Originally Posted by Cypress

I posted this in a different thread, but the information is the same. Average speed means almost nothing, and is waaaay down on the list of "usable data" to gauge performance.

I plucked three solo rides from my data that show three different average speeds in increasing order. A newer rider might think 15.8 to be easy, 19.5 would be iffy and 22.2 to be out of their reach. The thing is, the normalized power data is almost identical for two of the rides (261W/260W), but the ride with the lowest NP (245W) was the hardest. I don't mean to toot my own horn, but a newer rider wouldn't have been able to keep up on any of these rides, especially the 15.8 mph average.

If someone rode the same route every day for a year they'd notice that on the same route with the same windspeed, a headwind on the wrong sections can pull 1-2 mph off of an average. Even the difference in air density due to temperature can knock 0.5 mph off of an average. When I get asked "what's your average?" when someone is considering riding with me I'll just say "I can go whatever speed you want. Let's ride."