I have a Polar F6 about like already posted. A Garmin Edge 705 for outside with cad & hrm kit.

You wouldn't be able to get cad on the spin bike unless it had a sensor or it's own puter. We used to have those at one of my gyms. It would pick up my Polar hrm. Cleaning spray & sweat ruined them unfortunately with alot member use. At home you may have better luck.

My Polar also just makes a nice sport watch. It's water proof, so wearing it to the beach, or gardening/watering etc. it's safe to not get trashed. My watch piece has lasted me 6yrs now. Just had strap replacement / batt with batt service for watch piece. Fwiw.