One of life's little lessons is that drafting behind big vehicles requires plenty of care. Heavily laden semi trailers are usually pretty safe to draft 'cos they can't stop very quickly.
Empty buses can stop quickly.
In fact, an empty bus can stop faster than road bike with (*gasp*) rim brakes.
Always leave extra space in front of you when following a bus!
Fortunately, only light contact was made right at the end. Unfortunately, the rear wheel was about two feet in the air when the contact was made, causing a loss of control and a rather undignified dismount. No damage ensued and I don't think the bus driver even noticed... I suffered a little damaged pride and gave a little free entertainment for the frustrated traffic jam-bound motorists. The bike didn't get a scratch.
I think I'll take my own advice (rather than ignore it) to take more care out there! 🙂
Ritch