It was always my intention to fit a dynamo hub with USB charging to my Surly Disc Trucker and after a month of deliberating and 3 months of waiting I finally got a hub and light with a USB connection fitted.
My original plan was to go for the Schmidt Son 28 6 bolt disc fitting hub which is one of the most highly rated and expensive on the market. I ordered the hub in April from Spa Cycles who offered the best price on a complete build but by July I had given up waiting as the shop still hadn’t got it in stock despite an original order time of 3 weeks.
In the end I decided to go for the cheaper Exposure hub manufactured by SP Dynamo System. The hub model is the PD-8 weighing in at 410 grams with a 6 bolt rotor fitting. The hub is relatively new and there isn’t much information about online about these hubs; CTC had given it a good write up in their Cycle magazine in 2012 and the price of the hub is significantly cheaper than the Schmidt.
To go with the hub I wanted to fit the Busch + Müller Lumotec IQ2 Luxos U LED which has a USB charging port and switch which can be mounted on the handlebar. I was waiting for an online shop with a competitive price to get it in stock but with the hub bought and a month wait on the light I decided to go for the much cheaper Axa Nano 50 Plus Auto LED light. On the Axa the USB cable plugs directly into the light.
When the hub arrived it didn’t come with a cable connection and the light arrived with just bare cable ends. As a make shift solution I connected the cables using some electrical tape as can be seen in the hub photo but the correct connectors were easily obtained online as the Shimano connectors fit fine.
I had read a few reviews on the light with a few saying the quality isn’t great but considering the technology and price I wouldn’t say it was bad and after 200 miles of riding so far I haven’t had a problem. You can find some great information on a wide range of dynamo hubs and lights at http://swhs.home.xs4all.nl/fiets/tests/verlichting/index_en.html
The light has a switch on the back with 3 options, off, light on or USB charging only. Its hard to distinguish between the clicks but it works well enough. You can’t use the light and charge at the same time but I haven’t seen a light which gives you this option due to the power required to run both.
The light also has a front reflector as part of the design, this is a nice feature as without trying I now almost have a road legal bike as the Shimano XT pedals came with reflectors and the rear Cateye light has a reflector incorporated into the design; just wheel reflectors missing at this point although the Schwalbe tyre have reflective bands on them.
When using the light it stays on for a surprisingly long period when stationary, this is useful at night when stopping at traffic lights or when I arrive at work and the basement lights are off.
With some adjustment it was possible to fit the light under the ortlieb bar bag. This was important as when charging my phone I place it in the bar bag with the USB cable connecting the two.
So you might be wondering how well does the USB charging work; well I am yet to attach a multimeter and ride around measuring the exact voltage but I can tell you it does charge the phone at surprisingly low speeds. I recently got a new Samsung Galaxy S4 and I was worried about damaging it at first but after 200 miles its working fine. The phone beeps when it starts receiving power and this is almost immediately when the wheel starts turning. Before I used the Samsung I tested my old HTC wildfire and this started charging at 6 mph. The speed at which the phone started charging was one of my biggest worries, when touring with a loaded bike I average 8.5 – 10.5 mph depending on the terrain and distance.
I have been on a few trips with the phone so far and charging varies depending on the terrain and the apps that are running. A couple of weeks ago I road the Gospel pass and during a 40 km ride with 653 metres of accent the power only managed to maintain its battery level whilst running Googles Mytracks. We spent most of our time climbing at a slow pace and although the decent was fast it was over in a relatively short period of time compared with the climb.
Since then I have also used the dynamo hub for a five day trip covering 240 miles across Wales, I was able to keep two phones charged enough for the duration of the trip and both of them were used for calls and internet. A small HTC was easy to charge and if it was plugged in for more than a couple of hours I was able to achieve a full charge, Kates Iphone took longer to charge and was not plugged in long enough to reach a full charge. Surprising the Iphone would beep to say it was charging at just over 3 mph.
So charging whilst using the phones GPS to track rides gives mixed results although the battery level does not decrease. When not using the GPS the phone charges well and at low average speeds. Using the hub over five days of camping gave good results and although we didn’t use GPS tracking for the ride the phones got quite a bit of use and we were never without battery power.