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A Tiny Mirror Built Into Your Cycling Sunglasses? We Test TriEye

Ever wanted to have eyes on the back of your head while riding? TriEye cycling sunglasses offer just that—and we're surprised with how well it works.

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When I was a kid, I could have sworn my mom had eyes on the back of her head. How else did she always know when I was about to reach into the cookie jar when she wasn’t looking, or that I actually did throw that Nerf ball at my brother’s head? There was a solid chunk of time in my childhood when I believed that my rear-facing eyes would surely grow in when I became an adult. Even now, I still kind of wish that was a thing. This sentiment occurs to me mostly when I’m on my bike. As a deaf person, I don’t hear what’s behind me, and though I mostly ride on low-traffic roads with a bike lane, there are times when cars come by just a little too fast or when my fellow cyclists surprise me by passing just a little too close for comfort. When this happens, I think about what it would be like to have eyes on the back of my head. I’ve tried rearview mirrors on my handlebars, but they only work in one specific upright position (not aero) and helmet-mounted mirrors don’t stay in place for more than a mile.

As it turns out, I’m not alone in feeling this way. Carsten Fongen, a European cyclist who was hit from behind when riding in the Norwegian mountains, developed TriEye, a pair of cycling sunglasses with a built-in rearview mirror. A simple concept, to be sure, but as it turns out, one that’s deceptively hard to execute well.

TriEye Sunglasses: What We Liked

The mirror of the TriEye sunglasses is built in to the corner of the lens. The mirror is tiny—smaller than the nail on my thumb—which had me wondering at first how this could possibly work. In the past, when I’ve tried helmet-mounted or sunglass-mounted rearview mirrors, they’ve all been at least one square inch (most are bigger) and mounted quite far from the head. Could something so small and so close to my face actually give me a decent view of what is behind me?

As it turns out, the answer is “yes.” What I didn’t realize at first glance is that the mirror is not in a fixed position. Instead, it’s mounted on a raised ball with a small tab, which allows the user to rotate the reflective surface to an angle that shows what they want to see. It’s similar to the side mirrors on a car, where users can rotate up, down, left, and right until it’s in an ideal position to see the road behind. As for the size of the mirror, the position near the cheek makes it so that a small size is not an issue. In fact, anything larger would likely obstruct the view when looking ahead. Somehow, TriEye managed to get it just right.

The fact that the mirror is integrated into the sunglasses themselves, as opposed to mounted on the helmet or handlebar, makes checking the rearview an easy experience. One doesn’t have to take their eye off the road ahead to glance behind—it’s all right there, in one cohesive view. It takes some getting used to, for sure; having this view in my line of vision was disorienting at first. I don’t recommend wearing these sunglasses for the first time on a ride, but instead spending some time wearing the glasses while walking around outside, getting used to the new sensory input. Once your brain adapts to processing the front and rear view at the same time, then it’s time to hit the road by bike.

It was during this acclimation process that I discovered another valuable use of the TriEye sunglasses: knowing when someone is behind me on the trail. I spend a lot of time hiking and trail running, and I don’t always hear people coming up behind me (I’ve angered many a mountain biker). With the TriEye sunglasses, I had much more awareness of my surroundings, which allowed me to feel safer and more confident on the trails.

TriEye Sunglasses: What Could Be Better

Though most people who buy the TriEye sunglasses are doing it for the rearview mirror feature, they probably also want quality pair of sunglasses. Their satisfaction on this will depend on their definition of “quality.” There are elements of the TriEyes that are most-definitely high-quality: 100% UV protection, a large wraparound lens, and a row of vents along the top frame to prevent fogging. There are also lens upgrades available for those who want a light-changing photochromatic lens.

But if you’ve been wearing a high-tech, lightweight, barely-there pair of sunglasses, the TriEyes may feel heavy in comparison. On short rides, this weight is acceptable, but on longer rides of two hours or more, they begin to feel uncomfortable on the ears and bridge of the nose. This heft is especially felt in the nose piece, which could use more flexibility and ventilation for comfort. Small tweaks to materials and design could take the TriEyes from good to great.

TriEye Sunglasses: Conclusions

For those who want the security of knowing what’s behind them—whether it’s cars, fellow cyclists, or even fellow trail users on a hike or trail run—the TriEye sunglasses can be a real game-changer. A lot of thought, care, and real-world experience clearly went into the design, and the result is a streamlined, highly functional piece of safety gear for cycling, running, and other outdoor adventures.

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