Originally Posted by
rubiksoval
At that altitude, was there significant altitude-induced power loss happening over that last hour plus?
Absolutely. In my experience I've found the chart in
this article on Joe Friel's web site to be pretty accurate. I started out looking to average 300W, but by the time I got to about 8000', 300W is my altitude adjusted FTP. That, combined with the fatigue from going pretty hard for the last two plus hours ends up making the 300W unsustainable. That was kind of my plan, just ride at 300W until I couldn't and then just take what I could get for the rest. It wasn't like blowing up, it was like turning into a big headwind. You're still going just as hard, but slower now.