Trek CarBack bike radar lets you know when cars are approaching

“Car back!”

If you’ve ever been on a group bike ride, you’ve no doubt heard these two words shouted by a nearby rider. It’s also the name of Trek’s new $199 bike radar.

For safety-conscious cyclists, bike radars have been a game-changer. Usually mounted on the seat post, the radar units alert cyclists to cars approaching from behind. While they will work on any bike on any road, bike radar is most useful in suburban and rural settings. After all, if you’re doing some urban bike commuting, you’ll just assume cars are behind you because that’s how it is. But on more open roads with higher speed limits or free-flowing traffic, bike radars are fantastic.

While a handful of companies make them, the Garmin Varia is the best-known and most popular option. The Varia is so popular that it is nearing the proprietary eponym status of Kleenex and Taser among cyclists. Trek hopes to change that with its new CarBack bike radar.

Like other bike radars, the CarBack can be used with either a cycling computer or your smartphone. Mounted either on a seat post or the back of a Bontrager saddle, the CarBack can detect vehicles approaching from as far away as 150 meters, beeping at you once one is in its range.

The CarBack plays just as nicely with Garmin bike computers as the Varia does. When a car comes within range, your bike computer will chirp, the edges of the screen turn orange, and a dot showing the car’s relative position travels up the right side of the screen—exactly the same as riding with a Varia.

Speaking of the Varia, there are three significant differences between it and the CarBack. The first is the effective range, 140 meters for the Varia versus the CarBack’s 150 meters. While riding, I didn’t have the feeling that I was getting alerts sooner. But testing on a busy street demonstrated that the CarBack does have at least a few more meters of range than the Varia.