Garmin Varia Rearvue 820

The Garmin Varia RearVue 820 is the most capable radar tail light Garmin has ever built — and the first true successor to the RTL515 that changed how cyclists think about what's behind them. It detects vehicles up to 175 meters back with a 60-degree radar beam, classifies them by size and threat level in real time, and pushes that information to your Edge computer, compatible watch, or the free Varia smartphone app. You know what's coming before you hear it — and you know whether it's a sedan or a truck.

At 100 lumens in Day Flash mode, the RearVue 820 is 58% brighter than the light it replaces, visible from over 1.2 miles away. An integrated brake light detects when you're slowing and triggers a rapid-flash pattern automatically — no button press, no thought required. Four light modes cover every scenario: Day Flash for maximum daytime visibility, Night Flash at 40 lumens for after-dark rides, Solid at 25 lumens for steady output, and Peloton at 8 lumens when you're drafting and need radar without blinding the wheel behind you.

Battery life runs up to 24 hours in Day Flash and 30 hours in radar-only mode — enough for a full week of commuting or a 200-mile gran fondo without touching the charger. The move to USB-C means you're finally using the same cable as everything else in your kit bag.

The RearVue 820 connects via ANT+ and Bluetooth simultaneously, pairing with Garmin Edge computers for the full suite of vehicle tracking features — including same-speed monitoring, lateral vehicle positioning, and the new vehicle size classification that shows small, medium, and large icons on your screen. It also works with Wahoo, Hammerhead, and Stages head units for standard radar alerts, and with Garmin watches for on-wrist notifications. At 90 grams with an IPX7 water rating, it mounts to round, aero, and D-shaped seatposts with a quarter-turn mechanism that locks on and releases in seconds.

Garmin Varia RearVue 820 Highlights

• Radar Range: 175 meters with a 60-degree beam width — 35 meters farther than the RTL515.
• Visibility: 100 lumens in Day Flash, visible from 1.24 miles (2 km).
• Vehicle Intelligence: Classifies vehicles by size (small, medium, large) and threat level based on speed, trajectory, and lateral position.
• Automatic Brake Light: Accelerometer detects deceleration and triggers a rapid-flash braking pattern — no input required.
• Battery Life: Up to 24 hours (Day Flash), 15 hours (Peloton), 30 hours (radar-only). USB-C charging.
• Connectivity: ANT+ and Bluetooth simultaneously. Works with Garmin Edge, Garmin watches, Wahoo, Hammerhead, Stages, and the Varia smartphone app.
• Weight: 3.2 oz (90 g). IPX7 water rated.
• Mount: Quarter-turn seatpost mount with adapters for round, aero, and D-shaped posts included.

Final Take

The Garmin Varia RearVue 820 is the radar tail light for riders who want to know exactly what's behind them — not just that something is there. Vehicle size classification, threat-level alerts, an automatic brake light, and a battery that outlasts your longest rides. Once you've ridden with it, you won't want to ride without it.