My friend and I are experienced bicycle tourists. We are leaving UB to the west towards the Altay. It's going to be slow going with the roads but it's still less than 2,000 kms to the western border of Mongolia. Since we're on about a two month holiday, it is very likely that our tour will continue beyond Mongolia. My broad question is: Where best to go from Mongolia? To the north to Russia? To the east to Kazakhstan? To the south to China? Broadly speaking, we're looking for a great mixture of adventure, culture, and wilderness. The road conditions are obviously not too much an obstacle for us. Any suggestions? Thank you so much in advance. - Matt
Beijing to Irkutsk! 1,650 km. If you already have tickets/transport to UB, maybe UB to Abakan, via Khovsgol, into Tuva. Or UB to Urumqi. Hell if you can do 2,000 km on a bike over 2 months, the steppe is your oyster.
There is no border between Mongolia and Kazakhstan.
It is possible to cross from the Mongolian Altai to the Russian Altai. This is getting pretty common. I don't think you can ride across this border and there is no public transport across this border so you would need to find someone to transport you across the border.
There is a possibility to cross from Mongolia to China in the west but I am not clear how easy it would be to get from Mongolian Altai in the NW to this border crossing. It is a new international cross and reports are slim plus transport needs to be arranged in advance. Bulgan crossing 2011
If you want more information about the Russian crossing, try searching. There should be several reports.
Ruth
If you cross from the West of Mongolia (Olgii) into the Altai region of Russia, theres plenty of transport options while in Olgii. Check out the area just outside of the main entrance of the bazaar around 11 am and youll see plenty of jeeps with signs saying where they are heading. You should be able to find a person going to Altai here, but go a few days in advance as they usually dont leave that day, they are only looking for interested parties before getting the paperwork to cross. A note though, more than likely you will be overcharged going this way. I did this two years ago and I believe I paid about 5$ a person (brought 3 others I met in the hotel with me). So thats a price to work off of. The others in the hotel were getting charged around 20$ each.
Also down the main street is a big sign that says "Tourist", with a phone number. Call him for help with arranging a ride, you wont regret it.

Hello!!
We are a spanish couple who are right now in Ulaanbaatar with the bikes too!!
About your question, we just can tell you that we are planning to cross to China by the Bulgan-Takashiken border and we need, of course, visa for coming into China what is not very easy, although cheap. The question is that going by that way, you will find desert as long as we know in China too.
On our experience, going to Russia must be a very good idea. We have arrived to Ulaanbaatar from there and Russia is amazing!!
This is what we can tell you...
We wish you good luck and maybe we will meet on the road (or in the path)!!jejeje
Best wishes!!