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Busch & Muller IXXI rear light



Really well built, reliable back up light that lacks the power and brightness for standalone use

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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The Busch & Muller IXXI rear light is a single LED unit that is designed to comply with the strict German StVZO regulations for bicycle lighting. This brings with it a lot of limitations with regards to power output and the like and demands the question: is brighter better?

Usually in light reviews we would start with a look at all the various modes and burn times but due to StVZO compliant lights not being allowed to flash the B&M (Busch & Muller) has just two modes, on and off. Highlighting how rare that is these days my two year old son who loves to play with the huge selection of lights I've got gave it back to me telling me it was broken.

It's not very bright either thanks to another regulation stating that power has to be limited to 0.6W so you're looking at about 4 to 5 lumens in practice.

The unit is very well built and simple in design for a start with a button on the top and a USB charge point at the bottom covered by a rubber flap which is removed for charging. No matter how much rain I rode through the B&M never succumbed to any moisture issues and carried on working regardless for the full fifteen hour burn time.

To keep an eye on how much battery life you have left there is a small LED indicator that changes colour and once fully flat it turns itself off to protect the battery. Charging time is pretty short at just two and a half hours if you use the a mains charger or four hours from a computer USB port.

The lens gives 180 degrees of illumination so it's ideal for making you little bit more visible from the side at junctions and roundabouts. I had it positioned mid-way up the seatstay for that exact reason and the use of a small o-ring to fit means it stayed put on the slender tube. It stretches well enough to fit round a seatpost though.

So back to that question, is brighter better? Yes up to a point, I'm not recommending full on eye scorching rear lights but I like a lamp that's going to stand out in rush hour traffic in both power and an eye catching flashing pattern.

For this reason I don't think the B&M is beefy enough as a standalone rear light for use on our roads; it doesn't have the depth of illumination to stand out from a distance. While the 180 degree light angle is plenty the small single LED is pretty easy to miss on busy roads.

It does make a brilliant back up light though, either as a constant light source alongside a flasher or something you can chuck in your bag for emergencies. The 30g weight and £16.99 price makes it ideal for that.


Really well built, reliable back up light that lacks the power and brightness for standalone use

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Make and model: Busch & Muller IXXI rear light

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?

The IXXI is a rear LED light built to conform with the German StVZO regulations and for this reason it suffers against the opposition through lack of brightness and varying modes.

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

Integrated rechargeable lithium-ion battery

- 15 hours burn time

- Charging via B&M mains adapter takes approximately 2.5 hours

- Charging via micro USB port takes approximately 3-4 hours

- Indicator LED shines when the light is on

- Switches off automatically to protect the battery from depth charging

- Approved by German road traffic regulations

Rate the light for quality of construction:
Rate the light for design and ease of use. How simple was the light to use?
Rate the light for the design and usability of the clamping system/s
Rate the light for waterproofing. How did it stand up to the elements?
Rate the light for battery life. How long did it last? How long did it take to recharge?
Rate the light for performance:
Rate the light for durability:
Rate the light for weight, if applicable:
Rate the light for value:

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

I understand the light's output is governed by the regulations so in terms of performance for its designed purpose the B&M does exactly what it should. I don't think it's up to the task of dealing with British roads and our traffic, though.

Tell us what you particularly liked about the light

It's simplicity and build quality.

Tell us what you particularly disliked about the light

Lack of brightness.

Did you enjoy using the light? As a back up.

Would you consider buying the light? No.

Would you recommend the light to a friend? No.

Anything further to say about the light in conclusion?

The B&M is well built and robust enough to cope with our weather, it also has simple operation and fitting but its lack of flashing modes and brightness means it struggles to prove itself as a viable option against the competitors. IT makes a decent back up light though. Scoring wise it's saved by its quality and decent burn times.

Overall rating: 7/10

About the tester

Age: 36  Height: 180cm  Weight: 76kg

I usually ride: Kinesis T2  My best bike is: Kinesis Aithien

I've been riding for: 10-20 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,


With 20 years of road cycling and over 150,000 miles in his legs it's safe to say Stu is happiest when on the bike whatever the weather. Since writing his first review for back in 2009 he has also had a career in engineering including 3D-CAD design and product development, so has a real passion for all of the latest technology coming through in the industry but is also a sucker for a classic steel frame, skinny tyres, rim brakes and a damn good paintjob.
His fascination with gravel bikes is getting out of control too!

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