I've finally got my bike set up with a dynamo powered LED light and charger and I'm super chuffed with it. Now I've been riding it a while and am happy it's all working reliably, I thought it best to share:
The power from the SP PD-8 hub can be switched, via a little switch on the bars, from the front light to a USB carger, that happily charges my GPS or my smart phone, while they're on and working and faster than they use power.
The cockpit setup:
The USB cable can also be used to charge my joystick head torch if needed for multi-day rides involving camping.
Power is provided by a tiny, light weight dynamo hub from Shutter precision:
The light is a pre-production (available soon) Exposure dynamo light, with off-road-capable standlight. The standlight also powers the rear light, which is the standard, and well proven, exposure redeye should you want one for the on-road sections:
The charging can then be done by one of the many dynamo chargers available on the market, which just attach to the main power cable from the hub. Most of them come with selectable outputs either to the light or USB plug, to keep the intervention required to install it all minimal.
Forseeing the nay-sayers, here's a couple of FAQs I answered earlier:
1) So, dynamos are heavy, right? No! The Exposure light comes in at a flyweight 112g, with the SP hub another 390g, A total weight of 502g. Yes, a MaXx-D is only 337g, but you still need a front hub, and with a Hope Pro 2 coming in at 190g, that's a total weight of 527g, 25g heavier. And that's without factoring in having to run my battery light on a low light setting or the weight of carrying alkaline batteries as spares for the GPS or some form of battery charger.
2) Isn't a dynamo draggy? Well, Please excuse the maths, but if you rode at 20mph for an hour the light would pull about 6W from your legs during this time, this is equivalent to approximately 5.2kcal. There are approximately 72kcal in a McVites Digestive biscuit, enough to power your light for just under 14hrs and that's assuming you pedal down the hills and around every corner! So yes, it does draw a tiny bit of power, but I certainly can't tell the difference and it's a damn good excuse to eat an extra biscuit every few rides
There's a bit more detail on the details of my setup, and some pretty pictures of my bike and the rather special wheels Reynolds helped me out with ON MY BLOG HERE (CLICKY).
Enjoy..... Dynamo power FTW!