I’ve been using Zwift for 10 days and love it. I do have one question.

My average watts for first 3 rides was 140 - 150. My next 4 rides I can barely keep it above 100. Tire pressure is fine and Kinetics trainer is two weeks old.


Does the Kinetic broadcast watts or are you using zPower (estimated watts based on rear wheel speed? 

Any additional info would be helpful.

I assume it’s estimated based on rear wheel speed.

Did you select the correct trainer to get the appropriate power curve?

Also did you select the correct tire size?

I do not recall having done either of those. Where do I go to check?

Still doesn’t explain the sudden change from one day to another.

You make those selections on the Zwift pairing screen. 

If you selected the wrong trainer or wrong tire size it could absolutely explain the difference in watts.

You also could have been tired.

Went on the pairing screen and couldn’t find the option to change that information.

Please post a pic of your pairing screen. 

Hi Mike

As an aside, are your averages taken on different courses or different parts of the same course?

I setup my tire size on the first install, and now there is no way to change it.  I have a mountain bike 24 gears, and on flat ground 24th gear i can barely get 18 mph at 90 PPM.


can you give us step by step steps on changing tire size.  I think it’s a one time deal and you can’t get back to it.


Windows 10 PC fyi.




On the Pairing screen unpair the speed sensor and repair it and you should be able to choose your tire size.

No dice, I have a screen called paired devices for Windows 10.  I have three paired devices because I have the kinetic rock and roll.  I UUN (stupid spell check) UNPAIRED all three, and searched and selected them again, and no tire size option.


What version of Zwift are you running?

Doesn’t the Rock and roll broadcast watts: https://support.zwift.com/hc/en-us/articles/203152565-Which-trainers-does-Zwift-support-

If so there is no reason to pair the speed sensor or to choose a wheel size, it wont do anything.

Yea it gets watts, good to know wheel size doesn’t matter in that case.



I would guess it’s a matter of gearing with your MTB on Zwift, you just don’t have the big gears road bikes have.

ah, hopefully that is it i was wondering.  I am starting in 24th gear…does that make sense?