Originally Posted by
BarracksSi
Okay -- who's got a light meter and too many headlights?
No such thing.
Lumens are additive. No you wont see twice as far with twice the lumens because the beam spreads. To See twice as far you need 4x the lumens...or you can halve the beam angle.
The other issue is perception. If your 250 lumen light illuminates well for 16m (how far you ride in 3s at 20kph) but you want to see for 32m for those 40kph tailwinds ... well if you turn up the power to 1000lumens you get the same illumination out at 30m. Only now you have a really bright patch out to 15m which blinds your eyes, so you aren't SEEING quite out to 30m even though the illumination there is fine.
Solution...put a second light in with the same 250lumens but half the beam angle pointed out to 30m. Same illumination out at 30 but 500lumens instead of 1000.