It’s 4.30am. Dawn is breaking, it’s freezing, and I’m standing at the foot of the 5,416m Thorong La pass in the Himalayas with my bike. My aim is to cross the pass and descend to the Manang valley on the other side. From here to the top it’s 1,400m up, and then a fur ther 600m down to High Camp.The weather is fine, the forecast fair, but the air is thin – perfect conditions.