Power Meter Mess - Favero Assioma Duo

If you were on a road bike with a smart trainer then I predict that your watts would be a lot more similar inside and outside. As I’ve said previously, it’s because you’re on a spin bike with a different position, different resistance mechanism etc. You’re not comparing like with like. You’ve already shown that your power meter pedals aren’t faulty.

You might be right, but I don’t see that it could be for the reasons you mentioned.

My positioning outdoors is far worse than what it could be indoors. First, if you read further up in this thread you’ll see I used my Son’s mountain bike for testing the power meter pedals outdoors. My bike fit was not good, but still my wattage over the entire ride was 200+ watts at a heart rate of 133. The other bike I used outside was on a carbon high racer recumbent. This fit is obviously drastically different from what I have on a spin bike because I’m essentially laying down. Most studies show that less watts can be produced on a recumbent than an upright bike because you can use more of your body weight into the pedals on an upright bike. So the power on the recumbent was less than what I could do on the mountain bike, but still above 200 watts for an entire ride at a HR of 133. Now look at the spin bike’s power, where I ride more often and my bike fit is better, and on an entire ride the wattage is 116 watts at an average HR of 133. Again, it is hard to see how it could be bike fit when faced with this data.

Also, I struggle with the idea that the resistance mechanism could be the issue. The spin bike I have uses magnetic resistance. What do you think the most advanced Smart Trainer that the Pros use for Zwift uses? That’s right, magnetic resistance, whether your talking about a Wahoo Kickr Bike or a Tacx Neo, etc… They all use magnetic resistance.

Additionally, many of them use flywheels, just like a spin bike. The Wahoo Kickr line mostly does. I don’t think the Taxc Neo does though.

So again, I’m not saying that removing the spin bike from the equation and replacing it with a trainer will provide wattage closer to what I’m seeing outside. I think there is a very good chance that could be the case. It just doesn’t seem that the reasons why will be because of the reasons you stated or at least the data doesn’t seem to support it. It seems like it will be for something else, which is what I’m trying to determine.

Favero is now thinking the issue does reside with the spin bike, but they are trying to understand why since so many others use their power meter pedals with spin bikes and they don’t see data like this. I’ve given them all the latest data they’ve asked for and typically it takes a few days for them to respond. I’ll update this thread once I hear back from them.

Next time I ride on the trainer I’ll do a quick test - I’ll pair the Assioma Duos for power and unpair the Kickr Core for controllable and ride without any controllable and with only a double-side PM. It might well be a bug in Zwift. This might be a few days though.

Hi John,

So i dont do a long test. More like switching over from Zwift to Polar and Sufferfest. Same light effort with low heart rate. Last test i kept Polar on 50W, then change to Sufferfest and it gave pretty same 50W but then zwift gives 30W…so im really confused whats going on. I truly belive Polar is the baseline and it feels also most correct. (been training and testing 4yrs with Tacx Neo smart what i had so i kind of know my numbers). Also if u wonder low wattage, same ratio
applies with higher efforts.
Did also now with 100W first on Polar, got it steady, then change to sufferfest, exact 100W, quickly to Zwift and got 60W…did it multiple times with same result.

My guess is you’ll see close numbers between the Kickr Core and the DUOs. Both devices have been pretty well-tested to provide accurate results by many people. What I think I have is an anomaly, but the trouble being that it is a consistent anomaly. Riding outdoors provides 200 watts on average whereas indoors on the spin bike provides 115 watts on average. Very odd and I’m still waiting to hear back from Favero on what they think the culprit might be.

Gotcha. You definitely have something go on here that is different from the issue I have. My issue is consistent across many platforms indoors. Yours appears to be only with Zwift. This is just a guess, but it seems like it might be a configuration setting or a bug in Zwift for you. You might start with reinstalling Zwift and keeping everything at default and see if that helps. Just a thought.

Yday Sufferfest did amazing job to test things on their side and we finally got all matching with my favero pedals (they will redo abit their setup/instructions) Was truly super customer service and we changed tons on emails.
To make it short. Zwift is not showing correct power atmo and its something on their platform.