above: Sturmey Archer GH12 Dynohub on the author's 1939 RRA. Introduced in November 1936 at the Earl's Court Cycle Show, the first version Sturmey-Archer 12-volt Dynohub was a massive affair, fitted in a S/A tandem drum brake casing with a diameter of 5¼" and weighing close to 4lbs and featuring a magnificent lamp with switch control on the top and two lamps, one being a battery operated "pilot light". This set-up was publicised by Sid Ferris' 1937 Edinburgh-London record ride, 15 hours of which was done in darkness. In 1938, the lighter 2 lbs 10 oz GH8 8-volt DynoHub was introduced and finally the last version, the GH6 6-volt in 1945.