As others have indicated, your statement about the Reflex being a joke (i.e., worthless!) comes across as an exaggeration, but you're entitled to your own opinion. By the way, this is now a $10 dollar light (non-auto version) on Amazon and the reviews speak for themselves. There are indeed much better lights out there and more coming out every year, but the the big trend seems to be about everything being USB rechargeable with self-contained batteries that are difficult or nearly impossible to replace on the road, no reflective material in case your batteries died, not as many light patterns and much shorter run times.

Having said this, your Serfas suggestion intrigues me. You seem to know a lot about both the Serfas and the Reflex rear lights. Have you had a chance to compare both the Serfas and the Reflex side by side taking into account the mentioned parameters in previous paragraph? That sort of feedback would be a lot more helpful rather than fully discrediting someone else's experience with a particular product.

Regardless of light brand/models, it is a good idea to use two rear lights - one flashing and one steady - flashing mode serves as a warning and the steady/constant mode helps drivers with depth perception as they approach you.

Review of the Best Bicycle Tail Lights in 2012 « Stack Exchange Bicycles Blog
As I said, it's useless for DAYTIME riding. And it's not my opinion, just a fact. The original poster actually asked for a good DAYTIME light and Reflex is clearly not because its low power LED. Cygolite Hotshot (which I have) is barely adequate and it's over 20 times brighter according to the chart. Serfas is just as bright as Hotshot except it has a wide lens. I also have a new Hotshot 80 (i.e. 80 lumens) and it's significantly brighter than the original and Serfas & is actually very suitable for riding in sunlight. And yes, I also use two rear lights for the reasons you stated.

I agree too, the Reflex is completely useless in the daytime, it's barely useful at night! You need at least 60 lumens to be effective during the daytime and the Reflex has about 20, but it does have a nifty reflector that again is useless during the day.

The more tail lights one can have the better able motorists will see you. I've been doing the same thing that Chris Pringles says he does for a good 30 years and that's using at least two tail lights with the brightest one on steady and the others on flash. I like to put my 2 flashing ones on my stays and the steady one on my seat bag or on my seat post, this forms sort of a triangle. Combine that effect with ankle reflectors and whatever other reflectors you have and you should be noticed by all but a drunk. But get the brightest tail light you can afford initially then later add to it as money becomes available.

This is an interesting tail light, it's cheap, and it claims high lumen output but I would venture a guess that the actual output is about 1/2 of the rated lumens but at the claim 168 halved to 84 lumens this light should show up in daylight and it got high reviews by a lot of reviewers; see: https://www.amazon.com/Blitzu-Recharg...est+tail+light

I agree with everything you said except the Reflex doesn't have 20 lumens. More like 2. 20 lumens would actually make it a decent light for riding at night.

I like my B&M 4D senso.. 2AA, use what battery you like. German, rack mount.

Only blinks in tunnel mode .ie On but light sensor leaves it off, in senso mode, but enter a dark tunnel it blinks .

then off again in daylight. at night in that mode motion sensor turns it on , then off again when you have stopped
for more time than if lust at a stoplight.

Features a 3 position switch .. Off - On - and senso. B&M 4D senso Plus runs off the hub dynamo in the off mode
but goes off when I stop, (unlike newer lights with the capacitor stand lights)

so running in the daylight it just uses the Battery in the On Position
whether the Plus or not.. the 4D 'permanent' is on/off.

Are you saying it only has 2.20 lumens or 220 lumens? At 2.20 lumens we're talking 5 times less light then a candlelight produces, and you think that's good? At 220 lumens on the other hand I do not know of any tail light that has that kind power.

I mean "2 lumens". 20 lumens would actually make it a decent light for riding at night. There is a space between . and 2.

That sounds pretty intelligent and practical.

Every single "bike" tail light I found to be woefully inadequate. They simply aren't bright enough or visible enough. Here is what I used and for just $9, it came with 2 lights so I originally planned to install both. What I found was that ONE was so bright a second simply wasn't necessary:

Amazon.com: LEMONBEST® 2 x New 17cm General 6W Super Bright COB Bulb Car LED RED Daytime Running Light DRL Driving Lamp black housing: Automotive

I have yet to find any "bike" light that even comes close to the brightness of these. I don't know how many LEDs there are, too many to count, but I'd say at least 50 LEDs are on each light. The only down side is that they need a 12V power source, so I just used a little Velcro strap along with a little Lithium rechargeable battery pack I found in order to power it:

Amazon.com: Turnigy 2200mAh 3S 20C Lipo Pack: Toys & Games

Works great I strongly recommend!

