I built up a bike a few years ago that I concentrated on having the gears low as possible via a mountain crankset 22/32/44 and 13-36T custom cassette. What I discovered is that while having the low gearing is very good, I pushed the bulk of my riding into sub-optimal ring and cog combinations. I was shifting from middle to big ring a lot. Just something to consider... optimize the bike to be in the middle of the cassette and the middle chainring where the bulk of the riding is done.