Originally Posted by nslckevin

I think it's a lot less rare than people think. I know plenty of guys who can do 300W for an hour and plenty of them are in their 40's and 50's. The local young hot shot p/1/2 guys here in NorCal would be north of 350W. (for guys who are say 60-70ish kg)

Here is a good example. Mt. Hamilton out of San Jose. Part of the annual Mt. Hamilton RR. It's 18 miles of climbing but has two short descents that will lower your average power. Still, tons of guys over 300 watts for this climb. Not to mention that they still have more than 40 tough miles to the finish.

Personally, I looked through my Strava and found where I averaged 300W for 2:30 at age 56.