Any question answered...

So here's another question: I'm trying to choose a gear ratio for a new build, and I need to know what my current gear ratio is. But I've got hub gears, so it appears to have a single cog on the back but somehow magically produces 3 different gears. Which is the "true" gear, top, middle or bottom?
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Assuming a Sturmey Archer AW, 2nd is the true ratio, 1st is 33% lower, 3rd is 33% higher
Calculate your ratios here: http://www.sheldonbrown.com/gears/internal.html