I have seen some people having their rear lights or eve front lights mounted on the dropout/hub of the wheels. Those are rather tiny lights but impressively bright. I wonder if anyone here know more about those lights?

Might be Reelights. And if so, here's the first of at least 5 pages on Bing about them. https://www.bing.com/search?q=reeligh...=8-9&sp=-1&sk=

Thanks. Not sure if that's what I saw (my memory is that their lights didn't flash like these), but this is the first time I saw the lights you linked to. Looks great without needing batteries. However, it may have the same problem as the ones I saw, that is if you mount it on, say, the left side of the wheel, then the cars on your right behind in certain angle would not be able to see the light, which is blocked by the tire.

I have a Supernova E3 dyno powered taillight mounted on my dropout. Some people have told me it's very visible. I don't trust it by itself, I always add a flashing blinky in low-light conditions. Usually a Radbot 1000.

I got the idea from someone's flickr photostream

Lighton:
https://lightonlights.com/dynolight/

I keep meaning to get one of those because it looks so awesome. I also have some disk tabs on my fork that I'm not using and I'm considering mounting a light to those. My only concern is that it might get banged up if I'm going between some rocks/brush. I might try it next month when I get my new dyno parts.

Supernova e3 installation by canopus2, on Flickr

If they were, as described by the OP, "impressively bright", then they probably weren't Reelights.

I've got two pair of Reelights. They're kind of clever, but they're definitely "be seen" rather than "see" lights. (But the "never even think about them" aspect is indeed nice.)

there are also several products out there that use standard hardware to mount to rack braze ons and eyelets that allow you to mount regular lights on them.

These guys make nice mounts:

https://www.paulcomp.com/lightmounts.html

Interesting. I wonder what the beam pattern is mounted vertically like this.

I think that location is too low to cast a good beam. It accentuates the pavement's irregularities, and it might compromise the cyclist being seen.

I was watching a video someone riding behind me took of my dropout mounted taillight, and it's very visible. I never really intended on relying on that as my only taillight, but it's pretty good.

How does it look from the driver's seat of a car? I suspect the height of taillights is less critical than the height of headlights.

+1

A low mounted headlight is a bad idea, especially on dirt and gravel roads.

Personally I've tried everything from helmet mounts to fork mounts and combinations thereof. My own conclusion is that effective lighting depends a lot more on the lens configuration than the position of the lights. My other conclusion is that helmet mounted lights are the least traffic friendly location to put a light unless you deliberately look away from oncoming traffic - something thats not a natural (or always safe) reaction. Currently I've got lights mounted below the bars on one and rack mounted on another bike. Both are very effective. Lights with narrow beams for greater reach are actually better mounted low because as bike path traffic approached, they'll be above the beam.

A 15 degree spot puts out a beam that 26feet high at 100 ft but only 2.6 ft high at 10 feet. So actually, from about 35ft away, oncoming traffic would start to be progressively above the beam if the front lights were mounted on the dropouts.

If you had trouble with shadow issues, I'd say it was the light rather than the mounting location. Automotive lights are lower than handlebar mounted lights, and automotive driving lights and fog lights are even lower - deliberately.

The fork mounting isn't a problem for traffic or beam or pavement irregularities. Many cars turn off their brights when I am coming towards them with the E3. The only problem I have with the fork mounted headlight is the shadow it casts on the opposite side of your wheel. This isn't a problem on the road at night, but on a bike path or on a trail it means the light doesn't go where your turning (in the case of a right side fork mount this means left turns can be a little blind).