Originally Posted by
MyTi
...How would I get comfortable at 300 watts if I don't know when I'm doing 300 watts without a power meter?
Find a steep hill that's long enough to take a decent amount of time and is a steady grade, put accurate weights in Strava and see what it says. At slow enough speeds the wind resistance is not much of a factor and Strava will be close enough to know what 300 watts feels like. It will also track your improvement over time. The drawback is that 300 watts uphill does not feel exactly like 300 watts flat, but as far as perceived effort, legs lungs and heart, I'll bet you could generalize the perceived effort.