Bryton Gardia R300L Bike rearview radar

The Bryton Gardia R300L is a rear radar and tail light in one. It detects vehicles up to 190 m behind, shows alerts on the Bryton Gardia app and on compatible bike computers, and changes its light pattern with the threat level so drivers behind can see the bike.

At a glance

• Type: radar tail light (rear radar plus tail light)
• Brand: Bryton
• Radar: vehicles up to 190 m behind; Bryton’s quick start guide lists 24 GHz
• Light: 220° viewing angle; viewing range up to about 1.6 km
• Day flash: 73 lm, up to about 17 hours
• Water: IPX7 (1 metre for up to 30 minutes)
• Connection: ANT+ and Bluetooth (BLE); USB Type-C charging
• Weight and size: 66 g; 97 mm high, 40 mm wide, 20.9 mm thick

Alerts for traffic behind you

On roads shared with vehicles, traffic from behind is not always in view. Gardia R300L rates the threat from relative speed: green when no threat is detected, yellow when a vehicle is approaching, and red when a vehicle is approaching at high speed. On a compatible bike computer, with alert tones turned on, the computer beeps once when a vehicle is detected and once more when the threat has cleared.

Bryton states that the light is only an extra aid. It does not replace paying attention to your surroundings, and you should not stare at the screen while riding.

Light modes

Press the top button once to change mode. Press and hold for about 1 second to turn the light on or off. After pairing with a compatible Bryton bike computer, you can pick the mode on the computer and turn on auto switch. The user manual says auto switch follows that computer’s sunrise and sunset times.

Day flash is 73 lm. Bryton lists light viewing range as up to about 1.6 km. After more than 5 minutes with no movement, the light sleeps and remembers the current mode; it wakes when it detects motion again. Vehicle detection is off during sleep. Below 15% battery, the light dims to about half brightness. Bryton’s specification graphic notes that the brake light and warning patterns can use extra battery.

When a vehicle is detected, the yellow warning slowly flashes 2 times, then quickly flashes 3 times. The red warning slowly flashes 3 times, then quickly flashes 4 times.

Brake detection

A G-sensor is built in. When the light detects slowing down, it raises brightness by more than 50% for about 2.5 seconds to tell vehicles behind. You turn this on in the Gardia app or on a compatible bike computer.

Phone app

You can use it without a bike computer. Bryton’s support page says that after you download the Gardia app, the phone can show approaching vehicles, adjust the light, and display battery level. The manual adds that the app can use sound and vibration, including when the phone is in a pocket, and that it prompts you when new firmware is available. Turn on Bluetooth and switch on the Gardia R300L before pairing. After pairing, the link indicator flashes blue slowly.

Which bike computers it pairs with

The Bryton manual uses the Bryton Rider S800 GPS Bike Computer as the pairing example, and names Rider 750 and Rider 420 as computers that can show radar data. Bryton’s US site says the Bryton Rider S810 GPS Bike Computer and the Bryton Rider S510 GPS Bike Computer can pair with the Gardia R300L and show alerts for vehicles behind.

The manual also says the Gardia R300L can pair with other bike computers that support ANT+ radar. It does not list Garmin or other brands model by model. It supports the ANT+ light network, and a compatible Bryton computer can change this light’s mode after pairing. If your computer is not one of the models named above, contact us before ordering and tell us the brand and model so we can check remotely.

Seat post mounting

The manual says to mount the light as high as possible on the seat post, facing the rear, perpendicular to the road, with nothing blocking the light. The included mounts fit 27.2 mm, 30.9 mm and 31.6 mm round posts, plus D-shaped and aero posts. In every case the mounting face should stay vertical. Fit the rubber mount with the letter “b” upwards, then rotate the light to lock it.

Specifications

Item	Detail
Brand	Bryton
Model	Gardia R300L
Radar range	190 m
Radar frequency	24 GHz
Light viewing range	Up to about 1.6 km
Light viewing angle	220°
Size	97 mm high, 40 mm wide, 20.9 mm thick
Weight	66 g
Battery	Built-in lithium-ion polymer, USB Type-C charging
Water resistance	IPX7, 1 metre for up to 30 minutes
Operating temperature	-20 to 55°C
Wireless	ANT+ and Bluetooth (BLE)
Seat post mounts	27.2 / 30.9 / 31.6 mm round, D-shaped and aero

Battery indicator: slow green flash is about 50% to 100% left, slow yellow flash is about 15% to 50%, and slow red flash is below 10%. While charging, the light flashes green, then stays green when full. Dry the port, the rubber cover and the body before charging, and close the cover afterwards.

Specification source: Bryton user manual. Height, width and thickness follow Bryton’s dimension graphic; 24 GHz is from Bryton’s quick start guide.

In the box

• Gardia R300L
• USB-C charging cable
• All-in-one mount
• D-shaped seat post mount
• Aero seat post mount (listed on the Bryton site as Areo-Mount)
• Quick start guide

Frequently asked questions

Can I use it with only a phone, and no bike computer?

Yes. Bryton’s support page says that after you download the Gardia app, you can use the light without a bike computer. The phone can show approaching vehicles, adjust the light and display battery level. The app also prompts you when new firmware is available.

Which bike computers does the Gardia R300L pair with?

It pairs with the Bryton computers Bryton has named, and with other computers that support ANT+ radar. The manual names the Rider S800, and gives the Rider 750 and Rider 420 as examples. Bryton’s US site also names the Rider S810 and Rider S510. The manual does not list Garmin models. For any other computer, contact us before ordering.

Which seat posts does the mount fit?

It fits 27.2 mm, 30.9 mm and 31.6 mm round seat posts, plus D-shaped and aero posts. The mounting face should stay vertical, with the light facing the rear.

Does the tail light come on when I brake?

Yes. When slowing is detected, brightness rises by more than 50% for about 2.5 seconds. Turn the brake light on in the Gardia app or on a compatible bike computer.

Specifications and components follow the manufacturer's latest release and may change without notice. If in doubt, please contact us to confirm before ordering.

Last updated: October 2026