it turned out that Assiomas Uno read 30w higher than my Zwift Hub.
Fix is easy: just ride with Assiomas. Ok, this works for me on trainer. But I have my summer bike with Quark Sram Red Spider power meter. I havent tested it yet, but I am now 99% sure it reads lower than Assiomas. Something around 3-5% (due to L/R imbalance - Assioma reads from my stronger leg; Quark is dual-sided). I will test it in summer. If I confirm that, what would you do?
I have expensive pedals on that bike, which are 100g lighter than Assiomas. So I dont want to ride with Assiomas outside. I guess I should then lower my ftp/retest it in summer. That’s fine. But it messes up all TR data… until April it will think my ftp is 320 and then, when I start using quark, it will suddenly think that my ftp is lower by 15w or something. This basically will make TR data useless I guess. Too much noise. What do you think? It looks like the only solution is to upgrade Assiomas to dual sided just to have correct reading inside. I dont like this idea
The problem gets even worse when we consider Assioma on my MTB. I havent tested it yet, but again, it felt to me (I had 2 rides on it till now), that it reads lower than Assioma Uno/Quark, becasue it reads from my weaker leg… Power felt underestimated.
So… probably I have 3 different ftp. Suppose that Assioma Road=320, Quark=305, Assioma MTB=300. How would you deal with it?
Treat Quark as default, and then, when I ride on other bikes just mentally adjust power? So that when I do treshold on assiomas road, aiming at 305, I ride at 320, and when I do treshold on assioma mtb, I ride at 300? Just always add/take away adequate %w from my default quark 305w. I think this is the only reasonable option. Probably measuring HR will also help. And comparing it accross bikes. Does anyone have the same issue? How you deal with it?
I would do a session of various intensities with Zwift hub, Quarq, Pedals all connected up to separate head units/devices. Phone, Laptop, Headunit for example.
Make sure everything is calibrated properly. Then use something to compare - DCRainmaker and GPLama have something I think?
work out the differences, adjust scope across them all so they should match. I would pick the Quarq as the baseline/datum point to match to.
Retest, confirm numbers are the same. Doesn’t really matter if the 300w is actually 300w or 350w, it’s that 300w on one power meter is the same on another. Consistency > accuracy when it comes to different power meters.
I was going to make the same suggestion. If you’re talking 3 meters, the Quarq is the odd one out, so I would scale the two Assiomas to meet the Quarq.
Thanks, I forgot that I can scale up/down assiomas… So I simply need to test Assioma Road/MTB vs Quark, identify % difference and then scale down/up Assiomas accordingly. I guess this fixes my problem without testing ftp and other crazy stuff. I can then also clear data noise on TR becasue assioma road on the trainer will be scaled down adequately to quark power. Looks like problem is solved
First of all make sure that you are properly calibrating your power meters. That means doing so after they have warmed up.
Also, with power meter pedals you have to make sure they’re tight, then do a few sprints on them, then finally calibrate them. If the tension on the threads changes, so will the power readings.
Another thing with the Assiomas (and all power meter pedals) is that they will give wrong power if you don’t have the crank length set correctly in whatever app or device you’re using to RECORD the data. It doesn’t matter what the crank length is set to in the Assioma app because you’re not recording in it. Check and adjust as needed.
Then, do what @noahphence said. You only really need the power near FTP to be accurate, so do a sweetspot or threshold ride for your comparison. Then if you really do need to adjust power to get them to match, do so.
Another thing with the Assiomas (and all power meter pedals) is that they will give wrong power if you don’t have the crank length set correctly in whatever app or device you’re using to RECORD the data. It doesn’t matter what the crank length is set to in the Assioma app because you’re not recording in it. Check and adjust as needed.
So… crank lenght on assioma/sram app dont matter, what matters is crank lenght on my wahoo? So, I can have different crank lenght on those aps, but if wahoo is set to 170mm then every device will show correct number? Right? Are you 100% sure?
Yes. If you are recording the data on your Wahoo, then whatever crack length is set there is what will be used, regardless of what you set in the Assioma app.
Please read your power meter manuals. If you use the tool wrong you’ll get bad data. Assioma makes the BEST power pedals on the market. Accuracy is +/-1%. It’s unlikely you have two defective ones. Even if you did, then you’d work with Assioma to get them replaced.
-You can and should set your crank length properly in the Assioma app, since this tells the pedal what crank length it has but this is only used in the Assioma app
-However, your Wahoo/Garmin/etc GPS will use the crank length set in the Wahoo GPS.
-if you use RideWithGPS or any other app to record your ride, the crank length needs to be set correctly in that app
-So whatever device you use to record your ride needs to have the crank length set correctly. If it’s wrong there, your power will be wrong
Please read your power meter manuals. If you use the tool wrong you’ll get bad data. Assioma makes the BEST power pedals on the market. Accuracy is +/-1%. It’s unlikely you have two defective ones. Even if you did, then you’d work with Assioma to get them replaced.
They are fine. The problem is that they are single sided. Assioma Road reads left leg, Assioma MTB reads right. But I have L/R imbalance. 54/46. So, I assume quark is the most accurate becasue it is dual sided.
If I am thinking corrrectly, Assioma Road reads 104% of my true power (which equates power from two legs), while Assioma MTB reads 96% of my true power. Am I right?
I expect that I will have to adjust them by +/- 4% then to ofset these misrepresentations of my power.
I expect that real life tests on the road will support this.
I always felt that I can do more power on Assioma Road. Did not know why
300 vs 305 is insignificant, so I would just ignore that.
For the 320 one, there may be an option in your head unit to scale the reported power for that specific power meter. This is what I do with my Garmin - if your software supports it, just set the scale factor for your Assiomas to 94% instead of 100%.
