The Sturmey-Archer Dynohub is truly named:-
"THE WORLD'S FINEST CYCLE LIGHT"
The headlamp is of modern design and is the only cycle headlamp fitted with external screw-focusing. The front is securely fixed and is proof against rattle or detachment through vibration. A 3-inch diameter accurately made and highly polished parabolic reflector ensures a light of exceptional brilliance. The switch is placed below the lamp for weather protection and the connections are neatly made inside the lamp, thereby avoiding unsightly external terminals. The rear lamp is entirely sealed against moisture and its plastic red dome is visible at all angles from the rear, the bulb being of sufficient brilliance to be seen at a considerable distance.
The ultra - modern generator, which is covered by world patents, has no mechanical losses whatever and electri- cally is highly efficient, giving an output of 2 watts at 6 volts. Using the existing wheel bearings and having no troublesome contact brushes it is entirely without mechanical friction or wearing parts, so that the effort to propel it is negligible. Being gearless it is absolutely silent, and its position in the hub protects it from damage. Voltage regulation is remarkably good, giving a good light at low speeds without an undue rise in voltage at the higher speeds, so guarding against the burning-out of bulbs.