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I am going to purchase a dynamo hub and the way I like to ride is carefree abandon - going offroad, up and down curbs, straight through potholes, etc. My bike is a 90's rigid mtb with road tyres (26").

I like to do pretty much everything on this one bike and want the convenience of dyno lighting as well, will I have to be more gentle with a dynamo hub because it has delicate electrics?

I only found one thread elsewhere from some people who suggested that the SON Delux would be the best choice for rough riding: http://forum.cyclinguk.org/viewtopic.php?t=18685

However, the two I am looking at are Shimano's 3n80 and Shutter Precision's PV-8, which are not quite as well built.

  • There is the problem that the larger hub slightly increases the incidence of spoke breakage. – Daniel R Hicks Jul 26 '16 at 12:23
  • Hub dynamo are simple part that almost maintenance free. Just waterproof the cable from corrosion (connector don't like salt sprinkle on the road during winter time ) and service them if required. bicycles.stackexchange.com/questions/220/… – mootmoot Jul 27 '16 at 8:56
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I don't have direct experience with the SP hub, but the Shimano generator hubs are all perfectly robust and the short answer is no, don't worry about it. I suspect the same is true of the SP.

With Shimano generator hubs and routine rough riding, there is the question of overhauling them. They're not built in a way that's friendly to overhauling, and Shimano isn't exactly there to help you out. You have to take extra care to not break the soldered connection of the hub, and you have to replenish the RTV seals that you peel away to get to the bearings. It's do-able but something of a project.

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I have never owned the cheap and nasty dyno hubs you're looking at as alternatives, only the SON hub.

My experience of the SON is that it has not been necessary to ride gently, and observation of other owners suggests they don't do that either. I've owned mine for more than 10 years, and done enough distance that I felt it necessary to have the bearings replaced. I've toured on it and used it on load bikes as well as commuted, and the touring was done on short wheelbase recumbents where more than half the weight is on the front wheel. Suspension doesn't matter much because the hub isn't suspended.

I managed to break a spoke in a 36 spoke, ISO 406 wheel with a deep section rim, and I have no idea how that happened... but the hub was fine.

My issues have been more with the wiring, those silly push-through plugs don't work for me, as someone else mentioned in this answer to "Pedal-powered head/tail lights". They work ok, in good conditions, but when they fail it's impossible to fix on the side of the road. And they do fail, eventually. So I have soldered better connectors on, and I use much thicker wires with heat shrink at key points. I'd rather carry 50 grams of extra cable and plug, but have lights that work for 20,000km or more without servicing, than shave a few grams and have lights that "usually work". I didn't pay the price of a hub dynamo to get "usually works".

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Edit in response to question in comments: In my experience the hubs don't fail - it's not just that my one hasn't failed, it's that the bike shop that services it said that a car crash was the only time they'd seen one fail, other than the stories of people who open them up and wreck them. Don't do that.

By "usually work" I mean in the broader sense of "over the next five years". Having to sit down every year and cut the end off the cable, put on new heat shrink, re-strip the ends and re-install it... that's annoying. But it's better than having to do that at some random point during the year, on the side of the road. By "usually work" I mean the latter... you buy it, it works 100% until randomly it stops. Or becomes intermittent. That's not acceptable. I don't care if I'm riding in half a metre of seawater, I want my lights to work (I have done this and they did - some Australian bike paths don't deal well with flooding).

My approach was to look at the connectors, and the wire, and decide that I did not like them. So I put better ones on. They cost probably 10x as much as the supplied ones, but they work. And the soldered, heat-shrink-covered join on the old connectors seems to work too.

  • So you are saying that the main weakspot is cables and connectors, whilst the hub itself should run until internal/bearings failure? By 'usually works' do you mean connection failure, or bad conditions? – lazyrabbit Jul 26 '16 at 12:25
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I have commuted on a Shimano Alfine 36-spoke hub for several years. I just rode a Shutter Precision 32-spoke hub 4k miles across the U.S. on a loaded bike. I have had zero problems with either wheel. You might not want to ride a 32-spoke wheel, which rules out the Shutter Precision.

Based on reputation, I'm sure you would not go wrong with a SON. It is more costly, but think of it as a lifetime investment. Here are some results from a study by CTC in the UK:

enter image description here

Here is the link to the article. (If it loads as binary garbage, which it does for me, save the page with a .pdf extension and try opening it with Adobe.)

http://www.cyclinguk.org/file/public/feature-hub-dynamos.pdf

The SON Deluxe is very efficient and light, and it has a five-year warranty, but it is not so powerful at low speed. (If you decide to use a USB charger driven by the dynamo, this could be an issue.)

  • Thanks for this review, I am going to build a 36 spoke wheel, and have seen the SP hubs in 36h. You mention the power at low speed for usb charging, yes I want to charge and because I ride fast at 17-25mph, then even the SON Deluxe at those speeds should power anything, right? – lazyrabbit Jul 29 '16 at 7:29
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My experience is with a Shutter Precision hub and a Cinq 5 The Plug III USB charging adapter. That system will start charging an iPhone at about 10 mph and will shut off once you drop to about 7-8mph. You will be fine at 17 mph (with virtually any dynamo). But...

My system could just keep up with an iPhone displaying turn-by-turn directions from Google Maps when riding in urban conditions with a loaded bike. In hilly terrain, on a loaded bike, I sometimes could not charge my iPhone even when it was "off".

One challenge is that the Plug will stop charging when speed was low, but will then recharge its capacitor and try again to charge the phone. This causes the iPhone to activate its display, at which point the Plug would exhaust its capacitor and shut down again. Wash, rinse, repeat. This was annoying and wasted limited power. You can't turn off the "auto-on" behavior on the iPhone--this is a "feature". The only solution was to unplug the phone until I could maintain c. 8 mph.

Also, the Plug III/Shutter Precision system could not run my lights and charge at the same time. This seemed true even at high speeds. There is only so much power.

These are unavoidable constraints. I highly recommend the Plug III for touring. It gave me much-needed flexibility. Just charge early and often. There may be other USB charging systems out there that also work well.

One other hint: Google maps will provide turn-by-turn directions (and route preview) off-line if you have once captured your route. (It will not re-route with out a connection to its server.) And, it will provide turn notification on the lock screen and via audio. Thus, you can put your phone on low-power mode and airplane mode (phones use a lot of power just searching for towers) and still get directions while using much less power (battery). Doing this saved my butt in stop-and go traffic in places like Philly, Newark, Jersey City.

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