Spotted...

The often-perceived dichotomy between 'main streets' and 'back streets' is a bit of a red herring, though. People typically travel by the high streets and former roads into London because they are easiest to 'read' and have the longest history as major alignments. Other streets are often derived from field boundaries, from old alignments that have become obscured by time and building activity, or fairly modern residential settlements that weren't built with vehicular through traffic in mind.

With better knowledge of London, a rider will easily work out routes that aren't on main streets, but happen to be preferred by them--it can be factors such as wanting to see a tree you like, or a particular building, or something else that gives you a feeling that this is the way that you want to travel. It'll generally be a mixture of 'back streets' and 'main streets', and you can vary your route depending on how the mood strikes you.

Interesting perspective. I like :)

I flit between tending to go for the longest stretches of uninterrupted road or going for quieter residential streets depending on severity of traffic, light and time of day.
For example the choice between Essex Road and Balls Pond Road or taking the very cycle-friendly routes through "Debeauvoir Town"