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The Bryton Gardia R300L is a well-priced and effective radar and rear light combination, pairing easily with my head units and detecting cars from an impressive distance away. There are some small quirks like patchy pick-up of motorbikes and losing vehicles when they're moving at your speed, but overall it's an impressive piece of kit.
Not bothered about the radar? Check out our guides to the best rear bike lights.
The Gardia R300L is effectively a rival to Garmin's Varia radar system, at a lower price. Its purpose is to warn you about vehicles approaching from the rear, but it has a couple of bonuses thrown in too, namely the easy-to-use smartphone app and smart light capabilities.
Though made by Bryton, it pairs with most modern head units, and all of the most popular brands that I use. I tried it with a Garmin Edge 830 and Hammerhead Karoo 2 and both were simple to set up and worked well once connected. As you would imagine, both units have their own ways of displaying approaching cars (Garmin has moving dots on the right, while Hammerhead has car icons on the left), but the radar system worked very well on both.
It tracked well, giving an audible warning and using on-screen visualisations to show clearly how fast approaching vehicles were moving based on how quickly they moved up the screen, and then giving an audible beep and visual 'all-clear' message once the vehicle had passed or turned off.
Like the Garmin, the Gardia also has 40-degree field of view, for detecting vehicles that might be appearing around bends off-axis to your bike, but there are a lot of roman roads where I live, which came in handy for being able to see how effective the Gardia is at detecting over long distances. Bryton says it can detect vehicles up to 150m away, but on these long, straight roads I found it tended to pick them up from about 180-200m, identifying larger vehicles from slightly further away, as you would expect.
Having said it tracked well, it was slightly less reliable with motorbikes than cars, and there were a couple of occasions where I was surprised to find myself being passed by one.
Similarly – as Mike said with the Garmin Varia RCT715 he tested recently – when a car is moving at the same speed as you it would often get 'lost' in the radar, so would no longer appear on the radar visualisation. I didn't find this a huge issue because by the time they are behind you, you're aware they are there, and the point at which they speed up to overtake they get picked up again.
Although not ideal, I think it's understandable, as they would show up as static objects to a radar in the same way a rear wheel or saddle bag would. It would be much more of an issue if it constantly showed something behind you just because you have a bike with two wheels...
I also found that, at this time of year, it could quite often produce errant readings when there was non-vehicular motion behind you. In particular, cow parsley blowing in the wind could cause it to detect a car behind me, and when I looked around there was nothing there. It's not the end of the world and didn't happen too frequently, but it is something I noticed on windy days on lanes with a lot of billowing plants on the side of the road.
As a light it is also pretty effective, with five settings: high, low, day flash, night flash and group mode. (Or you can have it on radar only.) Flicking between them is just a case of a quick press on a single button on the top of the light.
A long press on this same button acts as the on/off switch, but as this is also a smart light that can be connected to your head unit, it effectively turns on and off with your head unit. So you start a ride and the light turns on too; you stop and it turns off. A nice touch.
The light can also detect changes in speed, which means it can act as a 'brake' light that flashes brighter when your speed suddenly slows. As with every other such brake light I've tried, it works okay but isn't perfect, because there is a natural lag between pulling on the brakes and the speed reduction filtering through to the light; it's not instantaneous, as it is on a car as soon as you press the brake pedal, so its effectiveness is debatable.
Another smart function, separate from the brake light, is the flashing light pattern changing when a car is approaching, increasing the chances of you being seen. This feature works through the radar system, which detects the distance a vehicle is away from you.
Both these functions come on automatically when the light is first turned on, but can be disabled or enabled again from the companion smartphone app.
Mounting is through a rotational clasp similar to a Garmin mount, which attaches to the seatpost with a rubber ladder strap.
I used this on a couple of different seatpost sizes and shapes and found it held well and didn't rotate or slip, even on flat-backed aero posts.
Battery life is dependent on the light settings being used, with a claimed maximum of 17 hours in flashing mode (day and night) and 12 hours in steady mode.
These are broadly what I found throughout the review period. I tended to use the Gardia during the day, so my most common setting was Day Flash, and I only needed to charge it a couple of times over a month of riding.
Charging is via USB-C cable, attaching to a port on the side of the light that has a dust/water cover. Charging takes a couple of hours from dead to fully charged.
A warning light comes on when the unit needs charging, but you can see a more accurate percentage either on the companion app or on a paired head unit.
The Gardia R300L costs £119.99, which is a good price compared with others on the market.
Overall, I was very impressed by this radar light. It offers the same kind of functionality as the Varia at a much lower price. The tracking is effective and easy to follow, the smart light elements are a real positive, and it's one of those pieces of kit that you can basically just leave on your bike and forget about thanks to the decent battery life.
There are elements that could improved, like tall plants setting it off in a breeze, and motorbike tracking being less reliable than car tracking, but really there is little to complain about. here
Impressive radar/rear light system that challenges Garmin's Varia and costs less too
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road.cc test report
Make and model: Bryton Gardia R300L Rear View Bike Radar Tail Light
Size tested: One Size
Tell us what the light is for, and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?
Bryton says: "Ride in total safety with the Bryton GARDIA R300L rearview radar.
This rearview radar with taillight offers double protection to support you on your outings. When vehicles approach behind you, in addition to notifications on the cycle computer and GARDIA app, the Bryton GARDIA R300 will automatically change the lighting mode to warn oncoming vehicles as well. Ride safely with Bryton Gardia R300L.
