Bryton Gardia R300L Review – Radar and Tail Light (R300)

Bryton Gardia R300L ReviewBryton Gardia R300 Review – R300L Radar and Tail Light

Here’s a detailed review of the Bryton Gardia R300L, which is a smart radar tail light for cycling with audio and visual warnings. It comes hot on the heels of the Magene L508 and the hugely popular but expensive Garmin RTL515 and RCT715 (Video).

At first glance, the Bryton, Magene and Garmin are three similarly featured products. However there are many detailed nuances and I’ll go through those further below but, interestingly, Bryton seems to be the most featured and most obvious purchase. Well…’obvious’, except for one ‘tiny’ flaw.

Price when reviewed: UK – £119, EU – 129€, USA $?

⭐⭐⭐⭐ Simply the best-featured radar tail light. But...
  • Price - 95%
  • Apparent Accuracy - 60%
  • Build Quality & Design - 90%
  • Features, Including App - 95%
  • Openness & Compatability - 95%

Verdict: great features, great price occasional false negative. Watch out Garmin.

Bryton Gardia R300L Review Summary

It’s easy to attach, pair and start cycling on the Gardia R300L. First-time setup should take 2 minutes.

The R300L model has all the available seat post mounting adapters you should need, be that for a TT bike or a commuter bike.

You can have confidence that its 73 lumens of light in day flash mode even beats that of the excellent Garmin Varia RTL515. That will make you visible on the brightest of days and you can be further confident that visibility is increased for several more reasons including a 190m radar detection range, wide 40-degree detection angle and in-your-face, smart flash patterns for drivers.

Like Garmin, Bryton has a Peloton, or Group Ride, mode to avoid blinding and annoying your cycling buddies and its accelerometer-activated brake light is a welcome feature that I hope Garmin copies.

Apart from that, what you see on your bike computer is essentially the same as if you owned the Garmin radar light.

Each bike computer/watch implements the standard ANT+ RADAR feature subtly differently. But they all essentially show a bar on one side of the screen to represent the road behind you. As vehicles are detected their progress is ‘plotted’ on the bar and you can see them getting closer without turning your head around. There will also be various beeps and colour changes to indicate increased danger or that a car is no longer behind you. That sounds complicated but it’s not and it all works REALLY well.

At €129.95, Bryton has aggressively pitched the price compared to the Garmin RTL515 making it MUCH better value for money and for no obvious downside. It’s priced at the same level as the Magene which is not quite as good and which now looks slightly overpriced.

Price when reviewed: UK – £119, EU – 129€, USA $?

Note: Garmin has had many years to refine its radar detection algorithms. This is Bryton’s first pass and it’s pretty good but it’s difficult to recommend this product until the algorithm is strengthened – this is a critical issue as it is a safety product. Once they’ve done that I’ll remove this mini paragraph and I would then recommend Bryton over Garmin. Put another way: I’m still using my Garmin Varia tomorrow.


  • Works with all brands
  • Highly competitive price for the features.
  • Market-leading brightness
  • Market-leading battery life
  • Good, alerting flash pattern
  • Works as a radar, as a light and as part of a light network
  • External battery charge indicator
  • Auto light-dimming when battery is very low
  • 2.5 second brake light
  • USB-C charging


  • Occasional false negative (Bryton are working on this)
  • No Lanyard or separate failsafe mechanism



In recent years, Garmin has iterated through several models of radar tail lights. The more recent ones are the RTL510 (ANT+), RTL515 (Peloton/Group mode + Bluetooth), and the RCT715, which adds video incident recording.

Bryton and Magene both kinda-announced competitor products in 2022, but the Bryton Gardia R300L is only formally released in March 2023.

Comparison Gardia-R300L vs Garmin RTL515 vs Magene L508

The headline specs shown here are the key ones to consider, and you can see that Bryton pretty much nails it in all respects by either beating or matching what the competitors offer.


Gardia-R300L vs Garmin RTL515 vs Magene L508
Source: Bryton

The only aspect worth pondering over is that Bryton has compromised night-flash brightness with battery life. It seems a sensible improvement to keep the 17 hours of battery life to beat Garmin’s 16 hours albeit at a lower LM level.

Here is a simple video recording of a 2-car pass which shows the flash patterns of all 3 light brands. The Wahoo is paired with the Bryton and controls the appearance of the car icons on the left side of its screen. The flash patterns of the Garmin (right) and Magene (left) are independent and based on their own vehicle detection



Comparison Gardia-R300L vs Garmin RTL515 vs Magene L508
Click to view on YouTube


If you look closely at that video you see the light patterns of the Garmin and Bryton changing at very similar times. But there seems to be a display lag from the Bryton to the Wahoo ELEMNT.


The Good and The Great

Bryton has paid attention to every detail of the R300L, which is not only impressive but also sets it apart from other bike lights. For instance, the adapters supplied for both D-shaped and pear-shaped seat posts are a thoughtful touch that demonstrates Bryton’s attention to detail.

Another great feature of the R300L is that when you press the ON button, the light starts flashing in the mode where you last left off. This is particularly convenient for me as I tend to always use the day-flash mode.

Bryton has also gone the extra mile by including a battery status light on the outside of the light, which glows amber when the power drops below 50% and red when it drops below 15%. This is an improvement over other lights which only alert you to a low battery level via your head unit. With those lights, I’ve found that the alerts often come just as I’m starting out on a ride, which isn’t very helpful as at that point there is no time to recharge it.

