I’ve looked at threads with similar topics but have some specific info
Just got some Assioma Favero pedals and I’m seeing a wattage difference of 20w-30w in favor of the pedals.
Now on both bikes I’ve tested it all on, I confess to the drivetrains not being the best condition (cyclocross bikes used as they should be and waiting for lockdown to ease to get the bikes properly serviced etc before the season starts ) . But chains are clean/lubed etc just not as well as I’d like as my good cleaning stuff is not with me at him at the moment.
But does that account for so much difference? Ftp is at 285 so roughly 8-10% difference.
Everything has been calibrated properly etc, I’ve emailed elite to see what they reckon but wondered if anyone has similar experiences. Crank length is also correct.
I know I can just use the pedals and do powermatch but I just wanted to check so I can try and track progress as best as possible.
Is the difference more or less constant at 200, 250, 300, 350 W?
From my podcast education experience, I can tell you that the best-lubed chains lose 4-6W and really dirty or unlubed chain can lose these 20W you have there (measured at 250 W).
I have the same combination of Favero and Direto. The pedals read ~20-25 Watts more than the trainer. In my case I am using Favero Uno (one sided) and know that I have a slight imbalance, which would explain some of the difference (2% = 6 W). Add drivetrain losses (3% = 9 W) and there is still some unexplained loss (2-3%). This is almost within the added tolerance of both.
Drove me crazy in the beginning, then i just decided to write off some hard earned FTP and train to the numbers of the direto (because pedals are one sided and i use the trainer more). Outside I adjust accordingly…
Still asking myself which one is true! No explanation, just confirmation that you are not the only one
P.S. I just removed the little washer between crank and pedal - have not checked after. Somewhere I read this might lead to incorrect readings if used with some cranks.
When you pedal, the applied force (torque) of your pedal stroke starts at the pedal – and gets transferred through the drive – crank arm, spider, chainring, chain – and ultimately arrives at the hub. It is at the hub where your force works to propel the bike forward (in unscientific terms). However, at every step along the way, a tiny bit of power is lost, or absorbed, in the drivetrain. Experts say that overall drivetrain power loss is approximately 2-3%. Therefore, keeping the math simple, if you applied 200 watts to your pedals, the pedals would see all 200 watts. The hub however would see roughly 194-196 watts.
Bu not perfect, even after calibration the Assioma are Plus or Minus 1-1.5% Accurate and Th Direto is of similar accuracy.
So if one device is on the + side accurate and the other -1.5% you have 3% difference, Then Drive train losses Very Well maintained bottom bracket and rest of the drive train.
So at 280 Watts 3% = 8.4w , then another 8.4 watts in the drive train if perfect.
That takes you to 17 Watts as all things get rounded up…
As you say your drive train is not perfect that will take you up a few more watts … And that’s you at the 20-25 watts.
The main thing is , is it the same over all power ranges.
I have the pedals (Duo) but use only outdoors. I might try them on the trainer to see what i get or will be posting like you soon afterwards
Do your FTP to pedals and workouts to Pedal FTP and you will be working at the right level
FWIW, I just got a set of Assiomas (love them!) and used the ZwiftPower site to compare my trainer power to the pedals. I looked to see how power tracked relative to each other over the duration of the ride, critical power curve, and cadence. For me everything tracked well, but you could do the same to determine if there is an issue or not. NOTE: The difference on the left side of the Critical Power graph is due to the trainer smoothing power during the structured portion of this test ride whereas the pedals reported the fluctuations that actually occurred.
I run Zwift and TrainerRoad in parallel but I think anyone can sign up for a ZwiftPower account. Once there, go to zwiftpower.com --> profile --> analysis. Load your workout files and then compare.
Original (2017?) Direto & Assioma Duo user chiming in. I found that the power offset varies from ~10 watts to about the same. I never quite nailed down what factors were influencing. Chain lube, chain line, Flywheel speed, temperature, will all matter to different degrees. I worried about it when I first got my assiomas, but now I blindly use powermatch in TR and don’t stress.
I didn’t know that zwiftpower could do comparisons like that… i might need to do another check some time soon.
Direto is 1646 when calibrating and number is 1650 on the bottom.
I’ll record my files for both and stick them in zwift power to check but I’m pretty sure it’s consistently different if that makes sense!
I don’t mind- I trust the pedals and will be using them for racing/outside etc I just wanted to work out if it was the chain etc as when it comes to proper racing I wanna get those lost watts back into the rear wheel
Noting a new chain/cassette, a good service and jockey wheels won’t solve though.
It also helps me work out my progression as times moves on- I just need to remember the jump up wasn’t all down to training
Quick question on your data… how did you record the non-zwift activity and is that blue curve on the power chart the Assiomas? Your data looks super smooth compared to mine.
This is a dual recording of Pettit on TR and Zwift. TR set to control the Direto using powermatch from the assiomas in ERG mode. Zwift using the Direto only as a power source, no trainer control and no grade simulation. I stopped pedaling at 10min to create a sync point. I used the small chainring to start, swapped to the large chainring from 20-40min and back to the small at 40min for the rest of the workout. Based on average power, when in the small ring the power difference between assioma duo and direto is .5%. When in the big ring, the difference was 2.1% Direto>Assioma. Pretty happy with that. I use a waxed chain and have a hybrid 9 & 10 speed drivetrain setup on my trainer bike.
I have a 2018 Kickr Core with Power Smoothing enabled, which is why the purple line is so smooth on the right side of the power graph, which is when I had TR control the trainer in a structured workout. The left side (first 20 minutes or so) were a free ride in Zwift.
I dual recorded my ride - Zwift and TR getting power from the trainer, my head unit (Garmin Edge 830) collecting power and cadence from the Assiomas. I have not enabled Power Match yet.
I’m not surprised about the power difference between the small and big chain rings. GPLama has a good video describing how the differences in flywheel speed affect a trainer’s ability to maintain power (sorry for no link - can’t access YouTube right now).
The last set I was working pretty damn hard obviously and the Direto was reading around 260 watts average. From my experience of other power meters and trainers- the effort was matching what the Faveros were saying- 300.
I held 280 for 40 minutes on it just a few weeks ago doing a TTT so i’m pretty sure something is up with the trainer and the pedals are giving me an accurate reading. My best 10 minute power from Tunemah with the pedals also matches my best 10 minute power from a race I did in December on Zwift.
If I take into account drivetrain losses etc on my older rides/races the pedals and the trainer align nicely: 280 on the Direto, 295 on the Favero’s. It is only recently the trainer is giving me way lower readings than expected for RPE and heart rate etc, and the pedals back that up.
Offset for the trainer is 4 off what it says on the bottom. 5 or more and they say tighten the belt I think? I’ve contacted Elite but heard nothing back as of yet.
I don’t mind as I will use powermatch and the pedals inside and outside, but I’d rather know if the Direto isn’t doing what it should and get it sorted, as it’s an expensive bit of kit and I’ve had it under a year.
Do you know if this is an update to fix your specific issue or a beta version of an upgrade to come? Since I have the same issue i am wondering if this will be fixed eventually…
P.S. I always assumed my favero uno is reading high, not the trainer reading low. So this would give me an immediate FTP boost. Bragging purposes only, because it changes only the number, not my power.
Not sure- may be worth getting in contact with Elite- they had me do a very specific set of efforts whilst dual recording and then asked for my serial number, then sent me the file.
I thought there was something up with my trainer before I got my pedals, just based on comparing efforts and outside rides/races I did with people who had PM’s. The pedals confirmed it and now the trainer is reading properly, so all good
