Originally Posted by revchuck

For me, the 14t cog is important. In a 34-14 combination, 90 rpm gives ~17 mph. For me, that's a comfortable cruising speed. Using the small ring in a headwind, the one tooth gap among the four smallest cogs makes it easier to maintain a comfortable cadence. My own preference for a cassette is 12-27, which gives a one tooth gap from 12-17. I don't notice the gaps on the larger cogs as much as on the smaller ones.