A lot of people ride their bikes to work even with dresses on!  Very few people wear helmets and they have no fear of the large double decker buses.  As a tourist, we tried to rent a bike but found out that you have to have a computer chip in your credit card for it to work in the UK.  They drive on the opposite side of the street than we do here in the USA and their steering wheel is on the right hand side of the car.  It takes a while for you to get used to looking both ways at a crossing as they are going the wrong way!  You have to be careful with the pedestrian crossing signs as they can have two on one crossing that are on different timers and there are a lot of blind corners when you cross.  I loved the tube or the underground it got us around town in no time and was not crowded.