Like this site? Help us to make it better.


Koo Eyewear Alibi sunglasses



Top-notch photochromic lens that works extremely well in low-light conditions, with a quality befitting the price
Excellent in low light
Fast-acting, high-quality lens
Secure but comfortable
Very good wind protection
Faff to pop the lens out
Not for big heads
Not dark enough for super-bright days
No hard case

At every product is thoroughly tested for as long as it takes to get a proper insight into how well it works. Our reviewers are experienced cyclists that we trust to be objective. While we strive to ensure that opinions expressed are backed up by facts, reviews are by their nature an informed opinion, not a definitive verdict. We don't intentionally try to break anything (except locks) but we do try to look for weak points in any design. The overall score is not just an average of the other scores: it reflects both a product's function and value – with value determined by how a product compares with items of similar spec, quality, and price.

What the scores mean

Good scores are more common than bad, because fortunately good products are more common than bad.

  • Exceptional
  • Excellent
  • Very Good
  • Good
  • Quite good
  • Average
  • Not so good
  • Poor
  • Bad
  • Appalling

The Koo Eyewear Alibi Sunglasses have a unisex half-frame design that's made to offer maximum visibility. Our test pair has a matt white frame and a fuchsia-coloured, fast-acting photochromic lens that's designed for year-round road and gravel riding. I found the lens superb for low-light conditions and suitable for all but the very brightest of summer days, and its high-quality lens is backed up with good comfort. But I do feel the Alibis are best suited to riders with smaller heads – and there is a definite knack to swapping the lens.

> Buy now: Koo Eyewear Alibi Sunglasses for £200 from Condor

I have to say that I really like the look of the Alibi sunglasses from Kask's sister company Koo. The lens changes colour as the ambient light lessens, becoming a translucent light-blue – which made me feel like a character straight out of a 1980s anime such as Battle of the Planets (Google is your friend if you don't know your Japanese popular culture...). And while the large lens means the glasses really do stand out, I did receive a lot of positive comments about them from fellow riders.

Koo makes a variety of lenses for its Alibis but ours came with a photochromic lens with a 1-3 filter category: 1 is pale for an overcast day and 3 is for bright conditions when the lens turns dark. The VLT (Visible Light Transmission) range of the lens is from 75% to 12%: during the dullest conditions it allows 75% of the light through, dropping down to just 12% when it's very bright.

2023 Koo Eyewear Alibi sunglasses - logo

The one-size-fits-all frame measures 142mm across the top of the lens, while the rounded arms are 110mm long. The frame is available in eight different colourways and is made from Grilamid, a thermoplastic material that Kask says is shock-resistant, light and non-allergenic.

2023 Koo Eyewear Alibi sunglasses - arm detail

I did find the textured arms quite stiff, and they feel tough too – though I wouldn't want to test the limits of their toughness by accidentally sitting on them. They grip very well though, and didn't budge or slip at all when I was riding on the drops. I could just about see the edges of the lens in my peripheral vision but not the Koo logo or the central support pillar.

2023 Koo Eyewear Alibi sunglasses - side

In use

The Alibis are very light, weighing just 29g, and it barely felt like I was wearing them at all. There are a few small ventilation gaps between the top of the lens and the frame, which presumably accounts for the lack of any steaming up when I was puffing my way up my local climbs. And I found they successfully shrugged off light rain too.

I wore the Alibis with a variety of helmets – from Kask, Poc, Lazer and dhb – to check for any compatibility issues and had no problems with any of them. I'd say the frame size is probably better suited riders smaller or medium head sizes, and with a 60.5cm head circumference I think I was close to the upper limit for these.

The lens

I have to say that the highlight of the Alibi sunnies is the performance of the photochromic lens, which I found very effective in a wide range of lighting conditions – from darkness to daylight.

I was amazed to find I was able to wear these while cycling at night on the Sustrans Bristol and Bath Railway Path. I kept having to check that it wasn't affecting my night vision – but it really was very good wearing them in the dark.

2023 Koo Eyewear Alibi sunglasses - nosepiece

They were especially welcome when riders with 2,000-lumen death-ray lights were heading in my direction, and they were similarly efficient at reducing glare from oncoming car headlights at full beam when I hit the road. For the tech-minded, I'd compare it with applying an 'easy eye' filter on a bright LCD computer monitor. And while my lens had a 12-75% VLT range, Koo also does one with a 15-87% range that would be intriguing to try out.

The glasses worked equally well in the sunshine too, with consistent colours across the lens – and the lens also reacts quickly, turning dark when you exit a tunnel or emerge from tree cover into bright sunshine.

2023 Koo Eyewear Alibi sunglasses - 2

I was testing these in winter, and on days when the sun was really low and I was riding directly towards it I was very glad to be wearing them. I think they might struggle in an absolutely clear sky under a blazing summer sun, but with the exception of days like that, I think these would be a great choice for the majority of year-round riding.

I did struggle with removing the lens at first, but I found there was a knack to it – you unclip the sides of the lens from the frame and then push the lens out from the central support piece. I eventually got the hang of it but it's not something I'd like to do very often, as I worry that I could damage what is a really nice lens.

2023 Koo Eyewear Alibi sunglasses - hinge inside

Koo sells a few separates for its Alibis: spare photochromic or mirror-finish lenses cost £44.99, spare nose pads £8.50 and a clip for fitting prescription lenses is £50.


