Our last hurdle, a 4100m pass, is a brown moonscape of moraine. Thence we speed down into a well-watered vale, calling happily to yak- and goat-herders with clunky roadster bikes or Suzukis or Yamahas, or sitting at the roadside. Thus we arrive at the lake Kara Kul, at 3700m. Afternoon sunlight catches tawny grass sweeping to the snow on Mustagh Ata, and rows of brooding glaciers creep down, valley by valley, from snow-fields hidden in the mist.

The hotel, with a row of numbered yurts and a hostile manager, is expensive and filthy. However, a young man leads us round the lake shore, driving his goats, to a mud and stone house. Here live a weather-beaten Kirghiz man and his wife and daughter, who does the work. Their living and sleeping platform is carpeted and cushioned, possessions are crammed into tiny cupboards lining the walls, a tiny yak-dung stove stands near the door, and a ghetto-blaster occupies the sill of the only window. Outside, the young man repairs a puncture in the back wheel of his bike. We can relate to that. We sit contentedly by the stove eating fresh-baked bread and drinking salted yak milk tea while the women bring out camel-hair bags, hats, scarves and trinkets in hope of a sale.

In the morning we turn our wheels down a long valley to the north. It becomes broad and open with every appearance of continuing for some distance. However, the road swings unexpectedly right and we find ourselves descending a mountain gorge, plunging in steep curves with traffic labouring the other way in low gear. In 25 kilometres we lose a thousand metres of Karakoram altitude. This is the Ghez defile, where Eric Shipton and H.W. Tilman came on horseback before the road existed.

Our last day, and the hills fall behind. We come onto the great plain of Central Asia. I want Tamerlane or Ghengis Khan to be galloping alongside us with upraised sword; but there is only empty grey gravel fading into haze. This plain gives no clue to its immensity, no feeling of romance. But should I expect that, pedalling over the dry plain? Perhaps, I think, I shall find romance at home when I read again of Kashgar and Urumqi (where we are going), and about Tashkent and Samarkand (where we are not). At fourteen I read of Samarkand in Fitzroy Maclean's Eastern Approaches, and it seemed to epitomise all that is remote and mysterious and difficult to attain. Perhaps it is as well that we are not going to Samarkand, for it would inevitably disappoint. Romance belongs in the mind.

The plain is irrigated. Donkeys pull little carts along the road, thickly lined with poplars; and walls with great double doors hide courtyards and homes and the lives of those within. We become tired and count the distance posts and do mental calculations which say this will be a hundred-kilometre day. In the towns children are walking home from school and the bazaars have bicycle shops and places where we could rest over tea, but we must reach the fabled city before nightfall.

At last the road widens into a concrete freeway with lanes for bicycles and donkey carts; and the glitzy towers of modern Kashgar beckon just as the trees and greenery of this oasis once beckoned Marco Polo. Our ride is done. In the foyer of the Chini Bagh hotel we shake hands and congratulate one another. It seems the right thing.

The Karakoram Highway had its difficult side: nausea, vomiting, diarrhoea, altitude-induced headaches, breathing and sleeping difficulties, loss of appetite, hacking coughs, chapped lips, unwashed bodies, freezing nights, punctures, a stove that wouldn't go, and dust and finely divided animal dung that got into everything. I don't regret it a bit.

We met a Japanese man in the Mountain Refuge in Gilgit. He bought a bicycle in Kunming and cycled across Tibet to Kashgar, then down the KKH. His hair was shaven so he looked like a Buddhist monk, but immensely powerful and strong. Even a cyclist who'd already twice crossed the Khunjerab was impressed. Now, when the red line across the map of Tibet tempts me, I remember the Japanese man and am satisfied that he has done it. And instead of cycling across Tibet I shall take my tent and camp in the green hills of New Zealand, and I shall dip clean water from the river and not filter it, and sit on a rock; and while the billy boils I shall read the travels of Sven Hedin or Peter Fleming, and I shall have seen enough to know some of what they write about.