Instructions for correctly pairing your GSC-10 Speed/Cadence Sensor to your compatible Garmin:
1. Once the magnets and sensor are mounted on the bike, turn on the Garmin and follow the menu sequence Settings > Bike Settings > [Bike 1] > ANT+ Spd/Cad. and press Rescan.
2. Update your Bike data in the Garmin to document the wheel diameter for the most accurate speed and distance readings: MENU > Settings > Bike Settings > [Bike 1] > Bike Details. In the "Wheel Size" field, select an option:
Selecting "Auto" will use GPS data to calculate your wheel size. ***Auto wheel size may vary in accuracy depending on the accuracy of the GPS and whether the magnet counts every wheel revolution during the test period***
Selecting "Custom" to enter your wheel size. You can either take out a tape measure and mark the distance of one wheel revolution on the ground, or you can reference the table of standard wheel sized and circumferences. Measurement is Length in millimeters (mm).
3. If you attach your Garmin to another bike, it is important to document a new bike in your Garmin's settings, and to switch to that bike, especially if the wheel circumference is different (mtn bike versus road bike for example).