Like a previous poster said I use it as a tachometer. In long challenging climbs where I am trying to either push hard all the way or try to achieve the best time, or ditto for a seated max effort of up to ninety seconds the cadence number is my most valuable variable of several that allows me to achieve the best and most efficient effort/pace. I just make sure I'm in the best gear pedaling at a targeted heart rate. However, of those mentioned if I had just one thing to reference, for me, cadence is the most valuable input.