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
)