Sturmey-Archer
Encyclopedia
Nottingham
Nottingham is a city and unitary authority in the East Midlands of England. It is located in the ceremonial county of Nottinghamshire and represents one of eight members of the English Core Cities Group...
, England. It primarily produces 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....
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...
s but has also produced motorcycle
Motorcycle
A motorcycle is a single-track, two-wheeled motor vehicle. Motorcycles vary considerably depending on the task for which they are designed, such as long distance travel, navigating congested urban traffic, cruising, sport and racing, or off-road conditions.Motorcycles are one of the most...
hubs.
The company was founded in 1902 by Henry Sturmey and James Archer under the guidance of Frank Bowden, the primary owner of the Raleigh Bicycle Company
Raleigh Bicycle Company
The Raleigh Bicycle Company is a bicycle manufacturer originally based in Nottingham, UK. It is one of the oldest bicycle companies in the world. From 1921 to 1935 Raleigh also produced motorcycles and three-wheel cars, leading to the formation of the Reliant Company.-Early years:Raleigh's history...
. In 2000, the assets and trademarks of Sturmey-Archer were sold to Sun Race of Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
which then renamed itself Sun Race Sturmey-Archer Inc and production moved to Taiwan.
Products
All SA gear hubs use epicyclic (planetary) geartrains of varying complexity. The AW is the simplest, using one set of planetary gears with four planets. The AM uses three compound planets with differently sized cogs on a common shaft to engage the gear ring and sun gear separately, while the close-ratio 3-speeds, and hubs with 4 or more speeds, use multiple planetary geartrains. Depending on the specific hub these may be in series with each other, or with one or the other set being selectable at any given time by locking a particular sun gear to the axle.AW hub gears
Three-speed bicycle
The three-speed bicycle is a bicycle that uses internal hub gears at the rear wheel hub to provide three gear ratios. Typically, in low gear, the rear sprocket turns faster than the wheel; in middle gear, the rear sprocket turns at the same speed as the wheel; in high gear, the rear wheel turns...
hub gear, introduced in 1936 and still in production as of 2008. It is the survivor of a much larger range of "A" model 3-speed hubs, including the AM (medium ratio for "club" riders), the AC and AR (very close ratio for time triallists) and the ASC (a unique 3-speed fixed gear). In 1939 a 4-speed model FW was released. This led to the development of a series of 5-speed models, and by 1994, 7-speed hubs were introduced. Production was low, and in the mid-2000s these were discontinued.
SW hub gears
The brief story of the Sturmey-Archer SW series medium-flange wide-ratio 3-speed hub provides strong substantiation of the merits of the AW design.Sturmey-Archer Gears Ltd. designed the type SW Mk. 1 medium-flange wide-ratio 3-speed hub in 1954 and began production in 1956, intending it to replace the AW series of large-flange hubs.
Compared to the AW's 25% reduction in 1st gear, direct-drive 2nd gear, and 33.33% overdrive 3rd gear, the SW offered slightly wider gearing, referred to by Brian Hayes as "super-wide" gearing, with 27.7% reduction for 1st gear, direct-drive 2nd, and taller 38.4% overdrive 3rd gear. Riders appreciate the nearly silent operation of its springless centrifugal pawls.
Smaller and lighter than an AW hub, the SW has fewer parts and was thought to be less costly to manufacture than the AW series that had been in continuous production since 1936.
The new hub turned out to be slow to shift and can't be 'pre-shifted' like an AW. More troubling, the unique crescent-shaped pawls can have slippage issues even when a gear is fully engaged, especially if the hub had not been continually supplied with fresh 10W oil. Production of the SW series ceased after just two years, 1956-57.
Sturmey-Archer had maintained reduced AW series production during these years to aid cycle makers in the tranisiton o the new hub. Upon terminating SW production in 1958, they shortly resumed previous levels of AW production.
After the failure of the SW in the market and the re-commitment to the AW, Sturmey-Archer began to widely license the design, with fully interchangeable clones of the AW eventually being made under labels including J.C. Higgins, Sears, Austro-Daimler, Brampton, SunTour, and others.
Dynohub
The Dynohub was Sturmey-Archer's hub dynamoHub dynamo
A hub dynamo is a small electrical generator built into the hub of a bicycle wheel that is usually used to power lights. Most modern hub dynamos are regulated to 3 watts at 6 volts, although some will drive up to 6 watts at 12 volts.-Models:...
for bicycles. The Dynohub was designed as a means of generating electrical lighting power for bicycles during the Second World War. The initial GH12 12-volt model was introduced in 1936. This was followed several years later by the GH8. This 8-volt unit was in turn supplanted in the 1950s by the lighter-weight GH6 6-volt version, which remained in production through the early 1980s. The term "dynohub" is sometimes applied generically
Genericized trademark
A genericized trademark is a trademark or brand name that has become the colloquial or generic description for, or synonymous with, a general class of product or service, rather than as an indicator of source or affiliation as intended by the trademark's holder...
to bicycle hub dynamos, but it originates as a trademark.
