Electric soup

When Mood Music
2013-02-16 22:41:00 determined

I like to track my cycling using the cyclemeter app on my jPhone, so jPhone nestles in a Lifeproof case which fits into a handlebar mount. The only problems I’ve had are

  • cold – it’s not fun when I need to remove a glove to interact with jPhone (Touchscreen gloves helped for a while until the touchy bits wore out.)
  • when cycling, jPhone’s battery only lasts for about 4 hours – continuous Bluetooth (music) and tracking location take a lot of power.

Tesla versus Edison
So I’ve been in search of a dynamo to keep jPhone charged for quite some time. There are some bottle dynamos that are supposed to work but I’m wary of friction-damage to tyres. It seems the best option is a hub dynamo, and the best of breed in this class appears to be the Schmidt Original Nabendynamo (SON).

Just to make things a little more complex, hub dynamos produce AC current: their power that varies with how fast the bike is travelling. AC is OK for lights, so long as the bike is moving, but no good for jPhones – they need 5V DC at 1A. So a rectifying stage is needed. Schmidt do not answer this challenge directly – they concentrate on hub dynamos and related lights. However Schmidt’s very helpful Frau Britta told me about Busch und Müller and their two solutions to this need:

Arrival and surgery
So now I knew what I needed – I just had to find someone willing to sell me the kit. A lot of searching later, I found Rose Verstand. After some paranoid checking that Rose’s product number foo was exactly the same as Schmidt’s product number bah (there are a fearsome number of SON variants – I needed the version with ISO 6-hole mounts for disk-brake rotors and 32 spoke holes), I ordered my SON and USB-WERK.

Thanks to DHL’s tracking, I could visualize my kit travelling across Europe: 5 days from Rose’s ‘biketown’ to my hot-and-stickies. The next stage was to fit the kit. I’ve not yet built a wheel but John, one of the mechanics at the Edinburgh bike co-op, seems to live for such tasks. Lev went home on Thursday, was on the operating table yesterday and was collected today. A few miles showed me that the new hub hadn’t added any noticeable weight or resistance, so it was time to fit the rest of the kit.

Lev ready for surgery Here’s the hub dynamo in place.


The first task was to fit SON-style clips to the USB-WERK charging cable. (It comes with clips for SONs and Shimano hub dynamos.) This was quite fiddly, especially flame-shrinking the insulation around the clips.

Attaching clips to the charging cable

Clipping the cable to Lev’s front fork was easy, but deciding where the USB-WERK should go was less fun. Lev’s top- and down-tubes are oval-sectioned and too thin for the USB-WERK’s attachments – the only option I found was to put the USB-WERK on the front of the head-tube.

USB-WERK attached to front of head-tube

The next task was to get power from USB-WERK to jPhone. USB-WERK’s output cable has a waterproof connection to a short USB female cable. This can be removed – a small condom keeps the connector safe.

Next steps
As you can see, a standard jPhone cable is far too long, and will slow the electrons, so I’ve ordered a much shorter jPhone cable. So that’s sorted.

over-long cable

The final problem is how to mount jPhone while it’s charging. When it’s in the Lifeproof mount, its charge-door can’t be opened. I could do some surgery to the mount but this may well render the mount useless and so waste £50. I’ve ordered a cheap and cheerful Revolution-brand mount, which will take charging cables. Because jPhone already has a front cover as part of the Lifeproof case, I’m dubious whether I’ll be able to control jPhone through two layers. Also, the Revolution mount will need to be attached to the top of Lev’s steering column, potentially displacing the Lifeproof mount. (I may be able to fit one behind the other – watch this space.)

For the moment, I can do this

Light fantastic
My final bike tasks for today were to replace the exhausted batteries in some of Lev’s skullies and knogs, and move his rear blinders (USB-charged lights). I had mounted the blinders on the saddle-post but using two panniers tends to occlude lights in this position. So I shimmed the pannier rack’s rear bar with bits of dead inner-tube, then positioned the blinders. (The other blinder was charging while I took the photos.) I’ve retained two rear skullies in case the blinders run out of charge, and repositioned the knogs on the saddle-post.

shimming two shims and one blinder in place
rear view knogs on saddle-post

Final thoughts
None of this has added any significant weight to Lev. But it has increased his value by over £300, so I now need to carry an extra strong lock-cable so his front wheel can’t be stolen. And yet Lev only cost £450, although I almost immediately bought him much better tyres costing £70.

Once I’m sure the hub-dynamo/USB-WERK/jPhone rig works, my final change will be to add a USB hub somewhere near the head-set, then string cables from it to the front and rear blinders.


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