There is a bird which produces exactly the same noise as my bike makes when it's a bit unhappy about changing gears. Kind of grinding, whirring, whining, rasping, shrilling, scraping. I noticed a bird making the identical sound. In Notting Hill Gate somewhere. Spooky.
Thought it would be worth writing a longer piece ("Oh God", I hear you cry, "No") about how to start cycling in London and keep safe. My first rule would be to assume that you're wearing a kind of Harry Potter Invisibility Cloak. Assume no-one can see you, even if you're wearing two dozen lights, a full body suit of luminous lycra and you're sounding every horn and bell at once. It's safer that way. I wonder if anyone else has a "top rule" which I could shamelessly steal and add to this blog?