Sadly, cops won’t even stop automobiles with clearly illegal lighting setups here, they’ll never care about bicycles.
It’s a better idea to be well-lit than to be underlit, as a bicyclist. But the way Americans drive I will continue to avoid bicycling at night near any motorways as much as possible.
Having an external battery pack can definitely increase brightness and runtime options, but single cell lights can also work for lots of people.
Lighting requirements vary a lot with speed and terrain. And I think there is additionally a relatively large range of acceptable brightness because of our eyes logarithmic sensitivity to light; even a 2x increase or decrease in brightness does not seem like a huge change.
Here is what works for me riding on curvy off-road trails in the woods of Ohio. My speed varies from roughly 5 to 20mph. You can read about my lights here. My handlebar light has a wide beam and about 6kcd. My helmet light has about 20kcd. I estimate my handlebar light is useful for illuminating a wide area up to 5m away which means the light puts about 240lux at that distance. And I estimate when I’m going fast I need to look 10m ahead on the trail and my helmet light puts about 200lux and illuminates a 6ft wide area at that distance.
According to this site:
200 lux is between a very dark day and an overcast day. Or about the level of lighting in a coffee break room or to do easy office work.
Lumintop B01 on the roadbike and xanes DL01 (or other torch with longer battery) on the mtb.
That said, I hardly ride in the dark nowadays.
I sure don’t understand this. Draining an 18650 in 20 min with any decent emitter these days would blind anyone near you. Don’t see how any bike light could use that much energy in an LED and not be way to bright to be used in the presence of others. I thought the sweet spot was around 10% on my C8 and that would last for at least 12 hours on a single 18650. Others say that just because it is a C8 with the throwy beam profile and hot spot of the HI make that unsafe for a bike light due to blinding. Seems to me that if the bright spot is kept on the road and the level is down in the 10% range again I don’t see how a bike light could be significantly different. What am I missing here?
the faster you ride, the more you need it really bright.
and if it is a real bike light, and has a decent pattern for riding, it can be bright without blinding
i’m not talking 10, more like 80 of max, 700 lumens or so
wle
I’ve cycled many thousand miles with the trusted Hope R4 lights for many years. It was pretty costly when it was purchased and proven the money spent is worthy.
I’m with the OP. Expensive bike-only lights with built-in batteries are not for me.
My commute is just over 18 miles (29 km) each way. Being able to carry a spare battery is an important feature for me, especially in the winter.
I ride mostly on paved multi-use trail, so beam pattern isn’t much of a concern.
I really like a Convoy s2+ with biscotti on the handlebars, and a rear-facing red Jaxman E2L on the saddle tube. If my supply of good 18650s every gets low, I plan to replace those with a Convoy S21a or a Sofirn IF25a on the front. Not sure about the red tail light in 21700, though.
one additional thing about a real bike light is, it will have a specific handlebar mount, it is not going to fall off
and you don;t have to fiddle with it, every time you want to use it
wle
I have good mounts for my flashlights that haven’t fallen off in thousands of miles of riding. What sort of fiddling are you referring to? I just turn my lights on before I ride.
2-Astrolux S42. Plus headlamp to look sideways. Or far away from the bike.
Cheers.
My commuter bike has a hub dynamo, and i replaced the very weak headlight that was on the bike when i bought it with a Busch + Muller IQ-X. IQ-X - Busch + Müller EN?
The IQ-X is approved for Germany and it does not blind oncoming traffic, but i also have a Convoy C8 XPL-HI on the handlebar, that is the “high beam”.
The rear light is from Busch + Muller and it also works on the hub dynamo LINE - Busch + Müller EN?
I use my BLF Q8 as my main bike light. I use a GoPro attachement with movable joint to have it pointed down in front of me, and ramped down to relatively low setting. So I can see the road, but to not blind anyone. When I go off the road and reach the forest, I point it almost straight ahead and put it on full blast. It termo regulates down and I leave it at that. I use the Q8 due to its capacity, and ability to go both very high and very low in light output.
That is interesting. I would like to see the dedicated light with such a pattern. Do they have an additional reflector like a car headlamp? Seems to me that even with the hot spot directed at the ground 700 lumen or so jus the spill on from a C8 would be blinding for oncoming traffic on a trail. Have not seen a light that would fix this with a beam pattern. Perhaps I am missing something?
That’s why elliptical TIRs are so in vogue. Basically no “hotspot + spill”, just a nice graduated hotspot, and the stripes toss the light left/right into an ellipse vs one big happy circle.
I don;t know really.
It doesn;t look to me like it is blinding cars. No one ever high-flashes me.
But it doesn;t have a sharp cutoff at the top either.
I guess I keep it pretty much pointed down at the road, maybe that makes it work.
The one I have is Thorfire, something with 2 leds and 2 reflectors, both pretty smooth.
To me it seems like a good throw/spill pattern for riding.
wle
After being unimpressed with real-life usefulness of the FW3A, I put it on my bike and I like it a lot, mainly because of the floody beam, battery check feature and also the bike blinker. The small size and light weight are a bonus.
Cut-off might be still useful on less populated paths since it makes the beam wider without lighting up the sky resulting in less eye fatigue due to absence of constantly shaking narrow circular beam + easier to spot animals attempting to come out of the forest. Fenix bc35r and bc25r seems to have a wide enough uniform beam, just requires swapping out the emmiter for 3200k 90cri one if one has aging eyes which tend to block out the cool white light making everything dimmer.
Cut-off might be still useful on less populated paths since it makes the beam wider without lighting up the sky resulting in less eye fatigue due to absence of constantly shaking narrow circular searchlight beam + easier to spot animals attempting to come out of the forest. Fenix bc35r and bc25r seems to have a wide enough uniform beam, just requires swapping out the emmiter for 3200k 90cri one if one has aging eyes which tend to block out the cool white light making everything dimmer.
The kids square lash lights to their handlebars. SC64c LE LH351D for now (both light bodies are fairly thrashed but still working)…
Streamlight PolyTac X lashed the same way on their bikes (which they ride less often since they think that bikes are for the elderly 
).
That’s pretty cool!