A single-speed bicycle is a type of bicycle

Bicycle

A bicycle, also known as a bike, pushbike or cycle, is a human-powered, pedal-driven, single-track vehicle, having two wheels attached to a frame, one behind the other. A person who rides a bicycle is called a cyclist, or bicyclist....

 with a single gear ratio

Gear ratio

The gear ratio of a gear train is the ratio of the angular velocity of the input gear to the angular velocity of the output gear, also known as the speed ratio of the gear train. The gear ratio can be computed directly from the numbers of teeth of the various gears that engage to form the gear...

. These bicycles are without derailleur gears

Derailleur gears

Derailleur gears are a variable-ratio transmission system commonly used on bicycles, consisting of a chain, multiple sprockets of different sizes, and a mechanism to move the chain from one sprocket to another...

, hub gear

Hub gear

A hub gear, internal-gear 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 hub-shell of the bicycle's rear wheel, as opposed to derailleur gears, where the gears and...

ing or other methods for varying the gear ratio of the bicycle.

There are many types of modern single speed bicycles; BMX

BMX

Bicycle motocross or BMX refers to the sport in which the main goal is extreme racing on bicycles in motocross style on tracks with inline start and expressive obstacles, and it is also the term that refers to the bicycle itself that is designed for dirt and motocross cycling.- History :BMX started...

 bicycles, most bicycles designed for children, cruiser type bicycles

Cruiser bicycle

Cruiser bicycles, also known as beach cruisers, combine balloon tires, upright seating posture, single-speed drivetrains, and straightforward steel construction with expressive styling...

, classic commuter bicycles

Bicycle commuting

Bicycle commuting is the use of a bicycle to travel from home to a place of work or study — in contrast to the use of a bicycle for sport, recreation or touring....

, unicycle

Unicycle

A unicycle is a human-powered, single-track vehicle with one wheel. Unicycles resemble bicycles, but are less complex.-History:One theory of the advent of the unicycle stems from the popularity of the penny-farthing during the late 19th century...

s, bicycles designed for track racing

Track bicycle

A track bicycle or track bike is a bicycle optimized for racing at a velodrome or outdoor track. Unlike road bicycles, the track bike is a fixed-gear bicycle and so has a single gear and neither freewheel nor brakes. Tires are narrow and inflated to high pressure to reduce rolling resistance...

, fixed-gear road bicycle

Road bicycle

The term road bicycle is used to describe bicycles built for traveling at speed on paved roads. Some sources use the term to mean racing bicycle...

s, and fixed-gear mountain bicycles.

The fixed-gear

Fixed-gear bicycle

A fixed-gear bicycle is a bicycle that has no freewheel, meaning it cannot coast, as the pedals are always in motion when the bicycle is moving....

 single-speed bicycle is the most basic type of bicycle. A fixed-gear bike does not have freewheel

Freewheel

thumb|Freewheel mechanismIn mechanical or automotive engineering, a freewheel or overrunning clutch is a device in a transmission that disengages the driveshaft from the driven shaft when the driven shaft rotates faster than the driveshaft...

 mechanism to allow coasting.

Advantages

A single-speed bicycle is generally cheaper, lighter, and mechanically simpler than its multi-geared equivalent.

Without derailleurs

Derailleur gears

Derailleur gears are a variable-ratio transmission system commonly used on bicycles, consisting of a chain, multiple sprockets of different sizes, and a mechanism to move the chain from one sprocket to another...

 or other gearing systems, there are fewer parts on the bicycle that require maintenance making this type of cycle useful for city commuting in all weather.

The drivetrain efficiency

Mechanical efficiency

Mechanical efficiency measures the effectiveness of a machine in transforming the energy and power that is input to the device into an output force and movement...

 of a single-speed can be greater than today's typical multi-geared bicycles. A straight chainline

Chainline

Chainline is the angle of a bicycle chain relative to the centerline of the bike's frame. A bicycle is said to have perfect chainline if the chain is parallel to the frame, which means that the rear sprocket is directly behind the front sprocket...

, lack of chain drag from rear derailleur jockey pulleys, and lack of chainrings, ramps and pins all improve efficiency.

As a single rear cog takes less space than the typical seven to ten cogs present on most multi-geared rear cassettes, rear wheel

Bicycle wheel

A bicycle wheel is a wheel, most commonly a wire wheel, designed for bicycle. A pair is often called a wheelset, especially in the context of ready built "off the shelf" performance-oriented wheels....

s can be built with little or no dish.

Disadvantages

As the single-speed bicycle lacks alternative gearing ratios, it is less versatile, as it cannot be pedaled efficiently outside of its single gearing range.

Without higher gearing options, the single speed bicycle is generally more difficult to pedal uphill.

Conversely, its dedicated gear ratio also limits top speed, and is slower than a multi-geared bicycle on flat or descending terrain once bicycle speed exceeds the rider's ability to maintain continuing increases in cadence (pedaling revolutions per minute), typically 85-110 rpm.

