Originally Posted by
zacster
While bottle generators are another thing entirely, and have lots of drag due to friction, hub dynamos may or may not perform better than the Magnic. I don't really know myself yet. I don't have any capability to perform the measurements either. I will have both a Magnic light and a dynamo light available to me in April so I'll at least be able to do a test of perceived drag, if I can feel either.
The Magnic cannot compete with a hub dynamo in terms of efficiency, because all it does is to replace the action of friction for a bottle dynamo, with Eddy current action, in transferring the rotation of the wheel to the rotation of the rotor in a dynamo. That transfer, necessarily lossy, is absent in a hub dynamo, since its rotor is rigidly attached to the wheel. The Magnic can have an advantage over a hub dynamo in terms of movability of the dynamo from one bike to another. However, wheels build over a reasonable dynohub can be had for about 60 euro in Germany - I am not sure about the US market. The price and the practical need to keep a dedicated Magnic mount on a bike really tame the incentive to use one. Still, I think it may be fun to employ a new technology just for the sake of it.