What's your favourite gear ratio?

I carry a chainwhip and a set of sprockets in one tooth increments between 13t and 22t in my bag at all times for this reason. You'll often see me dismounting and quickly adjusting my ratio whilst the lights are red, and then stopping again once I've built up some momentum in order to change it to something more appropriate for higher speeds.

This sounds very time consuming. I simply have a van follow me everywhere with a selection of appropriate bikes to choose from.

At least, I think that's why that van follows me everywhere :-/