The GH6 version produced a rated output of 6V, 2W from a 20 pole ring magnet with a stator having a continuous winding. Original headlamp
Headlamp
A headlamp is a lamp, usually attached to the front of a vehicle such as a car or a motorcycle, with the purpose of illuminating the road ahead during periods of low visibility, such as darkness or precipitation. Headlamp performance has steadily improved throughout the automobile age, spurred by...
bulbs are 6V 0.25A (1.5W) (e.g., CRY5) and a rear bulb of 6v 0.04A (0.24W) (e.g., CRY8). This is different from a modern standard bicycle dynamo, though replacements can still be had. Common substitutions are the modern standard 2.4W headlamp
Headlamp
A headlamp is a lamp, usually attached to the front of a vehicle such as a car or a motorcycle, with the purpose of illuminating the road ahead during periods of low visibility, such as darkness or precipitation. Headlamp performance has steadily improved throughout the automobile age, spurred by...
bulb and a tail lamp
Automotive lighting
The lighting system of a motor vehicle consists of lighting and signalling devices mounted or integrated to the front, sides, rear, and in some cases the top of the motor vehicle...
bulb of 0.6W. One rider reports much more light with a 6.3V 0.25A (1.6W) type 40 bulb.
Rated output was reached at around 20 km/h (12 mph), a rotational speed
Rotational speed
Rotational speed tells how many complete rotations there are per time unit. It is therefore a cyclic frequency, measured in hertz in the SI System...
of approximately 60rpm. The name dynamo implies DC
Direct current
Direct current is the unidirectional flow of electric charge. Direct current is produced by such sources as batteries, thermocouples, solar cells, and commutator-type electric machines of the dynamo type. Direct current may flow in a conductor such as a wire, but can also flow through...
output, but as usual with bicycle dynamos (known as generators in North America), output was in fact alternating current
Alternating current
In alternating current the movement of electric charge periodically reverses direction. In direct current , the flow of electric charge is only in one direction....
.
Dynohubs were offered as front hubs and as rear geared hubs. The AG was an AW 3-speed rear hub with inbuilt dynamo, while the FG was a dynamo similarly combined with an FW 4-speed.
Hub generators were absent from Sturmey-Archer's product range from the 1980s until the 2006 introduction of the X-FDD front hub, which combines a 6v, 2.4w or 3w dynamo with a 70mm drum brake
Drum brake
A drum brake is a brake in which the friction is caused by a set of shoes or pads that press against a rotating drum-shaped part called a brake drum....
.
Modern gear hubs (Sunrace Sturmey Archer)
The XRF8, XRD8, XRR8, and XRK8 8-speed hubs entered series production in 2007.SunRace Sturmey Archer have modified the design and manufacture in many respects; compared to the old AW hub, the current 3-speed equivalent (SRF3) now has an aluminium alloy shell for lighter weight. According to Schraner and Brandst; an aluminium alloy shell reduced spoke breakage due to aluminium being softer allowing the spoke to seat into the flange and disperse the stress at the bend in the spoke over a wider area.
The new hub also eliminates the no-drive position found on most AW hubs between normal and top gear.
3 speed fixed gear hub
In 2009 Sunrace Sturmey-Archer re-introduced a 3-speed fixed gear hub, the S3X.. This gives ratios of 100/75/62.5 (i.e. the top gear is direct drive and the others are geared down from it) and the internals are based on the newest 5-speed freewheel hub (in the same way as the original fixed ASC was based on the contemporary FC 4-speed hub).Other
The Sturmey-Archer name was also credited with the 49cc two-stroke engine fitted to early Raleigh mopedMoped
Mopeds are a type of low-powered motorcycle designed to provide economical and relatively safe transport with minimal licensing requirements.Mopeds were once all equipped with bicycle-like pedals , but moped has been increasingly applied by governments to vehicles without pedals, based on their...
s, although this was actually a reworking of Vincenti Piatti's "Trojan Mini-Motor" and built by BSA's motorcycle operation
Birmingham Small Arms Company
This article is not about Gamo subsidiary BSA Guns Limited of Armoury Road, Small Heath, Birmingham B11 2PP or BSA Company or its successors....
.
External links
- Sunrace Sturmey-Archer company site
- Sturmey-Archer site
- The Sturmey-Archer Story Details of the independently produced technical history of Sturmey-Archer from its inception to 1987.
- How to repair old Sturmey-Archer hubs
- Sturmey-Archer pages from Sheldon BrownSheldon Brown (bicycle mechanic)Sheldon Brown was an American bicycle mechanic and technical authority on bicycles. He contributed to numerous print and online sources related to bicycling, bicycle mechanics and maintenance, including his own website — and received numerous awards for his contributions.-Biography:Brown...
's website - Sheldon Brown's Sturmey-Archer Dynohub page
- Jobst Brandt's Dynohub page
- The demise of Sturmey-Archer A compilation of articles from Nottingham local newspapers, chronicling the closure of the Nottingham factory.
- Supplement to The Sturmey-Archer Story Comprehensive coverage of the latter years of Sturmey-Archer's British-based operation, including the closure.