Types of single-speed bicycles

While track bicycle

Track bicycle

A track bicycle or track bike is a bicycle optimized for racing at a velodrome or outdoor track. Unlike road bicycles, the track bike is a fixed-gear bicycle and so has a single gear and neither freewheel nor brakes. Tires are narrow and inflated to high pressure to reduce rolling resistance...

s are always single speed, mountain bicycles, road bicycle

Road bicycle

The term road bicycle is used to describe bicycles built for traveling at speed on paved roads. Some sources use the term to mean racing bicycle...

s, cyclo-cross bicycle

Cyclo-cross bicycle

A cyclo-cross bicycle is a bicycle specifically designed for the rigors of a cyclo-cross race. Cyclo-cross bicycles roughly resemble the racing bicycles used in road racing...

s, and hybrid bicycle

Hybrid bicycle

A hybrid bicycle is a bicycle designed for general-purpose utility and commuting on a wide variety of surfaces, including paved and unpaved roads, paths and trails...

s can be made as or changed into a single speed. Mountain bike single speeds designed for trail riding often have a relatively low, or easy and slow, gear ratio. This allows them to climb hills and deal with obstacles and gradients better. This typically requires the rider to be more fit or skilled than the average rider in order to traverse the same terrain. Single speed bicycles designed for road riding typically have higher, or harder and faster, gear ratios.

Single speed bicycles and fixed-gear bicycle

Fixed-gear bicycle

A fixed-gear bicycle is a bicycle that has no freewheel, meaning it cannot coast, as the pedals are always in motion when the bicycle is moving....

s are popular with bicycle messenger

Bicycle messenger

Bicycle messengers are people who work for courier companies carrying and delivering items by bicycle. Bicycle messengers are most often found in the central business districts of metropolitan areas...

s for their reliability and durability. Depending on the situation, a messenger may prefer a mountain bike

Mountain bike

A mountain bike or mountain bicycle is a bicycle created for off-road cycling. This activity includes traversing of rocks and washouts, and steep declines,...

 based single-speed, which can roll over many obstacles, or a fast and light road bike-based single-speed.

Statements by cycling industry representatives and journalists fueled the perception that major bicycle manufacturers discouraged modern single speed bicycles. However, increased popularity of the single speed has resulted in the design, marketing, and production of many models. In the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 market, bicycle companies Villy Customs

Villy Customs

Villy Customs is an American lifestyle brand specializing in custom designed beach cruiser bicycles for adults. Based in Dallas, the company was founded and is privately owned by entrepreneur Fleetwood Hicks, a former menswear fashion designer and health enthusiast, and it was chosen by...

, Bianchi, Cannondale, Fuji Bike

Fuji Advanced Sports

Fuji Bikes, is an American distributor of bicycles built in Taiwan, China, and Poland. The company is a descendant of , a bicycle manufacturer originally established in Japan in 1899. The company took its name and logo from Mount Fuji, a Japanese symbol of strength and endurance...

, KHS, Kona

Kona Bicycle Company

Kona Bikes is a bicycle company in Ferndale, Washington and Vancouver, British Columbia. It specializes in high-performance mountain bikes, racing and touring bicycles. The company name comes from the owners' love of Kailua-Kona in Hawaii....

, Raleigh, Giant

Giant Manufacturing

Giant Manufacturing Co. Ltd. is a Taiwanese bicycle manufacturer which bills itself as the world's largest bicycle manufacturer. Giant has manufacturing facilities in Taiwan, Netherlands, and Mainland China.-History:...

, Specialized

Specialized Bicycle Components

Specialized Bicycle Components, more commonly known simply as Specialized, is a major American brand of bicycles and related products. It was founded in 1974 by Mike Sinyard and is based in Morgan Hill, California-History:...

, Swobo, Felt, Trek

Trek Bicycle Corporation

Trek Bicycle Corporation is a major bicycle and cycling product manufacturer and distributor under brand names Trek, Gary Fisher, Bontrager, Klein and until recently, LeMond Racing Cycles...

 and Niner all have recently produced and marketed single speed bicycles.

Because one of the goals of a single speed mountain bike is simplicity, it is extremely uncommon to run across a full-suspension single speed bicycle, instead they are either constructed without suspension (fully rigid), or with front suspension forks. Rear suspension geometry can cause the distance between the crankset and rear wheel to change as it moves, requiring a sprung chain tensioner to maintain the correct tension.

Chain tensioning

Single-speed bicycle builders have devised a variety of methods for producing and maintaining the proper chain tension. The most common method is horizontal rear dropout

Dropout (bicycle part)

A bicycle dropout is a type of fork end that allows the rear wheel to be removed without first derailing the chain. The more inclusive term fork end refers to a slot in a frame or fork where the axle of the wheel is attached....

s or track ends. These allow the rear wheel to be moved fore or aft as necessary. Using chain lugs with track ends ensures that optimum chain tension can be achieved with the wheel remaining centered. Another method uses an eccentric mechanism

Eccentric (mechanism)

In mechanical engineering, an eccentric is a circular disk solidly fixed to a rotating axle with its centre offset from that of the axle ....

 either in the bottom bracket

Bottom bracket

The bottom bracket on a bicycle connects the crankset to the bicycle and allows the crankset to rotate freely. It contains a spindle that the crankset attaches to, and the bearings that allow the spindle and cranks to rotate. The chainrings and pedals attach to the cranks...

 or in the rear hub. If neither of these are an option, when working with an existing frame not originally designed for single-speed use for example, some kind of idler pulley, such as the Surly Singleator
or simply a short cage rear derailleur can be used to take up chain slack. As well, finetuning the combination of chainring, cog, and chain length may suffice until the chain develops significant wear.

