cheers skinny! no resistance and only 92 gear inches but i guess i'll give it a go.
Foolishly signed up for Red Hook Milan so trying to turn slow touring legs in to passable crit ones.
I don't know how much power you intend to put out, but whatever it is that gets me a 23 minute 10 mile TT will drive my rollers at about 35mph, and that's with a ton of aero drag from the 48 spoke wheels.
If they have some resistance and you've a big enough gear.
Just do a 20 min test. And use that as a measure of fitness. Then do another 20min test when you want to see if you've imporved basic aerobic fitness.