I've cycled the Pamir and down into the Wakhan Valley which I highly recommend. Did it fully loaded on a rigid tourer with 26" wheels, and planning on going back on mid fat / full fat next year. Cycling is challenging but the traveling is reasonably easy. Look at going east to west as Hindu Kush and the surrounding mountains are spectacular. Bit more wind but you'll not do much more than 40 -60 km / day once you hit the worst of the roads, and often less. Villages are frequent and pretty friendly as well. Visas aren't so hard, and worth checking at Caravanistan for updates.

Regards
G2G