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Finally got a pair of prescription sunglasses for summer, but apparently polarised lenses are potentially dangerous for cyclists according to Redditors due to light playing weird tricks on you. On my first day wearing them the only interesting thing I noticed was my phone screen shimmering like a foil trading card

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[-] WokePalpatine@hexbear.net 25 points 2 weeks ago

The redditors saying shit like "you'll miss puddles with polarized lenses" have to be nautiluses with pinhole eyes or something. No idea what world they're living in.

[-] doublepepperoni@hexbear.net 17 points 2 weeks ago* (last edited 2 weeks ago)

lmao, that's the exact example that kept popping up

As soon as I got the glasses I tried looking at water to see if there was some weird mindfuck shit going on and was severely disappointed

There was also something about the way sunlight filters through trees in forests (????)

[-] Abracadaniel@hexbear.net 16 points 2 weeks ago

I've been riding over a decade and only keep polarized sunglasses idk what these people are talking about. I've also cycled in a lot of forest, there's nothing lol.

[-] doublepepperoni@hexbear.net 9 points 2 weeks ago

I think one other example was not being able to see people inside parked cars with tinted windows, thus increasing your chances of getting doored. These sound like some real edge cases

[-] Abracadaniel@hexbear.net 12 points 2 weeks ago

More often the polarization makes it easier to see into a car in my experience. Anyway, yeah edge cases for sure.

[-] comrade_pibb@hexbear.net 5 points 2 weeks ago

smdh anti nautilism

[-] mantra@lemmy.zip 20 points 2 weeks ago

Yeah, don't listen to those people. Polarized sunnies are awesome no matter what you're getting up to. They aren't playing tricks with the light, they are filters, plain and simple. Looking up how they work would be better than any explanation I can conjure up, if you're curious about the science. The aren't a safety issue, though. I have been wearing them for decades and put miles and miles on my bikes, both commuting and doing things like adventure races. Happy cycling!

[-] FloridaBoi@hexbear.net 12 points 2 weeks ago

Just rotate them 90° and you can see what gets filtered. Been using them for years. I can see where dark sunglasses of any kind can be potentially dangerous in less than bright daylight but one could plan ahead and keep a lighter tint set or one with those photochromic lenses.

[-] Le_Wokisme@hexbear.net 9 points 2 weeks ago

polarized during the day, any old safety glasses at night if it's dusty or there are bugs flying around.

[-] CloutAtlas@hexbear.net 17 points 2 weeks ago

Nah don't listen to reddit. They kept saying you shouldn't cycle without a helmet after drinking a pint of vodka but I was doing that like 3 nights a week in Wuhan and I turned out ok.

[-] TrustedFeline@hexbear.net 11 points 2 weeks ago

idk if you're joking or not, since I used to be about that life until some unfortunate drunk biking accidents. Fortunately no head injuries (that I remember...), but that was pure luck. wear a helmet, and know that drunk biking is still really dangerous.

[-] CloutAtlas@hexbear.net 5 points 2 weeks ago

I was joking, I only did it a couple times. I usually don't get drunk due to my alcohol tolerance, so it was tipsy. Rental bikes don't come with helmets so I was winging it. Eventually I was getting taxis since they were dirt cheap

[-] Xavienth@lemmygrad.ml 7 points 2 weeks ago

Reddit is full of Americans and Americans don't have proper bike infrastructure. There is a cultural chasm between the Dutch who think biking with a helmet is ridiculous and Americans who think biking without a helmet is ridiculous, and that comes from Americans thinking a line of paint is bicycle infrastructure.

I'm not familiar with how good cycling infrastructure is in China, but given their ginormous roads, i suspect it's closer to America, and so biking without a helmet would be reckless

[-] JustSo@hexbear.net 14 points 2 weeks ago

only interesting thing I noticed was my phone screen shimmering like a foil trading card

if you can find a second polarized lens or glass/window with a polarizing film on it, you can play with viewing through both polarizing filters and rotating one. It's kinda cool. I think two identical lenses with one rotated 90 degrees blocks 100% of light (if the polarization is strong.) They're excellent for looking into rock pools and stuff, water in general I suppose. They cut so much glare and dazzle that otherwise only lets your eyes really see the surface of things.

