What does the gas station optician know about the organs you use to see the trail? Are those safety glasses from the hardware store really “just as good as my friend’s Oakley’s?” We chatted with an eyewear engineer from 100% to find out how they design MTB glasses and goggles, and what makes those higher-priced pairs worth more cash.
As the pandemic escalated PPE supply concerns at US hospitals in early 2020, the folks at 100% were looking for component manufacturers for the ongoing Goggles for Docs program. One particular engineer was able to step in and connect the necessary resources to get things rolling, and from there was hired into the current role as Chief Eyewear Engineer. We’ll do our best to translate the light-science they shared below.
The most important factors when designing a pair of glasses are the environment and weather conditions they will be used in. Engineers consider which colors in the light spectrum need to have higher contrast sensitivity for a given sport, which colors will be best to darken, and what will create the sharpest visual field for the rider.
To begin with low-light lenses, a clear lens is good as long as it has the right coatings, like the one that comes with most shield-style 100% frames. The anti-fog, anti-scratch, and anti-oil coatings help the lens last longer and make it easier to clean. The brand’s other low-light specific lens has a light yellow tint with a light flash mirror coating. The flash mirror reflects the glare that comes straight at the lens so you can see through it at all times. Then the yellow increases contrast and also filters out the blue light, which reduces eye fatigue. Any time you’re in heavy fog or low-light conditions, blue light is overpowering everything else. All lenses from 100% filter out all UV-A, -B, and -C but blue is still very sharp and powerful. As you move across the light spectrum it starts to even out; the longer waves become longer, with red being the least aggressive.
In summation, the flash mirror and base tint coatings on the lens enhance light filtration and reduce glare, so the rider can actually see things more clearly with less effort. That’s a boatload of work for a thin piece of plastic.
We asked the engineers about “blue blockers” specifically since the term seems to be hot again. The phrase is regularly misused and equally misunderstood. One of them noted that “when you create filtration you definitely want to block out blue, but you can’t block out all of the blue because you need it to see true color. It’s part of the primary colors. And blue comes in a lot of different forms depending on conditions. There’s also this thing coming off your computer called high-energy visible light (HEV) that’s very harmful to your melatonin creation. It also creates anxiety and stress. That’s where I’ve developed several different lenses with our partners to help block that HEV. But that’s a separate conversation”
Three of the key design elements for a lens are transmission (the actual amount of light hitting your eye), reflection, and absorption. Those three factors will help drive how well you see contrast, how well blue light is blocked, and how much heavy light in sunny conditions is shaded.
Out in the forest, a copper or vermillion base tint works well for contrast sensitivity, helping us better see the holes and pitches in the dirt. Those lens tints manipulate the waveband, and heighten those colors that are normally dampened out. Then, with the right exterior coating, each lens can achieve a specific shading property without diminishing clarity and color contrast.
The lens engineers gave a specific example of how a lens adjusts what you see. “If you use a copper base with a blue mirror, you’ll have around 40-45% light transmission. Then, if you go to a grey base it’s going to push that [light that reaches your eye] down way further, to 18-20%.”
They also said that a grey-based lens will allow for true color across the board, and is the easiest color on your eyes for longer rides. The grey won’t pop color contrast quite as much, which means your eyes will do slightly less work. In short, they recommend the higher contrast lenses for rides under three hours and a grey tint for all-day adventures.
When it comes to goggle lenses, the story is very similar. The lenses need to be tinted and mirrored to deal with those same three factors, and the frames need to be shaped for maximum ventilation.
Larger goggle and sunglass lenses can sometimes have a fishbowl effect, with distorted peripheral vision and overall optical effects that can lead to headaches. This is often noticeable with bargain-priced glasses, but some more costly shades exhibit this issue as well. This distortion occurs in clear and tinted lenses alike. While our eyes are strong and can correct a lot of that distortion, they will feel far better at the end of a ride if they don’t have to.
Eliminating lens distortion was one of the questions that required a decidedly complex response. Essentially, in order to get rid of that effect, you have to make the light that’s entering the lens come in at the same angle all across the bowed shield. To make that happen, 100% and some other brands create lenses that are thicker at the center and taper toward the edges. That thinning of the lens redirects the light to enter at a more consistent angle, so your eyes don’t have to do the work of correcting it. This, in addition to their coatings and overall durability, are the reasons a clear performance lens can be better than a pair of safety glasses from the hardware store.
The frame and overall shape of a pair of sunglasses is likely the element that most of us notice first, and the engineers that choose those angles have a lot of variables to consider. Basic frame measurements start with temple tip to tip, hinge to hinge, and temple length.
Face size and shape are also at the top of the list, right alongside coverage and protection. For example, the wide 100% Speedcraft model can be ordered with three different lens sizes to accommodate different size faces, browlines, nose bridges, and cheekbone shapes. So, even though the chassis is identical, they need to make different lens shapes and nose pieces for more fits, with the hope that anyone who picks up a pair of 100% shades will have everything they need in the box to comfortably fit them to their face. To finalize the fit they perform trials both in the lab and in the field, triple checking that all coverage and comfort attributes are dialed.
Once all of that is sorted, the designers need to ensure that the temple tips don’t interfere with helmet straps and shells while wrapping tightly enough against the head to hold them comfortably in place. In the case of mountain bike frames, they have to give the temple enough grip so that they don’t come off in rough sections of trail, or if you crash. Also, the upper edge of the frame can’t touch the helmet shell, as that will cause the glasses to shift and make annoying noises.
Wowee, that’s a lot to say about a pair of sunglasses. Another important element is the pantoscopic tilt, which is how the lens tilts to match the angle of most faces. It angles away from the brow and toward the cheekbones. That angle ensures maximum coverage, keeping things from flying into your eyes while allowing maximum airflow behind the lens to prevent fogging.
Apart from shading light, glasses are there to protect our eyes. A final distinction between gas-station optics and a well-engineered pair of performance glasses is that the latter has to pass several safety tests. Most gas-station lenses are made from a relatively fragile acrylic that will break and cut you on impact. Glasses that pass impact testing can withstand the force of a heavy branch or rock hitting your eye, and also won’t come apart and cut your face if you crash. The video below shows how some of this testing is done with various glasses, including those from Oakley.
While the $150-200 price tag for tested-and-perfected eye protection is laughably high compared to the $10-15 you can spend in a convenience store, the testing and engineering that goes into the lenses and frames do hold some significant value. Similar to how we might buy the best audio equipment to enjoy music on the way to the trail, purchasing high-quality visual equipment can certainly enhance the experience and safety for folks who can afford it.