Bikes are the only way to go in London as long as you keep an eye out for car drivers who seem to drive in a virtual neck brace that prevents them from looking out for other road users - then again you are probably used to that and lets face it, if they don't see a big yellow van with a flashing light on top they are going to miss a cyclist. How about swimming ? Is it incompatible with shift work or does doing it seriously as a kid take out all the fun in it ?