I own a Garmin 820.
If you have Garmin heart rate, speed and cadence sensors then you don't need the bundle. The 820 will work with existing Garmin sensors.
As an aside, Wahoo RPM speed and cadence sensors do both ANT+ and Bluetooth so these cover any device. Like the Garmin sensors, they don't need magnets.
-Tim-
Last edited by TimothyH; 08-05-17 at 02:50 PM.