Dan experimented at one time with wind vanes in his spokes, maybe he can comment. I think that was on a trailer but could be done on a wheel with the bike upside down.
I did indeed and as a wind-powered generator, it was very successful.
I used my Nomad -- with its own dynohub and charger -- sitting upright, brake levers locked and propped by a Click-Stand sitting in a tennis ball to prevent it sinking into soft sand.
My Extrawheel trailer was equipped with a SON28 Klassik dynohub, a B&M e-Werk charger and a voltage rectifier I made to power a switchable taillight with standlight function. The trailer was attached to the Nomad, but inverted on its own optional rack so the wheel was free to spin. After a lot of experimentation I developed some detachable wind vanes for the spokes that assumed a cup shape when filled with air, multiplying the wind-driven effect.
I found I could setup the lot at bedtime, plug in my depleted gadgets, and by morning they were full -- provided there was a nighttime desert wind, which nearly always held true. It actually didn't require much wind to spin the wheel. Winds below 9.5kmh, would not spin it. With a gentle push it would start at about 9.5kmh and by 13kmh it was self-starting and self-sustaining. I was not able to check wheel "ground" speed because the trailer was not equipped with a speedometer/computer, but I would guess based on charging that it was spinning about 12-16kmh in equivalent "ground" speed. At any rate, it was "enough" to charge or top off my gadgets by morning (about 8 hours' duration) while I slept. It worked as I had hoped in the desert but of course did not work at all well in the dense forests where I slept on the mountain passes on my way to the desert. A lot depends on conditions and of course, the vane design, load, and so on.
I now don't use the idea so much because of problems with my 2nd generation version of the trailer that revealed themselves in the fullness of time/use and are difficult to overcome despite my further development: The hub quick-releases specified to double as ball-mount hitches are not good as q/rs...the levers go "over-center" and lose clamping force and there is no ready substitute. Also, at the time I got my version (Extrawheel Voyager), the hitch tongue/fork was too narrow to accommodate the drawbolts on rear mudguards. In certain conditions where there was a strong "break" between bike and trailer -- say, coming off a road and through a shallow ditch to continue onward off-road -- the trailer would elevate to a point where the fork hit the bike's mudguard, either folding the 'guard or breaking it outright. I went though two replacement mudguards and even bought a longer Extrawheel fork trying to address the problem and have not yet found a solution. The maker was unresponsive on both the problem/solution as well as whether the newer model trailer forks will work with my older Voyager. Also, the trailer developed a persistent shimmy when loaded with water, the way I had hoped to use it from the start. I found it very sensitive to weight distribution in the panniers mounted to it and it worked okay with lighter loads. I now feel the cargo rating is less than I had hoped for or assumed on purchase.
If you were to invert a bicycle with dynohub and charger, I would caution it needs to be secured well, probably with tent stakes and lines to prevent fallover. You would also risk damage to your saddle and/or grips on rocky surfaces unless you could pad them in some way. For these reasons (and because I have a lot of easily damaged accessories like my GPS atop my handlebars) I have never inverted my bikes to fix a puncture or remove a wheel, preferring instead to lay my bikes on their left side and remove the wheel(s) in that position, which works when with panniers attached. To facilitate the process, I place my hub q/r levers on the right/drivetrain side for easy access.
Related links..
http://thorncyclesforum.co.uk/index.php?topic=4953.0http://thorncyclesforum.co.uk/index.php?topic=12293.msg90541#msg90541Best,
Dan.
