Please help me…I’ve got a Garmin Edge 500 and a GSC-10
I get a speed reading, but no cadence 
Call me a dummy, that’s fine. Walk me through, step by step, how to get cadence. I want to do SUFFERFEST properly. Thanks in advance.
Is it installed properly? Is the magnet on the crank running past the sensor with a gap of about 2-3mm? Is there a light flashing when you move the crank past the sensor? (hint, press the white button on the sensor)
Agreed. First make sure the correct lights are flashing.
Basically, go into a dark area (the LED is not bright) and press the white button. Hand spin the crank backwards. A light (either green or red) should flash every time the crank arm magnet passes the main unit. The other color (red or green) will flash for the speed sensor.
If that works, make sure in: Settings, Bike Settings, (bike name), Ant+ Spd/Cad, sensor details…you have the first option checked. It is: Spd/Cad Sensor.