Find out how to best protect them with the right cycling and running sunglasses.
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Product managers, engineers, laboratory staff: we gather all our optics specialists together to make our sunglasses.

As you scroll through this article phrases like ‘index of glare protection’ and ‘photochromic lenses’ might jump out at you and seem over complicated – but they’re not. Stick with us and we’ll explain, quite simply, what to look for when you’re buying sports sunglasses, which pretty much boils down to the lens category, whether the lenses can be changed, and tint.

1. Lens Category

You can cycle or run in any weather conditions. Sun, rain, fog... but in order to protect your eyes while seeing clearly, you’ll need to select a pair of sunglasses from the appropriate lens category.

First thing’s first, what does ‘lens category’ mean? It’s the index of glare protection , which ranges from 0 (the lightest lens) to 4 (the darkest lens) and there’s a lens category for every weather condition.

Basically, the brighter the outdoor light, the more glare you get, and the darker the lens should be. And the darker the sky, the lighter the lens should be to allow proper vision.

For cycling and running, choose category 0, 1, 2 or 3 lenses, depending on the sunshine intensity.

Warning! Category 4 lenses must not be used for road driving. These heavily tinted lenses are only for high mountain and sea conditions, where the sun rays are more intense.

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Category 0

For rainy conditions or at night .

Very low brightness outside.

Full UV protection.

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Category 1

For cloudy or foggy conditions.

Low brightness outside.

Full UV protection.

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Category 2

For partly sunny weather conditions.

Average brightness outside.

Full UV protection.

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Category 3

For sunny weather conditions.

Bright outside conditions.

Full UV protection.

2. Interchangeable Lenses

Weather is changeable – especially if you live in the UK! – and if you cycle or run regularly and need to be prepared for bright or cloudy skies, opt for sunglasses with interchangeable lenses .

That just means a frame with several sets of lenses that fall into various categories. Before going out, you just need to clip or lock the appropriate lens category onto the frame. Sunglasses may be sold with one, two or even three additional pairs of lenses.

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3. Photochromic Or Variable Tint Lenses

If you liked the idea of interchangeable lenses, wait till you read about photochromic lenses: lenses with a variable tint . Depending on the light conditions, the lens automatically and continuously adjusts its tint. The lens category changes progressively, without the need to change the lenses.

Like we said before, the weather can be changeable and it’s likely you’ll be moving between overcast and sunny areas within a matter of minutes on your bike or when you’re running, so it’s not always convenient to have to choose one single lens category. With photochromic lenses, you don't have to worry about choosing the appropriate lens tint.

For cycling and running, photochromic lenses usually vary from category 1 to 3 , in order to adapt to as many light conditions as possible.

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Optics Specialist

Whether you’re running or cycling outdoors, always choose lenses that have a full UV filter to protect your eyes from the sun's harmful rays. Want your sports sunglasses to last longer? Go for polycarbonate lenses, a highly shock-resistant material.