Headlight thread: B&M IQ XL

[Patrick Moore]

Dark falls just early enough now that I was able to use the new IQ XL tonight on the ride home from Vespers. B&M claims that the XL is the brightest dynamo light with a low beam putting out 300 lux and, oddly enough, high putting out 200.

Low is German-spec shaped and cut off while High just blasts the lumens into space. There’s a neat little handlebar button with rubber strap; you can flash your brights at people just as the grownups do in their cars. Anyway, I had fun playing with the High and Low beams.

The XL is perfect for the Matthews dirt road road bike since I ride both on tree-crowded ditchbank roads and paths and on streets and paved bike paths. 

Aside, a question: When I installed the XL I also installed a new Toplight Line Plus rear rack-mounted dynamo tail light, as the older one’s standlight did not work. Well, neither does the standlight on the new one. Might this be do to some incompatibility with the XL? Do you have to plug the power and ground wires in just so?

The rear light works fine, it just stops working when you stop moving.

Suggestions for a fix welcome; also suggestions for a rear rack-mount tail light with a standlight that does work without hassle.

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Patrick Moore

Alburquerque, Nuevo Mexico, Etats Unis d'Amerique, Orbis Terrarum

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[Patrick Moore]

That high beam puts out 250 lux, not 200.

One reviewer commented that the high beam is far less focused, so that the lux measurement — illumination in a particular place —  is less since the beam is more diffused.

On Sat, Aug 30, 2025 at 9:17 PM Patrick Moore <bert...@gmail.com> wrote:

…  B&M claims that the XL is the brightest dynamo light with a low beam putting out 300 lux and, oddly enough, high putting out 200.

[Eric Douglas]

Patrick--

I have the same setup on one of my bikes--   IQ XL  and   Toplight Line Plus.

Out of curiosity, I just put the bike on my stand and spun the front wheel for a while. Standlight works fine .  I then reversed the wires on the Toplight and---the Toplight works while the front wheel was spinning but he standlight did not work.

So, in the case of the standlight and the Q XL polarity seems to matter. So try reversing the wires and hopefully that will fix it.

Eric 

Brooklyn

[Patrick Moore]

Thank you, Eric. I thought I’d had the terminals swapped earlier and found that the light didn’t power on, but I’ll try that again.

How do you like the IQ XL?

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[Patrick Moore]

Yep, that solved the problem.

Once again, thank you, Eric.

On Sun, Aug 31, 2025 at 7:48 AM Eric Douglas <1ekdo...@gmail.com> wrote:

[Eric Douglas]

Glad I could help.

I really like the IQ XL.  The low beam is perfect for riding in NYC, and I find the high beam useful on windy county roads, where I find the wider beam really helpful.

I also like the ability to toggle between beams with the handlebar switch.  Good for flashing high beams when needed.

Eric

Brooklyn