Any advice on cycling this stretch?

This is going between Dushanbe and Aktau, yes?

I’ve done that route. It’s as safe as anywhere in Central Asia, i.e. the driving is worse than in Western Europe but better than in India.

The roads get fairly awful in the few hundred miles between Bukhara and the Kazakh border, so fit the biggest tyres your frame will allow. For that stretch, it can be 100 miles between truck stops so make sure you’re carrying a few litres of water. Don’t go overboard though: it’s a truck route on the Belt & Road so not completely deserted: you won’t die of thirst and can always flag someone down in extremis.

Those truck stops I mentioned are really good: they’ll have hot food, road food, somewhere to charge your phone and even rooms to sleep – they’re true oases in the desert.

The mountainous bit from Panjakent to Dushanbe is … mountainous. There will be lots of snow if you’re doing it in winter/spring. Don’t be a mug like me, don’t get benighted at 2500m altitude in March!

The Anzob tunnel, halfway through the Fan Mountain stretch, is absolutely dangerous. Do not ride though this tunnel. It (and other mountain tunnels in the region) are long, poorly ventilated and even worse lit. You’ll keel over from carbon monoxide poisoning, get hit by someone who can’t see where they’re going and die. Standard practice is to hitch through these tunnels: when I was there, I got a lift in a van in three minutes flat. If you really want to ride every inch of the way, take the high road over the pass rather than going through the tunnel. That will add another 1000 metres of ascent though, so is quite an effort.

It’s a great route, so have fun!