Fixed-gear bicycle

A fixed-gear bicycle (or fixed-wheel bicycle, sometimes known 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.

Uses

A fixed/freewheel rear hub (flip-flop)

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 almost 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 1959 British 25 mile time trial championship was won by Alf Engers with a competition record of 55 minutes 11 sec, riding an 84 inch fixed-gear bicycle. 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^{[dated info]} 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 relaxed road geometry, as opposed to the steep 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

 

Brakeless

Cyclist riding a fixed gear bike without brakes

Some fixed-gear riders think brakes are not strictly necessary, and brakeless fixed riding has a cult status in some areas. Brakes and their cables are said to add extra bulk to the simple appearance of a fixed gear.
Other riders dismiss riding on roads without brakes as an affectation, based on image rather than practicality. Riding brakeless can be dangerous, is prohibited by law in many jurisdictions, and may jeopardize the chances of a successful claim in the event of an accident.

Technique

It is possible to slow down or stop a fixed-gear bike by resisting the turning cranks, and a rider can also lock the rear wheel and skid to slow down or stop on a fixed-gear bicycle. Such a move is initiated by unweighting the rear wheel while in motion by shifting the rider's weight slightly forward and pulling up on the pedals using clipless pedals or toe clips and straps. The rider then stops turning the cranks, thus stopping the drivetrain and rear wheel, while applying body weight in opposition to the rotation of the cranks. This causes the rear wheel to skid, and slow the bike. The skid can be held until the bicycle stops or until the rider desires to continue pedalling again at a slower speed. The technique requires a little practice and using it while cornering is generally considered dangerous. A wet surface further reduces the effectiveness of this method, almost to the point of not reducing speed at all.
On any bike with only rear wheel braking, the maximum deceleration is significantly lower than on a bike equipped with a front brake. As a vehicle brakes, weight is transferred towards the front wheel and away from the rear wheel, decreasing the amount of grip the rear wheel has. Transferring the rider's weight back will increase rear wheel braking efficiency, but a front wheel fitted with an ordinary brake might provide 70% or more of the braking power when braking hard.

Legality

United States — The use of any bike without brakes on public roads is illegal in many places, but the wording is often something along the lines of "...must be equipped with a brake that will enable the person operating the cycle to make the braked wheels skid on dry, level and clean pavement..." which some have argued allows the use of the legs and gears. The retail sale of bikes without brakes is banned by the U.S. Consumer Product Safety Commission – but with an exception for the "track bicycle" (...a bicycle designed and intended for sale as a competitive machine having tubular tires, single crank-to-wheel ratio, and no free-wheeling feature between the rear wheel and the crank....).
UK — The Pedal Cycles Construction and Use Regulations 1983 require pedal cycles "with a saddle height over 635 mm to have two independent braking systems, with one acting on the front wheel(s) and one on the rear". It is commonly thought that a front brake and a fixed rear wheel satisfies this requirement .
Germany — All bicycles are required to have working brakes on both wheels, as well as reflectors and bells. In Bonn a local court accepted that the fixed-gear mechanism was suitable back brake, but high-profile crackdowns specifically targeted fixies in Berlin, in an attempt to control what police described as a "dangerous trend"
Australia — In every state, bicycles are regarded as vehicles under the Road Rules. By law, a bike is required to have at least one functioning brake.
New Zealand — By law all bicycles must have a minimum of "...a good rear brake..."—and those made since 1 January 1988 must also have "...a good front brake..."
France — To be approved for road traffic, a bike must have 2 brakes, 2 lights, numerous reflectors, and a ringer. However the laws are rarely enforced, and the sight of all kinds of non officially approved bikes is quite common.
Denmark — All bicycles are required to have working brakes on both wheels, as well as reflectors and bells.