After dying horribly trying to take the FTP test for the first time, I was trying to figure out why it thought I could do a warm up that included 3 mins at 285 and 2 at 310 - and a heart rate of 190 (ack!).
For fellow noobs, when you are setting up the FTP test, there is a slider on the right that lets you adjust the difficulty. It defaults to 257 if you don’t have an existing FTP number, and if you’re like me and don’t lower it to something realistic, you will die.
The more you know. 
The other way to do this is to set your FTP at 100 or a low number. And just do a nice hard ride of about a hour, then Zwift will determine and adjust your FTP.
Then you can go and do a proper FTP test the next day.
Thanks, good to know.
Anytime you ride hard for 20 min, Zwift will perform an auto FTP calculation and adjust your FTP if 90% of the average watts during the 20 min effort is better than your old FTP.
if you havent done a FTP test before where would be a good place to set the slider please?
Marc,
Are you talking about the difficulty slider? I would suggest putting it at 50% to start.
If you are talking about FTP I would suggest just doing a couple Just Rides were you push yourself for at least 20 minutes that way Zwift will automatically set it for you.
Hi thanks for this yes I mean the FTP test. I did a 30 minute ride but it didnt give me a FTP number. I guess I need to put a number of around 100 into the FTP data field first or it has nothing to “adjust”. I can try that but wouldnt going straight into the test be more accurate?
Marc,
Before you can do the test you would need to put a number into the FTP field.
I set the slider on the FTP test to 120 (and at the end was told my new FTP was 110). It all depends on what kind of shape you’re in, but probably better to guess low when you are first taking the test. I’m just getting started and I’m doing the beginner 6wk FTP builder program to improve it.