Review: Specialized Flux Expert Taillight

[Derek Dean]

Specialized FLUX Expert Taillight Review
Thanks to Eric Lee at Specialized Bicycles for providing a pre-production light for this review.

Specialized Bicycles has recently released 3 new bicycle lights. This review is for the FLUX Expert Taillight, which comes in a small rectangular box, along with all the hardware required for mounting, including a small hex wrench.

Physical specifications:
Height: 3”
Depth: 1.5”
Width: 1”
Weight: 60 grams
70 grams including mount
LED: P3 bin Cree XB-D LED for 110 lumen output at 530mA
Body Material: Aluminum, plastic
LED Cover material: Acrylic
Power: Built-in non user replaceable lithium-ion power pack
Charging: Built-in flip-out USB plug for charging from any powered USB port.
Water Resistance: Fully sealed for all weather cycling.
Warranty: 2 years
Price: $100

Like the FLUX Expert Headlight, the fit and finish on the FLUX Expert Taillight is outstanding in every respect. Again, this is a solid, quality piece of kit, and the attention to detail is obvious.

One interesting feature of this new taillight that might be of interest to road bikers, is it's uniquely sculpted body, which, according to Specialized, results in "zero drag".

Like the FLUX Headlight, the FLUX Taillight uses a specially designed reflector to precisely focus the light from an upward firing LED into a beam with exceptional visibility, even in bright day light.

Behind the reflector, in a small compartment with a frosted lens, you can just make out the 2nd small LED, which comes on in 2 of the 3 MODES (CONSTANT ON and PULSE ), giving the light virtually 360 degree visibility.

The FLUX Taillight features 3 Modes (with mode memory):
1. CONSTANT ON - 25 lumens for 10 hours
2. PULSE - Pulsing between 5-55 lumens for 6 hours (1 pulse/sec)
3. STROBE (2 strobes/sec) - 110 lumens for 14 hours during the day
55 lumens for 17 hours during the night

The Strobe Mode features a unique variable output which is controlled by a sensor on the light. This lets the light output it’s maximum 110 lumens during the day, but automatically brings that level down to a much more eye friendly 55 lumens at night.

Unfortunately, the variable output feature wasn’t enabled on my pre-production model, so I didn’t have a chance to check that out, but in theory it’s a great idea.

On the front of the light is the single rubber MODE button, which activates an electronic switch. The MODE button features a small clear “S” that glows a soft green color when the light is first turned on.

The MODE button serves as the ON/OFF switch (tap quickly to turn ON, press and hold to turn OFF), as well as switching between the 3 modes (a quick tap).

The MODE button sits flush with the surface of the light, and does require a substantial quick push to activate, meaning it would probably be difficult to accidentally turn it on in a bike bag, but, like the FLUX Headlight, I’d like to see it changed to a 1 second press and hold to activate the light as well as turn it off, giving added protection against accidental activation.

The backlit feature of the MODE button also serves two other functions. When the light is in use, it will give a quick indication of the remaining battery status, with Solid Green indicating 50-100%, Solid Amber indicating 20-50%, Solid Red indicating 5- 20%, and Flashing Red indicating that it’s time to recharge.

When you’re charging the light, that same backlit button gives a quick indication of the charge status, with Flashing Red indicating 0-90% full, Flashing Green indicating 90-99% full, and Solid Green indicating 100% full.

Another nice feature of this light is it’s built-in USB charging plug, which allows you to plug the light directly into a powered USB port to charge it’s built-in lithium-ion battery pack, which typically takes 1 hour to 90%, with an additional 20 minutes to 100%. When not in use, the handy flip out USB charging plug folds flat into the bottom of the light and snaps securely into place, out of the way until needed.

I found this flip-out USB charging plug to be very handy. No charger is included, but it’s quite simple to plug the light into your computer for an hour or so, and bam, it’s done. By the way, the Flux Expert Taillight's USB plug fits nicely into the port on the charger that IS included with the Flux Expert Headlight.

The Flux Taillight has been specifically designed to mount on an angled bicycle seat tube, and comes with the appropriate mounts to fit 3 different sized tubes, including a round 27.2mm tube, a round 30.9mm tube, and an oval shaped VENGE tube.

Attaching the mount is relatively easy and only requires a minute or two using the small included hex wrench. Once the mount is secured in place, it’s a simple matter to slide the light down into the mount where it seats with a secure, “click”.

