Is anyone familiar with smart bikes making it harder to reach power numbers for (more or less) sustained efforts than you would reach fairly “easy” when riding outdoors?
For example during VO2max efforts, but also in Zwift racing it seems harder to hold numbers that would normally be doable on the road bike. I’ve heard two people complaining about it and claiming their smart bike is reading low. Given the fact one has a Wahoo Kickr Bike (v1) and the other one has a Tacx Neo Smart Bike (v1) the smart bike might not be the culprit here.
The difference seems larger than the k(more or less) nown 5-10% indoor-outdoor difference.
Could it be that the biomechanics of a smart bike are different from a normal road bike on a trainer?
Personally, I feel between auto spindown calibrations and virtual shifting, some of the trainer power numbers are dubious at the moment. The pedals are probably most accurate. You didn’t mention where the two power source were recorded, if on Zwift or TP Virtual, sticky watts are also a consideration.
The suggestion to use one power meter for indoor and stick with it are sound, at that point it wouldn’t matter which is accurate.
Recently acquired a pair of Favero Assioma PRO-MX2 PM pedals and decided to throw them on my Peloton Bike+. DCRainmaker had a review years ago about how the power output on the Bike+ (note, this is not the original Bike which is notoriously all over the place with power data/calibration issues) and I thought I might as well give it a go. Pedals were linked to my K2. A couple of drop outs. But overall, cadence matched up perfectly as did heart rate (two separate HRM, one recording to Bike+, the other to K2). Power about 10-15 watts less with the Pedals.
Favero Assioma PRO-MX compared to my Power2Max ngECO crank on my regular bike. Not as long of a test as was on the rollers inside which I haven’t been on since last year. In first picture, magenta is PM pedals and the drop in power/cadence is me reclipping my left foot back into the pedal. Yellow is the crank data.
In second photo, magenta is crank data and yellow PM pedals. Early drop is me nearly wiping out. Not entirely sure what happened with the torque numbers in that second one.
If you have good power meters on your bike like Assiomas I feel like it is best to use the bike power so that outdoor and indoor power match and record data on your head unit. You can create a script to merge the data so you can get course data. This way everything is consistent. The power your getting on your head unit should be the same regardless what the trainer is doing. Why have two different power recording values, that seems like a bad direction to go in too me.
I use assioma double sided PM and Wahoo Kickr Core.
Wahoo gives higher values of aprox. 3-4%. The gap in absoulte numbers obviously gets bigger if I push bigger numbers.
Since outdoor riding is where performance matters for me the most I override trainer power in apps like zwift and use assiomas to read power and cadence instead. (it has helped me to ditch ERG and work on pacing as well, which is a bonus, ngl )
Anyways, 10 wats diff can hardly put you in a wrong zone, FTP is a spectrum of +/- couple of watts. Since it always differs a bit I see oportunity here to learn how to match the numbers to the RPE and follow taht xd
Dealing with this too now. What annoys me the most is that my pedals (Rally 200) sometimes report higher Watts, but usually it’s my Kickr (2020/2021 version) now that gives higher numbers.
Makes sense to take the pedal numbers since that’s all I’ve got anyway when outdoors… but it’d be nice if at least the variance between the two was more consistent.
How do folks draw the comparisons above by the way? Intervals.icu’s de-duplication works too well, I rarely get both recordings of a workout to play with, and it’s also not always super obvious which one of the two it kept, then.
Are the workouts on zwift that you do using ERG mode or not?
I spent a few weeks trying to do vo2max & threshold efforts on zwift on different routes with varying success, which seem to highligh my pedalling inefficiency to hold a set range/wattages and went back to staggered/set power ranges on workouts.
I found Rouvy manages these interval sets better whereas with Zwift and using the Companion app you get more of a sense of what the range is in-app.
fwiw, vo2max efforts are almostly always v.hard going.
Most the races don’t allow/enable erg as they’re freestyle,
i.e. you have to use the pyhsical or virtual gears for shifting/resistance and maintain it.
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