The GARDIA R300L radar sensor detects vehicles approaching from behind up to 150 meters away. Connected to compatible cycle computers, GARDIA R300L provides both visual and audible alarms to warn you of oncoming vehicles. The Bryton GARDIA R300L rearview radar helps you prevent nasty surprises while riding. When vehicles approach behind you, GARDIA R300L will automatically assign a threat level based on speed, to activate a warning light suitable for alerting oncoming vehicles. When connected to a compatible Bryton cycle computer, GARDIA R300L will use the device's built-in light sensor to adjust the lighting mode based on the current light conditions.
If enough light is detected, the taillight will switch to day flash mode to conserve battery or, during night time activity, it will automatically switch to night flash mode. Using an integrated g-sensor, the Bryton GARDIA Radar Rearview Light detects braking and warns vehicles behind you with a brighter light, reducing the chances of a collision when slowing down or in the event of an emergency stop. Using the connection via ANT+ and a function-enabled cycle computer, you can connect GARDIA R300L and a compatible front light directly to the cycle computer to form a network that allows you to manage all lights from the display - including switching on/off and adjusting cycling modes.
The Bryton GARDIA R300L Rearview Radar with Taillight is designed to report the location of cyclists and help oncoming vehicles locate them. During the day, the dedicated flash mode increases visibility up to 1.6km.
Bryton GARDIA R300L provides multiple lighting modes to support you during your ride to make you visible in any conditions, including fixed high intensity, fixed low intensity, day flash, night flash and group mode. With a compatible cycle computer, you can also adjust the lighting modes directly from your screen.
Tired of calculating remaining battery hours based on a percentage? With a compatible Bryton cycle computer or the GARDIA app, the remaining battery life will be displayed directly on the screen after pairing with the radar. By directly viewing the hours of autonomy left, you can more easily manage your trip and settings before leaving.
With an impressive 17 hours of battery life in day flash mode and up to 12 hours in steady mode on a single charge, the powerful GARDIA R300L rearview radar and taillight can support you no matter how far your adventure takes you. To further extend battery life, when the level is low, the light intensity is automatically lowered. Charging via USB-C also makes charging faster and more convenient than ever!
Bryton GARDIA R300L's innovative all-in-one mounting system makes attaching your device much easier. Just fix the GARDIA R300L rearview radar in the position of your choice and you are ready to go! The included stem can fit 27.2mm, 30.9mm, 31.6mm and aero round section seatposts.
Download the Bryton GARDIA app to unlock the full potential of your GARDIA R300L rearview radar and taillight. This official app allows you to not only view the status of approaching vehicles, but will sound notifications and vibrate when vehicles are arriving. You can also control the GARDIA R300L light directly from the app to easily configure your preferences and receive the latest firmware updates."
Tell us some more about the technical aspects of the light?
Bryton lists these specs:
Width: 40.0 mm.
Height: 97.0 mm.
Depth: 20.9 mm.
Weight: 66 g.
Water resistant: IPX7.
View angle: 220°.
LED indicator: ANT+ link & Bluetooth / Power.
Fixed at high intensity: 8 hours/20 lms.
Fixed at low intensity: 12 hours/5 lms.
Flash day: 17 hours/73 lms.
Night flash: 17 hours/12 lms.
Group: 11 hours/12 lms.
Radar only (light off): 24 hours.
Seems well made; feels like it would survive a few drops and bumps.
Very easy to use, whether it's the simple mounting system or how quickly you can pair it with a multitude of head units.
The rotational bracket keeps everything in place well and the ladder strap is easy to fit.
It's rated IPX7 so should be fine. There wasn't much rain while I was reviewing this, but it survived well in the small amount there was.
Good battery life.
Impressive light and radar performance giving clear indications of when vehicles are behind you. It also throws in some useful changes to the light settings as vehicles approach, which is a good safety feature.
No reason to think that it wouldn't last a long time.
A good price compared with the Garmin Varia.
Tell us how the light performed overall when used for its designed purpose
Very well. It picks up vehicles well, occasionally missing the odd motorbike. The smart light elements are effective, too.
Tell us what you particularly liked about the light
How effective the radar is – it's great to be aware of a car coming up from behind well before you hear it.
Tell us what you particularly disliked about the light
The false positives from billowing plants – not a frequent occurrence but a little annoying when it happens.
How does the price compare to that of similar products in the market, including ones recently tested on road.cc?
The Garmin Varia RTL515 is the best-known alternative and has a higher price of £169.99.
The Magene L508 costs £5 more and doesn't have the same range as the Bryton.
Did you enjoy using the light? Yes
Would you consider buying the light? Yes
Would you recommend the light to a friend? Yes
Use this box to explain your overall score
This is an impressive piece of kit that works well at detecting vehicles from far away and has some nice smart light features to boot.
About the tester
I usually ride: CAAD13 My best bike is: Cannondale Supersix Evo
I've been riding for: 10-20 years I ride: Every day I would class myself as: Expert
I regularly do the following types of riding: commuting, club rides, sportives, general fitness riding, fixed/singlespeed,
George is the host of the road.cc podcast and has been writing for road.cc since 2014. He has reviewed everything from a saddle with a shark fin through to a set of glasses with a HUD and everything in between.
Although, ironically, spending more time writing and talking about cycling than on the bike nowadays, he still manages to do a couple of decent rides every week on his ever changing number of bikes.