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We tend to carry quite a few gadgets whilst bicycle touring. We often encounter long stretches of road with little or no opportunity to recharge batteries, especially whilst camping in remote areas. Bicycle touring with a hub dynamo allows us to utilise the power output from a long day of riding to recharge our gadgets. I also use it to power my front and rear lights if I happen to get stuck riding after dark. Aside from these more obvious benefits, my favourite charm of the hub dynamo is the sense of self-reliance in remote areas.
This three part article covers my current hub dynamo system, including installation and performance / usage tips for bicycle touring. I have tailored my setup for off-road touring, but it would work well for road touring and maybe even 24hr Enduro (though my bike is a bit heavy!). If you’re in a hurry and want a quick ‘how to’, just check out the photos below.
28-May-2013 17:38, SONY NEX-5R, 5.6, 32.0mm, 0.002 sec, ISO 800
24-May-2013 13:49, SONY NEX-5R, 5.6, 41.0mm, 0.003 sec, ISO 200
Hub Dynamo System Overview
Mouseover the image maps below to view closeups of the different parts of the system (hub dynamo, USB charger and lights, respectively).
The SP PD-8 Hub Dynamo
Hub dynamos are available in a range of formats and prices. German made Schmidt SON has a long-standing reputation for its durability and efficiency. They also offer a five year warranty. However, $250+ is a lot to spend on a hub alone when you consider all everything else you need to buy for the wheel, lights, charger, etc. Shimano’s DN-3N80 hub dynamo is basically as you would expect from Shimano: a bit cheaper, a bit heavier and reportedly quite reliable, but they don’t look nearly as slick as a SON! Finally, the new kid on the block in hub dynamo technology is Shutter Precision (SP). I first heard about SP hubs on the blog of pro MTBer Rob Dean. Check out his customised dynamo system, which has been coined the ‘Deanamo’. SP offer a range of hub dynamos at around half the cost of a SON; they are lightweight and their performance specs rival the SON. They do not yet have the tried and tested durability reputation of the SON, so I am to some extent a guinea pig in testing them for long distance touring. Still, given the great the price and specs, I am willing to give it chance!
Hub Dynamo Benchmark Comparison
A recent article posted by CTC presented results from some benchmark tests comparing the SON, Shimano, Supernova and SP hub dynamos. I later noticed that SP pointed out a few corrections in the CTC article which they posted on Facebook. I contacted Charles Tsai at Intelligent Design Cycles (SP’s largest aftermarket distributor) to gather some more technical data regarding the hub dynamo efficiency benchmarks. He was replied with some additional info in response to the CTC article.
They should have compared the SON Delux to the SV-8. If they did, the SV-8 would be shown to be lighter and more efficient that the SON Delux. When evaluated on an even playing field, the data used in the CTC article indicates that SP hubs are more efficient under the official German StVZO regulation test conditions (i.e. hub dynamo running at 15 km/h with a 12 Ohm resistor load attached to simulate dynamo lamps).
I haven’t conducted any tests of my own, but I think it’s certainly safe to say that the SP 8 Series are very competitive with the SON in terms of weight and efficiency, and they blow it out of the water on price point! The raw data from this article (on which the CTC article is based) indicates that the SP 8 Series is indeed more efficient than the SON Delux! There is also info on SP’s website about a forthcoming PD-8/PV-8 X which claims a 6% increase in efficiency and supports both standard and 15mm axles! I also learnt that the Supernova Infinity S hub is actually a more expensive German re-branded hub dynamo using SP hub generator under the hood with some fancy weather seals to meet the strict requirements of German road safety laws for bicycles. The fact that Supernova are contracting SP’s technology and rebranding it suggests to me that they have quite a lot of faith in the quality!
Installing The PD-8 Hub Dynamo
Obviously, a hub dynamo is not complete without the rest of the wheel. You will either need to pay a wheelbuilder to build the wheel or you can do it yourself. I decided to build my own wheels and I’ve been pleased with the outcome so far. If you want to try your hand at wheelbuilding, I would recommend the book Wheelbuilding by Roger Musson. This guy has built some wheels! I wrote about some of my experiences as a first time wheel builder here and also after a re-build here.
Hub Dynamo Notchy-ness?
Once you have a complete hub dynamo wheel in your hands, your curiosity will inevitably make you want to spin it and feel the drag. The first time I did this, I was immediately concerned. I could feel a steppy, notchy-ness in the hub and I was pretty annoyed considering that I’d just laced up the whole wheel! Again I contacted Charles @ IDC and he referred me to this page on the Peter White Cycles site. I guess I am not the first person to ask this question! In summary, the notchy-ness is nothing to be worried about!
Should I Worry About Drag?
Do I notice the drag of a hub dynamo noticeable? I think I can just barely *imagine* that it’s there under certain conditions. Is it a problem? Not for me! For those who might be tempted to worry about the drag, Rob Dean posted a good analogy which measures the power lost to drag in terms of the number of additional biscuits per hour you could eat in order to produce that power. And as the CTC benchmark article also points out:
Tyre choice (or pressure) makes ten times more difference than how you power your lights! - ctc.org.uk
SP hubs are fairly new to market, so they haven’t yet had a chance to build a durability reputation like the SON. I have
only now ridden 2,000km 4,500km 10,300km on my PD-8 wheel , so I can’t yet comment on long term durability. I recently posted a question on SP’s Facebook Page asking about expected lifetime and service requirements. They quickly replied to say that the bearings are good for at least 10,000 km. 1st and 2nd place riders in the 2013 Tour Divide completed the race with SP dynamos. That’s 4500km and 60,000m vertical climb with plenty of dust, mud, rain and snow. Charles @ IDC also mentioned that there is an Australian rider who has already ridden over 10,000km in harsh conditions with no problems. Anyway, my hub has so far proven rock solid on the bumpy donkey trails and washed out roads of Mexico, river crossings of the Guatemala Highlands and even a bad crash which required a wheel rebuild. As long as I can avoid complete submersion in water, I hope the SP-8 will continue to remain problem free across Latin America!
Helpful Links For Hub Dynamos
- SP Series 8 Hub Dynamo - SP product home page
- SP Dynamo Series 8 Hub Review - a detailed review of the SP 8 Series hub dynamo
- SP Dynamo Wiring Instructions - Helpful installation notes by Charles Tsai @ Intelligent Design Cyles (International distributor for SP)
- Shining Examples - CTC’s hub dynamo benchmark comparison article
- Hub Dynamo Systems - a massive webpage about various hub dynamos and benchmarking including some heated debates about performance and test conditions
- Another Hub Dynamo Benchmark - This one is older and confirms that the SP hubs beat the SON in the lab
- Wheelbuilding by Roger Musson – An excellent resource for basically all wheel building