Hub dynamo

A SON brand hub dynamo
Schmidt-Nabendynamo

Small electrical generator built into the hub of a bicycle wheel that is usually used to power lights.

- Hub dynamo
A SON brand hub dynamo

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A Sturmey-Archer three speed hub, the most common kind of Sturmey-Archer gear

Sturmey-Archer

Manufacturing company originally from Nottingham, England.

Manufacturing company originally from Nottingham, England.

A Sturmey-Archer three speed hub, the most common kind of Sturmey-Archer gear
An exploded Sturmey-Archer AW
The internals of a Sturmey Archer FM four-speed, medium ratio, hub gear. It has substantially more components than an AW 3 speed. FC, AF, AC, and ASC hubs are similar.
Exploded View & Parts List of Type SW three-speed Mk. 1. Sturmey-Archer Gears Ltd., 1954
Sturmey-Archer X-FD front hub brake

The Dynohub was Sturmey-Archer's hub dynamo (generator) for bicycles.

"Dynamo Electric Machine" (end view, partly section, )

Dynamo

Electrical generator that creates direct current using a commutator.

Electrical generator that creates direct current using a commutator.

"Dynamo Electric Machine" (end view, partly section, )
The Faraday disk was the first electric generator. The horseshoe-shaped magnet (A) created a magnetic field through the disk (D). When the disk was turned, this induced an electric current radially outward from the center toward the rim. The current flowed out through the sliding spring contact m (connected to B') through the external circuit, and back through B to the center of the disk through the axle
Hippolyte Pixii's dynamo. The commutator is located on the shaft below the spinning magnet
Pacinotti dynamo, 1860
The Woolrich Electrical Generator in Thinktank, Birmingham
Small Gramme dynamo, around 1878
Low voltage dynamo for electroplating from the turn of the century. The resistance of the commutator contacts causes inefficiency in low voltage, high current machines like this, requiring a huge elaborate commutator. This machine generated 7 volts at 310 amps.

A small electrical generator built into the hub of a bicycle wheel to power lights is called a hub dynamo, although these are invariably AC devices, and are actually magnetos.

U.S. NRC image of a modern steam turbine generator (STG).

Electric generator

Device that converts motive power into electric power for use in an external circuit.

Device that converts motive power into electric power for use in an external circuit.

U.S. NRC image of a modern steam turbine generator (STG).
Early Ganz Generator in Zwevegem, West Flanders, Belgium
The Faraday disk was the first electric generator. The horseshoe-shaped magnet (A) created a magnetic field through the disk (D). When the disk was turned, this induced an electric current radially outward from the center toward the rim. The current flowed out through the sliding spring contact m, through the external circuit, and back into the center of the disk through the axle.
Hippolyte Pixii's dynamo. The commutator is located on the shaft below the spinning magnet.
This large belt-driven high-current dynamo produced 310 amperes at 7 volts. Dynamos are no longer used due to the size and complexity of the commutator needed for high power applications.
Ferranti alternating current generator, c. 1900.
A small early 1900s 75 kVA direct-driven power station AC alternator, with a separate belt-driven exciter generator.
The Athlone Power Station in Cape Town, South Africa
Hydroelectric power station at Gabčíkovo Dam, Slovakia
Hydroelectric power station at Glen Canyon Dam, Page, Arizona
Mobile electric generator
Protesters at Occupy Wall Street using bicycles connected to a motor and one-way diode to charge batteries for their electronics

There are two common kinds of generator in use on bicycles: bottle dynamos which engage the bicycle's tire on an as-needed basis, and hub dynamos which are directly attached to the bicycle's drive train.

Red light on the back of a bicycle

Bicycle lighting

Illumination attached to bicycles whose purpose above all is, along with reflectors, to improve the visibility of the bicycle and its rider to other road users under circumstances of poor ambient illumination.

Illumination attached to bicycles whose purpose above all is, along with reflectors, to improve the visibility of the bicycle and its rider to other road users under circumstances of poor ambient illumination.

