The reading of forty metres above sea level tells you the geography: the Musashino plateau, a broad terrace of the Tama River's old floodplain, flat as a table and covered in houses, farms and the long green ribbons of watercourses. Kokubunji, the nearest town, is a commuter hub on the Chuo Line, and the route out toward the west starts here, heading for the mountains that appear as a blue line on clear winter days.
What makes this plateau special is its water engineering. In 1653, the Tamagawa Aqueduct was dug to bring drinking water from the Tama River to Edo, about forty kilometres of open channel running along the ridge line, with minimal slope, and it fed the growing city for centuries. Much of it is now a footpath lined with cherry trees, and stretches near Kodaira and Mitaka are a lovely place to cycle. It was engineered by two brothers of the Tamagawa family, whose names are still remembered, and the surname became the canal's own.
As an exit from the city, the route is anything but wild. Roads are straight, the traffic lights are numerous and the speed limits are strictly enforced, so patience is more useful than a throttle. The reward starts further west, past Tachikawa and Ome, where the road tilts upward and the Chichibu-Tama-Kai mountains come into view. Early morning departures avoid the worst traffic, and Sunday dawns are particularly quiet.
Fuel is easy here, and many stations are self-service. Convenience stores sell hot coffee, rice balls and sandwiches. Spring, with the cherry blossoms along the aqueduct, is the most beautiful time to leave, and late autumn adds yellow ginkgo leaves on the pavements. Summer is hot and humid, so carry water and ride early. A few minutes by the old channel, listening to the passing bicycles, is a nice way to remember how much effort went into the city's water.