50 mph were attained on a bicycle. Around the same time, slightly earlier, the motorised bicycle (motorcycle or motorbike) was invented.
A typical bicycle is comprised of several parts. The principal and essential being: the frame, front forks, wheels, pedals, saddle, handlebars, chain and brakes. The largest part of the bicycle is the frame, and these vary in design depending upon the specialised intention of the bicycle.
A frame for a BMX bicycle being small, heavily braced and made of aluminium. The frame for BMX xyxling needs to be strong so as to endure the stresses of the bumpy ride, and the saddle low as competitors never sit down during a competition and as such they need space to sprint and jump with ease.
Cross-Country cycle frames are generally made of aluminium and carbon-fibre so as to be light weight. They are relatively small frames to allow quick and easy mounting and dismounting off road, and strong to endure off-road bumpy conditions. The smaller frames are often compensated for by having a longer seat post to allow a normal height saddle position.
The cycle speedway bicycle frame is designed primarily for strength, and as such is typically made from steel or aluminium.
Road racing bicycle frames are designed to be light and stiff. Traditionally they ewre made of steel, but by the start of the 21st century carbon fibre was being used for the more expensive models as this offered the same stiffness at reduced weight. The design of the tubes also developed over time, tubes becoming of a larger diameter, but thinner walls, to allow the same stiffness with reduced weight.
Bicycles are fitted with various types of brake, the most popular being the calliper, cantilever, hydraulic or disc and the V brake. The most common form of brake found on leisure bicycles, is that form used also on road racing bicycles. The calliper brake. Calliper brakes are a very efficient means of rim braking and basically comprise two blocks of rubber or plastic which are squeezed onto the wheel rim when the brake lever is squeezed by the ride.
Cantilever brakes operate on the same principal as calliper brakes, but are of a slightly different design at the wheel end, offering increased clearance between the tyre and the brake pads and as such are frequently employed for cyclo-cross bicycles and mountain bikes.
The most efficient form of rim brake is the V brake. The V brake also offers the most clearance of any rim braking system, and is most often found on mountain bikes.
Hydraulic or disc brakes are the most efficient and powerful form of bicycle brake. They use the wheel hub to brake, rather than the rim. Disc brakes offer the most clearance, and as such are used on mountain bikes, but are also expensive to fit and maintain.
Bicycle wheels are generally of one of three types. The most common and traitional bicycle wheel is the spoked wheel, comprising a rim connected to the central bub by a series of thin metal rods known as spokes. Spoked wheels are light in weight. Less common than spoked wheels, but offering greater strength and durability at the expense of weight are mag wheels which comprise a rim attached to the hub by a few, thick solid plastic bars. Solid wheels, also known as disc wheels, are made from composite material or carbon fibre are very strong, stiff, aerodynamic and very expensive. They are rarely used except as rear wheels in time-trialing and track racing.
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Mac is a prefix in modern Irish and Gaelic signifying 'son', as MacDonald, son of Donald. But there are numerous historical uses of the prefix in the sense of 'great', evidently a corruption of the 'mag' in 'magnus'. The Welsh equivalent is Map or Ap, the Norman equivalent Fitz and the Irish O'.
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The FN MAG is a Belgian gas operated, air cooled, quick change barrel, general purpose machine-gun produced from 1955. It is a very popular military weapon, having been adopted by over 80 countries and being built under license in Britain (as the L7A1 and L7A2), the USA, Argentina, Egypt, India and Singapore. It uses a gas-system operation similar to the BAR and a feed system adapted from the German MG42. The FN MAG is chambered for the 7.62 mm NATO cartridge and is belt fed, firing at a cyclic rate of 600 to 1000 rounds-per-minute at a muzzle velocity of 840 meters per second to an effective range of 1200 meters. The FN MAG has a 545 mm long barrel and is fitted with a blade foresight and an aperture/U notch rearsight. Various variants are also made for fitting to vehicles and helicopters.
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The L7A1 is a British made (under license) copy of the Belgian FN MAG general purpose machine-gun.
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The L7A2 is a British made (under license) copy of the Belgian FN MAG general purpose machine-gun.
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The L8A1 is a British gas operated automatic air-cooled tank machine-gun based upon the L7A1 (Belgian FN MAG). the L8A1 is chambered for the 7.62 mm x 51 cartridge which it takes from a belt feed and fires with a cyclic rate of between 650 and 1000 rounds per minute with a muzzle velocity of 838 meters per second. The L8A1 has a 737 mm long quick change barrel, shortened from the L7A1 to allow fitting in an enclosed space, and is fitted with a post foresight mounted in the flash suppressor and an aperture rearsight.
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The L8A2 is a British gas operated automatic air-cooled tank machine-gun forming an improvement of the L8A1 (Belgian FN MAG). the L8A2 is chambered for the 7.62 mm x 51 cartridge which it takes from a belt feed and fires with a cyclic rate of between 650 and 1000 rounds per minute with a muzzle velocity of 838 meters per second. The L8A2 has a 737 mm long quick change barrel and is fitted with a post foresight mounted in the flash suppressor and an aperture rearsight.
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The Ithaca MAG-10 'Roadblocker' is an American 10-gauge gas-operated shotgun. It has a three-round tubular magazine and can carry an additional round in the chamber.
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The Mag Tech MT 122-2 ML is a Brazilian bolt-action hunting rifle made from blued steel with a hardwood stock in .22 Long Rifle calibre. The Mag Tech MT 122-2 ML takes a 10-round magazine and has a 61 cm long barrel fitted with a micrometer sight and a mounting for a telescopic sight.
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The Mag Tech MT 122 is a Brazilian bolt-action hunting rifle made from blued steel with a hardwood stock in .22 Long Rifle calibre. The Mag Tech MT 122 takes a 10-round magazine and has a 54 cm long barrel fitted with adjustable sights and a mounting for a telescopic sight.
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The Probert Encyclopaedia was designed, edited and programed by
Matt and Leela Probert
©1993 - 2009 The Probert Encyclopaedia
Southampton, United Kingdom
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