The Garmin Edge 820 puts a color touchscreen and advanced mapping functions into the same size unit as the Edge 520, but it is much more powerful. With the Edge 820, the pre-installed Garmin Cycle Map provides turn-by-turn cycling-specific navigation, address search, points-of-interest, audio prompts, and even a round-trip Course Creator that will design a custom local route based on rider preferences for length and difficulty.
ANT+, WiFi, and Bluetooth connectivity allows for compatibility with power meters and Garmin Varia™ devices, along with allowing text, call, and other notifications from a paired smartphone. It also makes possible Garmin's GroupTracking feature that allows other Edge 820 users to join together to show real time positions, useful for keeping track of riders when they get split up, or for locating the exact position of a group ride when meeting up.
Advanced performance metrics include VO2 max, recovery advisor, FTP, performance condition, stress score, and other cycling dynamics when used with a heart rate strap, and power metrics include left-right power balance and power phase for determining evenness of pedalling. Strava Live Segments allows real-time KOM tracking with premium accounts, and while paired to a smartphone, built-in incident detection can send a message to an emergency contact in case of an accident.
All this data is easy to see on the 2.3" high-resolution color touch screen. Its ambient light sensor automatically adjusts for the best visibility in all conditions, and the touch functions are designed to work even when wet or when the user is wearing gloves. When power is running low, a battery-save mode shuts off the display while still recording GPS location and providing notifications, extending the remaining battery life by up to 50%.
2.3" display. Unit measures 1.9" x 2.9" x 0.8". Claimed weight is 2.4 oz. 15 hour battery life in GPS training mode. Rated IPX7 waterproof. 16 GB internal memory. Includes standard and out-front handlebar mounts, USB charging cable, tether, and user manuals.