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Lezyne Femto Drive Duo



Compact 'be seen by' light, but it's not the best value out there
Secure fitment to a helmet
Cheap batteries
Brighter than expected
Not great value

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.

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For such a small lumen count, the Lezyne Femto Duo is quite a punchy light for sitting atop your helmet. It's simple to use, should fit to any vented helmet, and the batteries last for ages. Also, I haven't had any issues with water ingress like we had on previous test models. There is some tough competition out there, though.

We last reviewed the Femto Duo back in 2016 and Dave's only real concern was that, with both the front and rear lenses also being a switch, they allowed water to enter the unit in heavy rain.

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In the last six weeks of testing, I haven't had any issues with that, even when testing it under the bathroom shower. I've fired water at it from all angles and even submerged the lens part of each end in water, with no ingress.

Lezyne doesn't give an IP rating for waterproofing so there is nothing to really gauge whether they should keep the water out, or to what level. Maybe I've just been lucky so far, but you could always try not to use the switch in the rain, and check for water inside the lens after riding – at least that way you can dry them out before any damage is done.

As for the light itself. Well, it's basically a front and rear Femto light, joined together by way of a composite bracket which allows you to run a Velcro strap through it so you can attach it to any vented helmet. Once in position, the light is held in place securely.

Operation, as I've mentioned, is controlled by way of pushing the lenses. Press and hold to turn them on or off, and apply just a small press to scroll through the modes.

2021 Lezyne Femto Drive Duo - front.jpg

Each 'end' has three Flashing modes, each one faster than the previous one, plus Pulse and Solid.

A run-time of 30hrs is given for the constant Solid mode, and 60hrs for anything that flashes or pulses. It's hard to gauge, as the Duo uses two CR2032 batteries either end, which I know from experience can be affected by temperature – the cold can shorten their lifespan.

> The best 2021/22 front lights for cycling & beam comparison

The front light pumps out 15 lumens, the rear 7 lumens. Both ends of the Duo can be operated individually, so you can run whatever combination of flashing or constant pattern you like.

2021 Lezyne Femto Drive Duo - rear.jpg

The front light puts out more light than you'd expect, and though you wouldn't (and couldn't) use it as a main light, it's bright enough to be seen on the floor, and I found it handy to be able to glance back at the cassette if I wasn't sure what gear I was in on very dark roads.

The rear one is still bright enough to be seen by, helped by the fact that it's elevated.


The Femto Duo is priced at £28, which is in line with something like Brightside's Topside Helmet Light at £29.99.

That's capable of putting out up to 100 lumens, though, while still offering decent burn-times, and it's rechargeable. It also gets an IP65 rating, meaning it'll cope with heavy jets of water. That's a lot of light for the money, and makes the Femto Duo look pricey and a little outdated in comparison.

> Buyer’s Guide: 22 of the best rear bike lights for 2021

Topeak's Headlux isn't that bright, but as a be seen light it still does a decent job. It also uses CR2032 batteries and offers good burn-times. It'll set you back £18.99.


Overall, the Femto Duo is a decent performer, as long as it continues to keep the water out. It's got some tough competition for the money, though.


Compact 'be seen by' light, but it's not the best value out there test report

Make and model: Lezyne Femto Drive Duo

Size tested: 15lm front, 7lm rear

Tell us what the light set 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?

Lezyne says, "Two-in-one safety light integrated into a versatile helmet mount. The Lezyne Femto front and rear light is coupled by a composite matrix junction. Compatible with nearly all vented-style helmets. The Lezyne Femto Duo's LEDs are housed in a super compact, lightweight and durable machined aluminium body. High-grade polycarbonate lenses provide side visibility and double as the power button."

It's a decent light that puts out more illumination that I was expecting.

Tell us some more about the technical aspects of the light set?

Lezyne lists:

* Small 2-in-1 safety light.

* Combined front and rear light coupled by composite matrix junction.

* LEDs are housed in machined aluminium body.

* Powered by two CR2032 batteries.

Rate the front light for quality of construction:
Rate the rear light for quality of construction:
Rate the front light for the design and usability of the clamping system
Rate the rear light for the design and usability of the clamping system
Rate the front light for waterproofing. How did it stand up to the elements?
Rate the front light for waterproofing. How did it stand up to the elements?

So far, so good. I haven't had the water ingress issues we've seen before.

Rate the front light for battery life. How long did it last? How long did it take to recharge?
Rate the rear light for battery life. How long did it last? How long did it take to recharge?

Battery life is good considering it uses CR2032s.

Rate the front light for performance:
Rate the rear light for performance:
Rate the front light for durability:
Rate the rear light for durability:
Rate the front light for weight:
Rate the rear light for weight:
Rate the light set for value:

Tell us how the lights performed overall when used for their designed purpose

The Duo gives out more light than I expected, and it fits securely to the majority of helmets.

Tell us what you particularly liked about the lights

Easy to use.

Tell us what you particularly disliked about the lights

Not as powerful as similarly priced competition.

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

The Brightside offers much more light and performance than the Femto Duo for basically the same money, while the less bright Topeak mentioned in the review is nearly a tenner less.

Did you enjoy using the lights? Yes

Would you consider buying the lights? Probably not, especially at full price.

Would you recommend the lights to a friend? Yes

Use this box to explain your overall score

The Femto Duo is brighter than expected and it's well made. It's up against some tough competition for the money, though.

Overall rating: 6/10

About the tester

Age: 42  Height: 180cm  Weight: 76kg

I usually ride: This month's test bike  My best bike is: B'Twin Ultra CF draped in the latest bling test components

I've been riding for: Over 20 years  I ride: Every day  I would class myself as: Expert

I regularly do the following types of riding: time trialling, commuting, club rides, sportives, fixed/singlespeed,

As part of the tech team here at F-At Digital, senior product reviewer Stu spends the majority of his time writing in-depth reviews for, and ebiketips using the knowledge gained from testing over 1,500 pieces of kit (plus 100's of bikes) since starting out as a freelancer back in 2009. After first throwing his leg over a race bike back in 2000, Stu's ridden more than 170,000 miles on road, time-trial, track, and gravel bikes, and while he's put his racing days behind him, he still likes to smash the pedals rather than take things easy. With a background in design and engineering, he has an obsession with how things are developed and manufactured, has a borderline fetish for handbuilt metal frames and finds a rim braked road bike very aesthetically pleasing!

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Simon E | 2 years ago

15 lumens for a light, is that even remotely visible with the proliferation DRLs and blindingly intense LED car lights these days?

CR2032s are so small they are easy to carry with you but fiddly to replace and there's no low battery warning so how do you know when the 30 hours is approaching?

Secret_squirrel replied to Simon E | 2 years ago

I had one of these on my commuting helmet for years. Zero issues with waterproofing.  It tends to dim before running out so you get plenty of warning.  Battery life was much longer than 30hr imo when on flash, which is the best way to use this light.  
Not a light to be used on its own but as an additional light that creates height in a cyclist I think it's a useful addition.  

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