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A fixed-gear bicycle (or fixed-wheel bicycle, commonly known in some places as a fixie) is a bicycle that has a drivetrain with no freewheel mechanism. The freewheel was developed early in the history of bicycle design but the fixed-gear bicycle remained the standard track racing design. More recently the "fixie" has become a popular alternative among mainly urban cyclists, offering the advantage of simplicity compared with the standard multi-geared bicycle. Most bicycles incorporate a freewheel to allow the pedals to remain stationary while the bicycle is in motion, so that the rider can coast, i.e., ride without pedalling using forward momentum. A fixed-gear drivetrain has the drive sprocket (or cog) threaded or bolted directly to the hub of the back wheel, so that the rider cannot stop pedalling. When the rear wheel turns, the pedals turn in the same direction. This allows a cyclist to apply a braking force with the legs and bodyweight, by resisting the rotation of the cranks. It also makes it possible to ride backwards. As a general rule, fixed-gear bicycles are single-speed. A derailleur cannot be fitted because the chain cannot have any slack, but hub gearing can, for example a Sturmey-Archer fixed-gear 3-speed hub, in which case is a fixed-gear multi-speed arrangement. Most fixed-gear bicycles only have a front brake, and some have no brakes at all. ==Uses== A track bicycle or track bike is a form of fixed-gear bicycle optimized for racing at a velodrome or outdoor track. Some road racing and club cyclists used a fixed-gear bicycle for training during the winter months, generally using a relatively low gear ratio, believed to help develop a good pedalling style. In the UK until the 1950s it was common for riders to use fixed-gear bicycles for time trials. The 1959 British 25 mile time trial championship was won by Alf Engers with a competition record of 55 minutes 11 seconds, riding an 84 inch fixed-gear bicycle.〔(【引用サイトリンク】 History )〕〔(【引用サイトリンク】title= Woodland gears )〕 The fixed-gear was also commonly used, and continues to be used in the end of season hill climb races in the autumn.〔(【引用サイトリンク】 title= Fixed wheel bike used to win the 2003 British national hill climb championship )〕 A typical club men's fixed-gear machine would have been a "road/path" or "road/track" cycle. In the era when most riders only had one cycle, the same bike when stripped down and fitted with racing wheels was used for road time trials and track racing, and when fitted with mudguards (fenders) and a bag, it was used for club runs, touring and winter training.〔(【引用サイトリンク】title=Examples of fixed-gear bicycles of the period, including the bike that Ray Booty used for the first sub-four-hour "out and back" 100 mile time trial in 1956 )〕〔(【引用サイトリンク】accessdate=2011-05-14 )〕 By the 1960s, multi-gear derailleurs had become the norm and riding fixed-gear on the road declined over the next few decades. Recent years have seen renewed interest and increased popularity of fixed-gear cycling. In urban North America and similar areas in other English-speaking cities, fixed-gear bicycles have achieved significant popularity, with the rise of discernible regional aesthetic preferences for finish and design details. Dedicated fixed-gear road bicycles are being produced in greater numbers by established bicycle manufacturers. They are generally low in price and characterized by relaxed road geometry, as opposed to the steep geometry of track bicycles.〔(【引用サイトリンク】title=Buyers' Guide To "Fixie" Bicycles! )〕 Fixed-gear bicycles are also used in cycle ball, bike polo and artistic cycling. Bike messengers frequently use fixies due to their durability, low maintenance, simplicity and ease. A fixed-gear bicycle is particularly well suited for track stands, a manoeuvre in which the bicycle can be held stationary, balanced upright with the rider's feet on the pedals. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Fixed-gear bicycle」の詳細全文を読む スポンサード リンク
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