Derek Dean
Flashlight Enthusiast
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
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