A few physical phenomena look a bit different through polarized lenses, but I get used to it very quickly and I've never heard anyone ever complain about the polarizing (ha) effect doing stuff like this. I'm sure there are edge cases and particular sensitivities, but online you only need like 3 people to agree early in a discussion and you can generate new lore for that online space.

People who've never worn polarizing sunglasses now wont, because they're afraid that it will make them vulnerable to sudden death or injury and they will helpfully repeat the misinformation to save the next person who didn't hear those three guys talk about the issue that one time.

Reddit is exceptional for this, people studied early on how to most effectively manipulate public opinion on reddit with first post and/or second post bias and a few other consensus building cognitive tricks that I can't remember. Sounds really sinister and it is when it's done to intentionally manipulate people, but redditors also just do it to themselves by accident all the time.

[-] doublepepperoni@hexbear.net 6 points 2 weeks ago

if you can find a second polarized lens or glass/window with a polarizing film on it, you can play with viewing through both polarizing filters and rotating one. It's kinda cool. I think two identical lenses with one rotated 90 degrees blocks 100% of light (if the polarization is strong.) They're excellent for looking into rock pools and stuff, water in general I suppose. They cut so much glare and dazzle that otherwise only lets your eyes really see the surface of things. A few physical phenomena look a bit different through polarized lenses, but I get used to it very quickly and I've never heard anyone ever complain about the polarizing (ha) effect doing stuff like this.

That's exactly the sort of neat stuff I hoped to see with my new glasses. All the supposed negative effects on Reddit just sounded really interesting to me. Maybe I will get a second pair of sunglasses thonk. I've only ever owned one pair of glasses at a time but after discovering how cheaply you can order them online from China I've already got several

I'm sure there are edge cases and particular sensitivities, but online you only need like 3 people to agree early in a discussion and you can generate new lore for that online space. People who've never worn polarizing sunglasses now wont, because they're afraid that it will make them vulnerable to sudden death or injury and they will helpfully repeat the misinformation to save the next person who didn't hear those three guys talk about the issue that one time. Reddit is exceptional for this, people studied early on how to most effectively manipulate public opinion on reddit with first post and/or second post bias and a few other consensus building cognitive tricks that I can't remember. Sounds really sinister and it is when it's done to intentionally manipulate people, but redditors also just do it to themselves by accident all the time.

Reminds me of the old ProZD skit about enthusiast subreddits

[-] insurgentrat@hexbear.net 8 points 2 weeks ago* (last edited 2 weeks ago)

Enjoy looking deep into water as you knock out all the polarised light from Brewster's angle that gets reflected off the surface.

Also you can see stress in transparent plastics as rainbows!

[-] SpookyVanguard64@hexbear.net 5 points 2 weeks ago

Another interesting thing you can look for is the band of polarized light in the sky created by Rayleigh scattering. Just look anywhere that's 90 degrees away from the sun.

[-] doublepepperoni@hexbear.net 2 points 2 weeks ago

Not sure if it's related but I have noticed the entire sky sometimes darkening when tilting my head to the side. Some manhole covers shimmer, so presumably other metal surfaces can do so too. I have another phone which doesn't have the foil effect, instead the screen just goes black when I turn it sideways. Very cool!

[-] SpookyVanguard64@hexbear.net 2 points 2 weeks ago* (last edited 2 weeks ago)

Yeah, the whole sky darkening should also be related to Rayleigh scattering, since all sunlight that gets scattered by the atmosphere will get polarized to some extent. The effect is just most intense 90 degrees from the light source.

The shimmery foil effect is likely due to birefringence. Basically some materials have a different index of refraction depending on the polarization and direction of travel, causing the light passing through to get split based on its polarization. Not sure exactly where the color shimmer comes from though tbh. I'm thinking it's some sort of interference pattern created by the polarized light components recombining out of phase or something like that, but I could be wrong about that. It's been like 4 years since I graduated with my physics degree, and optics was never my strong suit lol.

