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Fenix BTR20 Review

Publish Time:2014-04-08

Fenix has recently released a new bike light, which, improving on their older bike lights, now comes with a rechargeable battery pack. Previous models included a battery pack that required users to use their own batteries, either 2 X 18650 or 4 X CR123A primaries.
The bike light reviewed here is the newer one, and ships with an enhanced battery pack that lets riders know the current level of charge left in the battery pack by pressing the battery indicator button and 4 green LEDs on the battery carrier, which comes pre-installed with 2 internal 18650 rechargeable batteries.

---The BTR20 was kindly provided for Fenix for review---

These are the specifications directly from Fenix’s website:
1. Utilizes Cree XM-L(T6)neutral white LED, max 800 lumens output
2. Water Resistance: IPX-6
3. Instant Turbo with the remote pressure switch
4. BA2B rechargeable battery pack, battery switch-out system
5. Aspherical reflector with a wide beam angle
7. 4 brightness levels and one flashing mode
8. Digitally regulated output - maintains constant brightness
9. Low power warning on the headlight
10. Quick-attach O-ring mounting straps sized for 20mm-35mm handlebars
11. Easy, secure adjustment of the light’s direction
12. Made of aluminum alloy and quality plastic

The BTR20 comes with basically 6 o-rings to attach the light on any handlebar within 20-35 mm in diameter. The o-rings come in three sizes, small, medium, and large – with two o-rings of each size. It also comes included with a helmet mount, and extension cable, charger, and charger adaptors, along with of course the BTR20 and battery pack themselves.
The BTR20’s housing is made partially from aluminum and partly from plastic. The aluminum portion envelops the front half of the unit, where it hogs the LED in order to have effective heat transfer from the LED to the aluminum heat sink for eventual dissipation through air inlet cutouts and constant air flow. Fenix then made the back half, shown here as the darker grey side, plastic, in order to cut weight where aluminum wouldn’t have been very useful.

The reflector was designed with a small area of OP (Orange Peel), which is flashlight jargon for a textured surface. Manufacturers usually do this in order to smooth out the beam pattern. Hence, instead of having a highly defined hotspot and artifacts, the beam is smoothed out to have a soft transition. Flashlights designed to be throwers seldom have OP reflectors, because companies want to have a tight, pencil-thin beam as possible to maximize lux (maximum beam intensity/range)

And so, in my experience with the light, I do find the gentle beam pattern particularly easy on the eyes and overall, beneficial.

Another aspect of the BTR20 that’s important to note is the top ¼ of the glass was modified with the intent of diverting the upward facing beam back down onto the ground, creating a secondary beam below the primary hotspot, and lessening the chance of glaring drivers, fellow cyclists, or pedestrians. The secondary beam is exceptionally useful, as it eliminates the partial “blind spot” in the area a couple of feet in front of your front wheel, which is a cut above the beam profile from regular handle-bar mounted flashlights and much more superior to helmet mounted lights, which produces a complete blackout of the area in front of the tire, and attempting to illuminate the area in front of the tire always results in hurting my eyes and temporarily blinding me from the sheer increase in brightness when shining up close.

