On Monday, May 7, 2018 at 5:05:52 PM UTC+1, Jeff Liebermann wrote:

From the graphs:
http://www.myra-simon.com/bike/dynotest.html
at 16 kph, the range of output power is 2.5 to 3.4 watts.

That data was already ancient when I first saw it, c2002. One would hope that present-day hub dynamos are a spot more efficient.

With a hub dynamo, you're kinda stuck with the available products,
most of which max out at 3 watts at 10 mph.

A spot under, actually, 15kph, which isn't quite 10mph; it's the highest speed a lady commuter cyclist or housewife doing her shopping was assumed to aspire to. This is another example of thick German legislators setting a "standard" hostile to cyclists in cement. The EU, within which all nations generally follow the German bicycle legislation, is such a large market for hub dynamos, that even Shimano, a Japanese company, follows the German standard -- and of course doesn't want the costs of making two different classes of hub dynamos. That's how the 6V/0.5A/3W standard arose, not by conspiracy but by ignorant Teutonic lack of foresight (1). By now there's too much invested in that "standard" for it to change, so we can only hope that the lighting elements have another sudden splurge of development.

I am of the opinion, though, that an up-to-date hub dynamo (a correctly scaled SON, a Shimano, any of the latest contenders) attached to a BUMM Cyo or better makes the first adequate bicycle lamp, at the level of an old 6V VW Beetle from around the time you were in college, Jeff. A blinkie, verboten by the German "standard", is easily and cheaply added with a Chinese LED torch and a fish mouth or tiewrap mounting.

AJ
Rage, rage against the dying of the light -- Dylan Thomas

(1) Mind you, we should probably be grateful that those dim dead Germans didn't define some output equivalent to incandescent filaments back then, because in that case by now the only available hub dynamos would put out 0.5W.