If FTP is max effort of 1 hour, what would be 2 hours, 3 hours, 6 hours?


I was wondering how to pace a race / TT the other day, and wanted to know if there was an average formula to calculate what your max watt output would be based on your 1 hour FTP.

If my FTP is 270, then I should be able to hold that for 1 hour without blowing up.
Based on that, how many watts could I hold for 2 hours? (I’m assuming it doesn’t drop to half).

Is there a graph/curve that shows an estimation for that?
Or another way to work that out using weight and w/kg?

Thanks for any help or extra info.

The graph/curve will be personal to you. The only way is to try it and see. It very much all depends in your endurance. It will vary wildly for different riders.

For me it doesn’t fall away very dramatically. My actual max 1 hour effort is 259w (my 95% of 20min is similar) and out at 1.5hours I’ve done 242w (but that was an interval session so not necessarily fully efficient). After that my only long semi-effort was a high z2/low z3 on the Mega Prezal which was 205w for 3.5hrs. Beyond it’s just fuelling and boredom that stops me.

This isn’t unusual, your z2 power should be possible for a very long time, if you’re reasonably trained, and should be about 75% of your FTP

If you want to pace a 2 hour race specifically, it will matter how much you have trained (at fairly easy intensity) for 3-4 hours. If the answer is sufficiently (I’ve ridden 3+ hours 16 times in 6 months, for example, which I’d expect to be average) I’d be trying to do about 90% of my FTP for 2 hours.

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It will generate a power curve for you.

Once you finish the ride, you have the option of seeing your power-duration curve calculated by Zwift. You just need to click through the tabs which appear on the screen.

Zwift cannot predict what power you will be able to maintain for 2 hours, but it keeps the data of power at which you were able to ride at this power in the past.

If you want a prediction, you probably will have to use a more sophisticated software, e.g., WKO5.