A challenging route, no doubt. In the first part you cross many passes to reach a hidden lake. In the second part sand dominates most of the way. You travel along big sand dunes and across desert. Water can be found every 70km for sure, so you don't have to carry huge amounts. But a good 'water-management' is nevertheless very important here.
Right after the airport the dirt track gets very rough, but it soon improves. I ride over several passes through lonely valleys until you reach Char Nuur. The lake is surrounded by big sand dunes. Climbing a steep pass you get to the next valley which is very beautiful. Green meadows on one side and sand dunes on the other. Now you get to the highest pass where you pass through and imposing rock arch. very steep descent. Down below you can already see the sand field that you have to cross. 2km of very soft sand, extremely exhausting. From now on the road is always sandy and every now and then you will have to push while you follow a huge sand dune to your right. After Urgamal there one last pass and a barren desert to reach the next river. The last days along Chono Kharaiikhin Gol and Har Us Nuur are very rough one more time, but the sand is more coarse-grained here. In Myangad you finally reach the tarmac road again.
In the first part the track is actually quite good. But the climbs to the passes are very steep. In the second part there is a lot of sand. How much you have to push the bike depends very much on the current conditions. After rain the sand gets more compact and almost all is ridable. I had to push for about 65km. Worst was just before Urgamal where I pushed for a whole day (35km). Friends of mine who cycled the same route only weeks before only had to push for about 18km.
GPS is a must. You will not find it otherwise...
Nothing else but camping between Uliastay and Khovd.
Water can be found every 70km. All water sources are marked in the GPX file. So you don't have to carry huge amounts of water. Still be careful as you never know, where and when you have to push.
In Enderhairhan, Tsavhanmandal, Urgamal and Dorgon there are simple shops with a limited selection of supplies.