More and more people use and tag OSM with MTB-maps, so an overlay with color codes would be highly apreciated.
It would probably be sufficient to use mtb:scale=0-6 and class:bicycle:mtb=-3 to 3 which is most used.
See https://wiki.openstreetmap.org/wiki/Mountain_biking for details.
mtbmap.no is rendering with colors that represent the various values. See https://mtbmap.no/#14/59.8893/10.3949
Green is easy, blue a bit rougher, red difficult and black is really difficult/not ridable.
Green=0, Blue=1, Red=2, Black 3 and above. The class:bicycle above 0 is causing a highlighted color as you see on mtbmap.no.
This would make it a lot easier to plot MTB/Single track routes based on riders skill.
I am a premium member and hoped that the Bike Paths overlay would give something like this, but in Norway this does not add any value for mountain bikers.
Thanks for the suggestion. I think coverage could possibly be an issue, as I suspect many paths aren't tagged. We would need to investigate further at some point when we get chance.
Many paths are not tagged, so then no overlay - building routes should not be affected by this, this just to indicate the level of difficulty when plotting routes. New paths are tagged every day by mtb-bikers, so this is growing by the day.