Bryton Gardia 300L Rear Light & Radar – 190m Vehicle Detection, Brake Light & ANT+ Connectivity

The Bryton Gardia 300L is a combined rear light and radar unit that detects vehicles approaching from behind at up to 190 metres and alerts you — and the driver — automatically. It's the practical safety upgrade for road cyclists who ride on open roads and want advance warning of traffic without constantly checking over their shoulder. The radar assesses the relative speed of approaching vehicles and adjusts the light mode accordingly: a steady threat triggers a warning flash pattern; a fast-closing vehicle triggers a more urgent response. When paired with a compatible Bryton bike computer or the Bryton Gardia app, visual and audio alerts appear on screen so you can react without taking your eyes off the road.

The light itself uses a CREE XPEBRD-L1 LED with a 220° viewing angle — wide enough to be seen from the side as well as directly behind. The daytime running mode uses an interruptive flash pattern visible up to 1.6km in daylight. Automatic brake detection activates a high-intensity brake light mode when you decelerate sharply, giving following drivers additional warning. Battery life is up to 17 hours in day flash mode and 12 hours in solid mode, with USB Type-C charging and automatic dimming under low battery. The unit is IPX7 waterproof and connects via ANT+ and Bluetooth 5.0, making it compatible with the vast majority of bike computers, smartwatches, and smartphones — not just Bryton devices. The universal mount fits round, aero, and D-shaped seatposts in 27.2mm, 30.9mm, and 31.6mm sizes.

Browse the full Bryton range or our computers and GPS collection for compatible Bryton bike computers that display Gardia radar alerts on screen.

What It's Good For

• 190m vehicle detection radar — advance warning of approaching traffic with automatic light response
• Brake detection — automatic high-intensity brake light when decelerating sharply
• CREE LED with 220° viewing angle — visible from the side as well as directly behind
• Daytime running mode visible up to 1.6km
• Up to 17 hours battery life (day flash mode) | 12 hours solid mode
• USB Type-C charging with automatic low-battery dimming
• ANT+ and Bluetooth 5.0 — compatible with most bike computers, smartwatches, and smartphones
• IPX7 waterproof — suitable for all-weather riding
• Universal mount for round, aero, and D-shaped seatposts (27.2mm, 30.9mm, 31.6mm)

What It's NOT Good For

• Front lighting — this is a rear light and radar only; a separate front light is required
• Full on-screen radar alerts without a compatible bike computer or smartphone — the light functions standalone, but visual alerts require a paired device
• Very dense urban traffic environments where multiple simultaneous vehicle detections may reduce radar clarity
• Submersion beyond IPX7 rating — waterproof for rain and splashes but not designed for sustained immersion

Frequently Asked Questions

Does it work with non-Bryton bike computers?
Yes — the Gardia 300L connects via ANT+ and Bluetooth 5.0, making it compatible with the vast majority of bike computers, smartwatches, and smartphones that support ANT+ radar sensors, including Garmin Edge computers. For full visual and audio alerts on screen, your device needs to support the ANT+ radar profile. The Bryton Gardia app on your smartphone also provides full alert functionality without a dedicated bike computer.

How does the radar detection work?
The built-in radar continuously scans behind you and detects vehicles up to 190 metres away. It calculates the relative speed of approaching vehicles and adjusts the rear light's flash pattern to warn both you and the driver — a faster-closing vehicle triggers a more urgent warning. When paired with a compatible device, the number of approaching vehicles and their distance is displayed on screen.

How does brake detection work?
The Gardia 300L uses an accelerometer to detect rapid deceleration. When you brake sharply, it automatically switches to a high-intensity brake light mode to warn following drivers, then returns to the standard light mode when you resume normal speed. This works automatically without any button press or device pairing.

What seatpost sizes and shapes does it fit?
The universal mount is compatible with round, aero, and D-shaped seatposts in 27.2mm, 30.9mm, and 31.6mm diameters — covering the most common road and gravel bike seatpost sizes. Installation is tool-free and takes a few minutes.