In northern Pakistan, the Silk Road (a.k.a. Karakoram Highway or KKH) starts on the border between China & Pakistan at the Khunjerab Pass (4700m). Take a bus & jeep mountain bike ride up to the pass and begin the 3,500m descent over 270km winding down to through the mountains into the Hunza Valley and eventually emerges in ancient Gilgit. The KKH passes through hot furnace like valleys devoid of vegetation, bleached by the remorseless sun and dwarfed by range upon range of terrifying glaciated peaks. Much of the KKH is poor quality tarmac with plenty of washouts, streams, landslides and singletrack diversions, such as the 1500m descent from Hopar to Aliabad. Try the side trip down the Shimsal Valley gorge.