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.
[quote=“Tony_Virolainen, post:68, topic:533527”]
and
[/quote] Hi!
Is this only connected to the Favero pedals or with all watt-input devices? If its with all input devices, its okay and even for all, but if its only the favero - it should be events for those with these pedals since they have less watt out/in-put…
I don’t understand you question. Many of us use the Favero Assioma Duo power meters and they are very accurate. I have compared them to my Powertap hub and also to my Saris H3 smart trainer and they are with in 2%.
DC Rainmaker also tested them against many other power meters.
This is a very long thread and I have kind of skim read a lot of it so sorry if it has already been mentioned.
How are you connecting to zwift? is it via bluetooth?
have you set the pedals to broadcast power through the left pedal or both left and right individually? if it is the latter you’ll only be getting the power from one pedal and not the other.
I appreciate all comments everyone has made regarding this topic. As a final update I thought I might pass on where this has all landed. Favero did their best to try and explain the anomaly here and in the end they said their top engineers could only reach one conclusion. That is, there is something special with the flywheel on this specific model of stationary bike that is producing negative power and this is what is overall resulting in the reduction of total power output measured.
I can only agree with this conclusion because I certainly have no other explanation of how I could hold 200 watts for over an hour on any other bike outdoors, but only hold 200 watts for maybe 3 minutes on this stationary bike.
So I basically now only use my Favero power meter pedals for riding outdoors, which is fine. The data is still helpful and interesting to look at. However, it has forced me to no longer use Zwift. It just isn’t that much fun riding on Zwift when every time I ride I know that my power is way too low and it is very difficult to keep up on group rides. Fortunately, the weather is getting better where I am and I see more outdoor riding in my future.
Hey @Chris_Holton -
Yes, we’ve tried pretty much everything. I’ve connected to Zwift as well as many other programs via Bluetooth and ANT+. The data returned is the same.
Additionally, we have tested changing the DUO pedals to UNO so that only one pedal was being read and essentially the power is doubled to provide the overall power. We’ve also done tests where I leave it in DUO mode and just pedal on one pedal. Unfortunately, the data comes back all the same, that is, the overall power result only on the stationary bike provides dramatically reduced overall power numbers.
How could it produce negative power? I don’t understand that. The bike isn’t producing any data, is it?
It can only be that there’s some sort of interference between the power the pedals are measuring and the signal that’s actually being received by the sensor.
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And the crank length was set correctly? Don’t forget that as soon as you connect a Garmin head unit to the pedals, the crank length from the Garmin overrides whatever was set in the Assioma app.
Your guess is as good as mine, but this is what Favero left me with. They (and I) have tried every logical step I can think of and then some, but we are still left with power on the stationary bike that is about 65% - 70% of what it is on any other bike.
Oh yes, the crank length is set each time I move from bike to bike, but it isn’t much. The MTB and stationary bike are 170 whereas my recumbent is 172.5. Keep in mind that we’ve done plenty of tests without a Garmin head unit as well. All the data is consistent, just not seemingly accurate on the spin bike since its power reflects something like 65% - 70% of what it is on any other bike.
John-Paul, since you have DUO pedals, they generate tons of data which you can analyze to understand what is going on. All you need is to capture the data from pedals either on your smart bike computer (e.g., Wahoo or Garmin) or even on a free Android phone app Jepster. Then upload this data to one of the online depositories and import them into WKO5 or Golden Cheetah or into Garmin Connect if you have a Garmin head unit. You will see how much positive and negative power you generate, what is your efficiency, cadence, etc. This should have been your starting point, sorry if I missed it, but I do not seem to find this data in this thread.
Negative power from flywheel? Physically, it is a misnomer, but I think I understand what Favero support means. In this case, you should probably feel a lot of resistance and generate tons of power when you spin it up, and then a drop in power when its rpms stabilize. Also, when you stop pedaling, it should probably continue spinning for quite a bit at your chosen resistance. It would be the same thing as if you are riding on a bike slightly downhill - usually at your preferred cadence, resistance is fairly low and power drops. An excessively heavy flywheel could theoretically create a similar effect.
Thanks @Andrei_Istratov. I’ve actually done some of this with Golden Cheetah. I do have a Garmin head unit so I can see the data on Garmin Connect as well. The only thing that has really stood out is just the difference in overall power. I can’t say I even fully understand what negative power is, but again, this was Favero’s explanation. All I can really say is, which is so perplexing, is if I keep a steady heart rate on the stationary bike (say 130, 140, or 150 bpm) and then do the same on a flat road on an outdoor bike, the stationary bike will report power at about 60% - 65% compared to any other outdoor bike.
I know what you mean, but it isn’t really what I see from this stationary bike. “Generating tons of power” on the stationary bike just doesn’t happen. I can push to 800+ watts on any bike outdoors with these pedals. On the stationary bike it is pretty much a miracle if I can get to 500 watts with the same pedals. Outdoors I can maintain 200 watts all day. On the stationary bike I can hold 200 watts for about 4 minutes I think, but that’s it.
I think the only way I’m going to know for sure whether it is me or the pedals is to have a cyclist that can maintain 200 watts for an hour come to my house and ride the stationary bike. If they can hold 200 watts for 30 minutes and can say that it feels like 200 watts, then I’ll concede that for some reason I just can’t ride indoors, but can outdoors. 
And it wouldn’t be the pedals. However, it could be the other scenario and if they get exasperated quick (as I do) trying to hold 200 watts indoors then I’ll know there is something with the pedals or the bike or interference indoors or something. It just wouldn’t be me.
Fortunately, this opportunity might present itself now that the Pandemic here in Texas is finally getting beat up a bit. I have plenty of cyclist acquaintances I guess you could call them, but I wouldn’t feel comfortable asking them to come ride my stationary bike. However, there are a couple that might indulge me. We’ll see.
Thanks again for all the input here.
That is strange, I can generate the same with my Assioma pedals on the spinning bike or trainer or outside. I can probably get more power outside because I can rock the bike.
I also have stages PM on the spinning bike and it reed very simulator to the Assioma.
You are so right. It is crazy strange. I’ve essentially given up on trying to resolve it and cancelled my Zwift membership. Zwift just isn’t any fun for me when I can’t even keep up on an “Everyone” ride because my power numbers are so low. That’s ok though. The pedals seem to work fine on anything other than this stationary bike and with the weather getting warmer, I hope to be riding outside more. I’m sure I’ll come back to Zwift at some point. All the best.
Hi dear @John-Paul_Wood ,
I am Franz from Peru. I have problems with the power of my spinning machine + “favero assioma UNO” pedals vs my road bike with the same pedals and looking for information on the web I found this forum. However, the opposite happens to me: my power is much higher on the spinning machine (297 watts on average) than on my road bike (170 watts on average) for similar workouts.
I’m not exploring solutions yet, but based on your experience, is there anything I can try? Or do I just accept that I will have this problem forever?
Thank you very much and greetings!
Franz