Luxos IQ2 U dynamo headlight – review

Both ends of my commute are now in darkness, so I’ve been able to give the Luxos IQ2 U I’ve had attached to the MetaBike a good shakedown. Billed as the last dynamo light you’ll ever need, if you’re looking to upgrade your lighting it’s well worth a look.

Apologies in advance for the dire photos. My phone throws up its hands when it comes to having dark and light things in the same image (plus I’m too lazy to actually set up decent shots…). You get the idea.


Just to get the name out of the way, ‘IQ2’ refers to an updated lens system, ‘Luxos’ is Busch and Muller’s top-end light family, and the ‘U’ bit means this version comes with a fancy remote switch – the B is the same light without the switch.

The IQ2 U is the top-of-the-range for B&M headlights, with the following selling points:

  • Daytime running lights, dipped and full beam options
  • Standlight (so the light doesn’t stop when you do) and ambient light sensors
  • Remote switch for the handlebar, which also houses a USB socket

If you don’t read any further, all you really need to know is that I reckon the IQ2 U is the best dynamo headlight you can buy, providing you can mount it on the fork crown. It’s probably a bit bulky for handlebar use. It’s maybe a tad underpowered for flying downhill on pitch black country lanes, but I was perfectly happy up to about 45kph, and I’m a complete coward.

Light modes

There was all sorts of information flying around when this was launched a few months back, mainly stemming from some dodgy translations from the German manual. The IQ2 U has four different modes, which will be very familiar if you have driven a vaguely modern car:

  • Off. Ok, there are actually two modes here. If you don’t move for about five minutes the light will turn itself off and only restart when you start moving again. Call that the ‘soft off’. There’s also a ‘hard off’ which keeps the light off even if you’re moving – useful for wheeling through stations or if you want to push the maximum power to the USB charger. Hold the remote switch for two seconds to switch between ‘hard off’ and on.
  • Daylight running. You know the bright white little LEDs that many new cars have on all the time for ‘being seen’ in daylight? That’s what this mode is. If the light is switched on and the IQ2 detects that it’s in daylight, you’re in this mode. Indicated by a glowing orange LED on the back of the light.
  • Dipped beam. If the light is on and it’s gloomy or dark, you’re in this mode. Conventional, non-dazzling dipped beam steady headlight. Also shown by a glowing orange LED on the back of the light.
  • Main beam. Marginally-brighter-than-dipped, steady headlight, toggled on and off by a tap of the remote switch. Whilst on main beam, the back of the light displays a steady blue LED, as does the switch. You can also use this to ‘flash’ traffic (you know, letting out buses and such) when in daylight running mode, but I’ve always found hand gestures more effective.

Note that there’s no way to force the light to run in either daylight running or dipped beam – you just turn it on and the ambient light sensor works it all out for you. I haven’t had any problems, and it ‘upgrades’ immediately if you go into a tunnel or under some dense trees. Just be aware there’s an awful lot of electronic trickery that might potentially go wrong.

Rear view of the luxos
Rear view of the Luxos (as mounted on the front of a recumbent, in case the chainset is confusing…). Not the four cables (two from the dynamo, two to the rear light), plus thicker cable on the right heading to the remote switch. The think currently glowing orange is the combination switch/indicator light described below. Comments relating to the cleanliness of my chain will be spammed.

The LEDs on the back of the light body are clever, in particular the green one which indicates that your rear light is drawing power (marked RL in the photo above). If that light goes off, you’ve either stopped moving (so the rear is running off its internal standlight power), turned your rear light off, or the rear has failed. This is incredibly reassuring if you ever feel nervous about your rear lighting. Both green and orange LEDs on the light body dim in darkness, so they don’t dazzle you. Clever.

The remote switch, complete with blue 'main beam' indicator LED.
The remote switch, complete with blue ‘main beam’ indicator LED. My phone is over-dramatizing the brightness, but it’s enough for me not to want it point directly into my eyes. The rubbery hatch on the right is currently covering the USB socket.

The remote switch shown above contains the blue main beam indicator and an additional red LED to show when USB charging is available. Personally I found this useless – USB charging is almost always available if you’re moving above 15kph, regardless of whether you’ve got the dipped beam on as well. If you’ve spent a good chunk of time below that speed the charging might stop, but you’re hardly going to unplug whatever you’ve got plugged in – just leave it until you speed up again. I’d much rather have the green rear light indicator repeated on the switch as well.

