Sturmey-Archer was a company that manufactured bicycle hubs for many years. Their S3X series is a three-speed hub with ratios of 100/75/62.5 and is compatible with the latest five-speed freewheel hub. These hubs were available in steel or aluminum bodies.
The company was founded in Nottingham, England and was best known for the production of bicycle hub gears, brakes and other bicycle components. The company’s most successful years were during its days as a Raleigh Bicycle Company subsidiary. They also produced motorcycle hubs and gearboxes.
The Sturmey-Archer gear hubs use epicyclic gears to switch between speeds. The AW hub uses simple planetary gears, while the AM hub uses three compound planets. The sun gear engages separately from the gearing. In some models, the left bearing cone may overshoot.
The company also produced a two-speed hub that has the reverse pedal shift action. This hub was the first two-speed hub manufactured since 1941, but it was only produced in limited quantities. The company stopped production of this hub in 1972. However, the Sturmey-Archer S2 hub can be used with a derailleur gear system if you prefer.