i'm using a powertap pro wired... my friend upgraded and gave me her old one, but it seems to be reading correctly. ive used it side by side with her new one so the numbers should be reliable. i did the hill test on a steady 1.5 mile 6% climb... its more like an 8 min max since i get up there averaging a shade under 12mph. the flat was just a straight river bed road... but like many others have said, its definitely hard to focus and really hammer on the flats. i think i had a tailwind too, which i've noticed tends to lead to lower numbers because there's less force to deal with? and psychologically when i hit 26+mph i think its already too fast and i feel like i'll blow up any minute.