I think a lot of people use a 20min time trial effort test minus something like 5% to estimate FTP. Friel advocates a 30min test: http://www.trainingbible.com/joesblo...and-power.html and argues that the average for a 30min solo TT effort is really FTP (what you should be able to maintain for an hour or 40km TT). I think this depends on how good you are at pacing for a 20km TT.


The reason I asked about your W/kg is because it's easier to compare that number across a population of people who aren't the same size for varied terrain than raw power, except when you're talking about max power. Max power is pretty hard to test on a computrainer, though, because the bike doesn't move and you can get some tire slip.