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Sigma Buster 400 Headlight



Not class-leading, but a decent light with a great battery indicator and burn-times for its size
Good burn-times for its size
Intuitive battery indicator
Quick to install/remove
Narrow spot beam
Need to scroll through flash to get to high beam

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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Although you can use the Sigma Buster 400 to see by on dark lanes, it's a compact light that is probably best suited to being used as an emergency backup or as a 'be seen by' flashing light thanks to its reasonably low lumen output and torch-like beam. The run-times are pretty good, though, and you get a more in-depth battery life indicator than most at this price. Unfortunately, like so many others, you have to scroll through flashing to get back to the main beam.

Take a look at our guide to the best bike lights for more options, front and rear.

The Buster 400 is a dinky light, so it doesn't take up much room on your handlebar, and you can bung it in a jersey pocket or bag for emergency use.

The rubber band style strap is quick to fit to or remove from the handlebar, which is ideal if you have to leave your bike unattended. You can remove the light from the mount, but it's no quicker really.

2022 Sigma Buster 400 front light - mount.jpg

You can pull the strap tight which gives a firm grip on the bar, so the light stays in position on all but the roughest roads.

Modes & run-times

Operation is easy: a double tap of the button to turn the light on or off (which also stops accidental operation in the bottom of a bag), and a single tap to scroll through the five modes.

Looking at the three solid modes, high gives the full 400 lumens, which Sigma says has a range of around 120m and runs for 2 hours from the 2,000mAh battery, with the next two giving 4 hours (200 lumens) and 9 hours for 100 lumens.

Like a lot of what I'd consider to be entry-level lights, the Buster has a narrow torch-like beam. It works okay as long as the roads aren't too twisty; I'd say 15mph to 20mph is achievable on the flat, but you'll be scrubbing that speed on the downhills.

You also get two flashing modes: night flash, which lasts 5 hours, and day flash, 25 hours.

Night flash keeps the LED on at 100 lumens while laying a 300-lumen flash over the top; day flash is just a straightforward 100 lumens on flash.

> Best front bike lights 2023 — light up the road, trail or path with our top picks of the best front beams

One annoyance is that the only way to get back to high mode once you've left it is to scroll through all the modes, including flashing – not ideal on a dark lane, but the Buster isn't alone on this.

Battery life is shown via five white LEDs on top of the light, with one dropping out with every 18% that is depleted from the battery. Once you get to 19% the last one turns red, and once it starts flashing you've got less than 5% left.

I'd say it's fairly realistic, considering variables like temperature can affect things.


Charging is via USB-C and the port sits behind a rubber cover. Overall, the Buster gets an IPX4 rating, which means it's resistant to splashes, and while I'd like to see IPX6, like some lights at this price, I didn't have any issues with rain ingress or from it being splashed by the garden hose. Keep that rubber cover closed, though.

2022 Sigma Buster 400 front light - USB port.jpg

At £39.99 the Buster is in the same ball park as others with a similar output.

It's the same price as the Cateye AMPP 500, for instance, which I tested last winter. That does get an extra 100 lumen but battery life is shorter at 1.5 hours on high. You don't need to scroll through flashing modes, though – hooray!

The Sigma is a fiver less than the Ravemen CR450, but you are getting a bit more illumination, an alloy construction compared to the Buster's plastic, a remote control, an IPX6 rating and an impressive T-shaped beam pattern. Iwein tested it last year and was very impressed.


On the whole the Buster 400 is a quality little light. It doesn't do anything brilliantly for the money, as in it doesn't trump any lights that cost a similar amount, but neither is it full of niggles. For the money, something like the Ravemen is better, but if you can find a good deal on the Buster then it's a decent option.


Not class-leading, but a decent light with a great battery indicator and burn-times for its size test report

Make and model: Sigma Buster 400 Headlight

Size tested: n/a

Tell us what the light 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?

Sigma says, "The BUSTER 400 gives you a universal companion on the road. On the way to work or school or on a racing bike ride, 400 lumens and 120 metres of beam range keep you out of the dark. Depending on the mode selected, you can be on the road with the BUSTER 400 for up to 25 hours, with five pre-set profiles that ensure greater ease of use. Precise LED indicators show you exactly how much charge is left in the light."

A basic spot type beam, but it comes with decent burn-times.

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

Sigma lists:

* Maximum light output: 400 lumens

* Beam range: 120 m

* Five light modes: High (400 lm), Mid (200 lm), Low (100 lm), Night flashing (300/100 lm) Day flashing (100 lm)

* Burn time: 2 h in High mode, 3 h in Mid mode, 9 h in Low mode, 5 h in Night flashing mode, 30 h in Day flashing mode

* Charge time: 3 h

* 360° adjustable bracket

* Switch on protection (double click for ON)

* Splash resistant in accordance with IPX4

* Tool-free mounting

* Charging possible during operation

* USB-C charge function

* Five-stage charge indicator, six-stage battery indicator

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Rate the light for design and ease of use. How simple was the light to use?
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Rate the light for battery life. How long did it last? How long did it take to recharge?
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Rate the light for value:

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

It produces enough light to be able to ride on flat, dark roads at a decent speed.

Tell us what you particularly liked about the light

I liked the small increments of the battery indicator.

Tell us what you particularly disliked about the light

Scrolling through flashing to get to high.

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

It's in the same sort of ball park as many lights of this size, but the couple I have mentioned in the review are brighter, and have other benefits over the Buster 400.

Did you enjoy using the light? Yes

Would you consider buying the light? No, there are better options out there.

Would you recommend the light to a friend? Possibly

Use this box to explain your overall score

There is nothing that stands out particularly about the Buster 400, but it is a dependable light that gives enough illumination to ride by on the back lanes.

Overall rating: 7/10

About the tester

Age: 44  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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