Altona was Danish until 1864, a fact that surprises many visitors, and the quarter still feels a little apart from the rest of Hamburg. The water is just ten metres or so below the street at this point. It is the part of Hamburg most closely tied to ships and the sea, and you can smell it: tar, diesel, wet rope and fish.
Altona's Fischmarkt is famous for its Sunday morning gathering, which starts before dawn and draws everyone from party-goers on the way home to families buying eels and bananas by the crate. If your ride starts at the weekend, it is an extraordinary place for a pre-ride breakfast. The Elbchaussee, the long road that runs west along the river high above the water, passes grand merchants' villas and white mansions with gardens sloping down to the shore. It is lovely but slow, with many traffic lights and a low speed limit, and the cobbled and tram-free surfaces in the old quarters are better treated with respect when wet.
From here the way west is a gentle transition. Past Blankenese, where stepped lanes climb a wooded hillside, the road stays near the river, and the ferries that cross the Elbe, among them the passenger boats on the public transport network, give a flavour of the harbour city. Cafes and bakeries are plentiful in Ottensen, with its converted factories and independent shops, and the Altona district has fuel stations on the main routes, so the practical side of a start here is easy. Do be careful in the old streets, where delivery vans, cyclists and trams create a puzzle every few hundred metres.
The best light is early morning or late afternoon, when the sun picks out the river and the cranes. Spring and autumn are nicest, with fewer crowds and clearer air, and winter has its own raw beauty when the wind brings sleet off the water. Take a moment on the bank before you ride away: watching a container ship the size of a small town slide silently past makes the road ahead seem pleasantly modest.