If you don't mind A-roads, I'd head along to Lewisham and then A21, Catford -> Bromley. Then, if you want to bump up the miles a bit, keep on going to Orpington and beyond, out to Polhill via Knockholt/A224... (and then you'll be pretty much at the M25, so you get to turn around on a quiet little roundabout and do it all backwards!).
It's partly the Dulwich Paragon winter chaingang route, has some quite good stretches to work on spinning and speed, not too many traffic lights all things considered, and the odd up and down (good climb back from Polhill to Badgers Mount, and a nice quick one up into Bromley). But it can be quite busy, is grim with a headwind unless you have some mug to draft behind, and the little stretch between Green Street Green and the Knockholt turn-off becomes a hairy bit of dual carriageway.
If you don't mind A-roads, I'd head along to Lewisham and then A21, Catford -> Bromley. Then, if you want to bump up the miles a bit, keep on going to Orpington and beyond, out to Polhill via Knockholt/A224... (and then you'll be pretty much at the M25, so you get to turn around on a quiet little roundabout and do it all backwards!).
It's partly the Dulwich Paragon winter chaingang route, has some quite good stretches to work on spinning and speed, not too many traffic lights all things considered, and the odd up and down (good climb back from Polhill to Badgers Mount, and a nice quick one up into Bromley). But it can be quite busy, is grim with a headwind unless you have some mug to draft behind, and the little stretch between Green Street Green and the Knockholt turn-off becomes a hairy bit of dual carriageway.
Something like http://bit.ly/5NjVpB
Innit.