Varia RTL516 Rear Radar

The Garmin Varia RTL516 is one of those products that, once you've ridden with it, you never want to ride without. The rear-facing radar uses a frequency-modulated continuous wave sensor to detect approaching vehicles up to 140 meters behind you, sending color-coded alerts to a paired Garmin Edge computer, compatible bike computer, or smartphone running the Varia app.

On rural highways and country roads — the kind of roads that make up most bikepacking routes — this early warning system is transformative for rider confidence. A green bar means the road behind is clear. Yellow dots appear as vehicles approach, their position scrolling down the display as the car gets closer. Red means multiple vehicles or a fast-approaching one. You know what's coming 8-10 seconds before you'd hear it, giving you time to tighten your line, move to the shoulder, or simply prepare mentally for a close pass.

The integrated 65-lumen tail light seems modest on paper, but its behavior is what makes it effective. In the default peloton mode, the light flashes in a steady pattern. When the radar detects an approaching vehicle, the flash pattern becomes more urgent and rapid, specifically drawing the driver's attention. Studies suggest this dynamic flash response increases the likelihood of a driver noticing and moving over. The light is daylight-visible from a reasonable distance.

Battery life is exceptional at up to 16 hours in peloton flash mode — more than enough for even the longest bikepacking day. The radar sensor itself consumes minimal additional power. Charging is via micro-USB (not USB-C, which is a minor annoyance), and a full charge takes about 3 hours.

The seat post mount is secure and positions the unit at optimal radar height. For bikepackers with large seat bags that block the seatpost, Garmin offers a saddle rail mount adapter, and third-party mounts that attach to rear racks or bag straps are widely available.

Pairing with non-Garmin devices has improved significantly. The Varia app works on both iOS and Android, providing radar overlay on your phone screen. Wahoo ELEMNT computers also display Varia data natively. The ecosystem is no longer Garmin-only, which broadens its appeal considerably.