CTC article compares 5 dynohubs (Dec/Jan 2012/2013)

[Danneaux]

Hi All!

The CTC's Chris Juden, along with Olaf Schultz and Andreas Oehler have collaborated on a Dec/Jan 2012/13 dynohub test the CTC has made public in a downloadable PDF available here: http://www.ctc.org.uk/file/public/feature-hub-dynamos.pdf

While the article is interesting, it is not without controversy among manufacturers listed in the comparison tables. Taiwanese maker Shutter Precision (SP) have noted on their Facebook page...

A good review for SP dynamos at CTC magazine in the UK. However, German hub with 6V2.4W output is chosen to compare with SP PV-8(6V3W). It is not correct. SP dynamos are the lightest and most efficient at current market if comparing at the same level models.

SP also supply the hubs marketed by Supernova reviewed in the comparison, with upgraded seals and a slightly different hub shell design. Some models include disengagement clutches for drag-free running when not actively producing electricity; the Supernova models include revised, higher-drag seals.

Oehler works as a mechanical engineer at Schmidt Maschinenbau; this test also incorporates independent testing by Schultz and was reviewed by Juden. It appears Juden reviewed the others' results and tested a few hubs (it is not clear which or how many, but he mentions SP in the article) available in the UK he'd handled himself.

Some tidbits among the interesting findings reported...
• Dynohub drag is insignificant compared to tire (tyre) choice.
• Though mentioned, Juden largely dismisses the vibrations caused by eddy currents and transmitted through the forks to the handlebars. These indeed don't bother most people, but I have been contacted by some riders who had to change to a different dynohub or abandon them entirely because of it, especially if their hands are sensitive. From the mail I've received, it seems lightweight forks exacerbate the problem to a degree among those so affected. For more on dynohub vibration, see: http://swhs.home.xs4all.nl/fiets/tests/verlichting/index_en.html#Magneet-sterkte
• Indeed, the drag from most dynohubs is so small, one may as well leave them on continuously, especially with LEDs, which are much longer-lived and more efficient than tungsten-filament bulbs.
• Normal (non-dynamo) hubs have some drag, so Juden notes he subtracted this (figures for a high-quality free-running conventional hub) when calculating the dynohub drag. Some of the plain hubs used for test reference had greater reported drag than the SP-derived hubs with the clutches disengaged.
• Among the hubs Juden tested were three samples of an SP dynohub, and two of the SP-produced Supernova. He found a single model could vary more than the apparent difference between models. This seems like quite a lot of variation, but he notes...

"...one should ideally test lots of samples of each. But this is not an ideal world. Look on the bright side: You might be luckier with your sample!"

And what if you're unlucky?
• The charts in the article show electrical output power produced at only 10km/h (6mph) to magnify differences at low speed.
• Efficiency is rated at an average speed of 20km/h (12.5mph).
• Drag is calculated at 30km/h (19mph) with lights switched both on and off.
• All measurements assume a 700C wheel.
• Given the greater efficiency of LEDs, Juden says German authorities are now in process approving 1.5W systems with half the current (sorry) 3W output. I see this as bad news for those of us wanting a dynohub to double as a charging system for our gadgets, but Juden disagrees, saying "A watt-and-a-half should be enough to keep your phone/GPS/computer running...". Yes, it might, but charging times will increase as a result, which would be an unhappy result for those of us who regularly depend on dyno-charging multiple gadgets when well off the grid.

I was a bit disturbed to see the SONDelux in this comparison instead of the more comparable SON28-New, an update on the SON Klassik, and the source of SP's complaint of apples-to-oranges comparisons. IN the comparison tables, the SONDelux has the least weight, produces the lowest power, has the greatest (relative) efficiency and the least drag when on. The SP-produced Supernova Inf-8 had the least drag when off, thanks to the disengagement clutch (and despite what Juden feels are higher drag seals compared to the SP-branded dynohubs). Though the SON28 was mentioned in one of the included photos, it was not included in the summary tables of this article (though may have been included int he fuller test whose results are published on the CTC site and elsewhere; I have yet to check. For more on the SONDelux vs SP, see: http://swhs.home.xs4all.nl/fiets/tests/verlichting/index_en.html#andere-dynamo's

Andreas Oehler's article (referenced preciously on this Forum) derived from this data is here, and includes some interior photos:
Original German: http://fahrradzukunft.de/14/neue-nabendynamos-im-test/
Google-Translated here: http://translate.google.com/translate?sl=de&tl=en&js=n&prev=_t&hl=en&ie=UTF-8&eotf=1&u=http%3A%2F%2Ffahrradzukunft.de%2F14%2Fneue-nabendynamos-im-test%2F&act=url

Interesting reading!

Best,

Dan.

[NZPeterG]

Hi Dan Cool  I have been looking for a good review about Dyno Hubs
Loads of reading 

Pete
 

[JWestland]

Surprised to see SP performing so well at lower prices than SON. (SON gives you extra Magpie Points though for its sheer prettiness)

I got an old and draggy basic Shimano (HN030 off top of my head) on the XTC which is probably lowest in all had they tested it...however, they keep going and going and I'm not in a race... so happy enough

I see some commuters which lights on all the time, there's a lady on a Dawes from 15 years ago with a dynohub she just keeps hers on.

