I know that Wahoo does not advise setting the KICKR Bike so that SYSTM is controlling the bike, but power and cadence come from Power Meter pedals - Assiomas or Wahoo. Has anyone tried that? Did it work correctly in ERG mode, or did resistance bounce around trying to find the right level?
If SYSTM is controlling, but pedals are only displaying then there should be no problem.
I’m wondering what will happen if there is a noticeable divergence between what the KICKR Bike measures and what the pedals measure. For example, let’s assume a 10% difference, where the trainer reads 200W the pedals read 180W. Using SYSTM or any other app I set the trainer to control effort and tilt, and the pedals as the source of power, and do a 200W interval in ERG mode. SYSTM sends some sort of signal to the trainer telling it how hard to torture me… but does the pedal power meter show 200W or 180W? Is this stable - when SYSTM sees I’m only putting out 180W when the trainer has been sent a signal for 200W, does it increase the resistance, does this make the whole thing unstable with resistance oscillating around the desired value (already an inherent problem with ERG mode because of delays)?
I suppose I could test this, and I could probably figure out how to use the calibration options on the pedals to create a 10 percent difference, but I’m hoping some one knows or has a pointer to some source that describes in some detail how software controls the trainers - how much “smartness” is in the trainer and how much in the controlling software, does the software send a signal to set X level of power (using the trainer’s notion of power), or does it send a signal to increase or decrease resistance based on the pedal power meter’s reading?
Wahoo describes the result of having the trainer controlled by SYSTM but getting power from the pedals, as “poor trainer control”. The lack of responses to my post leads me to conclude there are only a couple of possibilities:
- The trainer control is so poor that there have been no survivors, or
- We are all sheep who have never tried anything that goes against the company’s will
So reluctantly, I am going to try a short session of “poor trainer control” after a few more cups of coffee and a few errands. I’ll report on my experience.
The ERG trainer control is not so poor that it killed me, or even seemed that odd once I got up to cadence. Instantaneous power levels may have been just a touch more bouncy, but nothing serious.
However, the KICKR Bike clearly receives the resistance as an absolute power level, the eyeball-average power over the intervals of the 10-min Warm-Up novid was clearly lower than it should have been, and in fact the I/F was off by the factor I would expect for given the two power meters.