Originally Posted by
Spoonrobot
Hmm, these runtime plots somewhat look like thermal stepdown.
nope, it is physically not possible with that small battery to maintain 1700 lumens for 2 hours. This is a clearly programmed stepdown
Originally Posted by
The_woo
[...]but given that the STVzo regulations that most cutoff beam lights follow limit the total power output to just 205 lumens, it's clear that most will not be suitable for fast riding on dark winding country roads.
Which light do you have on your velomobile that is so capable?
StVZO does not limit lumens. It limits lux above the cutoff (and it requires a sharp cut-off from max lux to less than 1.5 Lux within an angle of 1.5°), which requires very good optics for high power lights. There are a few StVZO lights with 800-1200 lm in low beam (i.e. Lupines (SL MiniMax, SL AX, SL Grano) or the Lezyne HP1350+ StVZO)
For my liking, the Detour has tad too much light in the foreground and middle, this makes it harder for the eyes to adapt to the perceived darker area in the distance.
I use a B&M IQ-XL in my velomobile, which has a very favorable light distribution for low mounting position, i.e. very little light directly in front of the bike and a very bright center spot (300 lux at the brightest spot). This allows very good adaption of the eye to the distance. Lumen output is about 550-600 lumens in low beam.
Here is a beamshot of the IQ-XL in low beam, mounted pretty high on my road bike bar. The first reflective side marker is about 55-60meters in front of the bike, the second in 110-120m:
