Ride Rye to Rye. Start at Old Spike Roastery, where they will do you a good coffee, and then head out via Crystal Palace towards Biggin Hill and Sevenoaks.
In Yalding, take a pitstop at the quirky Teapot Island café. It's a proper greasy spoon but incredibly charming, featuring a huge teapot museum and an outdoor seating area overlooking the river. Have a brew, and then make for the stunning High Weald AONB.
Towards the end of the ride, there's this amazing descent down to the coast where you emerge blinking from the tree-covered lanes into a wide marshy valley. You can see the sea, and little trains shuttling back and forth across the valley floor.
Finish by riding along the seafront and through the harbour. Stop for fish & chips, or at one of the many pubs and then get the train to Victoria or St Pancras via Ashford.
Thanks to Leo Hemsted for recommending this route.