Garmin Varia RTL515 vs. Magene L508 vs. Bryton Gardia R300: Which One to Buy?

CyclistsHub is supported by its readers. We may receive a commission if you buy products using our links (learn more).

This article compares Garmin Varia RTL515, Magene L508, and Bryton Gardia R300 bicycle radars with a taillight.

I used them all, so I feel qualified to share my experience and help you decide which one to buy.

In short:
Based on my experience, none of these radars ever missed a car. But L508 and R300 give more false positives (show a car that’s not there) than RTL515. They also have worse multi-object detection.
Garmin Varia RTL515 is the most reliable one but has the worst mount. Magene L508 is the sleekest and most customizable one. And Bryton Gardia R300 has the best mount.

The overall winner is the Garmin Varia RTL515 because it gives the fewest false positives, and its multi-object detection is the most accurate.

NOTE: The Bryton Gardia R300 I tested was a DEMO unit. Unfortunately, Bryton didn’t tell me more about the differences between these two.

Magene L508 vs. Garmin Varia RTL515 vs. Bryton Gardia R300

Here is the summary of the main differences between Garmin Varia RTL515 vs. Magene L508 vs. Bryton Gardia R300.

Physical Dimensions & Weight

There is no doubt the similarity between L508 and Varia RTL515. Garmin inspired Magene. On the other hand, Bryton has a more original “boxy” design.

I like the L508 because of the sleek look. However, its glossy finish is easy to scratch when cleaning from dirt, for example. R300 also appeals to me. RTL515 looks the worst, in my opinion.

See the differences in the following gallery.

Winner: Magene L508

Reliability

I used RTL515 for higher thousands of kilometers, L508 for lower thousands of kilometers, and R300 for hundreds of kilometers.

All radars have proven to be reliable. From my experience, none of them missed a car (i.e., false negative).

However, Magene L508 and Bryton R300 tend to give more false positives. They often alert me about a car, but it immediately disappears from my bike computer screen.

I am not sure what causes this. The signal probably reflects from some objects, but I didn’t find any pattern. It’s not such a big deal. Getting a false positive is better than not being alerted about a car. But sometimes, it’s annoying.

R300 gives fewer false positives than L508, but they are still pretty common (they occur several times per ride).

Remember, if you buy a device like this cycling radar, you should have zero tolerance for false negatives*. But you also shouldn’t 100% rely on radars, and you should use your other senses while cycling.

*Here is the explanation of the possible scenarios:
True positive = there is a car, and radar alerts you.
True negative = there is no car, so the radar won’t alert you.
False positive = there is no car, but radar alerts you.
False negative = there is a car, but the radar won’t alert you.

Another difference I noticed is the accuracy of detecting multiple cars. Varia is the most accurate. It’s like it sees the other cars behind the first car (probably based on some estimations) and keeps them on the bike computer screen.

Magene and Gardia are not as accurate. They only show them when they are clearly visible (in turns, for example). So, in reality, I see the other cars once the first one overtakes me.

So, this is one of the areas where Varia crushes its alternatives.

Winner: Garmin Varia RTL515

Mounts

Although all radars use quarter-turn mounts, they are not compatible with each other.

This is because Magene and Garmin mounts are rotated by 90°, and Bryton uses its proprietary mount.

So, for example, if you insert the L508 into the Garmin mount, it will look like this.

Garmin and Magene mounts tend to slide sideways, but Magene does so less often (it also depends on the shape of your seatpost). Therefore, I have to adjust the position of the radar during rides, especially if I ride on bumpy roads or cobblestones.

Garmin offers a fixed mount for round seatposts, but Magene does not. However, you can buy firmer third-party mounts, like the one from KOM.

Bryton’s mount has proven to be the most stable one. It doesn’t move at all.

Another difference is that the Magene and Bryton mounts are universal (they fit round, D, and V-shaped seatposts). For the Varia mount, you must replace the rubber part to fit the seatpost type.