When looking at the beam profile of the light, it’s easy to see why positioning the light correctly on the angled seat post is so important. The beam is precisely focused so that it can be seen even at a distance during the day, and it works exceptionally well.

I did a few tests (both at night and during the day), parking my bike against a post and walking back quite a ways. Even three long blocks away I could still clearly see the reflector focused beam of the FLUX Taillight. I had never considered riding with my taillight on during the day, but this one really helps you bee seen.

The only CON I have for the taillight is it’s limited one position mounting option. I have a big basket mounted on my rear rack that blocks the seat post, so if I were to use this I’d have to rig up something else.

Final thoughts: It seems to me that most of us don’t pay much attention to our taillight. It’s just there. However, when you consider that this is your main means of providing visibility for vehicles approaching from your biggest blind spot, it makes sense to use a taillight that provides maximum visibility….. both at night AND in the daytime.

The FLUX Expert Taillight does just that, in a refined, well thought out package that is not only easy to use and maintain, but built to last as well. For more information:
http://www.specialized.com/us/en/ftb/lights/lights-ftb/flux-expert-taillight

Thanks again to Specialized for providing this light for review.

Derek Dean

 

[Steve K]

thanks for the great review! Very good photos of the light.

I'll give Specialized credit for being very creative with the optics design! The usual reason to go with a reflector design like this is to get a unique beam shape. Is there any chance of getting some pictures with the beam projected onto wall at a distance from the light?

The use of a second LED to provide visibility in all directions is a nice touch too.

The lack of options for mounting locations would be a problem for me. I've got two bikes that don't have seatposts (i.e. recumbents), and even my regular bikes usually have the taillight mounted on a seatstay. I think I've got one with a seatpost mount on the light, but that's due to the frame being a bit small for me, and thereby exposing more seatpost.

Personally, I've got Cateye taillights mounted on two bikes, and really like them. Part of the reason is that they have a number of mounting brackets that allow the user to attach them just about anywhere. Cateye sells mounting brackets too, so I can move a single light to whatever bike I'm using (in principle).

The use of a non-replaceable lithium battery is common nowadays, but I still don't like it. I've stuck with lights powered by AAA or AA NiMH (as well as two dynamo powered taillights). Lithium batteries last a few years at best?? I've got Vistalight taillights on a few bikes that must be 10 years old, and they are still fine. One solution would be to design the light to use a replaceable lithium ion battery... are there any that are a suitable size? I'm only familiar with the 18650 size, and that seems rather large for a taillight.

Anyway, those are just a few points that I felt like getting off of my chest.
thanks again for the fine review!

 

[Derek Dean]

Howdy Steve,
Yes, the mounting options provided are extremely limited, but like most things, with a bit of imagination it's quite possible to come up with alternatives.

As far as the internal batteries go, my understanding is that it use two RCR123 batteries. I recently took the Flux Expert headlight apart (it was quite easy) and I think some one with an adventurous spirit could easily replace the two 18650 cells inside that light, so probably the same thing is true with this light.

You wanted a shot showing the beam projected onto a wall. Unfortunately, I live in a teeny tiny apartment (think bus station locker ), so this is the best I could do, but it does give an accurate representation of what the beam looks like. The light is about 3 feet from wall (and a tiny bit to the left), and the camera is about 5 feet from the wall:

The way the beam appears when looking at the light is that it's VERY focused from behind AND to the sides through about 60 degrees each side. If you go to the Specialized website they have a video up that shows how well this light shows up DURING THE DAY, so just multiply that to get an idea of how well it works at night.

 

[Steve K]

hi Derek,
That's an informative photo... it looks like the beam pattern is pretty narrow in the vertical direction, and wide in the horizontal direction. That's a pretty good design, IMHO. I don't know if a reflector is the only way to get that result, but I can't argue with the result itself.

As far as batteries go, as long as they are using a standard form factor, then it seems that a person could crack it open and change them out. Closing the light up afterwards might not be pretty, but is probably functional. ...or just add some wiring to an external battery??

Slightly off topic, I'm curious about who Specialized has do the optics design. They have traditionally used electronics design houses to design and produce their electronics. This sort of optics is a bit unique... I wonder how hard it is to find a company to do this stuff?? I deal with electronics suppliers at work, so I can relate to the issue of finding good suppliers and getting them to make what you want (and the challenge of fully defining exactly what you want).

 

[Derek Dean]

Howdy Steve,
I remember that Eric commented that they had hired a specialist to design the optics, but the rest of the light was designed in-house.

