Does it exist?

Needs to be:

Crown-mounted
Good for quick commuting and also off-road at moderate speeds
Weatherproof (so no USB charge port)
Not silly money (under a ton)
With decent buffer/standlight

I have a Busch and Mueller Lumotec IQ Cyo 40 lux lamp on my Brompton, its done a year now and is still going ok. I did run it on the sense setting, but just leave it turned on all the time now.

I’m not sure your two objectives are really compatible.

I’ve got a B&M Lumotec of some form on my Brompton. It’s good enough to make your way across an unlit park on a commute but I’d not want to ride singletrack on it. My Canyon commuter has a Supernova E3 which is significantly brighter.

Both have properly shaped beams which mean they don’t dazzle oncoming traffic (or other cyclists – nothing worse than someone coming at you on a two way path with some blindingly bright flashing monster) and they use the light effectively. Both are more than enough to be seen.

Off road your requirements are different – you want to throw more light upwards and outwards to read the trail and spot any low branches.

Simons has a fair point, the cut off is quite distinct.

From all i’ve read Exposure Revo or K-Lite from Travers for off road usage, and the B&M for road usage.

Agree with the above, the peeps who ride with lights brighter than a car at full beam are super obnoxious

BM IQ Premium is 80 Lux.
No USB port and weatherproof.

Ok offroad on simple stuff, but anything techy and I put an Aldi special on the bars.
The cut off is a bit limiting otherwise.

Good points re differing beams/intensity. By ‘offroad at moderate speeds’ I mean if I get caught out down a farm track or across a moorland rupp then I can probably get home without going at walk-speed, neither plunging over a quarry.

Already have an X2 unit for pure off-road but it’s assentially a rough-road/back-lanes touring bike that will be getting the PD8 setup. Had a quick gander online at B+M lights but the choice seems extensive!

Confusing, innit?
This seems to give a good explanation of what everything means.

SON Edelux 2 perhaps. Very happy with it after owning one almost 3 years, road and open tracks kind of use, handles a bit of singletrack better if you use a bar mount as a back up but is OK without (watch those branches). Can also be angled up a bit when off-road if needed.

Now have a rear SON plugged into it and it’s a great system. One switch controls both lights.

For riding on road the German lights are much better than off road lights. The reflectors are really well designed *but* they’re not all the same – look at the beam patterns on the Edelux lights on here

https://www.nabendynamo.de/produkte/edeluxii_en.html

Yet another example of where ‘regulations’ and ‘red tape’ deliver really useful results. So many lights sold in the UK are shit. https://medium.com/@charlesarthur/the-herald-of-disaster-or-why-you-should-welcome-regulations-fbaaeaed17e5