ever heared about the fractal geometry of coastlines?
http://en.wikipedia.org/wiki/Fractal
have a lot of fun mapping (that dimension)!

Thank you everybody for your suggestions and comments. I'll try downloading the GPX tracks of other users and I'll also "reride" the tour with the suggestions you've given to me.
Happy mapping!

Hey Hannes! I hope to contribute a lot. Hope you've had a nice time mapping Hamburg and much fun with the OSM project!