Hmmmm....
It's not desperately reliable. From Marylebone station the whole of central London is "quicker by bike" - certainly not true; it's only 25 minutes to the City on the tube, and half an hour on a bike. There's a very odd patch around Canada Water which is "quicker by public transport" - it's not, unless you're lucky with your changes, as the Jubilee line through the centre of London is not quick, and the journey down to the tube at Marylebone is a long one. Then if I look in the other direction, apparently Northwick Park is quicker by bike. Oh no it's not. Coming in the other direction, I've got a GPS-timed track, down the hill, of 55 minutes. By train it's 12 minutes to Harrow-on-the-Hill then 5 back towards London towards Northwick Park.