It should register your heart rate fine, whether you label is as spin or workout.
As an aside, because your wrist doesn't move much when you are on a stationary bike, whether a spin bike or a recumbent, all it has to work with for calorie count is the heart rate. So if it gets bad HR readings for whatever reason, the calorie burn for the exercise will be off. I think it does a little better with calorie readings for walks, runs, hike, bike rides on real bikes, etc, because it has both HR info, and movement info.
Scott | Baltimore MD
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