There is no official bike ride that I'm aware of. For the past few years I've ridden the embassy circuit, eating, picking up free stuff, enjoying the entertainment. I've only done the EU tour, so I can't speak about the others. Particularly good parties from past years were at the German, French, Swedish, Finnish, British, Austrian and Czech, although the Belgian, Polish, Hungarian and Spanish are also worth a stop.
And you can say you biked to 16+ countries in one day.