Last night got the folder ready for this morning and decided to top up the tyre pressure. Came down this morning to find the rear tyre flat. I tried pumping it back up but it was flat again when I got home this evening. The bike hasn't been used for a week and the tyre was definitely inflated before I decided to top it up. If anyone can think of a mechanism whereby a puncture can occur overnight inside one's house just from topping up the tyre I'd love to hear it .