Originally Posted by
gauvins
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Question for you. USB charger brand A delivers 3W@20kmh. USB charger brand B delivers 6W@20kmh. Do you think that wheel drag is the same in both cases or that if B produces more it means that the circuitry creates more drag in the generator?
If the answer were B (more output means more drag), what would be your opinion on the merits of B? Could be a good thing -- once you've recharged your batteries, drag falls to almost zero, the sooner the better.
I am most certain that when you draw 6 watts out of a hub instead of 3 watts, the drag (rolling reistance) will increase, probably double. I assume you are talking about your Forumslager (spell?) charger.
While I can't feel rolling resistance when I ride with the light on or USB charger in use at roughly 3 watts, I know that there is resistance. When I am off the bike, if I lift the front wheel off the ground and give it a spin it will keep spinning much longer if my light is turned off than if the light is turned on. That resistance is too small for me to feel when pedaling, but it is obviously there when I spin the wheel by hand.
I would rather ride at a 3 watt drag all day than a 6 watt drag for half the day. I might not feel the difference, but I still think it is better to have a more constant effort. That said, I have had some long days where the sun is getting really low on the horizon late in the day and I wished the ground was all downhill.