Bicycle Master Plan is a bike map that allows visualizing cycling related data from different sources in multiple layers. Built heavily around data from OpenStreetMap, it allows full visual customization using CSS.
The CSS style for MTB-Scale is currently:
.bicycle-yes.surface-gravel, .bicycle-yes.surface-dirt, .bicycle-yes.surface-grass, .highway-cycleway.surface-gravel, .highway-track.bicycle-yes
I suggest adding the following tags:
.bicycle-designated.surface-gravel, .bicycle-designated.surface-dirt, .bicycle-designated.surface-grass, .highway-track.bicycle-designated
And possibly:
.bicycle-designated.surface-unpaved, .bicycle-yes.surface-unpaved
The definition of unpaved on the OSM wiki is vague and it is recommend to use a more precise tag:
A feature that is predominantly unsealed (unpaved); i.e., it has a loose covering ranging from compacted stone chippings to earth. Unpaved roads may, in aerial imagery, show evidence of water along their course; in such circumstances, the waterway should not be tagged as a stream, though it might appear as such. This value gives only a rough description; use a more precise value if possible.
The CSS style for MTB-Scale is currently:
.bicycle-yes.surface-gravel, .bicycle-yes.surface-dirt, .bicycle-yes.surface-grass, .highway-cycleway.surface-gravel, .highway-track.bicycle-yes
I suggest adding the following tags:
.bicycle-designated.surface-gravel, .bicycle-designated.surface-dirt, .bicycle-designated.surface-grass, .highway-track.bicycle-designated
And possibly:
.bicycle-designated.surface-unpaved, .bicycle-yes.surface-unpaved
The definition of unpaved on the OSM wiki is vague and it is recommend to use a more precise tag: