Bryton Gardia 300L Radar: My Review After 12 Months…

Pubic service announcement: you should get a rear radar light for your bike.

Yes, they win the prize for least exciting velo tech 2024. And 2023. Probably 2026.

Yes, they’re quite costly for something that doesn’t cause loin rumblings of cyclo-desire.

But take it from me, for this is my blog and I am the only one speaking, you will feel so much safer and more chilled when there’s a device dangling out of your rear end… And you start riding with a radar.

There’s A Video!

There’s always (sometimes) a video. On my YouTube channel.

Back To The Review

A radar adds an extra sensory input on the bike, to supplement your eyes, ears, nose and gonads. Wobble-inducing glances over your shoulder are a thing of the past.

[Whispers] (It also sees dead people)

My Garmin Varia review was a love letter to the whole concept.

Finally, after a long lead time, Bryton released its own rear radar light, the Gardia.

Bryton Gardia on seat post

After an even longer lead time – I strapped it on in March 2023 – here are some thoughts.

Bias warning. Bryton sent me the Gardia to try. They didn’t send any cash money, more’s the pity, but did include in the box some socks, a water bottle and, bizarrely, a branded gimp face mask.

Bryton socks and water bottle

I’ll try to be as fair as possible but let’s agree to disagree that this is great merch.

Feel free to apply liberal handfuls of salt to whatever guff spouts from my cakehole.

But first…


Disclaimer Time

[Duh nuh nuh nuh…]

I can only give my own impressions on whether the radar functionality works. My testing, if we can call it that, will always be limited and take place in a limited number of riding conditions and situations.

Bryton Gardia R300L riding

I’ll cut to the shaft. If you go for a Gardia then subsequently get hit by a person driving a large chunk of metal, don’t come back and sue me as a perverted wraith.

Or any sort of ghost.


How Do These Radar Jobbies Work?

Before your pants overfloweth, I’m not going to explain how radar functions. It’s something to do with bats.

Or the no doubt highly complex algorithms that separate signal from cars.

Instead I’ll canter through how the growing stable of bike radars twerk from a user’s perspective.

Basically they sit strapped akimbo your bike’s seatpost and cast their electrical tent-sticles backwards to sense for approaching vehicles, be they planes, trains or automobiles.

Bryton Gardia radar

They then connect to your bike computer, or your mobile telefono, and you’ll get an alert each time there’s a taxi up your jacksie.

How this alert looks differs depending on the bike computer brand. Generally there’s a bar down the side of the screen and moving dots, or car icons, to denote each approaching vehicle.

Bryton Gardia R300L alert

Also, penises…. Penii:

Bike radar penis icons

Amber colouring implies it’s coming at a reasonable speed, red tells you it’s coming fast. Of course I am talking about the car.

Green means all clear. There may also be bleeps.

Bryton Gardia R300L radar all clear

The Gardia is also a smart light. Not strictly a radar function but a separate rear light would occupy the same seatpost real estate, as no one says, so it makes sense to the combine them.

The Gardia has a few different light settings: solid beam, peloton, flasher mode – my favourite, obviously. Switching between the modes is via the button on the top, or, if you’re blessed in that way, from your bike computer.

Does The Bryton Gardia Work As A Radar?

Bryton sent me the device before it was released.

I didn’t publish anything on launch day because, for me, the performance of the device was not up to par in terms of vehicle detection and tracking. There have since been numerous firmware releases and things have improved materially.

To be honest, it’s been usable for a while. The subsequent delay is entirely down to my own moral failings.

Bryton Gardia car passing

And to answer the question, the Gardia does work as a bike radar. It detects approaching vehicles (and faster cyclists). It sends the appropriate alert to my head unit. It clears when there are no more vehicles to pass.

It certainly isn’t, at least on my local roads, detecting cars from 190m away. It’s much more like 50-100m, which generally gives enough notice to be ready for a pass.