Not very practical for the original poster who asked for a good daytime light. Not bad as a secondary rack light but Serfas is a much better option.

Oops, you're right. My mistake. Anyway, it looks like a good thing for some other purposes.

Yep, I've done several test videos of bike lights at night and YouTube compression made 'em all useless. So I did a 2-minute video last night and posted it to both YouTube and Vimeo.

The Vimeo version isn't too bad. Gamma is darker, but the reds are more saturated.

The YouTube version is slightly brighter, but the reds are desaturated and more orange.

Neither looks like the original on my photo/video editing desktop PC. Both were shot using a Nikon V1 and 10-30 kit zoom, ISO 1600, on 720p. I didn't edit this clip at all in order to avoid any pre-upload compression. I haven't found any freebie video software that handles lossless simple edits, including Avidemux. So I just reshot this same demo several times until I got it down to about 2 minutes in one take. I may reshoot using my Fuji X-A1, which has better video quality but fewer options for manually setting exposure -- a problem with nighttime videos.

I wanted to test my theory that pairs of lights with separation help motorists to better perceive distance and speed of bicycles at night. This video demonstrates riding away from and back toward the camera, and seems to confirm that some separation between lights can lend a better sense of approaching/receding speed and distance. So it may be a cost-effective way to improve our visibility without spending more than $100 on a single light, or mounting more than one reasonably visible light on the rear rack. Combining a rear rack and helmet light, each costing about $15-$30, might be a cost effective option for some folks.

• **Front of bike handlebar: Serfas SL-255, steady medium.
• **Front of helmet: Vivo-Bike Illuminati, flashing.
• **Back of helmet: Blackburn 2'Fer, flashing red.
• **Rear rack, large light: Planet Bike Rack Blinky 5.
• **Rear rack, small light: no-name red LED that came with Vivo-Bike Illuminati.
• **Rear rack, low near hub: pair of no-name red LED from Dollartree, $1 each.

"Bicycle lights nighttime comparison of paired lights to evaluate perception of distance and speed."
Vimeo version.
https://vimeo.com/166782753
*-*-*-*

YouTube version.

20 lumens is nothing, sorry to pop your bubble, but 20 lumens is only the amount of light given off by 2 candles, no where near enough to see by while riding a bike.

The reason I questioned your number was just in case you had a typo.

Well, I don't know about you but I do not use my taillights "to see by". Guess to each his own...

lol. that was my bad, I was in a conversation about head lights on another forum and got mixed up. DUH!!! anyway, still though at 20 lumens is considered to be the lowest powered tail lights you can buy these days and are marginal at best. I've seen these dim type of tail lights on the road and their barely noticeable, but like you said, to each their own, I rather have something significantly brighter and those brighter ones can be bought for not much more money than a person would waste on a dim 20 lumen job. I had a 20 lumen tail light I bought in the mid 90's which was considered bright in its day...LED technology has way surpassed that now. That light I bought in the 90's I threw away because even a cheap Cateye LD600 blew it away, not to mention how much more inferior it would be to my Light & Motion Vis180 (not the Micro Vis180).

By the way, I can see my surroundings at night with my L&M Vis 180, so it could be used as red flashlight if I had to use it as such.

Actually, you can still buy plenty of tail lights under 20 lumens and Cateye Reflex is one of them. Almost all of $10-15 are:
https://www.bikelightdatabase.com/taillights/
Adjust the slider on the left to 0-20 lumens & see for yourself. Majority of those light are actually 1-2 lumens.

As noted in my edit, above , there is a simple turn it ON switch position .

Thanks for taking the time to do the videos. Only the YouTube one seemed to work. As I said before, video's just don't do lamps justice. This is particularly true when it comes to ones that aren't very bright. On video your two seat stay lamps look almost like candles when actually they might be fairly bright. On the other hand a video will make a moderate lamp look almost super bright. Then when viewing the really bright lamps they look so bright that they appear like a super ball of light. Eventually once the output gets so high most videos can't accurately depict the variance in intensity.

Just a couple days ago I purchased a couple small/cheap usb rechargeable lamps to try out on my seat stays. Just one alone is not very bright but would be useful enough to get someone seen if on flash. Two, are a bit better but when on steady they are just barely adequate. Now coupled with my good Performance/Serfas clone lamp on the seat post the overall effect is much better, particularly when someone gets closer to the bike.

I know that having a lamp on steady can be useful so likely I'll use the smaller lamps on steady. I like the brighter lamps on flash for two reasons; first, they attract more attention at distance and secondly, well....the battery will last longer when on flash. IMO, it is more important to be spotted at distance. With a "triangle pattern" array and a 100+ lumen helmet rear lamp going ( not to mention wheel lights and standard reflective bike clothing/shoes ) I would be hard to miss at night.

