I found the one thing that was still missing in my trip preparation: a compass bell! Best investment ever.
Also pictured here is the CatEye wireless trip computer, which communicates wirelessly to a sensor near the wheel. This little device keeps track of current speed, average speed, total distance traveled, distance since a user-defined marker and total time traveled. During previous trips the wire between the sensor and computer always broke before the trip was over. So I decided to go wireless this time.
It should be noted that this particular trip computer has been mounted on my bicycle for two weeks now, and it has only worked once. Today I found out why: bending over and holding the computer near the sensor makes it work, but when it's mounted on the handlebar there's no signal. People who have seen my bicycle know that it's quite small, and the distance between handlebar and wheel is really small as well. In other words: while the by-wire solution is incredibly crappy, the wireless solution is even worse. Maybe I'll just give up on these little toys and get a GPS instead.
Oh, and on that note: don't get a Gisteq. Their software is crappy, their support is non-existent and people on their forum are complaining a lot that the Gisteq's GPSes battery stops functioning after a couple of months, or that the GPS itself just falls apart because it's made of brittle plastic. I don't have an alternative yet, but I won't be getting a Gisteq GPS again, that's for sure.