I discovered this Open Source project and have spent the day getting familiar with it.
It is great!
As I have a Mac, using Garmin maps is a pain: first convert them on a Windows computer then install them in BaseCamp. I have been running Windows under VirtualBox (also Open Source) but that is also a pain.
OpenMTBmap is great when combined with Qlandkarte GT (also Open Source) It can visualise both vector and raster maps and both are routable. I have been looking at the Belgium topographical map today and it is really quite good. Not all the tracks I know are there but there are enough for anyone to plan a MTB tour.
Once I am more used to the 2 programs I may be able to contribute to the maps and help improve them for the future updates (made roughly every 6 weeks)
I have tested the maps on my Garmin GPSmap 60CSx: works perfectly and the roads are routable on the handheld. I’ll certainly be using it in the future, on the trail and we will see how it performs