The FIT File with DC Rainmaker and DesFit Is Garmin's New Varia 820 Radar "Too Good"?
Mar 29, 2026
They dig into Garmin's new Varia RearVue 820 radar and what makes it unusually capable. Conversation covers brighter lights, longer and wider detection, and the tricky UI that takes time to learn. They debate lane/orientation usefulness across regions and compare accuracy, false positives, and classification quirks against rivals like Wahoo and Lezyne.
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New Detection Features Increase Information Overload
- The Varia 820 adds vehicle size, left/right orientation (lane) detection, longer/wider range, and better same-speed hold.
- DesFit and DC Rainmaker both found the UI initially overwhelming but useful after multiple long rides to learn patterns.
Drone Tests Showed Extended Range And An ANT+ Bug
- DC Rainmaker tested detection range with a drone and found validated detections up to ~220–240m, exceeding the prior 170m spec.
- Shane Miller discovered a bug where ANT+ broadcasts capped or misreported distance, causing brief erroneous short-distance blips.
Use Secure Bluetooth Or Update Firmware To Avoid False Blips
- Update older bike computers or use secure Bluetooth to avoid the ANT+ distance-capping bug; Garmin issued a firmware fix that caps ANT+ broadcasts at 196m until secure BT is used.
- Treat distances beyond ~196m as noncritical; Garmin notes practical cyclist safety isn't impacted between 196m and 220m.