Cycling & Electricity Generation: The Hub Of The Matter

There is a risk that might be entering a phase of being a useful website once again… In response to this post earlier in the week about the Denham handlebars on my new touring bike – the Koga WorldTraveller-S 2.0 – which also made reference to the USB charging device that is connected to the Son 28 front dynamo hub, I have received a detailed and very interesting email from David Sinclair.

Before I get to David’s comments, however, a quick reminder of the set up that I will be running on the Koga. I’ve opted for a Son 28 front dynamo hub. Here are a few technical details:

There are, as far as I’m aware, two ways of connected the dynamo to a USB plug. The first – which is the one that Alee Denham talked about in his response to my question earlier this week – is to do so directly. The USB plug is often inserted into the stem of the bike and this is the case with Alee (see image below). This does not allow you, however, to plug a device such as an iPhone or GPS tracker directly into the USB plug. The current would be constantly changing as you speed up and slow down on the bike and this is incompatible with direct charging. The solution is to attach a power storage pack to the the USB plug and this, over time, will charge. Attaching your device to the storage pack will then allow you to charge your device. There’s no reason why you can’t attach the dynamo, power storage pack and your device in series as the power back smoothes out the current to give a constant feed to the device.

This photograph – taken after an accident (hence the missing handlebar) – shows Alee Denham’s USB plug fitted into the top of the frame end of the stem. It’s a ‘cinq The Plug‘ device. Photo credit: Facebook / Alee Denham /

David Sinclair’s components are different but, essentially, this is the set up that he is also running on his custom bike made by Hewitt Cycles in Lancashire:

“We have Shutter Precision PD8 front hubs (a step down from your new SON 28) and these power a Sinewave Reactor stem charger which reportedly provides 5V/1A charging. Both have performed flawlessly to date, but it took a bit of messing around to find the best thing to charge and here is where I will impart my advice.”

I like advice… David continues:

“I initially plugged in a big 20,000 mAh power bank and tried to charge it but nothing happened despite doing silly amounts of laps of my housing development in the dark winter evenings. To check there was any current being produced I bought one of these amp meters which shows you in real time what the charging output is. It turns out the actual output varied from around 0.2A to 1.1A depending on speed (as Alee says, going less than 10kph will not charge anything!), and in any case it just wasn’t enough current to activate the power bank’s charging system as this was rated for a 2.1A input which is now basically the minimum industry standard.”

I’m not great on the technical stuff (as you know) but I am following David’s line of thought very well (with images of him cycling around a suburban housing estate much to the bemusement of his neighbours…)

“So after fishing about on the net the best electrical advice I could find was not to go too big with the capacity of the power bank and to go for a power bank that is rated as a 1A input to match the Sinewave Reactor. These are getting harder to find these days as 1A inputs have not been the norm for a good few years now as “fast charging” takes over, but I bought a couple of these Anker Astro E1s and they have performed perfectly, charging from empty to full in around 150km of ‘standard’ cycling at circa 14 km/h, and holding enough charge to charge your standard smartphone roughly twice (i.e. you basically generate a phone battery’s worth of charge (2600 mAh) every 75 km). They also charge at 2A, which means your phone charges a bit faster from them!”

So, if that is the set-up you are thinking of running, I think David’s advice is very sound indeed. Let’s hope the progress of technology outside the world of bicycle dynamo hubs never renders the Anker Astro E1 obsolete.

On my new Koga WorldTraveller-S, however, I’m doing something a bit different. Instead of having a USB port in the stem, my USB port will be attached to the front headlamp, and there’s a good reason why. First of all, this is the headlamp in question: the Busch & Muller Lumotec IQ2 Luxos U(!) – the exclamation mark is mine btw…

You’ll note that in the middle image above, the cables are shown and leading from the switch (that is attached to the handlebars) is a USB port! Here is the description from Busch & Muller (B&M):

“Charges USB devices (mobile phone, GPS, MP3 player) with USB energy. An integrated lithium cache battery supplies constant voltage.”

It’s the second sentence which is of particular importance and David picks up on this point in his email:

“It looks like the B&M system you have gone for also outputs at 5V/1A so the advice above stands true, although the B&M system has a cache battery to hold the charging current a bit more steady (like a mini internal power bank in the device itself). Needless to say, if you are running with the lights on there is little point in charging at the same time.”

I am genuinely intrigued to find out how well the set-up works in practice so expect an update on the matter in the post-delivery period sometime in July. I am preparing myself to discover that, actually, a bicycle dynamo hub is simply incompatible with effective charging of a modern power-hungry device such as an iPhone X. On my previous longs trips, I have never run out of power using the tried and tested method of plugging everything in at the campsite overnight. Again, David Sinclair, comments along similar lines:

“All that said, we did find it was easier just to plug in the original 20,000 mAh power banks we also had with us in campsite toilet blocks / cafes / pubs / McDonalds etc. and each of these would charge a phone roughly 7 times which basically negated the need to charge on the move as long as you were in one of these places for a few hours at least once a week, but it’s still a cool facility to have I suppose.”

And then there is, of course, the solar power option. My experiences back in 2013 as I cycled Along The Med… were not particularly good. Was this, I wonder, because of an incompatibility between the solar panels and the batteries that I was attempting to charge as outlined by David above? Perhaps. You’ll note from the image below of the equipment that I took with me as I cycled from Spain to Norway… in 2015, the solar panels were absent…

“The equipment needed to cycle from Tarifa to Nordkapp” – the full list is here

…but perhaps there is hope yet. I’ll give David the final word on the matter:

“I’ve heard that solar charges are coming on leaps and bounds these days although I haven’t yet taken the plunge. You can basically unfold them all over the top of your panniers on the back of the bike.”

What do you think?