After my Wahoo Speedplay power pedals crapped out last year, they sent me a repalcement pair…but based on a few rides, they seem to be measuring low, as well.
Ordered a pair of Favero Assiamo pedals, which I tried out today while dual-recording the data from my H3.
From a topline view, the data seems to track well, but if you zoom in to smaller sections, there seems to be a decent amount of variance. Not certain it really matters that much, as I usually don’t get that detailed in my analyses, but thought I would solicit some feedback from those that have used the @dcrainmaker analysis tool before.
OK, here are some screenshots. In the below graph, the purple line is the H3 and the blue line is the Assiamos. The occasional dropout for the H3 is interesting, especially since it is never noticeable while riding.
For grins and giggles, I did a quick ride this afternoon with the Wahoo Powerlinks on the same H3 trainer. On these graphs, the purple is the Speedplay Powerlinks and the blue is the H3 trainer. At first, I was worried that I had spent money on the Assiamos that I didn’t need to, because the data seemed to be tracking well. But you can see after I made a small effort later in the ride, the two data sets begin to diverge immediately and the Speedplays then start to read noticeably lower for the remainder of the ride. (But the dropouts from the H3 are present in this file, as well)
Again, these are essentially brand new Speedplays, after they warrantied my older pair. I maybe have 10 rides on them (was focusing more on gravel rides after I got them), if that. But the RPE vs. displayed wattage was noticeable right away. The above graphs just confirm it.
Looks like the assiamos track well to me, do the pedals just have a higher recording rate compared to the trainer, so the trainer is effectively smoothed?
Hard to say why the Assioma data is noisier than the H3 without know the technical deets of each. The Assiomas need to measure pedal forces in multiple directions and then calculate the instantaneous net tangential component to determine torque and then power. There are more inputs and it requires a pretty high measurement rate compared to measuring pure torque at the rear axle, so this could possibly account for it.
Saris claims a 2% accuracy, while I believe the Assiomas are 1%. Maybe it’s something to do with your pedal mechanics / smoothness that is smoothed by the trainer as suggested by Saddlesaur.
Here is a snip of a semi-random two minute portion of a race (selected due to significant variation between highs and lows in power) from a few days ago. Assioma Duos & TacX 2T. Without doing any numerical analysis, it does appear that the pedals have a bit more variation than the trainer, but pretty minimal.
The snip below, however, shows a significant different in power “smootheness”, and it’s between my Keiser M3i spin bike and my pedals. I did a dual-recording test ride to see how accurate the Keiser is, hence the 1min at different power outputs (I did about 12min, with 1min at each of a variety of cadences/power combos, plus one sprint in which the pedals had a 1.5% higher max power reading than the spin bike).
The spin-bike is a fixie (no coasting), and it has a lever to a adjust resistance (25 settings, digitally displayed), but while in the saddle it feels similar to always being in erg-mode. While the pedals had a bunch of drop-outs, you can see that the pedals read with a some power bobbing up/down, while the spin bike reads almost dead-flat. The averages are the same, but the pedals show the actual power delivery I’m putting out, while the spin-bike’s flywheel inertia provides massive smoothing.
I have the Saris H3 but with garmin power meter pedals (1 sided) and the H3 reads about 20% higher. Even across 2 sets of pedals so i just assume its due to how its measured i.e pedal vs at the flywheel.
You can’t really compare a trainer power to a one-sided power meter. One measures actual power and the other measures one leg and doubles it. Apples and oranges, really.
To further the apples vs oranges…doesn’t a smart trainer measure changes in flywheel speed and estimates power based on that? It has no strain gauges or anything, right?
Assuming accurate PM pedals and an accurate trainer, the pedals should read a few Watts more than trainer due to losses in the drivetrain. Of course single sided is OK for most purposes, but it won’t be as accurate as double sided or total power. Avg L/R power might only be a few percent different but the difference can be significantly larger at differing levels of exertion or different phases of a workout.
That’s how I understand it too but mine read less. It’s quite annoying but only for continuity, I’m not really fussed if my FTP is the higher or the lower number (hopefully higher ) but I’d rather them be the same lol.
End up going off HR and RPE in the end and looking at numbers afterwards.
) but I’d rather them be the same lol.