Hi Ben,
Like Gareth said, I just got back from Mongolia. I’m more into technical enduro, so we were making our way between the northern and central route, through the mountains, west to east. Gobi and the south is apparently more flat.
I was using OSM maps. They are fairly accurate but need a little creative navigation here and there. Some roads were way off from their location on the map or just completely impassable, as we found out the hard way 🙂
You definately need a good paper map to back up any electrical navigation. Also take dust into account, as it’s….bountiful. I was using a Garmin Montana 600, which performed well in the dry and dusty conditions of Mongolia as well as the super wet in Siberia. I guess the iPhone might work if you get it sealed properly. I would recommend getting a proper GPS unit though. I’ve yet to see a phone that actually works consistently in navigation for several days.
Like konabunny said ADVRider and HUBB are the best resources for all info. I also have a bunch of .gpx, POI:s as well as general info on fuel, food etc. Feel free to drop me a line if you need the info.
It’ll be an epic journey for sure. Mongolia is incredible.
contacts: http://therollinghobo.com/the-hobo