Time taken to complete the course isn't a great indicator of changes in fitness, since time can be readily affected by conditions on the day (wind conditions as an example). But power is power, provided you are conducting the test in a reasonably similar environment (altitude, terrain and it's not hideously hot or cold). It also helps to make sure you are not overly fatigued on the day of the test.
The length of the test is typically 10-miles or 16-kilometres. Doesn't need to be exact as it's power we are interested in, not the precise distance or time taken. Of course, if you ride 10-mile TTs regularly, then they are perfect opportunities to use as tests.
Today I was scheduled to do my first such test since returning to the bike.
So what happened?
Well of course today it decided to be a stormy rainy yukky sorta day, didn't it. And right now I don't need the hassle or riding in the rain.
So that left me with the other alternative - to get on the ergo bike and go for it. So that's what I did. Only trick is I have no speed/distance data on the indoor ergo bike, so I opted for a 25-minute long test.
Unsure of how hard to start with, I decided on starting at 220+ watts and then to go by feel from there. Here is the power chart from my effort (yellow = power, green = cadence):
Overall, for the 25 minutes I had an average power of 248 watts and a peak 20-minute average power of 252 watts.
So that's not too bad all things considered.
Testing continues later in week, with a Maximal Aerobic Power test.