Looking to find a steady on 350 lumens red light, rectangular/square, thin, USB-C rechargeable light no larger than 3" width by 3" height & 3/4" thick that has just an on/off.
Does such a thing exist?

I found plenty on Amazon just searching "350 lumens bicycle taillight" but I'm betting lots of them you have to take the 350 lumens claim with a grain of salt.

I have a Cygolite taillight that claims 350 lumens. But it's thicker than 3/4". It works quite well. Sometimes I have to futz with it to make it dimmer, when a cyclist needs to follow me.

"Ooh. Bad radiation burns there. Sorry about that."

Definitely bright as id like, but thats all it has that checks for boxes.
I really don't want the chipset functionality; simple on or off & flat backing.

Oh yeah. The user-interface, if I may call it that, is pretty dumb. The overloaded left button is on/off and also mode-switch. I keep forgetting what the right button is. I think it changes the flash intervals for some modes. It might also be the way to change the brightness of the steady mode. And I have to futz with it every time I want to adjust it. And while futzing, I have to be careful not to point the light towards my eyes. So yeah, it's not perfect.

When you say "simple on or off" do you mean the on/off powering of the unit, or easy-mounting and -dismounting off the bike?

The Cygolite Hypershot 350 USB has:

• Steady mode
• Memory mode -- your last mode is remembered, so that when you start up the next time it's in that same mode (ie, mode=steady); so long as you don't change modes to one of the other 6 it'll remain in "steady" mode
• 350 lumens output -- 2hrs duration, at that "high" setting; wish duration on "high" were greater, but it's simple enough to ride with two of these units, and to use a power bank to charge-up the drained one while the other is running, for extended rides
• Very compact shape -- a bit wider than 1"W, about 2"T, and a bit over 1" thick (off the flat mount)
• A rear rack mount that's flat against the rack (to which the light mounts); and the light itself quickly disconnects from that mount
• While it sticks out from the rack a bit more than 1", it's very compact

Question: Why is it that "flat" is important? And, why is it that only 3/4" thick (off the mount) is important?

The only output number I have seen for these is from the Cygolite web site, where they state, "350 lumens flashing".

Have you ever seen a source specifying the output for their "steady" modes?

In the flashlight world, it's not uncommon to see independent output measurements performed by enthusiasts as part of their reviews, but that's not often the case with bike lights.

Yes. Primarily the former.

Space claim restraints.

Independent verification of any claimed output/durability/efficiency is the sort of thing almost never done with a great range of products. Leaving manufacturers to essentially claim whatever they will.

Given Cygolite's descriptive remarks and manuals are so spartan, can't say that I've seen any other references to "350 lumens" anywhere.

What I can say is that the Hypershot 350, in practice out on the road, is so vastly above the brightness and visibility of every other taillight I've ever used or seen. Works sufficiently well for the great majority of cycling situations. Bummer that it doesn't appear to be the case, here.

I have the smaller Cygolite Hotshot Pro 150. Yes, the 150 lumens is for the brief, sharp flash. The web page says 150 lumens flash, 90 lumens steady. 2 hrs to 210 hrs run time -- that 90 steady must be the 2 hours. The single flash mode has an extremely brief, very bright flash. So it's eye catching, even in noon sunlight. And it has a long runtime too.

Ah, so it's almost certain, then, that their Hypershot 350 puts out fewer lumens on "steady" mode as compared to the "flash" modes.

Still, it's darned bright. I've got a pair of them. With one on a flash cycle and the other on steady, it's hard to miss; with one on pulse and the other on flash, impossible to miss. From a very great distance away from the bike, night or day.

Agreed the Hypershot 350 it very bright in steady mode. When I was comparing my own lights, I also did not find a published lumens for steady/solid here are my notes, but they did have it for the HS 200:

Cygolite Hotshot Pro – 200 Lumen Bike Tail Light
LUMEN OUTPUT: Flash Max: 200, Solid: 120

Cygolite Hypershot – 350 Lumen Bike Tail Light
LUMEN OUTPUT: Flash Max: 350, Solid: 200-210 estimated (used the approx 60% of max listed for the Cygolite 200) and 120 would be the minimum maximum, based on the Hotshot Pro 200 maximum solid.

