Sturmey-Archer is a manufacturing company originally from Nottingham, England. It primarily produces bicycle hub gears, brakes and a great many other sundry bicycle components, most prominently during their heyday as a subsidiary of the Raleigh Bicycle Company. In the past, it also manufactured motorcycle hubs, gearboxes and engines.
The company was founded in 1902 by Henry Sturmey and James Archer under the guidance of Frank Bowden, the primary owner of Raleigh. In 2000, the assets and trademarks of Sturmey-Archer were sold to Sun Race of Taiwan which was renamed Sun Race Sturmey-Archer Inc and production moved to Taiwan.
All Sturmey Archer 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 machined from a common shaft to engage the gear ring and sun gear separately, while the close-ratio three-speeds, and hubs with four 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.