See & Be Seen: Trek CarBack Bike Radar Review

Trek has been on the forefront of daytime running lights for bikes for a long time now. I have used and trusted Trek’s Flare and Ion DRL’s since they were first introduced in 2015. Actually, let me reinforce my reliance upon these lights — I never ride without them. Last year, I tested the Garmin Varia system built into the Cannondale Synapse Carbon 1 RLE and I was hooked. Now, Trek has combined their fantastic Flare rear light with a rear-sensing radar for a match made in heaven.

Trek CarBack Radar Rear Bike Light Features:

• DRL visible up to 2km
• Radar vehicle detection back to 240m
• ANT+ compatibility with all major head units (Garmin and Wahoo Tested)
• Visible power gauge
• USB-C charging port
• Versatile mounting system
• MSRP: $199

Head on a swivel or a Trek CarBack?

We’ve all been there. A busy street, with cars buzzing by while you’re trying to make sure you avoid potholes, road debris, narrowing shoulders and busy intersections — all at 25 mph or greater. Wouldn’t it be nice to also have a little warning of how many cars and when they are approaching? The Garmin Varia system has long been the only option on the market, but recently, others have come onto the scene and Trek is aiming for Garmin head-on with their new Trek CarBack rear radar system.

Compatible with Trek’s versatile Blendr mounts, the CarBack either attaches to your seatpost or to a saddle mount (I tested both). I used the Blendr mount on the back of a Bontrager Verse Elite Saddle. As you can see in the pictures above, when mounted to the back of the saddle, it appears pretty bulky. Once on the bike, you don’t even think about it, but when it comes time to lift and hook my bike onto the wall of my garage, it does get in the way of grabbing the back of the saddle. If that’s a serious issue (it’s not, really), it’s just as easy to use the seatpost mount. However, the higher you can mount the CarBack, the better line-of-sight it will have. Oh, and also, make sure it’s mounted as vertical as possible.

As I expected, the seat Blendr mount is definitely more secure and robust. Obviously, the CarBack won’t get turned sideways, but it does expose it to more bumps/bruises. The seatpost mount is good, but can have a tendency to turn sideways if you’re running it on a gravel bike and riding rough terrain. The included strap is sturdier than an existing one from one of their lights, so you’ll want to use the one included with the kit (but it still slips downward and can move on rough roads).

Setup is easy with both Garmin and Wahoo head units. Simply turn it on and pair it up. You’ll be led through a sequence of disclosures that essentially reinforce your need to remain vigilant on the bike because no radar is perfect. The on-bike notifications differ, but the indicators are essentially the same, with an indicator of approaching vehicles. Truthfully, I prefer Wahoo’s more elegant and less-intrusive radar experience.

Speaking of better line-of-sight, I’ve found that on undulating or curvy roads, the radar will lose track of vehicles. However, just keep those vehicles on your internal radar because after a curve or a roller, the car will likely be back. As all the warnings state, the radar is great, but you still have to be aware of your surroundings. But, it removes a lot of stress by simply knowing there are vehicles approaching.

Some may wonder how well the radar detects actual, moving vehicles. In my testing, there were zero false-positives between parked and moving vehicles. I have noticed that when a vehicle is traveling behind you at your same speed for a few minutes, they drop off the radar, but a quick glance behind and they are indeed there. Be sure to keep that in mind. Also, it will detect other cyclists sometimes and show them as vehicles. It’s not perfect, but I’d still call it heaven sent.

Trek CarBack vs Garmin Varia RTL515

I know what’s on your mind… how does it compare to the venerable Garmin Varia? Unfortunately, I don’t have the Varia on hand right now, but have used one in the past with great success. It’s great to have both options on the market. The retail pricing is the same, so you’ll have to choose the radar that works best with your bike. I already use plenty of Blendr mounts and Bontrager lights, so the CarBack fits best in my ecosystem.

Size

The Varia is longer, narrower and thinner than the Carback. The Carback is definitely a boxier design. I’d love to see it a little narrower, but perhaps the radar needs all that width to improve accuracy. With a shorter length, the CarBack can fit easier on shorter seatposts.

• Varia dimensions: 3.9″ L x 1.6″ W x 0.8″ D – 2.5 oz.
• CarBack dimensions: 2.75″ L x 2″ W x 1″ D – 3.2 oz.

Performance

Both units feature various lighting settings from solid to daytime strobe. Both have rechargeable batteries with the Varia using micro USB and the CarBack using the now-standard USB-C. As expected, the CarBack’s updated sensors do detect vehicles at a greater distance.

• Varia radar distance: Up to 140m
• CarBack radar distance: Up to 240m

Battery life

I’m overloaded with all the batteries needed to go on a bike ride. If it’s not one thing, it’s another, so a long battery life is important, as is the ability to easily check the battery life. The CarBack wins in the battery checking department with more granular status indicators.

• Varia battery life: Up to 15 hours in daytime flash
• CarBack battery life: Up to 12 hours in daytime flash

Light brightness

It’s important to be seen out on the road. I’m all about the most obnoxious and bright flashing tail light to let others know that I’m on the road. I’ve gotten comments from drivers in the middle of South Dakota, thanking me for having those lights — saying they could seem me from way back. The CarBack wins the brightness game.

• Varia day flash: 65 lumens
• CarBack day flash: 90 lumens

Both units offer great features and will provide peace of mind on your next ride. It’s great to have alternative radar options on the market to expand the use and availability of rear-facing bike radars.

Buy Now: Visit TrekBikes.com