Bryton Gardia radar distance

It’s not all plain sailing though. The Gardia is subject to the challenges that face all devices in what is now ‘the bike radar category’ (as opposed to just the Garmin Varia):

  1. If a vehicle is going at the same speed as me (and the radar), the Gardia sometimes signals the all clear, rather than remembering it is there. This is ok if the car is literally behind you waiting to overtake – I’m generally aware of this. But if the vehicle is masking other cars behind it, then the Gardia can leave you blind to this.
  2. On a related note, the Gardia isn’t great at tracking multiple cars approaching. Which is fair enough. Presumably the front car bounces back the radar pips, before the car behind gets a look in. Other radars (cough, Varia) have the issue as well but seem slightly better at separating them out.
  3. Sometimes, after the front car passes, the Gardia will signal the all clear before an ‘OH SHIZZLE FUG ROLLOCKS there’s another one’ alert suddenly tells you that, seemingly out of nowhere, there is another vehicle right up your harris.
  4. The Gardia has given false positives, signaling a car behind when there is in fact none. The device is either sensing motorists in the other realm or… is just getting it wrong. This has improved muchly with firmware updates. My last 3 hour ride had none. And the issue is annoyance not safety. As long as they’re infrequent, I’ll go with the flow. Man.

Finally, we come to the radar performance biggie. False negatives. Or in humanspeak, the radar failing to identify at all that a vehicle is approaching.

I’m racking my little meecro-brain but I can’t remember the Gardia doing this. Maybe the odd time, a few firmware revisions back.

But other reviewers, including DC Rainmaker, have definitely experienced the Gardia failing to track vehicles. Which is enough to slap a minor health warning on the device, if you decide to buy one.

I’d say this, and remember the bit about not suing me: para mi, the Gardia has sufficient radar reliability to use on a ride. It adds to my overall road sense on the bike.

Can you devolve your safety awareness entirely to the Gardia?

Of course not, but then you’d be a moron to give this up to any device, even to the Apple Vision Pro.

But if you keep your wits about you, the Bryton Gardia adds extra data points ‘pon which your wits go to work.

This Is The Interlude Where I Ask You To Subscribe to My Email List

[Blank look]

I mean. You do you.

(Here’s the link)

The App

There’s always an app.

My take, based on no actual data, is that most radar buyers already own a bike computer. In which case the Bryton Gardia app is largely used to ensure the firmware is up to date (worth doing, since each update I’ve downloaded has improved its performance).

Bryton Gardia app firmware

That said, you can use the app as a head unit for the radar. With your phone ‘fixed ‘pon the handlebars, and the Gardia connected by Bluetooth, the app will show the same vertical bar and moving blobs display as on a compatible GPS device.

I’ll be honest, I’ve got twelvety-throusand compatible GPS devices and no desire whatsoever to attach my phone to the handlebars. So I’m in the bucket of app-wranglers using it for updates.

Bryton Gardia app light control

And it works fine. Each firmware update has been quick and hassle-free. At times I’ve found the original Bryton Active app, which connects and configures Bryton bike computers, a bit buggy. The Gardia app is less complex and I’ve not had similar issues.

Which is gurr-reat.

Looks and Build Quality

Unless you spend hours sat gazing at your bike, the aesthetics of your rear light shouldn’t matter a great deal. You’d have to be quite the contortionist even to glimpse it whilst riding, let alone muse upon it.

It’s more a question for the rider behind you.

Bryton Gardia radar seatpost

Now, most people don’t chomp on my back wheel (is that the expression?). It’s more likely I’m hanging out the back of another rider (that’s definitely not the right).

But if anyone did, and their eyes were drawn to my radar light rather than my magnificent gigabuttox, I’d have no shame in them perusing the Gardia.

Let’s not gild the willy. It’s a radar bike light, not Rodin’s thinking chap. But it looks smart, appropriately, with clean lines and a pleasing rectangularity.

Bryton Gardia looks

Build quality wise, the plastic construction seems robust. The Gardia has held up well to my crap-coated, pot-hole sprinkled Derbyshire stomping lanes.

In terms of operation, the Gardia goes with a single top-mounted button, not unlike a certain other device in the segment.

Recharge-wise, it has a rubber-flapped aper-sphincter at the bottom rear. Unlike the farmin harrier, at least the one I have, the Guardia goes with USB-C. Which is modern.

Smart Light Functionali-tah

For me, rear lighting is a set-it-and-forget-it arrangement. I’m not sure I’d go out of my way to buy a non-radar smart light for my rear end.

But a radar the Gardia has, so a smart light it is. As my Zen master tells me.

And by smart, Bryton means two things. First, the lights can be controlled by another device. Second, the lights react to external stimuli.

Bryton Gardia

If you have a bike computer with smart light controls, you can change light mode from the device. For this discussion, that would be a Garmin Edge or a Bryton Rider device. The newer Wahoo ELEMNTs only just got smart light control and I haven’t tried it yet.

