- Rochester Hills MI
The difference that I see is that from 15 to 21 the 11-speed has 3-tooth jumps where the 12-spd goes up by 2s. I tend to notice these differences, especially when riding in situations where one gear feels a little too high but downshifting makes it feel a little too low -- like a 10rpm difference in cadence between cogs. I remember on my old road bike that had a triple crank and a 11-27 10-speed cassette, the gears were very closely spaced (many just a tooth difference) and I enjoyed clicking from gear to gear while keeping my cadence almost constant. That's one of my criticisms of the 1x drivetrain trend in general: huge gaps between gears.So instead of cog 18 you would get 17 - 19 cog? And all the rest is the same.
My 2c: too much fuss changing the drivetrain components for that (little?) effect.