A hub dynamo is a small electrical generator built into the front hub of a bicycle wheel that is usually used to power lights. Often the hub "dynamo" is not actually a dynamo, which creates DC, but a low-power magneto that creates AC. Most modern hub dynamos are regulated to 3 watts at 6 volts, although some will drive up to 6 watts at 12 volts.
The market was largely pioneered by Sturmey-Archer with their Dynohub of the 1930s–1970s. This competed effectively with contemporaneous bottle dynamos and bottom-bracket generators, but the Dynohub was heavy with its steel housing and was discontinued in the 1980s. Around 2009, Sturmey-Archer released new hub dynamo/drum brake units with an aluminum housing, designated X-FDD [1] and XL-FDD. [2]
The Schmidt Original Nabendynamo (SON) can power two 6-volt lamps in series at speeds above about 19 km/h (12 mph), and Schmidt manufactures lamps designed to facilitate this. These lamps have optics based on the Bisy FL road lights. The efficiency of the SON is quoted by the manufacturers at 65% (so just over 5 W of the rider's output is diverted to produce 3 W of electrical power) but this applies at only 15 km/h (9 mph). At higher speeds the efficiency falls. Bicycle dynamos instead use permanent magnets to eliminate the need for a battery to excite the field and initiate electrical generation.
Shimano offers a variety of hub dynamos under the "Nexus" brand, such as the DH-3N70/DH-3N71, advertised as having significantly less drag than the Nexus NX-30.
SRAM manufactured the i-Light hub dynamo until 2017. [3] The D7 series was available for both rim and disc brakes while the D3 series featured several rim brake varieties. In a 2006 review by the German Stiftung Warentest, the efficiency at 15 km/h (9 mph) of a D1 series i-Light hub dynamo was 66%, 10% better than a SON-28. [4]
SR Suntour offered the DH-CT-630 hub dynamo series with integrated overvoltage protection. [5] It was apparently discontinued in 2010, as it is absent from 2011 and later SR Suntour catalogs. [6]
SP Dynamo Systems offers about 10 different models of hub dynamos. Quick release hubs for disc brakes and rim brakes. Also a 15mm thru-axle for mountain bikes with disc brakes. They claim a very high efficiency and light weight compared to other hub dynamos currently on the market. [7] [8]
Kasai makes a series of Dynacoil hub dynamos for rim and disc brakes with both quick-release and through-axle models. In 2020 they introduced the FS line of field serviceable hubs that can be repaired or serviced. Unlike most hub dynamos that require unlacing the wheel and sending the hub back to the factory to repair the dynamo or replace bearings, the FS hubs are serviceable by the user or a local bike shop. [9] Kasai claims 72% efficiency for the hub at 16 km/h(10 mph). [9]
Improvements in design and materials have led to improvements in efficiency. Early designs had multiple copper windings and heavier magnets. Modern designs utilize stronger neodymium magnets, a single copper coil winding, and claw poles. Bicycle Quarterly reviewed seven different hub dynamos in 2005. [10] The SON28 was found to be the most efficient, although its cost was significantly higher than models from Shimano.
In electricity generation, a generator is a device that converts motion-based power or fuel-based power into electric power for use in an external circuit. Sources of mechanical energy include steam turbines, gas turbines, water turbines, internal combustion engines, wind turbines and even hand cranks. The first electromagnetic generator, the Faraday disk, was invented in 1831 by British scientist Michael Faraday. Generators provide nearly all the power for electrical grids.
A bicycle brake reduces the speed of a bicycle or prevents the wheels from moving. The two main types are: rim brakes and disc brakes. Drum brakes are less common on bicycles.
A bicycle wheel is a wheel, most commonly a wire wheel, designed for a bicycle. A pair is often called a wheelset, especially in the context of ready built "off the shelf" performance-oriented wheels.
A hub gear, internal-gear hub, internally geared 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 shell of the hub gear, in contrast with derailleur gears where the gears and mechanism are exposed to the elements. Changing the gear ratio was traditionally accomplished by a shift lever connected to the hub with a Bowden cable, and twist-grip style shifters have become common.
