The ground drops away. One minute you are on a busy highway, grinding through traffic on the highlands north-west of Nairobi, and the next you are on the lip of an escarpment, looking down several hundred metres into the Great Rift Valley, a vast, hazy trough that runs from here as far as the eye can see. On a clear morning you see the cone of Mount Longonot across the plain, an old volcano with a crater, and the pale glint of Lake Naivasha and the Mau escarpment on the far side. It is one of those views that makes you stop and be quiet for a moment.
The viewpoint is on the old road between Limuru and the valley, where curio stalls line the verge, selling carved animals, soapstone bowls, beads and baskets. Bargaining is expected, and the sellers are good-humoured, though they can be persistent. Nearby, tucked into a fold of the escarpment at Mai Mahiu, is a small church built by Italian prisoners of war in the 1940s, a surprising piece of history in the middle of Kenya, and the nearby mission station at Kijabe has been a centre for education and medicine for more than a century.
The valley itself is part of the East African Rift, one of the great fractures of the earth's crust, where the continent is slowly pulling apart. Volcanoes, hot springs, soda lakes and steep faults mark its path through Kenya, and the escarpments are the walls of the trough. It is a landscape on the move, in geological time.
The riding is a different matter. The highway from Nairobi to Uganda is one of the busiest roads in East Africa, packed with heavy lorries, buses and matatus, the minibus taxis whose drivers have their own ideas about road space. The descent from the escarpment is steep and winding, with trucks crawling down in low gear and others overtaking with more optimism than judgement. It demands full attention, so avoid riding after dark, keep your distance, and take care on the corners where oil and fuel spills are common. The old road, which runs parallel through Kijabe, is quieter and slower, and much more pleasant on a bike. Baboons sometimes sit on the walls, and cattle and pedestrians use the verge.
Limuru, about thirteen kilometres away, and Kijabe have small stations and shops, and Naivasha has plenty. Nairobi is about fifty kilometres behind. Carry some cash, a bottle of water and a layer, because the air at this altitude can be cool and the sun is strong. The best time to come is early in the morning, when the air is clear and the valley is still blue with haze.