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Dynamo hubs - anyone a user?

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Wiggle currently have one of their own brand 650b wheelsets with a dynamo front hub at a pretty significant discount. They call the wheels "Audax" so I suppose that gives you an idea what they are designed for!

But the product listing is very weird because it says nothing really about the dynamo hub itself. It doesn't appear to come with any wiring or fittings for using the dynamo either - although having never bought a dynamo hub perhaps that is the norm.

Because of the discount, I'm toying with the idea of splashing out them as a second set of wheels for my gravel bike. I sometimes use that bike for, so far, overnight bikepacking trips and then long day rides. And I at least have the dream of doing some longer tours - I looked quite seriously at cycling to my old home in Finland the other summer, meeting my family there for a holiday afterwards before all flying home together. It didn't happen but its something I'd still like to do. I also think that with 650 wheels I could put quite chunky tires on them which might be better suited to some of the bikepacking I do in the Peak disctrict - I've ridden the bottom bit of the Pennine Bridleway on 35 mm 700c tyres and some more volume would have been nice. I'd like to do the whole Pennine Bridleway for instance, or the Second Cities gravel route up to Glasgow.

The dynamo would be more for keeping my phone charged for navigation and the like, rather than lights for through-the-night Audax rides or whatever. Do dynamos produce enough electricity to either charge a phone directly or charge a power pack? Considering how useful a tool a phone has become for just everything when away from home, not worrying about how to charge it would be my main interest in a dynamo.

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 greg_may_ 27 Jun 2020
In reply to TobyA:

I've had two in the last few years (5 or so). An SP 15mm thru-axle which has done about 10,000km including the Tour Divide until it died, and a SON with about 6,000km on my commute bike. Both are wired to an Exposure Revo Mk1.

They make things a lot easier when it comes to winter time - the stand light on the Revo is good when you've stopped at lights etc, or are going slow.

I've played with using the dynos to charge - had a setup for the TDR, it worked, but only above 15kph when the hub generates more than 5V. My advice...don't count on the charging aspect to work. They do, but they are slow. I used a small power pack which powers my GPS  - it trickle charges during the day, but at night, I want all power going to the lights.

FWIW, I converted originally for 24hour racing - and it's great on the flats and downs - but less so on the ups. Not all dyno hubs are created equally, but they are worth the hassle of getting them set up.

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I had a front dynamo wheel for a while. Ended up getting rid as two USB power packs were far cheaper, lighter and more useful. 

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In reply to TobyA:

You got me curious about dynamo hubs... perhaps this article might help? 
https://www.cyclingabout.com/best-dynamo-hub-bicycle-touring-bikepacking/

The Wiggle listing has Q&A question which asks about 3W compatibility. Someone linked the dynamo to:

https://www.kttw-hub.com/pro.php?m=d&pid=297&cid=12&f=4

That’s enough digging for me! 

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 cb294 27 Jun 2020
In reply to TobyA:

Take the wheel with the front dynamo in your hands and spin it. The difference between a normal wheel, a wheel with a top end hub dynamo (e.g. SON), and a cheapo one (up to rather expensive Shimano models) are staggering. Then consider that you will have that extra rolling resistance, maybe around 10W for a good model, at every single km you cycle, and whether it is worth it for your purpose.

I would not consider a hub dynamo setup for long distance touring (except maybe for winter touring), but for winter commuting a top end version is brilliant. My former winter commuting bike was a steel frame Patria with a 14 gear Rohloff rear hub, a SON hub dynamo in front, a Busch and Mueller LED rear light, and a Supernova E3 narrow beam LED front light. This was bright enough to light up the cycle path for the next 100m. Only sold it because I moved and it was too heavy for my steep uphill daily commute.

CB

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 Dave Cundy 27 Jun 2020
In reply to TobyA:

My mate  Mark has used a dynamo hub for charging his GPS trip computer on cycle tours.  Although it charges it on the move, it appears to discharge it when he stops  (at traffic lights, nav checks etc).

The simple solution would be to put a diode in the charging circuit but that would drop the voltage by 0.6V.  Which would drop the voltage below the threshold needed to charge his GPS.

So my advice would be to 1) ascertain what voltage the dynamo produces at your typical cycling speed and 2) think about how you stop it becoming a load on batteries when you slow down, or stop.

PS  I'll ask Mark if he's solved the discharge problem yet (and if do, how).

PPS.  I use an 8 amp hour battery instead of a dynamo.  It lasts for two days, so i can manage an overnight campsite without having to recharge. No use for the Tour Divide but ok for my european trips

Post edited at 13:44
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 Schmiken 27 Jun 2020
In reply to TobyA:

I have 3 dynamos. The SP ones that most companies  use (rebranded) output 3V at around 75% efficiency. Which means you're using approximately 4W, and considering most people can output 100W without raising a sweat is nothing really.

Most dynamos do not come with wiring, it tends to come with the light instead.

Dynamos are not good at charging phones or GPS directly due to the AC generation. It's better to use the dynamo to charge a power pack and then recharge from that.

If you do get a light, unless you're mainly riding off road look for a Busch and Miller - the beam patterns are far superior.

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In reply to Schmiken:

> Dynamos are not good at charging phones or GPS directly due to the AC generation. It's better to use the dynamo to charge a power pack and then recharge from that.

Would your standard power pack with a micro usb input and usb output work? I have various of different sizes which I take as back up for the phone if out cycling or mountaineering already. Or would you need something specific to work with a dynamo?

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In reply to PPP:

I saw that but the Taiwanese site didn't help me understand it any more!

Thanks anyway.

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In reply to greg_may_:

That's really interesting. I did wonder how people who do the tour divide and similar races and long rides in the wild keep their phones or GPSs charged. I presumed dynamos were more practical solution than say a solar panel system.

Thanks!

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 Andy Hardy 27 Jun 2020
In reply to TobyA:

You're definitely approaching this from the wrong end. Get an e-bike with the biggest battery available, then, you can divert some of the power to the sat-nav / phone, and you'll get there quicker. Win-win!

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In reply to TobyA:

By coincidence I was looking at some bikes on the internet last night that are outside my price range. On page 37 of the pdf is a section on dynos and usb charging.

http://www.sjscycles.com/thornpdf/thorn_mega_brochure.pdf

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