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Old September 10th 17, 06:24 AM posted to rec.bicycles.tech
bob prohaska
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Posts: 102
Default Is there an updated Dynotest somewhere?

Sepp Ruf wrote:

As the more recent tests were mostly conducted "by SON's Andreas Oehler or
one of his buddies," they have not met r.b.t's stringent anti-corruption
criteria:

https://www.cyclingabout.com/dynamo-hub-drag-lab-testing/
(is a translation of
https://fahrradzukunft.de/14/neue-nabendynamos-im-test/


That article actually comes somewhat close to what I was looking
for. The real disappointment is the photo: It shows a (very expensive)
Schmidt hub containing a clawpole armature.

That is somewhat borne out in the efficiency. It's only around 50%.
Seems to me Schmidt has considerable room for improvement. Even the
cheapest electric machines use laminated armatures.

If that represents the state of the hub dynamo art it's in a bad way.
They're obviously aware of eddy current losses (note the notch in
the visible pole piece) but the losses extend to the entire volume
of magnetic material. It's as if they're unaware of the skin effect.

Some things that have changed since the dynotest age:

- bottle dynamo market has mostly bifurcated into "cheap replacement" and
"pointless hipster specialty" items
https://fahrradzukunft.de/18/labortest-felgenlaeuferdynamos/

- more (bottle) dynamos feature inbuilt hard voltage limitation, potentially
limiting light output

- new, low-power "1.5W" generator category, marketed at dragophobes


subjective advice:
Shimano generators have improved. For their 3 Watt hubs, stay away from
anything even more basic than their, from old to new, DH-3N30, DH-3N31,
DH-C3000 hub lines.

Get (import) an identical pair of low-to midrange Shimano hubs, and in case
of failure, beat SON's (or Taiwan's) service turnaround time hands-down by
locally rebuilding the wheel.


For the moment I think I'll try to revive my old Soubitez roller dynamo
and hope somebody gets past the 19th century.

Thanks for posting!

bob prohaska

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