Throughout the years bicycle designers have produced belt-driven bicycle

Belt-driven bicycle

A belt-driven bicycle is a chainless bicycle that uses a toothed synchronous belt to transmit power from the pedals to the wheel. The belts are typically made by the same manufacturing companies that produce timing belts for automobiles, machineries, and other synchronous belt drive...

s. While these belts cannot be shifted between gears like a chain, they offer singlespeed or hub geared drivetrains with improved increased wear resistance, quieter operation, and lubrication-free cleanliness. Belts also do not change length during their lifespan in the same way that chains "stretch" or increase in pitch as their link pivots wear. This keeps the pitch of the belt's teeth constant and dramatically decreases wear on gear teeth. Belts have failed to overtake chains in popularity for bicycles because they have historically been less efficient. Also replacement of the one-piece belt requires traditional diamond bicycle frames to have a special split chainstay.

Single-speed cycle conversions

Single-speed bicycle builders have converted many former multi-geared cycles into single or fixed speed through the removal of the derailleurs and associated hardware. The simplest conversion uses the existing freewheel/cassette and crankset, the chain being cut to fit the desired gear ratio. However this retains unnecessary weight and the chainline will most likely not be perfect. A more thorough conversion will involve replacing the freewheel with a single-speed one, and re-dishing the rear wheel. On bicycles with vertical dropouts, a chain tensioner is often required to allow the correct tension on the resulting shorter chain.

A very popular "off road" mountain bike gearing

Bicycle gearing

A bicycle gear or gear ratio refers to the rate at which the rider's legs turn compared to the rate at which the wheels turn. Bicycle gearing refers to how the gear ratio is set or changed. On some bicycles, there is only one gear so the ratio is fixed. Most modern bicycles have multiple gears,...

, for the 26" wheel size, is 39:18, approximately a 2:1 gear ratio

Gear ratio

The gear ratio of a gear train is the ratio of the angular velocity of the input gear to the angular velocity of the output gear, also known as the speed ratio of the gear train. The gear ratio can be computed directly from the numbers of teeth of the various gears that engage to form the gear...

  and 56.35 gear inches

Gear inches

Gear inches is a system that assigns numerical measurements to bicycle gear ratios, to indicate how low or high a gear is.Gear inches has no current physical significance; it corresponds to the diameter in inches of the main wheel of an old-fashioned penny-farthing bicycle with equivalent gearing...

, for versatile trail riding. A great "on road" gear ratio, for the 26" wheel, is 42:17, approximately a 2.5:1 ratio and 64.2 gear inches for versatile tour riding. Many British enthusiasts used to tour

Bicycle touring

Bicycle touring is cycling over long distances – prioritizing pleasure and endurance over utility or speed. Touring can range from single day 'supported' rides — e.g., rides to benefit charities — where provisions are available to riders at stops along the route, to multi-day...

 on 27–inch–wheeled ligtweights on a single fixed–gear of 69 inches before multi–speed gearing became universally popular, though this certainly made for tough work.

A reasonable "road" gear ratio, for the 700 x 28c wheel size a, is 46:17, approximately a 2.7:1 ratio and 71.75 gear inches, for very versatile asphalt riding, and a better lifespan with good road duty.

Fixed-gear setups work especially well with higher 40s chainrings, so the rotation ratio is closer to a wider 3:1, avoiding the tighter ratios, which will spin too fast, especially when descending steep hills.

Note that the larger diameter gear and chain ring, clearly, offers the best longevity, with much better wear characteristics than smaller gear and chain ring sets and less rounding of the teeth, over time.

Flip-flop hubs

Flip-flop, or double-sided hubs are threaded on both sides. Usually one side has a track-type threading, (with lock ring) and the other side is threaded for a single-speed standard freewheel. It is possible to find them with track threading on both sides, but not easily. The cyclist can then change gears manually by reversing the drive wheel.

The usual way to use a flip-flop hub is to have a fixed gear on one side, and a single speed freewheel on the other. Ideally, the freewheel sprocket would be one or two teeth larger than the fixed sprocket. This allows for extended hill climbs at a lower ratio than the fixed gear provides. The freewheel in this gear also allows the cyclist to coast on a steep descent

Competition

Single speed riders sharing the common reclining type of philosophy may wish to take part in the Single Speed World Championship

Single Speed World Championship

The Single Speed World Championship, or SSWC, is an annual event. It is only open to bicycles with a single gear ratio. Those bicycles can be either singlespeeds or fixed-gears...

s.

External links

• Singlespeed.net
• Single-Speed FAQ
• Singlespeed.nl
• Cyclofiend Singlespeed Gallery
• The Gear Junkie - In-depth review of a single-speed bike.
• Single Speed Bike news