Eeens..

 

Ok, so not exactly top secret, as you can buy them from your LBS. It’s a Shimano DH-3D70 dynamo hub. Quality is meant to be equivalent to XT/Ultegra, plus it’s disk brake compatible. Which is nice.

It says on the side that it generates 3W at 6V. I’m assuming that’s AC, but have yet to attach a scope to check. I’m planning to connect it to a Luxeon 3W LED front light, plus battery backup, autocharge and auto switch to battery at slow speeds. I’d also like to add a 5V regulated output to a USB socket. The idea being that devices such as mobile phones and PDAs can be charged on the bike - which could be pretty handy for touring purposes. It’s a bit of a back burner project, so don’t expect anything too soon :)