Garmin Varia RVR315 Rear View Radar Review 2026: Radar-Only Tested
Why a Radar Belongs on Your Bike
Most road training happens with traffic behind you, not in front. A rearview radar gives you visual and audible warning of approaching vehicles before you can hear them, which matters most on narrow lanes and fast A-roads where a lot of long-course bike training actually happens. The Garmin Varia RVR315 is the radar-only version of Garmin’s Varia line, for riders who already have a tail light they like or don’t want one running for group rides and races.
Key Features to Consider
- Up to 140m detection range — the radar tracks vehicles approaching from behind and displays them on a compatible Edge computer or Garmin watch, with distance and closing speed shown as dots.
- No integrated light — this is the RVR315, distinct from the RTL515 which bundles radar with a tail light. Choose this if you already run a dedicated tail light.
- Up to 7 hours battery life — shorter than the RTL515’s 16 hours since there’s no light to power, but enough for most long training rides on a single charge.
- Mounts to D-shaped, aero and round seatposts — using the included quarter-turn mount, compatible with most modern TT and road frames.
On the Bike
The radar itself uses the same detection technology as the pricier RTL515, so you’re not sacrificing accuracy — only the integrated light and its longer runtime. If you already own a bright tail light you’re happy with, or you race with lights off, the RVR315 gets you the same situational awareness for less money and one less thing to charge.
Price and Verdict
At £109 (RRP £129.99) from Tredz, it’s a meaningful saving over the RTL515 for riders who don’t need the bundled light. Given how many triathlon training routes involve unavoidable stretches of fast open road, this is one of the more genuinely useful safety upgrades you can make to a bike computer setup.
Care and Maintenance
Wipe road grime off the sensor lens after wet rides — a dirty lens can reduce detection range. Update the firmware periodically via Garmin Connect, since Garmin has previously improved radar sensitivity and false-alert filtering through software updates.
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