Tourist, the equation in [MENTION=113466]steelbikeguy[/MENTION]'s paragraph labelled 1. is "Voc = K x f" which states that the output voltage of a generator increases as the speed of the rotation of the generator shaft. The equation can be derived from basic physics by any formal student of electrical engineering, and both steelbikeguy and I earned our EE degrees many years ago. It says that for the voltage to rise as the speed increases is totally natural, it's how generators work. The USB charger does not "forces the hub to generate more watts with more resistance at those higher speeds." The hub generates more voltage just because it is turning faster.

I didn't pay too much attention to the data that compares different USB chargers. I'm not saying there are or are not differences, rather I'm trying to say that if there are performance differences, they might be because of differences between the circuit designs of the various USB chargers under test.

Steelbikeguy, thank you very much for generating and interpreting all this data regarding the SON hubgen.