The hardest part of cycling in Central Asia is arguably getting in the door.
The Soviet Union broke up long ago but the red tape remains and it’s very easy to spend weeks trying to get your papers in order.
On the upside, this does deter a number of tourists so as you persist just think of the reward of being the only visitor at a major archaeological site like Merv in Turkmenistan! There are no bus tours or cruise ships here.
While it’s possible to just get one visa at home for your starting country and then pick up the others on the way, we don’t recommend this option unless you have a few months to spare. Central Asian embassies are not known for their efficiency and it’s rare to find one that will issue you a visa in a day or two. Normally you have to collect a few documents, possibly including a letter from your home embassy or an agency, and then wait several days for processing.
Waiting around in capital cities is expensive, not very interesting and frustrating. Better to arrange it all before you leave home and then you can concentrate on cycling when and where you want to. Start this at least three months before you leave.
The one advantage to getting visas as you go is that it does allow a bit more flexibility. All Central Asian visas have fixed entry dates so if you arrange everything from home and then decide you want to move on to the next country earlier or later it might not be possible.
You can’t a visa at any land borders in Central Asia. A few airports may give visas on arrival but check before you go. Regulations are constantly changing. Rules on extensions vary. They’re impossible to get in Turkmenistan or Uzbekistan but easy in Kyrgyzstan.