The android navigator application tried to make me drive my car through a barrier. In osm the highway has a node with a "barrier=cycle_barrier" tag. How does navigator handle barrier tags? Does it require additional tags?
I have solved similar problem by specifying in OSM the node as barrier=block, access=no, bicycle=yes, foot=yes, house=yes. While it works well for motor vehicles, it has also blocked access to other types of transportation. It looks like MFN does not evaluate all tags correctly (at least on Windows Mobile platform). In your case [gertom], the tag barrier=cycle_barrier is blocking bicycle traffic only and thus logic is correct to allow any other type of transportation.