Of course for added daytime awareness I would probably only use a single lamp at it's brightest setting. I have a special torch mounted under my seat just for this purpose. Rapid 3-pulse/pause flash pattern/ amber led and about ~100-150 lumen ( over-driven ).

Yeah, Vimeo is quirky. It often takes much longer to load and play on my mobile devices, so I use it only when the video isn't available anywhere else.

The YouTube version appeared a bit better about 12-24 hours after uploading, so perhaps it takes awhile before the HD version shows. Comparing the two now, the Vimeo version is only slightly better -- mostly more contrasty with slightly more saturated reds in the lights.

Just a couple questions; What was the rear "helmet lamp" you were using and how far away from the camera were you when you made the right turn ( Youtube vid )?? That looked to be an older Planet-bike 5-led lamp as the main lamp ( within the triangle ) you were using if I'm not mistaken (?)

Blackburn 2'Fer on the rear of the helmet.
Yup, Planet Bike Rear Rack Blinky 5 on the rack.

Just over 100 meters/335 feet from camera to the far turn at the end of the block. About 20 feet from the camera on the near turns. I used a 35mm (equivalent) moderate wide angle for a relatively normal perspective approximating our vision (40-42mm would be closer to how we see things, not counting peripheral vision).

I thought about ordering the Serfas TL-STP, but it would have taken a week. The Planet Bike was available for same-day delivery via Amazon. It seems adequate as a nighttime taillight. The Bontrager Flare R appears to be brighter for day/night use, but twice the price.

I'm wondering about modifying something like the Serfas SL-255 headlight with a red filter/diffuser. It uses a pair of AA batteries, lasts a long time per set, probably bright enough to compensate from light loss through a red filter. Not sure it's worth the trouble, though, with the Flare R and Serfas Thunderbolt already available.

I had a chance to compare the Planet Bike Rear Rack Blinky 5 against dozens of other lights during Wednesday evening's Ride of Silence. Several folks took photos and videos and comparing my lights against others, they're all about equal in apparent brightness.

The Planet Bike light is brighter within a narrow aperture, typically what a motorist would see from behind -- it appears like a brighter horizontal line a few inches wide. From other perspectives/angles of view, it appears somewhat less bright but diffused and still visible.

One photographer caught a couple of snaps of me from behind under a dark underpass, and my combination of Planet Bike Blinky 5 on the rear rack and Blackburn 2'Fer on my helmet, and smaller blinkies on the rack and seat stays showed up well, especially compared with the cyclists using only a single bright blinky on their seatpost, seat stay, etc.

So I'll keep the Planet Bike like. I'd rather have had a AA battery model and might eventually get the Serfas TL-STP. But the Planet Bike light seems good enough for my needs for low light and nighttime use.

I got to see a Cygolite Hotshot yesterday afternoon while in my car, not sure what model it was, but it was very noticeable from a quite a ways away in the daylight, but as I drove and passed him the light got dimmer and dimmer the more I got away from being directly behind him, but it was very bright and very noticeable.

Probably CH original because it's very directional. The new model Hotshot 80 has a larger spread lens. I have both and they are great as main rear lights.

Coincidental that you should say this. About a week ago I added two small rear lamps to my seat stays for the same "Triangle effect" that you mentioned. While they're not that bright, maybe 10-15 lumen each, on flash they are still eye-catching. Not sure how I'm going to use them, steady or flash. If I use them on flash I'm thinking of putting my seatpost lamp ( Performance Axiom ( Serfas TL-60 clone ) on low steady. Funny but on low/steady the Performance lamp just blows the two small lamps out of the water. Thats' okay with me though as it should still have a better effect at long range. Not to mention I'll still be using a very bright ( ~ 180 lumen on high flash ) Gemini Iris lamp on back of my helmet set on pulse/flash, the brightest setting.

Today I did some more shopping on Amazon. I'm already thinking about upgrading the seat-stay set-up to something brighter...maybe. Found something I thought was interesting as I like what I'm seeing with rear lamps that use the narrow/mirco-led format. The newest version of the Serfas Thunderbolt is interesting because it now offers an audible warning when in low power mode, expensive though. Anyway I like that the lamps with the narrow design mirco-led panels can be made to mount parallel with a seat stay ( on some models ). The down side is that they don't offer great run times on high. The upside is even on low they are still damn bright. I found something on Amazon I think I might like....Ah, shoot me...damn if I ain't a bike light junkie! Sometimes I wish I didn't own a credit card.