OpenStreetMap
I went out on my daily ride today and mapped a stack of MTB/dirt bike trails. Most are either singletrack or heavily eroded wider tracks. There's a lot of damage done by the dirt bikes but it's council land so who's to stop them? It just makes it more technical :p.
There was one point where someone had built (what I'd class as) a massive jump. It goes over the Fernleigh track (the disused railway part) and is about 10m across with a 10m drop. You'd want to be going fast enough! A sort of chasm has been cut into the rock for the railway line so it's fairly sheer cliffs on both sides of the jump.
Shame I only just missed out on the Mapnik update, use osmarender if you want to view the trails.
There's a good chance I've missed a couple, but 90% of the tracks should be marked.
Discussion
Comment from daveemtb on 20 August 2008 at 12:27
Great to see people adding mtb trails. Just wondering, how do you tag them? It seems slightly odd to tag them as cycleways, but neither are they really footways!
Comment from Biogenesis_ on 20 August 2008 at 14:47
Yeah, it's a tricky one...Especially when it comes to routing. I tend to just tag them footways as they tend to be the same width and track condition as trails marked as bushwalks and quite often they are on land that technically shouldn't have anything at all let alone mountain or dirt bikes.
Anyway, I guess the best tagging would be along the lines of "highway=footway, surface=unpaved, bicycle=yes", but it's all a bit of a fudge. Basically if you're using the map you just want to know where the tracks are and possibly which are wider than others (eg highway=track and highway=footway is common to designate firetrail and singletrack).
In the end there's nothing official so it's up to mappers in your area to come to some sort of consensus. Around here a lot of the trails get marked as highway=cycleway surface=unpaved as a lot of trails are mainly used by MTB'ers.