Audax rides

Thank you for that. The idea was to have an easy run in along the Mosel and the Rhein but the additional miles between Trier and Koblenz through the river undulation would not count as in an audax it is the shortest route between controls is that right?

Thats right. Sad but true...

However assuming you are doing this as a GPS DIY, you can add in extra controls to include some of the squiggly bits following the river and knock off a corner elsewhere to bring the on the road closer to the nominal distance. Do accept though that youre likely to be 10-12kmover, thats usual. You should be able to lose 10-15km though. That will get you home ~40minutes earlier!