Originally Posted by
TheKillerPenguin
I am curious - what makes your area so difficult for doing a longer 20min test?
Since this is a guessing thread, I'm going to guess that there are too many stoplights to do a good 20 min test.
To the OP - target 95% of your 13 min power in your 20 min test. If you are feeling good 1/2 way through bump it up, and if you feel good with 5 min to go bump it up again.