Would I buy a new one, would be tempted to go for SP...though as they are newcomers my worry would be long term performance on which Shimano and SON are proven.

[NZPeterG]

Hi JWestland,

It look's to me they tested the lower powered Son and Not Son 28?

I still do know which way to go? But still have loads of time to work it out.

Pete
 

[Danneaux]

look's to me they tested the lower powered Son and Not Son 28

Yes, Pete -- that they did, though the SON28-New is mentioned as an update to the SON28 Klassic in one of the photo captions it didn't make th etest-summary tables. Having owned both, I think the SON28-New has marginally less drag than the Klassik, and very close to the same power output. It is styled like the SONDelux, but has more power and is the one you want if you wish to power and charge gadgets.

Would I buy a new one, would be tempted to go for SP...though as they are newcomers my worry would be long term performance on which Shimano and SON are proven.

Jawine, SP had some early reports of short-lived bearings, but I'm not seeing those complaints anymore, so they may well have been resolved after an early batch. It is a very interesting design, but some configurations are limited wrt available spoke holes/features, according to their website: http://www.sp-dynamo.com/ShutterPrecision.html

The Shimano offers a great deal of value for the cost in terms of overall usefulness, though it depends on usage. I went with SON in part because it has (factory replaceable) shielded cartridge bearings, and I have in past occasionally had dreadful-lousy luck with cones dying prematurely (thank goodness for Wheels Mfg offering replacement cones. In the 1980s, it was very hard to get replacement cones for Japanese hubs at many bike shops here in the States. Unless it was Campagnolo, the hubs effectively lasted only as long as the cones, and those varied greatly in quality. Many were rough-ground, hardened, then finish-ground right through the hardened surface into the softer parent metal beow). I'm really hoping the SON bearings will offer a service life similar to my Phil Wood hubs in talc-fine desert playa, and I am also hoping the vented temperature compensation of the SON will translate into long service life in my use as well. Only time will tell for me, but their track record over the years is good.

One downside of the SON? I dearly wish it had Shimano's convenient electrical connector instead of the two spade connectors. One lead always removes pretty easily, but it can be a struggle to remove the second one near the dropout/fork end. I have solved the problem with a short pigtail ending in a Dean's R/C connector and leave the other end attached to the spade lugs. It positively transforms the process of removing a front wheel with SON's spade connectors if they've been attached for awhile. Silicone dielectric grease on the terminals helps greatly, too.

Best,

Dan.

[Pavel]

I agree with all said .. but will say that despite the increased price I will not buy anymore shimano dynes.  Nothing much against how they work but the devil being in the details I find that the attachment system for the wires to be so greatly inferior to the simple but brilliantly reliable Son setup ... that it trumps all other details for me.  It is really an a Achilles heel, the way the Shimano is designed.  Cheap plastic - easy to accidentally disconnect and easy to loose on the road.  Add to that the incompatibility, that if you mix and match wheels it would be a no-go, plus the fact that my Nomad "Deserves" the best ... I will continue with only Son products in the future.

Does that sound harsh?   

[JWestland]

I've never had any bother with the plug on my Shimano hub...it's a bit fiddle to strip wires and get them in on first install, but after that it's never come off by itself and is easy to remove.

SONs do look the part no doubt, on a budget I wouldn't hesitate to recommend a cheep and cheerful Shimano though

[peter jenkins]

I've had a SON 28 on the Club Tour for about 6 years and my IQ Fly and Seculite are contantly "on". I don't notice any drag and have had no trouble with the set up as yet. It must have 30,000 kms on it by now. I echo Dan's comments about the spade connectors, though.

I've recently bought a SP for my (20") Moulton.  I've only done about a thousand Km's on it but I can say it's very well finished and seems to be the goods at this stage. I'm running a non switchable light with it that I will probably upgrade to an IQ Cyo. Like the SON, there's virtually no drag.

If anything untoward occurs, I will post the news, but as it was (just) less than half the price of a SON I wouldn't be able to complain much if it only lasted half as long.

Cheers,

pj

[Danneaux]

Peter!

I'm so looking forward to your long-term use report on the SP dynohub. 'Seems to me a pretty nifty thing to have more choices at a greater number of price points in the market. I share your view that if a component works similarly well and is a bit shorter-lived but costs less, it can still be a terrific value.

Until I got Sherpa, I'd never owned a dynohub, and having one seemed like magic compared to the long string of sidewall-roller bottle dynos And with plain bearings for added drag! Remember the Union 9814? Tipping it against the tire felt like I'd thrown out an anchor. And the noise!) or bottom-bracket/chainstay bridge mounts (lovely smooth turning quiet things with cartridge bearings by Sanyo that worked well with clean tires in the dry...and lived a hard life when riding in rain or having to deal with mud).

The SPs are beautifully finished from all I can see, and if they offer another viable option at reasonable price, I think that's wonderful. Shimanos are good value as well. To be honest, any dynohub seems like a dream compared to what came Before!

Best,

Dan.

[JWestland]

I remember bottle dynamos...dreadful, mega resistance and always slipped on the rims 

(However, they are still made...there's versions more expensive than a dynohub!)