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I am getting a 10 watt difference between pedals and Tacx Neo 2. I did a 5 minute set and the pedals reported 341 watt average and the trainer 331 watts. So that equates to a roughly 3% difference. Given drive train loses is that an acceptable figure?
So long as the numbers are repeatable
The actual numbers don't matter a jot.
Tbh go look at DC rainmaker.....10watts is nothing.picking the correct trainer/pedals/crank can be the difference between winning and losing on zwift. ....which is why zwift racing will never be taken serious without controlled inputs.
Just pick the number that makes you feel better.
3% is buggerall.
Two different measurement techniques getting to within 3% of each other - that’s pretty impressive.
I think that is pretty good. It would be interesting to see if the 10 watts is a constant offset though across the range, if that is the case then it is more significant lower down the range.
Segal's law is an adage that states: "A man with a watch knows what time it is. A man with two watches is never sure."
If one is +1.5% and the other is -1.5% then that's pretty impressive.
Or (tongue in cheek) maybe one is -50% and the other is -53%. You wont know for sure unless you use a third power meter 🙂
It's probably what you could expect, if one was perhaps +1% of its claimed accuracy measurement and the other was -1% of its accuracy range. Plus a little discrepancy between manufacturers and drivetrain losses.
I got 2watts difference between my Elite Drivo and Favero pedals at 330w. It was the Drivo that was high, the pedals low.
You'll lose or gain a few watts depending how you feel day to day, so I'd pick the one you spend the most time using as the reference and just be aware the other unit may be up or down slightly.
Cheers all. Given the comments above I'll stop worrying about it.
Do you have the raw data rather than average? You want the root mean square error really to give the average difference. But I wouldn’t be worried by 3% either
You wont know for sure unless you use a third power mete
Less tongue in cheek - perhaps you could tell this to Boeing? The 737 Max would still be flying if they had heeded this.