dynamos, but it originates as, and remains, a trademark. The GH6 version produced a rated output of 6 V, 0.33 A (2 W) from a 20-pole ring magnet with a stator having a continuous winding. Original headlamp bulbs are 6 V, 0.25 A (1.5 W) (e.g., CRY5) and a rear bulb of 6 V 0.04A (0.24W) (e.g., CRY8). This is different from a modern standard bicycle dynamo, though replacements can still be obtained. Common substitutions are the modern standard 2.4 W headlamp bulb and a tail lamp bulb of 0.6 W. One rider reports much more light with a 6.3 V, 0.25 A (1.6 W) type 40 bulb. 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. Rated output was reached at around 20 km/h (12 mph), a rotational speed of approximately 160 rpm. The name dynamo implies DC output, but as usual with bicycle dynamos (known as generators in North America), output was in fact alternating current. Dynohubs were offered as front hubs and as rear geared hubs. The AG was an AW three-speed rear hub with inbuilt dynamo, while the FG was a dynamo similarly combined with an FW four-speed. An SG 'Super-Wide' three-speed Dynohub was planned between 1954 and 1960, but never produced. An FG hub can be converted to have 5 gears using the same methods of modification as would be used for an FW to enable individually selectable sun gears. Hub generators were absent from Sturmey-Archer's product range from 1984 until the 2006 introduction of the X-FDD front hub, which combines a 6v, 0.4 A (2.4 W) or 0.5 A (3 W) dynamo with a 70 mm drum brake. Modern gear hubs (Sun Race Sturmey-Archer) The XRF8, XRD8, XRR8, and XRK8 8-speed hubs entered series production in 2007. 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). According to Schraner and Brandt, an aluminium alloy shell reduced spoke breakage due to aluminium being softer allowing the spoke to