fixie bycycle

beginning

 In Australia, "fixed-wheel" is the normal term for the subject of this article — meaning the opposite of freewheel, and "fixed-gear" usually refers to a single-speed bicycle.

A fixed-gear bicycle (or fixed-wheel bicycle, sometimes known in the USA as a fixie) is a bicycle that has no freewheel, meaning it cannot coast — the pedals are always in motion when the bicycle is moving.

The sprocket is screwed or bolted directly onto a fixed hub. When the rear wheel turns, the pedals turn in the same direction. This allows a cyclist to stop without using a brake, by resisting the rotation of the cranks, and also to ride in reverse.

Track cycling in a velodrome has always used fixed-gear track bikes, but fixed-gear bicycles are now again used on the road a trend generally seen as being led by bicycle 

USE
The track bicycle is a form of fixed-gear bicycle used for track cycling in a velodrome. But since a "fixed-gear bicycle" is just a bicycle without a freewheel, a fixed-gear bicycle can be any type of bicycle.
Traditionally, some road racing, 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 fixed-gear was also commonly used, and continues to be used in the end of season hill climb races in the autumn. 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. 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 fixed-gear bicycles have achieved tremendous 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 a very forgiving, slack road geometry, as opposed to the steep, aggressive geometry of track bicycles.
Fixed-gear bicycles are also used in cycle ball, bike polo and artistic cycling.
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.
The fixed-gear bicycle is often identified with the hipster subculture