Average Power

mseanschmidt said:

How important is average wattage for analysis

It's important to some extent but it's not everything and it has some disadvantages.

I don't pay a lot of attention to it on rides like what you describe because it's a function of the terrain and other external factors so it's not a really great description of the ride. Average power is good for rating reasonably steady efforts like intervals, time trials, hill climbs, etc. Also, energy = average power multiplied by duration of time so it does have somethign to do with how many calories you are burning by riding.

If you want to get into the math of it, the average (also called "the mean"😉 is influenced quite a bit by outliers, values far away from the center of the distribution of all the power values your power meter recorded for the ride, and as a result, you take a big hit in average power when you coast for sort periods of time, stop at traffic lights, etc. If it were up to me, we'd have our power meters indicate MEDIAN power, which is less sensitive to things like coasting and is sort of the center of all the values recorded. It would be a more interesting number to watch. Not perfect but more telling of rides like this. (OK, off the soap box.)

A better number, expecially for rides like what you've described is normalized power, but to calculate that conveniently, you need software called Cycling Peaks. Well worth the investment if you get more serious about training with power.

mseanschmidt said:

What is a "good" average watts?

That's way too open-ended to answer. It's like asking "What's a good speed?" Everyone is different, with different levels of ability and without actually riding that same circuit along with you, it's tough for us to tell how hard it was.

I'd say that the important thing for you is to pay attention to how that number changes as you ride more and more. How much longer you can ride at that effort level on that sort of terrain. That sort of stuff. Challenge yourself and you'll see the numbers improving over time.

Strongly recommend the book "Training & Racing with a Power Meter" by Allen & Coggan.

Chapter 7 describes in detail the limitations of Average Power and energy expenditure (not that this info isn't useful) and provides an understanding of what other important metrics can be obtained from the power meter data.

Average power is good for assessing performance where the effort is more or less steady state. Great data for performance tests on a trainer or flattish terrain.

However Average power doesn't always indicate the physiological "cost" of a ride, especially where the effort is highly variable (think of a race, or hilly terrain).

That's where the other metrics (such as Normalised Power that SteveB mentioned) come into play.

Have a read of the various articles here:
cyclingpeakssoftware.compower411Open ↗

and plenty of items here listed in resources page:
trainwithpower.nettrainwithpower.netOpen ↗