I have a Dinotte XML-3. It's 2000 lumens on high, 1000 on medium, and 500 on "low".
The 2000 lumens is too bright for dark country roads, unless I'm on a downhill. Reflective street signs are way too bright with this much light. So I usually run it at 1000 or 500 in dark areas.
City streets are bright enough to see even without much light. But I normally use the 2000 lumen setting in the city, and aim it more downward. Then the area in front of my bike is brightly lit, competing very well with car headlights. Cars can wash out my view of the road if they crest a slight grade and send light into my eyes while the road is in shadow. And the bright pool of light on the ground makes me a lot more visible to drivers.
For night group rides, it's on 500 and aimed way downward, unless I'm at the front, then it's usually 2000.
overheating
Modern lights should run at medium or low settings without getting very warm. My much older Dinotte from 8 or 9 years ago was 200/100/50 lumens, and the 200 setting would only last a few minutes without airflow before it automatically went to lower lumens. The case got very hot. Newer LEDs are way more efficient, staying a lot cooler.
Last edited by rm -rf; 11-23-17 at 10:46 AM.