A,
Great question, I don’t recall seeing it on the forums before. I don’t yet have a formula for 5K to rFTP, but we can still base it off of your time. Our original (and many system’s current) protocol was 100% average FTP for a 30 minute TT, but we’ve dropped it to 95% of 20 minutes to make it a bit easier on the athlete.
So, if your 5K is 30 minutes, take 100%. If it’s 25 minutes, take 97%. It’s not precise, but it’s accurate (close enough) for you to essentially pro-rate the time between 20 and 30 minutes to match between 95 and 100%.
David