One thing I am noticing with Power Cranks is the improvements come quickly and dramatically. My first rides back on the Power Cranks I could only manage 60-64 R.P.M. Avg. for 30 minutes on the Compu-TRainer. Now I can do 72 R.P.M. only three days later. My legs feel better too.
at this rate, before it is over, you will be up to 5 hour rides at a cadence of 100 … NOT 
Don’t bet against it my friend… If nothing else, I’m determined.