^Same here. I rough it in by measuring, but it's impossible to correctly measure sitting height on a curved surface. After measuring, I ride the bike on the flat, unclip one pedal, put my heel on it and continue to pedal. My heel should barely touch the pedal at BDC with a locked knee. But even that isn't accurate enough really, so the next thing is to see if I feel the correct amount of power in my leg at the bottom of the pedal stroke. I know what it's supposed to feel like, or at least what I like it to feel like, so that's my final check, maybe a mm or two refinement. The first couple of rides I put my multi-tool in my jersey pocket and probably stop a couple of times for adjustment.