Now, Steve, just for you...I decided to investigate a bit, and heck, there are only 3 looooong hex screws holding the taillight together (located on the bottom, two visible, one under the fold-out USB plug). So, here's a look inside:

Below are two views inside the bottom (connection to the USB plug). It's nice to see that the single RCR123 cell is NOT soldered in. I'm not quite sure how to move that metal piece, but it might be easier from the other end.

Below is the other end of the battery tube (top end). That's a foam block on top of the metal piece. Notice the 3 short straight wires that plug into the head of the light to provide power and on/off/mode selection.

Finally, below is inside the head of the unit, which appears to be sealed. It's nice to see the brass threaded screw inserts. It's not very apparent from these photos, but there are O-rings for both areas, keeping the unit weather sealed.

So, there you go. It looks like replacing the internal battery is definitely doable. Of course opening it like this might void the warranty, but that will probably have expired by the time you find it necessary.

 

[angerdan]

Hi Derek,

thanks for your review of the Specialized Flux Expert Taillight.

I wonder how the horizontal beam characteristics are.
Can you capture a photo on which this will be shown?

And do you know when the taillight will be regulary sold?

 

[BrianMc]

You can Google for more, but here is one:

http://www.eriksbikeshop.com/Specia...om/ Lights-and-Safety/Specialized/963/search

Here is a video of the high level falsh spread against a white garage door:

 

[angerdan]

Recall for all Specialized Flux/Stix lights (front&rear)

Unfortunately there's an recall for all Specialized Flux/Stix lights (front&rear).
specialized.com/us/en/safety-notices
Lights - Rider Notice.pdf
cpsc.gov/en/Recalls/2016/Specialized-Bicycle-Components-Recalls-Headlights-and-Taillights/

In German:
specialized.com/de/de/safety-notices
Lights - Rider Notice_ger.pdf

Positive:
Flux taillights will be replaced, so you will get the new version

 

[darkmilk]

Unfortunately there's an recall for all Specialized Flux/Stix lights (front&rear).
specialized.com/safety-notices
Lights - Rider Notice.pdf
cpsc.gov/en/Recalls/2016/Specialized-Bicycle-Components-Recalls-Headlights-and-Taillights/

In German:
specialized.com/de/de/safety-notices
Lights - Rider Notice_ger.pdf

Positive:
All Flux taillights will be replaced, so everybody will get the new 2015 version with 110lm

No such luck here (Australia) they're offering a "Stix Combo" package as the replacement for the Flux taillight, trying to sell that by saying it's a bonus front light! Two almost useless lights (well under 1/4 the power and no side visibility, no good for all-weather commuting) in exchange for what has been far and away the most awesome tail light yet really doesn't cut it. If you talk to them but decline the recall then your details go on the "can't sue us" list. The headlight will be repaired, in Melbourne.

Has anyone heard if the problems are the PCB or the cells? Something specific to the lights, or is it just lawyer fuelled paranoia around the normal Li-Ion dangers and user abuse? My headlight did cook its cells using it as a DRL in summer as they are down to less than 1/4 capacity after 18 months.

At this point I'm going to consider the tail light a mod host ... a new PCB and cells to reuse the great reflector design.

 

[Strahler]

Hi there ,

looking for a light with proper beamshape, i fell over your review.
I already really like the text-part, but i somehow miss the pictures, instead i only get a "Please update your account to enable 3rd party hosting" - Error-Message.
Looking online for that results in: Its a quite common problem since Juli '17: Photobucket, the picture-Host-Service you're using, seems to have changed its buisness-model, now rather wants money than ads.
First, can anybody confirm the error? Second, if so, would you please reupload the pictures somewhere else? That would be very nice . I guess you're not only helping me decide but others too

Proud first ever cpf Post
Marcel

PS: I'm getting pishing-alerts from my Chrome and my antivirus, maybe they'd be gone, too, or ist that a known problem here at cpf?
PPS: Sorry for my english, shool is like ages ago ...

 

[angerdan]

Yea, error is causes by policy of photobucket.
Maybe you'll find some here:
candlepowerforums.com/vb/showthread.php?389052-Specialized-Flux-Expert-Elite
enduro-mtb.com/en/news-new-products-from-specialized-stepping-up-to-27-5/
mtb-news.de/news/2014/03/10/specialized-flux/
mtb-news.de/forum/t/specialized-flux-neue-bikebeleuchtung-aus-kalifornien.688718/