Ok, I'll take that as fact since I don't know any better. What would the frequency of the oscillation be? I thought about this while most of you guys were sleeping. Household AC alternates at 60 cycles per second, and it is maintained with such precision that you can use the alternation to keep clocks on time. How does a generator, dependent on the wildly varying speeds of a bicycle wheel maintain a constant alternating current?! Like I said, I have no idea. What I do know, however, is that LED bulbs (Light Emitting Diodes) must have DC in order to work. And the polarity of the DC matters, as an earlier poster discovered, since all diodes block current flowing in the 'wrong' direction, it's just that most diodes don't also emit light. Just about all the devices we use, incandescent (halogen are incandescent) lights excepted, most of them need DC to work properly. If the power source is AC (it usually is in a home) it must be turned into DC (rectified) using diodes in a unique arrangement. That is the purpose of the warts that take up two spaces on your powerstrip, to turn the 110V AC into DC. Usually at a lower voltage as well but the main thing is to stop the AC from alternating. So if the generator hub is producing AC then there is a bridge rectifier somewhere, either in the hub itself, or in the housing of the light, but you cannot present an LED light bulb with AC, it simply won't work. And I simply have to assume that it is an LED light that is in use. In 2019 there simply is no good reason to still be using halogen lights.