Garmin’s long-awaited follow-up to their RTL515 Radar is here – the Varia RearVUE 820. With longer range, brighter light, better battery life, and the most impressive radar performance I’ve tested to date. After several days of real-world road testing (and a lot of time riding in traffic), this in-depth review covers everything from unboxing and battery bench tests to head-to-head comparisons with the gold-standard RTL515. But there’s a catch. Digging deeper uncovered a critical ANT+ radar distance issue that affects how threats are reported on many bike computers. If you’re considering the Varia 820 this is everything you need to know.