Garmin Varia RTL515 vs. Magene L508 vs. Bryton Gardia R300L: Which One to Buy?

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This article compares Garmin Varia RTL515, Magene L508, and Bryton Gardia R300L 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.

Magene L508 vs. Garmin Varia RTL515 vs. Bryton Gardia R300L

Here is the summary of the main differences between Garmin Varia RTL515 vs. Magene L508 vs. Bryton Gardia R300L.

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. R300L 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 R300L 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 R300L give more false positives. They often alert me about a car, but it immediately disappears from my bike computer screen.

I don’t know 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.

R300L gives about the same number of false positives as the L508. 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. 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 R300L

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 R300L. The ‘brake light’ feature on L508 and R300L is a nice addition, but I don’t miss it on Varia.

Winner: Magene L508 and Bryton R300L (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 still uses a MicroUSB charging port. L508 (introduced in 2022) and R300L (introduced in 2023) already have USB-C.

It’s tough for me to declare a clear winner here because I didn’t measure Varia’s battery life when I bought 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 got this functionality in 2024.

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 of the bike computer’s wake-up function. L508 can’t be woken up by the bike computer; I have to turn it on manually. R300L and RTL515 can be woken up by bike computers.

However, the R300L 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 R300L. These radars can automatically go into sleep mode after detecting your bike in a stationary position for longer than 5 minutes and automatically turn 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 R300L (2)

RTL515 vs. L508 vs. R300L Pros & Cons Summary

I summarized the pros & cons of all radars below.

My Verdict

The most important features of every bicycle radar are its reliability and accuracy. The Varia RTL515 offers the highest accuracy in multi-object detection and the fewest false positives, making it the winner of this comparison.

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 R300L, 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.

Varia RTL515 vs. Magene L508 vs. Bryton R300L FAQ