Hub dynamo

This competed effectively with contemporaneous bottle dynamos and bottom-bracket generators, but the Dynohub was heavy with its steel housing and was discontinued in the 1980s.

The efficiency of the SON is quoted by the manufacturers at 65% (so just over 5 W of the rider's output is diverted to produce 3 W of electrical power) but this applies at only 15 km/h (9 mph).

Bicycle dynamos instead use permanent magnets to eliminate the need for a battery to excite the field and initiate electrical generation.

In a 2006 review by the German Stiftung Warentest, the efficiency at 15 km/h (9 mph) of a D1 series i-Light hub dynamo was 66%, 10% better than a SON-28.

Kasai makes a series of Dynacoil hub dynamos for rim and disc brakes with both quick-release and through-axle models.

Modern designs utilize stronger neodymium magnets, a single copper coil winding, and claw poles.