zPower adjustment slider

we know that even the same model trainer can have differences in resistance. I propose there should be an adjustment to account for this. We should be able to adjust zPower by steps (+3, +2, +1, 0, -1, -2, -3) kind of like exposure adjustment on a camera. Or have some kind of power adjustment number we can enter (eg. -20W)

For my personal experience, I feel like my zPower is too high. I go too fast in the game when compared to my data in real life. I get around the problem by increasing my in game weight, but this is a very crude work around. I would like to be able to subtract a certain value from my zPower to adjust for the variance between Zwifts power values for my trainer (Blackburn Tech Fluid), and my actual trainer.

Another use case for such a feature is that you could use the adjustment to handicap yourself when riding with a friend who is an absolute beginner. So instead of having to ride slowly with a friend like in real life, you could simply slow yourself down virtually so they can keep up. 

OBVIOUSLY there would be concerns with cheating if people add zPower instead of subtract. Perhaps we could allow only downward adjustments to zPower

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It sounds like you’re not using the trainer that you’re selecting from the trainer select menu, correct?

zPower is calculated based on specific variables, including the resistance unit. If you’re using a trainer with a different resistance unit, you’re not going to get accurate numbers. You can’t choose a trainer that’s “close” to your actual trainer and expect accurate values. It’s apples and oranges.

In this case, you should use the “Not Listed” trainer option or consider a power meter/smart trainer if you’re looking for more accurate values. If you’re using a trainer that’s not supported, you can also submit a support ticket and request that we add it. There’s no guarantee that we will, but it helps us gauge demand and prioritize adding new trainers accordingly.

Hi Jason, 


Thanks for the response. I am definitely using a supported trainer. Blackburn Tech Fluid




I’m sorry for the confusion on my part - it sounded like you were using a different trainer than the one you were picking.

We haven’t heard of significant power discrepancies between the trainers we test with and ones out in the field from manufacturing variance. If you feel your real-life numbers and your ones in Zwift are significantly different from what you’re seeing, let me know how big the gap you’re seeing is.

While we may consider an adjustment similar to what you’re suggesting in the future, I’d like to see if there’s an error in our calculations now (keeping in mind that zPower is estimated, so there will always be some variance).

Hi Jason. No worries.

I have no hard numbers to back up my claims since I have no real power meter. It’s just a hunch I have. I’m flying down the road at 40km/h in game, and i’m not working nearly as hard as I do hitting 40km/h in real life. 

My climbing speeds in game are fairly close to real life, but speed on the flats seems at least 5km/h too fast. 

Did you check our zPower guide? Make sure that everything there lines up with your setup if you feel you’re reading high.

I’ve also passed on your feedback to our developers, and we’ll be double-checking the Blackburn Tech Fluid this week as well.


Not sure if my request is the exact same one, I’m personnally using a non supported rollers set (Tacx Antares + speed/cadence sensor) , so I am using the ‘unlisted rollers’ option. I clearly think that my power in Zwift is overestimated by at least 30%, and so far my only option will be to overestimate the wight of my avatar by the same factor but I do not like too much that idea … I am clearly not ready to invest into a different supported trainer, or into a powermeter, so I would vote for this requested feature to fine tune the power estimates manually to ensure the virtual ride is as accurate as possible.