Light effectiveness

I’m not going to show outdoors beam pictures, as I never find them particularly useful. Peter White has some good shots, if you’re desperate.

In terms of brightness of the light, I ran the entirety of LEL (so several nights in pitch dark) using only the dipped beam, and felt comfortable up to about 45kph. Beyond that I was on the limits of being able to spot potholes in time, but then I was also permanently knackered, so my reaction time probably wasn’t world class…

The beam itself is very usefully shaped, albeit not that smooth. There are definite panels of light that you can see on the road surface (and the photo below), primarily:

  • A bright ‘letterbox’ covering the road surface from a little way in front of you off to the horizon.
  • A slightly dimmer bit joining this letterbox to your front wheel, ideal for any last minute pot-hole dodges.
  • A bigger and again dimmer shield shape around that (see below)
  • Dimmer ‘wedges’ running from the central letterbox round to each side, for ‘being seen’ from the side, spotting junctions and reading signposts.
  • Another bit that runs off the top of the letterbox above the horizon to light up street signs and give advance notice of badgers, etc.
Luxos beam picture, courtesy of my boiler cabinet. This is the standlight.
Luxos beam picture, courtesy of my boiler cabinet. This is the standlight. In terms of references, the light is about 60cm from those doors, and the vertical wooden frame illuminated to the left is just behind the light (impressive side visibility, eh?). In use, this beam picture is obvious stretch out somewhat, so the very bright rectangle in the centre of the screen covers a decent length of road.

The standlight is the same, but dimmer. Perfectly adequate for being stationary.

Main beam is also the same, but very slightly brighter. I’ve only been testing this recently (I needed to order a longer cable to bring the remote switch onto the recumbent handlebars), but so far I’m pretty disappointed. It would be useful if this option threw more light towards the upper corners, but it just seems to be exactly the same beam shape, just a smidgen more powerful. Call it the difference between 100% and 105% – generally the only indication you’re in full beam is the blue indicator rather than any increased visibility. I have found handy for boosting the much dimmer standlight though, so if I’m feeling slightly exposed whilst stationary at the front of a queue of traffic at a junction, I’ll flick on to main beam just to make sure I stand out from the headlights of cars behind.

Final point on light: as long as you’ve been trundling along at a reasonable pace beforehand, the IQ2’s internal battery can keep the dipped light going at full brightness for about 15-20 minutes of crawling uphill before you drop into the duller direct power routine. Even then, I could get by at 8kph with the power provided by a SON delux generator in a 622mm wheel.

Another final point: because the lens on the IQ2 is huge, side visibility is superb. Even from directly behind the light I can see two very narrow strips of illumination, so anyone coming at you from the side has no excuse for not spotting you.

Side on view of the Luxos, showing the great sideways visibility.
Side on view of the Luxos, showing the great sideways visibility.

USB charging

Along with the fancy light, this is the other big selling point. The remote switch has a covered USB socket which you can use to power various gizmos. A handlebar mounted GPS is the obvious choice – my EDGE 705 ran off it for five days continuously without too many issues. There was a lot of early concern about waterproofing or this arrangement, as the USB standard doesn’t allow for properly waterproof connections. Provided you ensure that the remote cable runs up into the light body rather than down (to prevent water running along it and into the casing) and keep the remote switch itself sheltered under the handlebars, you can charge in the rain. If I was using it for a long distance event, I’d probably cover the connections with tape just to be on the safe side.

[Edit, April 2014: the new Luxos IQ2 model has a permanently connected wire, which removes the risk of water ingress, but also prevents you using a cable extension if you’ve got a longer-than-normal-bike length from mount to handlebar. I wrote an update here]

You can run the headlights as well as charging.

Construction, mounting and other points

This is a big, bulbous, heavy light. Mounts are available for handlebars, but it’s really meant to be at fork crown height where it’s protected a bit more from being knocked around. Recumbent boom light tabs are ideal. The standard wire mount is a little pathetic, but just about does the job. Mine requires a tiny twist once a week to straighten it up again, as the entire thing pivots around the mounting point. If you’re not worried about driving a screw into your bottom bracket axle, you could probably tighten it up enough to avoid this.

The light body itself is a shiny plastic. Nothing to write home about.

Fatty light from the front
Fatty light from the front, and in rather poor focus. Oh well. You can just make out some of the LEDs at the top of the lens, along with ScotRail’s scintillating seat upholstery in the background. The weird thing protruding below the light is the MetaBike detachable light mount, which I occasionally use to mount either a reserve blinky or a camera.

