Finding new ones isn’t easy. The replacement needs to fit your budget and face, look good, and protect your eyes. When I found a pair I liked, I had a new choice to make. Which lens did I want? What’s the difference between lenses, other than colour? Read on to better understand lenses and more before buying your next pair of cycling sunglasses.
Full-spectrum UV protection
Sunglasses protect the eyes from harmful UV rays; the same ones that damage the skin, in fact. There are three types, UVA, UVB and UVC, present under sunny and overcast skies. Your lens of choice should provide “full-spectrum UV protection”, or at a minimum, have the UV400 label which covers UVA and UVB only. UVC rays are the most harmful, but nearly all get absorbed by the Earth’s atmosphere.
Not all sunglasses block UV rays, but those that do don’t have to cost a fortune. An economical pair provides the same UV protection as the most expensive ones on the rack. But don’t expect the lens quality to be the same. A quality lens gives the wearer a more pleasurable visual experience as what is seen is sharper, and clearer, with limited distortion.
Field of vision
Have you ever made a sudden movement to avoid a pothole, broken glass, or other obstacle you didn’t see until the last minute? It could be because your current glasses have a poor field of vision, or how much the wearer sees around them as the eyes focus on a central point. For road cyclists, this is down the road, for example. A larger field of vision means more time to react to avoid potential blind spots and hazards.
Your field of vision directly affects how you interact with the road and your surroundings. Your glasses should provide good peripheral awareness and clear horizontal and vertical lines of sight so you can ride in safety. An enhanced field of vision is one benefit of large “shield-type” glasses seen on the faces of cyclists everywhere. Many of those models are rimless, further increasing the wearer’s field of vision.
Visible light transmission (VLT%)
Visible light transmission (VLT%) measures the amount of light that passes through any lens. Higher values equate to more light getting through and also determine how bright and clear the wearer sees. Lower levels of VLT come with darker tints and glare reduction as less light reaches the eyes. Glare is a reduction in vision, both physical and subjective, due to intense light contrasts in the field of vision.
Lens colour and thickness, what they are made of and any coatings they have, affect the VLT. Tints with a VLT between 10 to 18% are common in everyday cycling eyewear. Lenses with lower VLT values typically come with a mirror coating. This makes them a good choice for riding in ultra-bright sunlight, such as near water, because of the reflection.
The amount of VLT a cyclist needs changes based on where they ride and the conditions. This explains why manufacturers offer different lens options with every frame. Too much transmitted light strains the eyes. While not enough creates a darker image with little contrast of the road ahead of you, something that is ultimately dangerous. VLT is broken down into five categories.
- Category 0: Clear or a very slight tint for maximum light transmission, often used for indoor or in overcast conditions. 80 to 100% VLT
- Category 1: Light tint that provides modest VLT suitable for overcast or low-light conditions. 43 to 80% VLT
- Category 2: Medium tint for moderate light reduction typically used for outdoor activities in average sunlight. 18 to 43% VLT
- Category 3: Dark tint for a reduced amount of light reduction excellent for strong sunlight conditions. 8 to 18% VLT
- Category 4: Very dark tint for minimal light reduction, particularly designed for extremely bright conditions or high-altitude sports. 3 to 8% VLT
Lens and construction materials
Cycling sunglasses need to be comfortable, durable, lightweight, fit well, and protect your eyes from UV rays and flying debris, but not all are made the same. Glass, plastic and polycarbonate are the three materials of choice. Glass is the most resistant to scratches and provides the best clarity. But it’s heavy and can shatter on impact or in a crash, so should never be used in sports eyewear.
Plastic is less expensive and does a better job than glass to filter UV rays, but it’s the least durable. Polycarbonate is the best option for cycling and sports eyewear due to its impact resistance, high-UV filtering capacity, and featherweight.
Lens coatings and treatments
Your favourite colour may not be your best lens choice, particularly in a mirror finish. The exterior is not the same as what the eyes see through the lens. Try different colours to find what best matches your cycling conditions and vision comfort. Mirrored coatings, common in sports eyewear, reduce glare, provide more clarity and reduce eye strain in bright or extreme sunlight.