A utility bicycle, city bicycle, urban bicycle, European city bike (ECB), Dutch bike, classic bike or simply city-bike is a bicycle designed for frequent very short, very slow rides through very flat urban areas. It is a form of utility bicycle commonly seen around the world, built to facilitate everyday short-distance riding in normal clothes in cold-to-mild weather conditions. It is therefore a bicycle designed for very short-range practical transportation, as opposed to those primarily for recreation and competition, such as touring bicycles, road bicycles, and mountain bicycles. Utility bicycles are the most common form globally, and comprise the vast majority found in the developing world. City bikes may be individually owned or operated as part of a public bike sharing scheme.
A racing bicycle, also known as a road bike is a bicycle designed for competitive road cycling, a sport governed by and according to the rules of the Union Cycliste Internationale (UCI).
Sturmey-Archer was a manufacturing company originally from Nottingham, England. It primarily produced bicycle hub gears, brakes and a great many other sundry bicycle components, most prominently during its heyday as a subsidiary of the Raleigh Bicycle Company. In the past, it also manufactured motorcycle hubs, gearboxes and engines.
Bicycle lighting is 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. A secondary purpose is to illuminate reflective materials such as cat's eyes and traffic signs. A third purpose may be to illuminate the roadway so that the rider can see the way ahead. Serving the latter purposes require much more luminous flux and thus more power.
Dirtsurfing is the sport of riding a Dirtsurfer brand inline board. This new Australian boardsport is correctly known as inline boarding because Dirtsurfer is a trademark protected brand name.
A roadster bicycle is a type of utility bicycle once common worldwide, and still common in Asia, Africa, Latin America, and some parts of Europe. During the past few decades, traditionally styled roadster bicycles have regained popularity in the Western world, particularly as a lifestyle or fashion statement in an urban environment.
Kronan bicycles are marketed by Kronan Trademark AB, also known as Kronan AB. Kronan AB was established in June 1997 by three former-students, John Wahlbäck and the Avander brothers, Henry and Martin. In autumn 2003 the company was bought by the Brunstedt family with Mary Brunstedt as the company's current CEO.
Strida is a portable belt-driven folding bicycle with a distinctive A-shaped collapsible frame, designed by British engineer and designer Mark Sanders. The first model, Strida 1, was released in 1987 and the latest, Strida 5.2, in 2009.
Bicycle suspension is the system, or systems, used to suspend the rider and bicycle in order to insulate them from the roughness of the terrain. Bicycle suspension is used primarily on mountain bikes, but is also common on hybrid bicycles.
A dynamo is an electrical generator that creates direct current using a commutator. Dynamos were the first electrical generators capable of delivering power for industry, and the foundation upon which many other later electric-power conversion devices were based, including the electric motor, the alternating-current alternator, and the rotary converter.
The Swiss Army Bicycle has been utilized by the Swiss Army beginning in 1905. There have been three models, the MO-5, MO-93, and the MO-12. The Swiss Army disbanded its elite bicycle infantry units in 2003, but still uses bicycles for training, and many army bicycles remain in private use. The most famous Swiss bicycle infantryman is Federal Councillor Ueli Maurer, who commanded a bicycle infantry battalion until 1994 and still uses his army bicycle. In 2012, the Department of Defence, Civil Defence, and Sport purchased 4100 of the new, lighter MO-12 or Fahrrad 12, which are also available for private purchase.
Alfine is the name of a comfort and urban oriented product series by Shimano. It is mainly known for internally geared hubs, but includes also hydraulic disc brakes and levers, chain tensioners, dynamo hubs, cranksets, shift levers, and complete wheels.
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. The series is primarily aimed at the "comfort" market such as urban commuters and tourers, and as such is not made to withstand the rigours of off-road or mountain biking. The free-wheeling Nexus internal gear hubs are compatible with Shimano's "roller brake", its version of a drum brake, but not with the Shimano disc brakes used with the higher-end Shimano Alfine internal gear hubs.
The SRAM i-Motion series of products is a sport, urban, and trekking oriented product series developed and manufactured by SRAM Corporation. Branded i-Motion are internally geared hubs, shift levers, and dynamo hubs. Related to the i-Motion series are also changeable free or fixed single speed hubs, hybrid epicyclic and derailleur gear hubs, and hydraulic disc brakes. The i-Motion series of products were developed at SRAMs Schweinfurt R&D and manufacturing plant in Germany, formerly of Sachs.
A magneto is an electrical generator that uses permanent magnets to produce periodic pulses of alternating current. Unlike a dynamo, a magneto does not contain a commutator to produce direct current. It is categorized as a form of alternator, although it is usually considered distinct from most other alternators, which use field coils rather than permanent magnets.