You’ll need a T25 spanner to adjust the angle of the light (you can see the screw head in the sideways visibility photo two up). This makes it slightly more difficult to pinch.

If you want to be able to reach the remote whilst on a recumbent, you’ll need the 1m extension cable – part number 479KKLIN/KLIN. Starbike currently have it in stock – you want the ‘phonejack/jack plug’ option.

Comparisons and closing points.

I’ve had long-term use of two other modern high-end lighting systems – an Exposure Strada battery-powered light and a Supernova E3 dynamo job, so I’ll compare against those.

The Luxos:

  • Works better for me as a commuting light, with much better side visibility and the highly useful daytime running mode. The Strada has an effective daytime pulse mode; the E3 is either on or off…
  • Meets the German lighting standards and has a (tiny) front reflector, so is therefore one of the few headlights that meets UK legal standards, if that bothers you. The E3 does as well, the Strada doesn’t (to the best of my knowledge).
  • Puts slightly less light on the ground than the E3 and Strada.
  • Is less sexy than either the E3 and Strada – no machined metal bodies here.
  • Works with all dynamo rear lights – a huge plus. Supernova state their lights can only be used with their own-brand rear light, which is a tiny blinding LED thing with no reflector. Size beats brightness when it comes to rear lights, in my opinion.
  • Is a damn sight cheaper than the Strada providing you’re already set up with a dynamo, and of comparable price to the E3.
  • Has built-in USB charging. The others would require extra cables and kit.

The Luxos does the job for me.


Add Yours →

I have an IQ2 – after a time started to behave in unpredictable manner. I determined that the USB connector was the cause. I figure some water go in a did some damage. I am hopefully going to try to replace it. Secondly I had the electronic tabs broke off the light where the wires attach. The light still works but I cannot charge it any more. I hopefully can find an electrician to solder on new slightly heaver tabs. I am a long distance tourer and this happened after over 10,000km with some very rough roads and I ride a trike without front suspension. I am just looking at fixing it now and another tab broke off. It is a very good light otherwise. Hey and it has been laying around for about 5 months and it still has power.

Any further word on the long term reliability of the product, after wetness and other duress?

Hi Kando

Tricky one. I ended up unplugging the remote cable due to a few cases of water ingress at the socket, and after that it’s been absolutely solid. They’re now on v3 (I’ve got the first version), and have made good progress at sorting out those waterproofing issues. It’s safe to say it’s a reliable light, but if you must have something completely bomb-proof, I suspect you need an Edelux.

How long is the switch cable? I’m looking to put one of these on an M5 M-Racer.

I replaced the unit with a newest version. Both the problems that I had with the old unit have been resolved.

I suddenly find myself in the market for a decent dynamo light and stumple upon your reviews – I need look no further. SOLID reviews, an absolute delight. Thanks so much.

As noted this product has been upgraded from early versions. Feedback from customers mainly positive. Have had one unit fail totally but then again also had a SON hub fail in separate instance. With B&M (and SON) you know products will be supported as core business is lighting.

The stand light has failed on mine after 2 years of not much use. (I do not cycle commute)
The uk distributors and B & M have no interest in repairs or service exchange so ill just have to run and additional light.
Its a shame when you by the best and get second rate treatment/products.

I had had a Luxos IQ2 for six years, did at least 60.000 km when it stopped working at the beginnin of last year. I sent the light to Busch + Müller’s headquarters in Germany (I live in Italy, near Venice) asking them to repair it only if the cost was less that 60 euros. Within a week I received a brand new light, latest model at no charge. As simple as that.

My Luxos failed for the 2nd time in 35000km/ 5years. The first time it was replaced under warranty. On the 2nd time I have to buy a new one. This is not what I expect form such an expensive product. I suspect that the electronics inside of the head light body is not sufficiently protected for the conditions it has to work in. There are a lot of vibrations and also there might be ingress of water during long rides in the rain or when cleaning your bike with water. I am very satisfied with the USB port, the signalling of the condition of the rear light and the amount of light coming for the device

Hi Frans. Thanks for the input. Mine is still going strong after seven years (albeit not your mileage!), but it’s not totally reliable. Particularly when it’s been heavily rained on, it sometimes won’t turn on again for the next ride.

In a subsequent post I decided that I’d prefer to separate lighting and charging. Combining the two adds complication to something essential (lighting), when, as you say, the reliability isn’t really there.

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