Free Software to Analyse power files

[Toolish]

Ok, got a powertap...went and destroyed myself to do an FTP test but can't seem to find any free software to split out the 20 minute interval and look at the power figures.

I have a free training peaks account, and I got an email saying me Threshold has been updated...but I can't work out how to view in depth ride details.

Can I do what I want to do with free software, or do I need to get WKO?

[toolonglegs]

Golden Cheetah