In preparation for the Rhine Cycle Ride I've invested in an AMOD AGL3080 rechargeable GPS data logger. I've wanted one of these for a while as a means of recording high quality GPS tracks to be used for photo geotagging and a few other ideas I have in mind.
The great thing about this unit is the fact that it can be recharged via the USB port, unlike it's predecessor, which is why I've held off on the purchase until now. The other key feature is that with it set on a 10 second recording frequency it has enough memory capacity for 3,833 logging hours which is just oceans, enough for the Rhine Cycle Ride many times over.
Apart from being rechargeable the unit can also run on standard AAA batteries which is great, just in case I'm not able to get to a mains charging point. Should work well, I'll report back!