Frank Krygowski wrote:
Good info from Sep Ruff (and I wish I read Deutsch).

But Bob, can I ask what your objectives are?

Simply to make a well-informed choice. Hub dynamos represent a lot of
money when a wheel is laced on them, a Schmidt is expensive even before
that. It would be nice to know what I'm getting before paying for it.
The application is daytime running lights.

I ask because some of this may not matter much any more. Seems to me
there was a time when it made sense to worry about which dynamos might
put out a little more power, or which had a little less drag. But with
modern LED dynamo lights from Busch & Muller, there is plenty of light
available right where you need it; and almost any dyno can supply the power.
You'll never notice the differences in drag between the various hub dynos.

Yes, lights are better, but the materials available to dynamo builders
are better also, and I have (possibly misguided) hopes that somebody,
somewhere, is exploiting them. Rare earth magnets are one improvement,
use of laminated armature poles would be another. Together they might
be worth a factor of two, redeemable either in efficiency or weight.

I agree that the Shimano DH-3N30 works perfectly well. The two bikes I
ride most often at night have hub dynos. But on a couple bikes that I
ride only occasionally at night, I've got old bottle dynamos or roller
dynamos. They work very well and have the benefit of zero drag when off.
Yet those bikes have good lights available whenever needed, with no
battery worries.

I've got a Breezer with a DH-3N30 hub dynamo and have worn out a
couple of Union rollers on my Cannondale. Neither type seems decisively
better, and neither is impressive. The Shimano is huge and heavy, the
Unions were noisy and prone to bouncing if anything stuck to the roller.

And a bottle or (if you're really lucky) a roller dynamo can be had for
free these days. It's a benefit of being out of fashion. Their main
disadvantage is trickier installation, requiring understanding their
wiring and perhaps fabricating a bracket. But I can handle that.

As can I. At this stage I'd like something better and am looking for
guidance as to what (if anything) is better.

Thanks for reading!

bob prohaska