Sturmey-Archer
The company was founded in 1902 by Henry Sturmey and James Archer under the guidance of Frank Bowden, the primary owner of Raleigh.
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.
Most notable was the 6-prong ramped sliding clutch which was mounted between springs, this gave the advantage of lateral movement being possible without shifter movement and allowed gears to be pre-selected while pedalling, the ratio would change when pedal force was relaxed, freeing the mechanism to slide into the new gear and under spring pressure.
The gear ring dogs would ratchet around the clutch using the ramps and springs if the hub was trying to engage Normal and High gear at the same time, though allowing this to happen through slow shifting can cause excessive clutch wear and render the hub inoperable.
1939 also saw the introduction of the FM four speed medium ratio hub, which was mechanically very similar to the AF and FC.
The FW led to the development of a series of internally similar 'S5' five-speed models, and by 1994, Sturmey-Archer were producing seven-speed hubs.
The brief story of the Sturmey-Archer SW series medium-flange wide-ratio three-speed hub provides strong substantiation of the merits of the AW design.
This is more pronounced in hubs which are sticky inside from incorrect lubrication, and ones which have been allowed to wear through poor maintenance or, less commonly, heavy use.
Both the SB and SG would have used a modified set of SW internals with a shortened planet cage to facilitate the additional functionality on the left side of the hub.
Technical drawings for both the SB and SG exist and both appeared in catalogues, however there is no evidence that either hub went into production and the AB/ABC and AG re-appeared alongside the AW in 1958.
After the failure of the SW in the market and the re-commitment to the AW, Sturmey-Archer continued to widely license the design, with fully interchangeable clones of the AW eventually being made under labels including J.C. Higgins, Sears, Austro-Daimler, Brompton, Brampton, SunTour, and others.
In 1966 Sturmey-Archer launched a new two-speed hub with a backpedal shifting action similar to the Fichtel and Sachs 'Torpedo Zwei Gang Duomatic'.
The S2 – Sturmey-Archer's first 2-speed hub since the demise of the T series in 1941 and the last two speed they would make in the UK – featured a direct drive and a 28.6% gear reduction.
To achieve this radically different mode of shifting gears, the hub featured a unique driver with a 4 spline keyed socket in the middle (similar to, though not interchangeable with, later 'No Intermediate Gear' AW drivers), into which sat a selector sleeve.
The term "dynohub" is sometimes applied generically to bicycle hub dynamos, but it originates as, and remains, a trademark.
[7] LED conversions are possible and will output a much brighter light than incandescent or halogen bulbs, though the LED alternatives require the fitting of a voltage regulator and will strobe 10 times per wheel revolution if not fitted with a capacitor or rectifier to smooth the AC current output from the Dynohub.
[9] Sun Race Sturmey-Archer have modified the design and manufacture in many respects; compared to the old AW hub, the current three-speed equivalent (SRF3) now has an aluminium alloy shell for lighter weight (a painted-steel shelled 'Steelite' version is still available, and branded AW).
[10][11] The company produced front hub brakes to match such as the 70mm X-FD model, featuring sealed cartridge bearings.
[1] In 2010 Sturmey-Archer launched a new range of duomatic 2-speed hubs, re-using the S2 name from the late 1960s, these hubs – designated S2 (freewheel), S2C (backpedal brake), and S2K (6 bolt disc brake) – share their general engineering principles with the original S2, but do not share any internal components.
The Sturmey-Archer name was also affixed to the 49 cc two-stroke engine fitted to early Raleigh mopeds, although it was actually a reworking of Vincenti Piatti's "Trojan Mini-Motor", and built by BSA's motorcycle operation.