(I am taking an intro to materials science class right now though, and one of the main ways to create birefringence is passing light through a non-cubic crystal structure, so I imagine we'll probably cover that once we cover optical properties in the next few weeks. Speaking of which, martensite is the only microstructural variant of steel that I'm aware of that has a non-cubic crystal structure, so I wonder if those manhole covers you're seeing are made of martensitic steel.)

[-] HexReplyBot@hexbear.net 1 points 2 weeks ago

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[-] culpritus@hexbear.net 13 points 2 weeks ago

I ride with polarized lenses and haven't ever had any significant issues related to it. Could there exist some strange situation where polarized lenses are not ideal? Sure, that's plausible I guess, but seems like a weird thing to be concerned about when riding a bike. The cars are much more of a real threat.

The only thing I can think of would be if safety signals were being displayed via LCD screens or some other polarized light source. That could cause some issues, but you just push the glasses out of the way for a few seconds and the problem is mitigated.

[-] PKMKII@hexbear.net 10 points 2 weeks ago

Yeah I’ve noticed with mine that some glass material that looks normal without them has the rainbow/foil effect. Some LED screens look dark at certain angles as well, but I don’t think either of those things are likely to cause you problems while cycling.

[-] SpookyVanguard64@hexbear.net 9 points 2 weeks ago* (last edited 2 weeks ago)

Some LED screens look dark at certain angles as well

For anyone curious as to why this happens, it's 'cause a lot of screens have a polarization filter on them as well, and the difference between the polarization angles of the two filters determines how much light from the first filter (i.e. the screen) makes it through the second filter (i.e. your sunglasses).

Longer (but still oversimplified) explanation:Photons are emitted with random polarization angles relative to one another, and a polarization filter will selectively let photons through based on how closely they match the filter's polarization angle. If the difference between the polarization angle of the photon and filter is 0 degrees, the photon passes through without problem. If the difference is 90 degrees, the photon is completely blocked. And of course, there's a gradient on anything in between. The end result however is that all photons that pass through the filter will now have a polarization angle that matches the polarization angle of the filter.

So when you have light passing through two polarization filter (i.e. an LED screen and polarized sunglasses), the amount of light that makes it through the second filter is entirely dependent on it's polarization angle relative the the first filter. If the two filters are perfectly aligned, then 100% of the light coming through the first filter will make it through the second filter, since all of the light coming through the first filter will be polarized at the same angle as what the second filter will allow through. But if that second filter is then rotated 90 degrees, suddenly none of the light from the first filter will make it through the second, since all of the light that makes it through the first filter will be polarized at a 90 degree angle from what the second filter will allow through. And naturally, any angular difference that's between 0 and 90 degrees will allow between 100% and 0% of the light through.

[-] tombruzzo@hexbear.net 8 points 2 weeks ago

I've been fine riding with my sunglasses. It does that wavy thing when I look at the readout on my ebike right where it says how far I've gone this trip. Otherwise it's been all good

[-] JustSo@hexbear.net 5 points 2 weeks ago

oh true I forgot about the LCD thing. that can be really annoying actually.

[-] PorkrollPosadist@hexbear.net 8 points 2 weeks ago* (last edited 2 weeks ago)

The only potential issue with polarized glasses is if you are a dentist who uses a cycle computer to monitor your heart rate, cadence, speed, and dual side power meters while riding on your cervelo. It makes it hard to read the screen.

I ride with polarized glasses all the time. Keeps the bugs out of my eyes (more important than the UV protection IMO).

[-] TrustedFeline@hexbear.net 7 points 2 weeks ago* (last edited 2 weeks ago)

ive heard polarized lenses are banned for pilots (idk if its FAA or airline policies), which makes sense since they're looking through thick windshields with specialized coatings. never heard anyone say that about bikes, though. That just seems silly

[-] DataCrime@lemmy.dbzer0.com 7 points 2 weeks ago

The issue is polarized puddles become invisible which can ultimately lead to chafing… J/K

this post was submitted on 11 Apr 2026
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