I’ve recently identified a SERIOUS issue with the Turbo Muin B+ power data accuracy, having finally gotten round to buying some proper power meter pedals and running a comparison. My FTP value based on a ramp test using the Muin B+ was about 20% higher than the value achieved using my pedals. At first I thought there must be a fault with the pedals (wishful thinking, it turns out), so had replacement spindles sent out that had been calibrated and validated for accuracy at the factory… Same issue. The pedals are reportedly accurate to within 1%, so I’m trusting their data. After digging around, I found a similar user review that says that the Muin over-reads power particularly badly for shorter intervals, compared with longer intervals, which would exacerbate the discrepancy given that the FTP data was derived from a ramp test with 1 minute step-intervals. It also reputedly gets less accurate the higher the power, which again would exacerbate the issue, given that the later intervals in the FTP test were in the 400W+ region.
This was a massive wake up call for me: I would not trust the Muin B+ data for any remotely serious training purposes.