Technically, spinning ( and regular cycling ) are not step-based activities. Not sure why one would expect to get any steps out of it without doing any steps. Steps you see from spinning are just an error caused by more vigorous wrist movements ( especially when pedaling standing ). Last Sunday during my ride my tracker gave me over 8000 steps because the ride was incredibly bumpy and full of potholes. Usually, on a smooth surface, I get a lot less. Mind that the watch knows nothing about your feet and can't tell if they are moving or not. It all depends on wrist motion.
