Originally Posted by Dunbar

You mean this 20 minute test? It sounds like torture on an indoor trainer.

20 minutes easy warm up
3 x 1-minute wind ups with a minute rest between (100 RPM pedal cadence)
5 minutes easy
5 minutes all out (hard at first, but not so hard that you can't complete the effort)
10 minutes easy
20-minute time trial effort (like the previous 5-minute all out effort, keep in control, hard but steady, you don't want to over cook it and die at the end)
10 to 15 minute cool down

Take 95% of your average 20 minute (time trial effort) power to estimate FTP.