Winner: Bryton Garia R300

Light Modes & Visibility

Let’s now compare the light modes:

I honestly don’t care about the number of light modes because I use the flash mode 99% of the time.

In some countries (like Germany), flashing bike lights are prohibited, so you must use a solid light.

What I care more about is visibility. Garmin and Bryton were much brighter than Magene until it got a firmware update that allowed you to increase the brightness in the Magene smartphone app. However, this increase leads to faster battery drain.

Another difference is that you can adjust the time intervals of individual light modes in the Magene app. This is not possible with RTL515 or R300.

The ‘brake light’ feature on L508 and R300 is a nice addition, but I don’t miss it on Varia.

Winner: Magene L508 and Bryton R300 (just because of the wider offer of the light modes)

Battery Life

The Varia I tested was about 2 years old, so its battery probably depreciated a little, but it still keeps decent capacity.

Magene and Gardia are far behind the claimed battery life. This is disappointing because the difference between real and claimed battery life is more than 30%.

NOTE: RTL515 was introduced in 2020, but it still uses MicroUSB charging port. L508 (introduced in 2022) and R300 (introduced in 2023) already have USB-C.

It’s tough for me to declare a clear winner here because I didn’t measure the batter life of Varia when I had it new. However, other reviewers claim they squeezed 14+ hours from a new unit. I remember not having to recharge it after a week of riding more than 10 hours. So clearly, the battery has degraded a lot over the years.

Unfortunately, all radars fall behind the claimed battery life.

Winner: Garmin Varia RTL515 (see the explanation above)

Devices Compatibility

All devices are compatible with 3rd party computers with ANT+ and Bluetooth.

Bike computers like Garmin Edge, Hammerhead Karoo 2, and others will also allow you to adjust the light mode. Wahoo computers don’t have this functionality.

However, you will mostly see only 3 light modes (flash, solid, light off) and not all of them. So it’s better to use the power button if you prefer other light modes.

One of the differences I’ve noticed is the reliability when waking up the bike computer. While I can’t wake up the L508 with the bike computer, so I have to turn it on manually, I can with the R300 and RTL515.

However, the R300 behaves unpredictably at times. Sometimes it turns itself on when it detects movement (e.g., when I take it with me and mount it on my bike). I have no explanation for this behavior.

The RTL515 is much more reliable, especially with the Garmin Edge bike computers that can wake it up. Unfortunately, I didn’t find a way to wake it up with Wahoo head units.

Winner: Garmin Varia RTL515

Other Differences

Here are a few more things I want to highlight.

The first one is auto-sleep on L508 and R300. These radars can automatically go into sleep mode after detecting your bike in a stationary position for longer than 5 minutes and automatically turns on once you start riding. RTL515 doesn’t.

The second is the smartphone app. All apps can replace a head unit with your phone because they can show the traffic. The Magene app also allows you to customize the light modes. I like Bryton’s app the most because it is the nicest and cleanest one.

When writing this comparison, Magene L508 was incompatible with 3rd party apps like the Cadence app or Ride with GPS. The other two radars are compatible with them.

Total score: Garmin Varia RTL515 (3), Magene L508 (2), Bryton Gardia R300 (2)

RTL515 vs. L508 vs. R300 Pros & Cons Summary

I summarized the pros & cons of all radars below.

Varia RTL515 vs. Magene L508 vs. Bryton R300 FAQ

My Verdict

The winner of this comparison is Garmin Varia RTL515.

Every bicycle radar’s most important feature is its reliability and accuracy. The Varia RTL515 offers the highest accuracy in multi-object detection and the fewest false positives.

Additionally, it provides excellent visibility and is compatible with most bike computer brands. However, its mount tends to slide, and it does not allow customization of light modes.

If you are willing to tolerate false positives, you can opt for the Magene L508, which is the most customizable but has the poorest battery life.

Alternatively, you can consider the Bryton Gardia R300, which has the best mount and app but frequently gives false positives and is inaccurate in multi-object detection.

I hope you find this comparison helpful. If you do, feel free to share it or comment below.