I use it with my treadmill, it will keep my heart rate in a certain zone automatically and I don't have to fuck with the speed/elevation. Most cardio equipment comes with this built in now. If you are looking to use one outdoors on your bike there are many options, but make sure you get one with a zone alarm, it will alert you when you're out of your target zone. Stay away from some of the Polars that don't allow you to change your own battery, they make you send it in for replacement. Also note that after a few years the sensors in the chest strap will be destroyed from the acids in your sweat and it will no longer be a battery problem if it doesn't work. But still you should get a good 2-3 years out of it even if using daily. Also, when done wipe it down with a cool damp towel, that will shut the battery off quicker and make it last longer.