Red light on the back of a bicycle
Early bicycle lighting: candle lamps, oil lamps and carbide lamps
Early bicycle lamps and two early bottle dynamos (1935)
A carbide lamp
A home-made HID light assembly consisting of a 10 watt HID light (right) and a 30 watt HID light (left) as well as three 1 watt Luxeon high power LEDs
A group of amateur cyclists during a night ride in Chișinău. The great majority of the participants have their front light devices enabled, but only the most powerful ones are visible on the asphalt. The street lights provide a sufficiently bright light, thus reducing the lighting equipment role to being observable in traffic.
LED headlight Cateye EL-300
Rear LED light mounted on the seatpost of a road bicycle
Shimano Nexus hub dynamo
Dismantled bottle dynamo. Left: Housing with internal permanent magnet rotating through the friction wheel. Right: Induction coil
Magnetic bike lights
An illuminated bicycle jacket made out of clear vinyl, fiber optics, LEDs, and Christmas Lights that improves rider visibility
Wheel-mounted bike lights

Hub dynamos are built into the front or rear wheel hub. These are generally the most reliable and most efficient of the three types.

Bottle dynamo mounted on a bicycle.

Bottle dynamo

Small electrical generator for bicycles employed to power a bicycle's lights.

Small electrical generator for bicycles employed to power a bicycle's lights.

Bottle dynamo mounted on a bicycle.
Dismantled bottle dynamo. Left: Housing with internal permanent magnet rotating through the friction wheel. Right: Induction coil
Positioning of a bottle dynamo

Two other dynamo systems used on bicycles are hub dynamos and bottom bracket dynamos.

An opafiets, a single speed traditional Dutch roadster with double top tube and coaster brake

Roadster (bicycle)

Type of utility bicycle once common worldwide, and still common in Asia, Africa, Latin America, and some parts of Europe.

Type of utility bicycle once common worldwide, and still common in Asia, Africa, Latin America, and some parts of Europe.

An opafiets, a single speed traditional Dutch roadster with double top tube and coaster brake
Contemporary gents' roadster
The Dutch omafiets is a ladies' roadster of classic design
Three-speed 1971 Raleigh Superbe sports roadster with 26-inch tires and Dynohub
Roadsters are known in East Africa as Black Mambas, and are often used as cycle taxis or boda-bodas.
A British ad from 1897 showing a ladies' bicycle/roadster
Gentleman on a 1920s roadster, Germany
Farmer on roadster bicycle used for freight in Indonesia
An {{lang|nl|opafiets}} or {{lang|nl|stadsfiets}} is a traditional Dutch gent's roadster
A 2012 Sohrab roadster manufactured in Pakistan
Modern Batavus roadster with Nexus hub and roller brake

The classic gents' roadster, AKA the English roadster, has a lugged brazed steel diamond frame, rod-actuated brakes and of late, cable operated drum brake systems have been widely produced for the European market, upright North Road handlebars, a single gear ratio or three- or five-speed hub gears, a chaincase, steel mudguards, steel cranks, 28 x (ISO 635) wheels, Westwood rims, and often a Sturmey-Archer hub dynamo.

Vélib'

Large-scale public bicycle sharing system in Paris, France.

Large-scale public bicycle sharing system in Paris, France.

A Vélib station with its distinctive grey bicycles.
An automated Vélib' pay station.
Bike attachment points at a Vélib' station.
Velib' station at night, Cadet Street.
BSoD on a Vélib' station in 2009.
A Vélib bicycle rack with nearly all its bicycles taken.

Vélib' bikes are equipped with a locking system, a front basket and always-on LED lighting powered by a front-hub dynamo.

Shimano Nexus Inter 8 hub excluding auxiliary components.

Shimano Nexus

Shimano Nexus Inter 8 hub excluding auxiliary components.
Shimano Nexus Inter 3 hub laced with spokes and mounted on a bicycle.
Shimano Nexus Inter 7 Hub Gear
Nexus front hub with attached roller brake.

Shimano Nexus is a brand of bicycle components which includes products such as epicyclical gear hubs, cranksets, shifters, brake levers, hub brakes, hub dynamos, and a CPU for automatically changing gears.

Dublinbikes

Public bicycle rental scheme which has operated in the city of Dublin since 2009.

Public bicycle rental scheme which has operated in the city of Dublin since 2009.

A Dublinbikes docking station
A Dublinbikes kiosk

A Shimano hub dynamo in the front wheel generates power for front and rear always-on LED lighting.

Smoove

French company that designs, manufactures and markets products related to bike-sharing.

French company that designs, manufactures and markets products related to bike-sharing.

The Bike Stand
RFID/Keyboard electronic lock
Secured bicycle parking
Bicycles are redispatched by a fleet of electric vans
Vélopop' in Avignon
A station in Vicenza, Italy
Bike in Action, Nicosia, Cyprus

rear hub gear and front hub dynamo;