When you know that you are mad for cycling when:

1. briskly walking past broken glass you put your left hand down and wave it a little to warn the pedestrians behind.
2. driving down Barbur boulevard you absentmindedly speed up to draft off the car in front.
3. calling ‘on your left’ when passing a slow label-reader in the supermarket with your trolley
4. you consider bringing a bottle filled with Perpetuum on a long dissecting day in the lab for fear of bonking before the end of the day.
5. you debate endlessly before work trips about whether to bring your bike or instead rent once you get there.