Snow!

Had exactly the same experience. Though I found the bus drivers liked to drive on my tail as always. I was trying not to think. If I lose it now, the bus wont be able to stop in time and I will have 50 odd tons on top of my head. So I started skidding my rear wheel deliberately and making it look like I could come off any second until the fucker backed off

A typical London double-decker bus is about 15t unladen. (Pointless point of information.)