I am doing several training sessions from Zwift and in the latest, I am doing I am asked to do free rides, like with 1 min, 4 min, 8 min durations.
I find it really hard to determine the amount of Watts I will try and hold during such a period. Even in the one minute (they told me to go for it) I went for it, but I totally blew up after 45 seconds and my legs were rubber.
Is there a broad guideline where time is compared to your % FTP? Like if FTP is 95% for 20 min then 5 minutes try and go for 125% or something?
The free ride is exactly that. It’s your chance to give as much as you feel you can give. If you’re tired then use it for recovery.
If you’re feeling good then give it your all.
If you don’t have an idea based on your own intuition and previous riding of workouts what I would do is have a look at your Zwift power curve next time. Note down some key powers from there in regards to the durations that you are interested in. The power curve shows your ‘best ever’ so it’ll only show based on your existing rides, which if you’ve not been zwifting long might not be ‘your best’. So as a starting point maybe try just a bit more watts than your power curve suggests you can do. After half your free ride duration has elapsed think about whether you might be able to lift the watts a bit more for the final half based on how you are feeling and do so if you think its possible. Once you are riding more and get more used to how you expect your body to feel for different efforts you won’t need to rely on looking at your power curve beforehand (and your power curve as your ‘best ever’ might show more watts than your ‘current best’.). You’ll start to just know. Hope that helps.