Originally Posted by
RChung
Constant power output is time-minimizing only when conditions are constant. If conditions are variable (like, changes in gradient or wind), the time-minimizing strategy is also variable. The amount of variability that is time-minimizing is limited by your power-duration and your ability to recover from excursions above threshold. In practical terms, it's also limited by your ability to vary and control your power output.
That all said, a "close but perhaps not optimal" time-minimizing strategy is to go *almost but not quite* constant power: you want to go *very slightly* harder when you're going slower than the overall average speed (e.g., when road gets steeper) and go *very slightly* easier when you're going faster than the overall average speed (when the gradient eases off a bit).
Good feedback. When I first got a PM, I realized just how "unbalanced" I was on variable grade climbs. I'm talking on the order of 80-100 watts. Really pushing too hard on the steeper parts, and practically coasting on the flatter portions. I've "only" been using a PM for about 4-5 years, and I'm still trying to re-train my body to push harder on flatter roads/climbs. What feels like cruising power on a climb feels like turning myself inside out on a dead flat road, still to this day. So yeah, I basically do exactly this now, a little bit harder on the steeper parts, and a bit easier on the flatter parts, but keeping the overall output closer to my power goal for the overall effort, instead of more wild fluctuations. Also it depends a bit on the profile, I'm always wary of those steep finishes. Roads with flatter finishes I'm much more apt to "dial it up to
400 watts" early on and try not to blow up at the end.