Author Topic: dynamo hubs  (Read 2550 times)

jags

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dynamo hubs
« on: October 28, 2012, 10:42:21 pm »

Danneaux

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Re: dynamo hubs
« Reply #1 on: October 28, 2012, 11:32:13 pm »

Andre Jute

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Re: dynamo hubs
« Reply #2 on: October 29, 2012, 12:42:35 am »
I don't want to pour cold water on your parade, guys, but the writer of this article is employed by Wilfried Schmidt of Schmidt Maschinenbau, the maker of the SON hub dynamo. Of course his own products come out top of the tests! For the record, no deliberate dishonesty is alleged or needs be involved; proper scientific testing is designed to remove even implicit, unexpressed bias, for instance in the design of the test protocols, and in not using the instruments of any one manufacturer to measure the results of all.

If this farce was played out in the US or the UK there would be an outcry about bias. That it happens in a foreign language doesn't make it any more acceptable. Ask yourself, how loud would you screech if the CTC Magazine hired the Dawes designer to trash Thorn bikes under the spurious claim that it was a "scientific test". (The magazine would take years to recover its credibility; my guess is that the uproar would very likely kill it.)

For the record, I have both SON and Shimano hub dynamos and am pleased with both for different types of riding. Also for the record, I've had some converse with Andreas Oehler and I don't think he's dishonest, but what I personally think is as irrelevant as his results. He works for one of the combatants and is therefore not a fit person to publish comparative tests, period.

One wonders (for about 0.0001 of a second, less than the blink of an eye), which hub dynamos would be at the top of the table if the test were conducted by Shimano engineers...

Sorry fellows, but there are a good number of these zenophobic German expressions of commercial nationalism about and they're promotional material, advertising plain and simple, not independent tests, and shouldn't be treated by us as reliable information on the same level as, say, a test conducted by Chris Juden for CTC or by the reliable and independent Dutch cycling association.

Andre Jute

Danneaux

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Re: dynamo hubs
« Reply #3 on: October 29, 2012, 03:17:43 am »
Hi Andre,

I absolutely agree with your cautions of test bias; they are well-taken and occurred to me immediately on seeing the article was the same as on the earlier test from 2006, and yes Andreas Oehler is a SON employee which must of necessity call the test results into question. Of course, the world is crying out for objectivity in tests of dynohubs, but...this is what we've got. I consider the collective information presented as a data point and nothing more until we have the independent testing you called for. As with any research and especially with such "captive research", it is up to the reader to use due diligence in (dis)qualifying and considering both the methodology and the results.

Even so, the SON to SON comparisons are interesting, particularly in light of the earlier 2006 tests ( http://translate.google.com/translate?sl=de&tl=en&js=n&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&u=http%3A%2F%2Ffahrradzukunft.de%2F14%2Fneue-nabendynamos-im-test%2F&act=url ). I was particularly interested in the 2006 SON28 Klassik comparisons to the neu SON28, and these are unlikely to suffer as much from tester bias given both models are produced by Oehler's employer, SON.

Yes, Oehler's tests show SON dynamos as the no-load, low-drag champs, but he concedes (and the test results show) the Sunup Eco also did very nicely in exhibiting little drag in a no-load state despite its geared drivetrain -- nearly on-par with the SON offerings, depending on speed. I was interested to read the Shutter Precision clutch-actuated dynamo exhibited such high no-load drag, apparently due to seal friction. This correlates with some anecdotal reports I've read, and I would like to see another test of this unit done elsewhere.

Interestingly, the SON units did not trounce the competition in drive power at 12 ? load at various speeds; the lowly Sanyo appears to have acquitted itself nicely in the electrische leistung (electric power) production chart; unfortunately, it is also the high-drag champ when it is not powering lights, with 12.4 watts of drag at 50kph using a 700C wheel as show in the antriebsleistung (propulsion power/effort/drag load) chart.

Yes, I heartily agree and wish this had been an independent test, but Andreas did show and briefly describe his test rig; it would not be hard for an independent tester to duplicate it and publish comparative results. It is important to note the tests were conducted in the workshops of Olaf Schultz in Hamburg, who has worked with Oehler on lighting issues before. Schultz' dynohub, lighting, and regulation pages begin here (GoogleTranslated to English): http://translate.google.com/translate?hl=en&sl=de&u=http://www.enhydralutris.de/Fahrrad/Beleuchtung/index.html&prev=/search%3Fq%3Dolaf%2Bschultz%2Bhamburg%2Bfahrrad%2Blicht%26num%3D20%26hl%3Den%26safe%3Doff%26prmd%3Dimvnso&sa=X&ei=J-ONUPnRCeWg0QWiooAo&ved=0CCQQ7gEwAA ...and are worth a read with this test in mind.

All the best,

Dan.
« Last Edit: October 29, 2012, 03:27:06 am by Danneaux »