Photochromic glasses, what no one says, advantages and what they are
The photochromic glasses made a big step forward in terms of lens quality, the lenses adapt to ambient light in open spaces. Photochromic lenses almost magically darken or lighten depending on the amount of sunlight. In this post we will see how these photochromic sunglasses work and why they are so useful for mountain bike and especially for road cycling.
How do photochromic lenses and glasses work?
This type of lens includes a substance – copper or silver chloride – that reacts to ultraviolet rays emitted by the sun and causes the photochromic lens to darken, trapping more or less light depending on what is in the environment at the time.
The first idea to make these photochromic sunglasses work is that you must be outdoors, they don’t work inside a car for example, most of them only react to ultraviolet light. This means that they do not work with artificial light or if sunlight is filtered through any glass -for example windows-
Advantages of photochromic glasses for mtb and cycling
In sports such as cycling, the advantages of these photochromic sunglasses are diverse. Often the brightness changes during the day and where a while ago there was a bright sun now there may be grey clouds that have darkened the day. In those cases your lens will not detract from your vision at any time, on the contrary it will adapt to the ambient conditions.
In the mountains these changes in light are more frequent, especially if we go into wooded areas where there are more shadows. With photochromic sunglasses for cycling we will not have to take them off every time this happens, thus reducing the risk of getting something in our eye or losing control of the bike.
Even if without sunlight, say in the early morning or at night, you don’t have to do without them or replace your lenses with clearer ones, with photochromic glasses you are always protected without impairing your vision.
Here’s what no one tells you, or don’t knows so much about photochromic glasses
People who want to buy one of these photochromic glasses often wonder what are the best photochromic cycling lenses? And the truth is that there are more and more and of different qualities on the market.
I have a pair of prescription glasses with photochromic lenses and I am delighted. When it comes to buying, almost everything you find on the internet talks about their advantages and reasons for buying them, but some things I think we should know are not always told.
There are different types of lenses, qualities of photochromic filters.
1.  They take a few minutes to get dark
The lenses do not darken and lighten instantly, they usually take 40-100 seconds to do so, even much longer in some cases, it can take hours. In 90% of situations they work very well but think that if you go into an area of light and shade.
2.  Does not darken at high temperatures
As you read, sometimes it can be very transparent at higher temperatures and the photochromic glasses become much less dark. First always check the temperature ranges for the lenses you are thinking of buying, in beach areas in summer with high temperatures can be a problem.
3.  They not clear with a lot of cold
They do not darken, as with heat, in very cold situations photochromic lenses darken a lot. But the problem is not that, the problem is that they can take even hours to become clear again, forcing you to remove them in some situations. And if you have to have other glasses on hand.