To give more technical details:
- I only observe this on my stationary rig. I think that with road riding, the signal would be too noisy.
- Smart trainer: Cycleops Hammer 1, which infers cadence (sometimes inaccurately). I don't have a cadence sensor per se.
- Trainer controller: iPad running Rouvy
- Chest band: Garmin and Wahoo chest straps; have observed "dips" with both.
- I see this happening when my cadence is in the 70s or 80s and my HR is in the 110s-120s. So I don't think cadence lock would explain it anyhow (although that is fascinating).
- I do have an optical HR-tracking watch (Apple watch) and could try capturing data using that, but haven't done so yet.