I moved to Croydon a month or two back and have almost stopped cycling to work, I work near Kensington Olympia. I have cycled home once, it took me over an hour, but I did go on a circuitous route via Putney and Brixton as I had some people to see.
It takes me almost 50 mins by train so I don't mind the distance, even up and over the hill, as it keeps me fit.
The reason I don't cycle anymore is simply down to the pollution and traffic, I can handle anything up to 45 mins each way through heavy traffic but over that and I just get tired of concentrating and begin to feel overcome with soot.
What we need are cycle express ways of car free routes which have rights of way running into London from each and every direction, and a series of cycle ring roads also carfree.
Looking at the network of overland rail routes into London, there seems to be plenty of unused land on the sidings, surely we could borrow a meter or two on each side of most rail tracks to convert into cycleways, naturally bridges and tunnels would have either reduced space for cycles, upgraded to fit cycles or avoided with an alternative route.