Additionally, the R300L offers a brake mode, similar to the Magene but unlike Garmin, which emits a solid red light when the internal accelerometers detect rapid deceleration.

The R300L is also compatible with a range of bike computers, including Wahoo, Garmin, Hammerhead, and Stages, thanks to its support for the RADAR protocols that trigger on-device animations. It also supports a Garmin light network, which enables your Garmin device to check the light’s status and automatically turn it on/off. Another appreciated feature of the R300L is its USB-C charging port, which is missing on the Garmin RTL515.

Like Garmin, Bryton offers a smartphone app that can be used if you do not use a bike computer and mount your smartphone to your handlebars. The app also updates the firmware, allows customization, and ensures that the R300L remains up-to-date with the latest features.

Overall, it’s clear that Bryton has taken a very careful approach to the design of the R300L, addressing almost every shortcoming of the Garmin RTL515 that reviewers and owners have criticized.

Bryton Gardia R300L Review battery status


The Bad & The Ugly

There are two problems. The first is that both the Bryton and Garmin do not come supplied with a lanyard, so there is a risk of the rubber mount snapping and you losing the Bryton. Admittedly, the Bryton rubber mount is well-designed with multiple points of failure built in. That said, I would have preferred an adapter to a standard Garmin mount as my rear Garmin mount is well and truly bolted to my seat post.

That’s a relatively trivial point.

False negative detections are however a material point, and I have conducted extensive testing of the Bryton device throughout its beta stage of development. This testing culminated in the final beta version that will be used in the retail release.

The detection algorithm was continually developed and improved throughout the product development process. However, as of today, there are still instances where “lurking cars” that tail you are not detected. It’s worth noting that Garmin also has some (lesser) issues with this scenario as vehicles are only detected by their frontal area and closing speed. Despite this limitation, it’s unusual for a tailing car to maintain your exact speed, and a car typically periodically speeds up or slows down slightly while lurking. Garmin seems to pick up on these mini-closing events more often than Bryton. Additionally, there appears to be a slight lag with the Bryton when such a vehicle speeds up and eventually decides to pass you. As a result, a vehicle can suddenly appear right next to you when you may have forgotten it was there. However, Bryton is aware of the issue and will likely release new firmware by the time you read this.

In the Box

The Bryton GardiaR300L Bike Radar with Tail Light comes with the Bryton Bike Radar, a 3-adapter mounting kit and a USB cable.

Bryton Gardia R300L Specifications

Here are the Bryton GardiaR300L specifications

  • Dimension: 97 x 20.9 x 40 mm
  • Weight: 66g
  • Viewing angle: degrees
  • Water rating: IPX7
  • LED power/status indicator
  • Modes: high solid, low solid, group ride, night flash, and day flash,
  • Brightness: maximum lumens of 20 (high solid), 5 (low solid), 12 (group ride), 12 (night flash), and 73 (day flash).
  • Battery life is 8 hours (high solid), 12 hours (low solid), 11 hours (group ride), 17 hours (night flash), 17 hours (day flash), and 24 hours (light off).
  • Connectivity: ANT+ and Bluetooth
  • USB-C rechargeable.



  • Real-time alerts for approaching vehicles from behind.
  • Brightness increases and flashes to notify approaching drivers of a cyclist ahead.
  • Flash pattern is daytime-visible from up to 1.6km/1 mile away.
  • Persistent flashing to notify the driver behind you that there is a bike ahead until the vehicle passes by.
  • The brake mode light illuminates for 2.5 seconds when deceleration is detected and continues if you keep braking.
  • Automatic low battery feature that dims the light to a lower lumen when the battery charge drops below 15%, which extends the battery hour for additional usage time.
  • All-in-one mounting mechanism


The Bryton App

The Bryton Gardia app has two broad purposes

  1. Shows vehicle positions on the smartphone screen for those of you who ride with a smartphone on their handlebars
  2. Device admin for most settings and firmware updates

Don’t forget that when part of a light network (typically only Garmin Edge bike computers) some settings can be made without using the app.

Supported Brands

“Garmin Edge, Wahoo ELEMNT, Bryton, Hammerhead, Stages Dash, and even some Garmin Fenix/Forerunner watches support the radar mode of the Gardia R300L. The computer places some form of bar on either the right or left side of the screen and one or more car icons show the progress of cars behind you.


ANT+ light networks are less widely supported. For example, we have yet to see anything from Wahoo.


In its brightest mode, it is painful to look at the light. It’s THAT bright.

Take Out

From the perspective of features, Bryton’s R300L radar tail light is market-leading. It has every feature, from a brake light to a bright light; from a light network to a flashing light pattern. However, it still needs one more tweak to make it the go-to radar light for everyone.

If only the close vehicle detection were just slightly better to match that of Garmin.

It will be interesting to see how the competition reacts. Magene recently released its product, so I imagine the only way it can compete is by lowering the price. Garmin will probably continue periodic discounting with the RTL515, but ultimately they will come out with an improved version of the RTL515 for about the same price level as now. However, it won’t have a video as that sets the price bar too high for volume sales.

Price & Availability

There are two SKUs, the R300 and R300L. They are identical in every respect except that the R300L also contains a D-cross-section seat post adapter. It’s not initially available in North America

Price when reviewed: UK – £119, EU – 129€, USA $?

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