There are different mirror finish treatments: flash, full, gradient and multi-layer. Full, gradient and multi-layer are the most common in cycling eyewear. Full coatings cover the entire lens front and are highly reflective, making them excellent for cycling in bright conditions. A gradient mirror coating is obvious from the exterior as the finish wanes from top to bottom. The top mirror reduces glare while the lens tint on the bottom is to better see objects below eye level.
Multilayer mirror coatings, found in premium cycling eyewear, reduce the maximum amount of glare, improve visual comfort and offer the best colour contrasts. Eyewear with a mirrored finish does not automatically mean UV protection. Verify the lenses offer the UV protection you need. High-end cycling eyewear typically has a scratch resistant coating and a hydrophobic and oleophobic lens treatment to repel water, dirt, oil and unsightly fingerprints.
Lens colour
Lens colours also perform differently based on the ambient light and weather, and most cyclists will need more than one option. Like a mirror coating, lens colour has no effect on how well they block UV rays, so be sure your glasses provide at least UV400 protection. Below you’ll find the lens colour guideline frequently used for cycling.
- Gray: Suitable for bright and sunny conditions, gray lenses offer the most versatility, true colour perception and reduce brightness without too much distortion.
- Amber: Enhances depth perception and colour contrast in low-light and bright conditions, making them ideal for riding in partly cloudy or overcast skies.
- Rose: Increases contrast on overcast or cloudy days and enhances visibility in low-light conditions. It’s a good choice for long days in the saddle as rose filters out blue light, preventing eyestrain.
- Yellow: Great to improve visibility in the low light of early-mornings, late evenings and foggy weather. Yellow lenses improve depth perception and contrast in these conditions, making obstacles stand out.
Photochromatic lenses
If you’re on a budget and looking for a do-it-all solution, photochromic lenses are the closest contender. Indoors they appear clear, but once outside, the lens darkens in response to the amount of ambient light.
Photochromic lenses won’t get dark enough to comfortably tackle intense sunlight. They typically max out around the 2nd category VLT%, but do a good job in everyday light. And you avoid the need to switch lenses as you ride since they adapt automatically to the current light conditions. Photochromic lenses are usually sold separately as replacement lenses only, so check if it’s available in your frame and brand of choice.
Polarised lenses
The sun produces random light waves that travel in one plane only and polarised lenses stop them, reducing glare. This is done through a special filter that blocks horizontal light waves while letting vertical ones pass through. Polarised lenses are great for riding outdoors at high-altitudes or near large bodies of water since light reflects off of it, creating glare.
Some people naturally experience distortion or see patterns through polarised lenses. And they may not be suitable for viewing LCD screens or digital displays on the bike. You may have to remove your glasses to view your GPS unit or phone, for example. It depends on your device.
Polarised lenses aren’t available in every model, but will improve the view, contrast and clarity by eliminating the glare caused by horizontal light waves that occur when reflected off of water. Choose models with an embedded filter in the lens as opposed to an exterior coating that wears off with time.
Fit and conclusion
No eyewear will do a good job if they don’t fit correctly. Frames should be proportional to the shape and size of your face, fit comfortably on your nose and ears, and stay put while you sweat. Many of today’s models come with a selection of nose pieces, so check the box and try them for your best fit.
Every label has their branded technology such as HiPER®, 8KO®, Prizm™, Clarity™ and Chromapop™, for example. The names are different, but the object is the same, to provide cyclists with the best possible eyewear to safely navigate roads and trails with optimal contrast, vision and comfort. Some brands offer prescription options, too.
Before investing in your next pair, ask questions and read the fine print to learn what you get for your money and if it is right for you. Still not sure? Your local optician can help with the fit and selection process. Many brands are sold directly to consumers, but you can’t try them on. Give preference to brands with a return policy in case you don’t like them or they don’t fit properly. And remember, customised frames and colours are cool, but you can’t return them. Dial in your model and fit first, then go nuts!
