I don't have a power tap but I do have a computrainer. I'd like to do a MAP test and want to make sure I understand what to do. Starting at 100 W I increase wattage by 5 every 12 seconds and I do this until failure? I should have a friend record my progress and then average my power over roughly the last 60 seconds? I know a computrainer isn't perfect but if I use this for future tests won't the information at least be consistent?