Backwards and forwards across the Danish German border

The 130 km long Deutsch-Dänische Grenzroute (German Danish Border Route) from  Højer (DK) to Flensburg (D) is based on two interlinked routes on both sides of the Danish German border: Danish Nationalroute 8 and Nord-Ostsee Radweg. During the trip east from the North Sea to the Baltic one crosses the border thirteen times. It is possible to cycle a circular route which is over 200 km long. It looks like an interesting route. It is on our list of possibilities in case we have a week to spare this summer. However I suspect would be easier to cycle from Flensburg to Højer and back again, if you wish to travel by public transport to your starting point. The city is on both the Danish and German main line railways. The website gives all the info you need to cycle the route.

Vennbahn

We both enjoy cycling along national borders, crisscrossing from one country to the next. For us Britons it is fascinating that within a metre that laws, language, coffee flavour and cakes change completely. In Britain one needs to cross over or under the sea to experience this change. We are also fascinated by the concept of the enclave, an island of one country in another. The Vennbahn cycle route from Aachen (D) to Trois Vierges (LUX) offers the chance to experience slightly artificial enclaves and frequent border crossing on a former railway line, i.e. with very few steep hills. The enclaves arose because two German counties were annexed by Belgium in 1920 under the Treaty of Versailles. In addition Belgium was granted the Vennbahn railway between Aachen and Luxembourg. At the time the line connected the Ruhr coal mines and steelworks with the iron ore and steelworks in Luxembourg. It was of commercial and military importance. Unfortunately the line ran in part to the east of the border of the new Belgian cantons and so a number of German villages found themselves to be enclaves, because it was necessary to cross the railway line back in to the Fatherland. This gave rise to interesting smuggling activities, coffee, for example after WWII when coffee was very expensive in Germany and cheaper in Belgium.
We are hoping to cycle the 125 km route from Aachen to Luxembourg later in the summer. The problem in the moment is what do we do once we arrive in Luxembourg. Although there is an extensive network of cycle routes in the Grand Duchy of Luxembourg the routes in the north are steep if memory serves correctly. More research is required. We could take a train from Trois Vierges to Trier and go home cheaply on a Rheinland-Pfalz ticket, but it seems to be a lot of railway for a little cycling.