Trek CarBack Review: Too Little, Too Late?

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I have tested all cycling radars available on the market, including Garmin Varia RTL515, Magene L508, Bryton Gardia R300L, iGPSport SR30, and more.

Now, we have a new member: the Trek CarBack bike radar. So, what’s new? And will it be competitive with other radars? I bought it to conclude an in-depth review. I was probably the first person in the Czech Republic to test this radar. Below are my conclusions.

My CarBack rating at a glance:
Reliability 4/5 | Multi-object Detection 4/5 | Battery Life 3/5 | Brightness 5/5 | Side Visibility 1/5 | Mount 2/5 | App 3/5 | Price 3/5 | WEIGHTED OVERALL SCORE 3.2/5
More about this cycling radar scoring.

Trek CarBack Specifications

Below, I summarized the technical specifications of the Trek CarBack radar.

Also available at trekbikes.com

Trek CarBack Pros and Cons

Form Factor

Trek CarBack is much wider than other radars on the market. It was probably not designed with aerodynamics in mind. I’d guess it’s targeted at more casual cyclists because it creates more drag (since it’s not hidden behind the seatpost but its sides extend past it), which can cost precious watts.

I’d also expect much longer battery life than the claimed 7-12 hours. You learn more about how long CarBack lasted in the Battery Life section.

I like the battery level indicator on its side, but I’m sure the LEDs (paradoxically) cause unnecessary battery drain.

Package Contents and Setup

The CarBack comes with a universal mount, USB-C charging cable, and manual.

Pairing the radar with my Magene C606 bike computer was flawless. It has ANT+ and Bluetooth connectivity. Like most other sensors, it uses ANT+ to connect to bike computers and Bluetooth to connect with smartphones.

Mount: The Biggest Weakness?

The mount provides a solid fit and doesn’t slip on rounded or aero seatposts. But it feels cheap. The end of the rubber is secured with a rubber ring, but this solution doesn’t quite work, so the end of the strap flaps. Additionally, the mount socket is proprietary, and removing the radar requires two hands. It also allows radar to be mounted on only one side.

Detecting Distance and Accuracy

The longer vehicle detection distance of 240m, which should be CarBack’s killer feature, is not a deal breaker for me. For comparison, other radars range between 140 and 190m. The most important thing for me is the radar’s reliability.

Based on my first impressions, the radar detection is very inconsistent. This means that it sometimes detects them from a long distance (usually slow-riding cars/trucks), but sometimes, it struggles and detects them at the last possible moment (<50m). This usually applies to fast-driving cars. In most scenarios, however, it detects the cars at about the same time as Garmin Varia RTL515.

I’ll keep testing this for more accurate results and update this section accordingly. So, stay tuned.

Line Detection

CarBack is the first radar on the market to detect lane position. This feature is only available on the Trek Accessories smartphone app and does not work on bike computers. Personally, I doubt its usefulness because I don’t know many people who use a smartphone instead of a bike computer, and I simply don’t see the added value. However, from a technology standpoint, it’s probably an interesting development.

I’ve tried the feature, and in most cases, it works by showing the vehicle in the middle, then in the pass zone, and then again in the middle after passing, where you are not in danger. With all other radars, I instinctively assume that any vehicle passing me is a potential hazard. I don’t need an app to tell me that.

Battery Life

The claimed battery life of CarBack ranges between 7 and 12 hours, depending on the light mode used. I always test radars in day flash mode. The actual battery life was almost the same as the claimed one. My CarBack with radar on lasted ~11.5 hours, and then another hour with the taillight on and radar off.

Unlike other radars, CarBack turns off the radar when the battery drops below 5%, but the rear light continues to flash. So don’t rely on the radar when the battery is too low!

Other Issues with CarBack

The CarBack disappointed me even more by failing to turn off using the physical button on a few occasions or by failing to switch light modes. I noticed this was only the case when paired with the Garmin Edge 840. Surprisingly, the radar did not turn off, even holding the button for more than 30 seconds (which is normally enough for a “hard reset”). I could only turn it off by turning off the bike computer. I managed to capture this failure on video, which will be in a video review I’m preparing.

Finally, although it has excellent brightness, the light doesn’t change its flashing pattern when you’re being overtaken to alert the driver. This is another disappointment, as it’s one of the most useful features of radar tail lights.

Price

The price is the same as the Garmin Varia RTL515. CarBack costs $199 (£169.99 | €199.99 | AU$299). So, I’m wondering what the main reason is for choosing this radar over cheaper but similarly capable (and more consistent) competitors such as Magene, Bryton, or iGPSport radars.

Based on my first impressions, I expected much more. I’d still recommend the Garmin Varia RTL515 despite its micro-USB charging port.

Trek CarBack vs. The Competition

The following table compares Trek CarBack with other bicycle radars, like Garmin Varia RTL515, Bryton Gardia R300L, Magene L508, and iGPSport SR30.

Conclusion

My first impressions of the Trek CarBack are mixed. I’m more disappointed than excited. Detection is inconsistent. Specifically, it detects some cars from around 200m away but others only at the last moment (50m or less).

So far, Trek hasn’t lived up to its bold claims, and given the radar’s high price, I’d recommend the Garmin Varia RTL515. However, Trek may be working on a firmware update that could improve accuracy.

Another weakness is the mount, which appears poorly designed and uses a proprietary socket. The form factor is also not ideal for the discerning road user due to its less aerodynamic shape (the CarBack really doesn’t look good on road bikes).

The CarBack has excellent brightness, but unfortunately it doesn’t change the light pattern when someone overtakes you. Its battery life indicator is a nice touch.

What do you think of the new radar? Let me know in the comments.

Also available at trekbikes.com