I very much agree. The Hypershot 350 is what I run, and I'm not actively searching for "something better".

It serves admirably for the type of riding I'm doing, and does so at a price that won't make me cry if I have to replace it.

I just read the most recent replies to this thread, and it served to remind me that it's time to charge my Hypershot 350. I try to charge it after every third or fourth ride.

Before I plugged it in, I played with it a bit to see how to adjust the various modes. Now I know how to dim the steady mode. The left button is for on/off and for changing modes. The right button is for adjustments. Once it's in steady mode, pressing and holding the right button makes it brighter or dimmer, depending on I-don't-know-what. If I hold it too long, it will go to minimum brightness, and if I release it before then, it will go to medium brightness.

And I have to do the experiments without looking at the light directly. I pointed it at a white surface. I thought it was safe. But now that I'm done, my eyes hurt a bit. I need a better way. Cygolite should make a better user interface. And they don't have any way of indicating the charge of the battery. Come on, folks, get with it.

I have one like this: https://www.amazon.com/NiteRider-Sol.../dp/B07DGGJGXJ only in a 100 lumens brightness, and it's awfully bright as it is. I do like it, only has one button and four modes, dim/bright flash (flash flash flash FLASH), pulse mode (full on dim with bright flash), bright steady, and dim steady. And when you turn it off, it will flash either blue or red indicating whether or not it needs charged. Blue is OK, red means the battery is getting low. The battery seems to last a good long time, and is USB rechargeable.

They do make a 250 lumens version which I thought about getting, but some reviews said that the battery charge doesn't last very long.

I have used a DiNotte Quad 4, which was replaced by the Rossa. It is rectangular and USB-C rechargeable. It has one button that sets the mode and powers on and off. It fits your height and width, but is almost 1" deep. And it claims 250 lumens. I am skeptical of lumen claims, but the Quad 4 I had was very bright to the eye. Aluminum casing, industrial look. Expensive.


Dinotte Quad Red tail light mounted on seat stay


I moved the Quad 4s (front & back) to my wife's bike and replaced them with DiNotte D6, which claims 500 lumens.


The D6 taillight, 2024

Good luck with your search.

Are those two taillights able to be used while being charged by a battery bank?

I have the H350, but unfortunately the mounting options are too delicate & like to rattle within the cavity it locks in place to.
I'd be willing to use the H350 if a flat mount along with a Quick Release connection was available.

DiNotte has a "daytime only" light that they claim to be even brighter than the D6, and that is powered by an external 4-cell or 8-cell battery pack: DiNotte Daytime Red.

They claim that it is light enough to be used with quarter-turn mounts (that they sell).

Nope. They have internal batteries.

Some - but not all - internal-battery lights can operate while being powered through their charging port.

I have seen some people who use something like an Outbound Lighting Detour on its own internal battery for everyday rides, but plug it into an external power bank to keep it going for dusk-to-dawn endurance events.

My answer to Troul's question should have been, I don't know, rather than Nope. I'd think that if Troul wanted an external battery bank, he'd consider the DiNotte light John mentioned, the Daytime Red, rather than the Rossa or D6.

DiNotte is responsive to phone calls or email. 603 929 0123 or Sales@dinottelighting.com. And I give DiNotte an edge because it is located in Hampton, NH, just an hour from MetroWest, Mass. I like Hampton Beach!

the use of charging while on would not be a habitual thing; unusual conditions.
that being addressed, the space claim restricts a dedicated aux battery.
DiNotte hasn't responded to a submitted inquiry.

That D6 looks like a glorious monster of a taillight. Their specs claim 3400 mAh. That, and the overall shape of the light, make me think that they might be using an 18650 battery.

I doubt that DiNotte would be interested in doing so, but I would love to see a similar format, but with a standard 18650 battery that could be swapped quickly in the field. I don't know how much larger and heavier the package would have to be to allow that, but I really like the idea of a great taillight that is self-contained, but that can be restored to 100% capacity in seconds.

That idea is inspired by my Fenix BC30 V2.0 headlight, which uses a pair of standard 18650 batteries that can be swapped quickly and easily.

I just tried mine (the one I linked to above) and it will not turn on while being charged.