The Bike Light That Keeps You Safe in Traffic

What It Is: A seat post-mounted bike taillight that detects approaching cars and alerts you to their position and relative risk on a handlebar-mounted display unit.

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Why We Like It: If you've pedaled any number of miles on American pavement, you know the inherent danger bicyclists face sharing the road with inattentive car drivers. While you can be on high alert and ride defensively, you still have to trust that trailing cars will give you space when they blow past. That fear is real, as reported in 2014 by the League of American Bicycles, which found 40 percent of fatalities in bike-car crashes occurred as a result of cyclists being hit from behind.

The Garmin Varia Rearview Radar won't entirely eliminate such risk, but can help give a cyclist far greater peace of mind when on the road. The system works in two ways: In its most basic form, a taillight with built-in radar detects approaching traffic — cars, motorcycles, and even other bicycles — from as far as 150 yards away. Plus, red LED lights flash with greater frequency and intensity as those vehicles get closer to you. Hopefully it gets the drivers' attention so they don't crash you into a ditch.

The light can be paired with a dedicated head unit or compatible Edge cycling computer (currently Edge 1000 only), which alerts you to possible danger. When the coast is clear, the unit displays your bike as a green dot. That changes to orange whenever Varia picks up a car — only vehicles moving toward you at a faster speed than you're traveling will be detected. And the car's relative position is displayed as a white dot that inches closer to your own as the car approaches. If a car is accelerating at an extreme rate, your dot turns red, signaling a serious risk.

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We put the rear light and head unit to the test on remote country roads in upstate New York, as well as traffic-clogged avenues in Manhattan. On rural rides, the unit allowed us to relax our guard a little and enjoy the ride more. At one point, we found ourselves on a two-lane road running parallel to an interstate. There, it's all but impossible to hear an approaching car over the whiz of vehicles on the highway. A quick peek at the head unit showed that the road behind us was empty, so we didn't have to swivel around nervously to check the lane. At other times, it picked up multiple cars traveling together, displaying each as a separate white dot, so we knew how many cars to expect. Back in the city, the light performed far better than we anticipated: On 6th Avenue, it alerted us to the traffic in the adjacent lane only, not those further to the side.

Of course, in either situation, the Varia is not a substitute for remaining vigilant, checking your backside and blind spots before veering left to avoid a hazard or make a turn. But because it can help you relax a little, it allows you to better focus your attention when necessary.

Nitpick: At product launch, the Varia light is only compatible with Garmin's top-of-the-line Edge 1000 cycling computer. But the company has said a forthcoming software update will let you display threats on Edge Touring, 810, 520, 510, and 25.

[$200 taillight only, $300 bundled with head unit; garmin.com]