While the Alibis are undeniably expensive – they're well made, have a premium feel and smart looks. And that price is comparable to those of other premium brands' photochromic glasses and the same as the top-priced sunnies in our best cycling sunglasses buyer's guide.

Anna Marie tested that £200 SunGod Airas Base Frame with a photochromic lens. The lens clarity and fit were excellent but they didn't quite protect from the wind as well as hoped.

Our sister site reviewed the Melon Optics Alleycat glasses, with a photochromic lens that worked well. I own a pair of these and found them a very close match to the Alibi. The Alibi's lens is better in low light, while the Alleycat's lens better at shedding water droplets. The Melons are not only £60 less but you also get a hard case, which is disappointingly absent with the £200 Alibis.

But you don't need to spend that much for photochromic glasses. The Tifosi Slice Fototec Light costs just £94 and Stu also found they could be ridden into the night, though their lens coverage is limited.

For an even more budget option, Decathlon offers its VR Race II Photochromatic HD sunnies, which come in at very wallet-friendly £49.99.


Koo's striking-looking Alibis are a very good pair of sunnies. They have a top-quality photochromic lens that's suitable for the majority of year-round riding in the UK. I think they're probably best suited for smaller heads and it's a little tricky removing the lens, and while the price is undeniably expensive, it is comparable to other premium photochromic glasses.


Top-notch photochromic lens that works extremely well in low-light conditions, with a quality befitting the price test report

Make and model: Koo Eyewear Alibi sunglasses

Size tested: One Size

Tell us what the product is for and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?

The Alibi, from Kask's sister company Koo, is a unisex half-frame pair of sunnies designed for maximum visibility for road and gravel riding. Our test model has a matt white frame and a fuchsia-coloured photochromic lens for year-round riding in typical UK conditions.

Tell us some more about the technical aspects of the product?

One size, Half-frame design


142mm wide (across the top of the frame lenses)

110mm (Sunglasses arm length)

High-performance lens with ventilation holes (Koo also sell spare lenses, available with a mirror or photochromic finish for £44.99)

Grilamid frame (available in 8 different colours). Grilamid is a thermoplastic material that is shock-resistant, lightweight, and non-allergenic.

White Matt / Fuchsia Photochromic

Filter category: 1-3 (1 being pale lenses for overcast days, up to 3 which means dark glasses for bright days)

Visible Light Transmission: 75-12%

Rounded arms for a stable and secure fit

Soft touch nose pads (Koo sells spare nose pads for £8.50)

Compatible with KOO Optical Clip for prescription lenses (Koo sells this for £49.99)

Rate the product for quality of construction:

Quite stiff to close the arms, but I feel that's a good thing, as they stay secure and stable when you're wearing them.

The arms curve slightly downwards, which is good for storing them upside down on helmets. I tried them with lids from POC, Kask, dhb and Lazer and found they they stayed secure in all of them.

Rate the product for performance:
Rate the product for durability:

I wouldn't want to take the lenses out too much. You have to release a tab at each side of the lens to unclip it, then release the lens from the frame at the top and pull it clear of the nose clips. And as they're a frameless design you don't want to drop these on to a hard surface, as you might chip the edge of the lens.

Rate the product for weight (if applicable)

These are very light so you don't feel the weight at all.

Rate the product for comfort (if applicable)

Very comfortable.

Rate the product for value:

At £200 these are undeniably expensive, but the price is in line with similar quality glasses from other premium eyewear brands.

Tell us how the product performed overall when used for its designed purpose

They worked very well indeed. I didn't expect to be able to ride in the dark with them but actually found them great for riding in low-light conditions. For most of the year, these would be my go-to glasses, unless it was absolutely blazing sunshine.

Tell us what you particularly liked about the product

Their low-light vision is really good. I also think they're a great-looking pair of glasses and it wasn't just me – my fellow riders also loved them.

Tell us what you particularly disliked about the product

They won't be suitable for heads bigger than mine, which is around 60.5cm in circumference, so I think the Alibi is better suited for medium or smaller size heads.

Removing the lens is a little bit of a faff and I was scared of damaging it in the process, but that could be me being over-cautious.

How does the price compare to that of similar products in the market, including ones recently tested on

At £200 these are comparable to other premium photochromic glasses we've tested. The performance matches them, so I think at £200 they are in the right ballpark. Other more budget-friendly photochromatic glasses are available and these are mentioned in the copy.

Did you enjoy using the product? Yes

Would you consider buying the product? Yes

Would you recommend the product to a friend? Yes

Use this box to explain your overall score

I found the Koo Alibis a very good pair of cycling sunnies. They have a top-quality photochromic lens that's suitable for the vast majority of UK riding. But I think they're more suitable for riders with smaller heads, and removing the lens can be a bit of a faff. And while there's no getting away from the £200 price, it's not out of line with similar sunnies from other high-end names.

Overall rating: 8/10

About the tester

Age: 43  Height: 181  Weight: 92 Kilos

I usually ride: GT Grade  My best bike is: Boardman ASR 8.9

I've been riding for: Over 20 years  I ride: Most days  I would class myself as: Experienced

I regularly do the following types of riding: commuting, club rides, sportives, general fitness riding, mtb, Zwifting

Add new comment


Sriracha | 1 month ago

The good wind protection is all for naught if yours eyes still water because of the price.

Latest Comments