With Bryton computers, getting to the controls is not quick. From the data grid display on the Rider S500, I counted 10 screen swipes or presses to get to the relevant menu. Not something I’d be doing frequently on a ride.

The Garmin controls are more conveniently located in the pull-down quick access menu. You just have to work out how the Garmin options map to each Bryton light mode.

Bryton Gardia rear light

If you don’t have a bike computer, perish the thought!, the Gardia phone app also controls the light.

Going back to the external stimuli, when the radar detects a rear space invader (car), it invokes a warning pattern of slow and quick flashes to alert the driver. For the avoidance of doubt, that’s the light doing the flashing.

The Gardia has a gyroscopic sensor, which detects you slowing down and then increases the light intensity for a couple of seconds, to act as a brake light.

Finally, if battery juice drops below 15%, then the Gardia reduces brightness by 50% in order to squeeze out the maximum tumescent goodness.

And then quickly to canter through the…

Light Modes

Of which we have five. Six if you include ‘off’.

High Solid and Low Solid are pretty self explanatory.

Bryton Gardia smart light

Group Ride is, as the tin suggests, a mode intended not to va-dazzle the riders behind you. Ideally I’d describe it as a slow throb, but for reasons of decency I won’t.

Finally we have two battery saving alternatives, Day Flash and Night Flash.

Here’s a table of brightness levels and flash patterns, taking from the Gardia manual. I’ll leave you to work out the difference between Light Intensity and Lumens.

Bryton Gardia radar light modes

And all of the modes are fine. I’m sure they’re as visible as the stats imply. Light bulbs in the 21st century are, as far as I can work out, a solved problem.

I tend to stay in Day Flash or Night Flash because, based on no research at all, it feels like the active change in state is more eye-catching to drivers from afar, before the radar-induced flickering kicks in.

It’s also one of my core life principles: Always Be Flashing.

Battery Life And Charging

Bryton’s claimed battery life stats support said core life principle:

Bryton Gardia battery life table

Even with the retina-burning 73 lumens kicked out by a day flash, you should still get 1.5 to double the battery life versus the solid modes.

This bad little bike tech reviewer couldn’t be harrised to validate these battery life claims.

First it’s boring, second I don’t actually want to run out of juice on a ride.

Even though I’m not meant to rely on it, it’s disconcerting when a flat-batteried radar fails to pre-announce the car that suddenly appears at your shoulder. So I tend to recharge the Gardia, and my Varia, more frequently than I need to.

To give an idea though, my recent 1 hour ride, where I dicked around getting video of the different light modes, battery life according to the app ticked down by 7%. Which scales up to 14 hours of lighting, assuming you too select dicking around mode.

Bryton Gardia app display iPhone

Again, the lesson: keep your high and low solids for the Thomas, outside stick to flashing.

Finally, charging is a via a USB-C port, so it’s future proof for when we move to the promised land of only needing one cable to charge them all.


Clearly we have the Garmin Varia, the OG in this space. Certain young YouTube thrusters have created excellent review videos of that device.

Garmin Varia on seat post

You might be aware that Magene has also released a radar-cum-smart light. I’d forgotten until I started working on this post. It costs about the same as the Gardia, which makes it a bit less than the Varia, but does essentially the same thing.

Depending on interest, I might buy one and do a threeway. And also compare all the devices together. Yak yak yak.


It took some time to get there but the Gardia is a good radar and rear light combo. Be aware of its limitations, and keep your riding wits about you, and I think you’ll find it a useful 8th sense on your velo adventures. It’s good that the Gardia, plus the Magene, give Garmin some competition in this arena.

It’ll be interesting to see where the next generation of rider assistance aids go. I’m hoping for a head up display piping a permanent loop of Sportive Cyclist videos directly into my an-us.

Schnell schell kartofelkopf.

Monty - Sportive Cyclist
Monty is an enthusiastic road cyclist with only moderate talent. He started Sportive Cyclist in 2013 to record the journey to his first 100 mile ride, the RideLondon 100. Over time the blog has expanded to include training advice, gear reviews and road cycling tales, all from the perspective of a not-very-fit MAMIL. Since you're here, Monty would also like you to check out his YouTube channel. Also, Monty really needs to stop referring to himself in the third person.

1 thought on “Bryton Gardia 300L Radar: My Review After 12 Months…”

  1. I want penises!
    That sounds really wrong 😂
    Please do a thing on how I can get them on my wahoo, and also how I can switch back once I’ve stopped giggling at them like a little child


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