To me, the jump from helmet mounted flashlights to a dedicated bike light was like going from a tunnel-vision view to a dramatically more expansive range of view. I still use a flashlight on my helmet, because that way I can shine to my sides when cornering, and other useful functions.
Part 2
The underside of the BTR20 is made of soft rubber to both grip the handlebars tightly and prevent scratching them.
Instant Turbo Pressure SwitchFenix incorporated a pressure switch that users can mount on their handlebars to momentarily have access to max output. In my riding, I found a couple useful tasks that the switch provides.
For instance, during the day, when I’m at an intersection with stop signs, and there is a vehicle waiting as well, I usually like to give them the courtesy of going first, and the pressure switch lets me quickly pulse my light twice, which is I suppose the universal “go ahead” sign.
During night riding, the same principle applies.
Fenix ensured that the cables, especially at critical parts, such as connections, were adequately shielded from the elements, such as rain, fog, and other foreign particles. The connectors are essentially beefed-up portions that “snap” together tightly. Sometimes riding back home from school, I’ve had my fair amount of rainy days. Here in Miami, for some reason, sometimes the rain drops tend to, which I believe, stick together as they fall, and when they hit you it feels like someone is pelting you with tiny rocks. Anyways, I haven’t noticed any effects of heavy rain on the bike light, it kept chugging along just fine.Battery PackFenix made the battery pack with a rubber contact side with a Velcro strap, to grip your bike frame and not scratch it.
Part 3
The only way it appears to open up the battery pack is to use some allen wrenches:
With extension cable:
The AC adapter provided cannot really plug into anything without using any of the included adaptors. Fenix includes the American and European adaptors. Once you install one though, there aren’t any problems with the adaptor coming off, it attaches itself to the charger like a dog that bites and never lets go.
Helmet Showdown – Flashlight vs Bike light
First a bit of context. The red helmet with the totally-cheap string flashlight mounting solution is mine, and I will be using my little sister’s helmet to compare the different characteristics.

The flashlight I have on my red helmet is an old ArmyTek flashlight with a cool-white XP-G, while the BTR20 is equipped with a neutral-white XM-L. The difference between the two LED’s are their respective capabilities and limits. An XP-G driven at 1.5 amps could be considered to be the upper limits of the LED. An XM-L, due to its larger size can handle much higher currents, sometimes as high as 3 amps given appropriate heat sinking and good batteries that can handle high draw currents, and so it generally used where brightness is valued over range.

As a side note, there are already XP-G2s and XM-L2s, which do not have the thin wires visible when looking at an LED up close, and are slightly brighter than the older generation of XP-Gs and XM-Ls. Fenix, however decided to use an XM-L because of the tint, the neutral-white tint available in this LED class. Neutral-white tints are better suited for outdoors usage, where color rendition is more valuable than a few more extra lumens. Cool-white tints can tend to “wash-out” colors. However, nor are neutral-white tints “yellowish” like incandescent lighting or sodium vapor street lights. They are just white, with their tint leaning towards the warm side of the spectrum.

An XP-G is a smaller LED than the XM-L, so it is better suited in applications that require throwing light farther down range, rather than winning lumen competitions, since the smaller LED has a higher surface brightness and is easier to collimate due to its smaller size in a reflector. ArmyTek rates the flashlight at 500 LED lumens, while Fenix rates theirs at 800 ANSI lumens. The difference between the two brands’ claims lies in their standards. ANSI is a standard that aims to allow consumers to better select products with performance measured on a consistent benchmark, and to prevent the outrageous claims by companies competing several years ago (for instance, claiming that an XP-E equipped light had 1200 lumens – impossible without blowing out the LED.)

Therefore, by ANSI standards, lumens are calculated on an OTF guideline – so instead of measuring lumens calculated by the current driven to the LED, they are measured in an integrating sphere, say, a few inches in front of the LED after being on for a period of time (I believe it was 2 minutes). This incentivizes flashlight companies to design more efficient heat sinks (If their flashlights have poor heat sinking, the heat produced during the first 2 minutes of operation before measuring output, it will significantly decrease the measured lumens [for example, decrease by a good 100 lumens – hardly noticeable by human eyes in high outputs, but looks bad on paper] and thus hurt their sales and competitive edge against other brands) and promotes competition based on performance rather than baseless claims.

And so, going back to the review, the ArmyTek 500 lumens rating could possibly be actually slightly lower, however, because it was designed as a thrower with a deep, completely mirror smooth reflector, it out-throws the BTR20. In the BTR20, however, it is armed with XM-L, so that accounts for its higher brightness rating.
Part 4
Unlike the fixed position on the flashlight, you can swivel the BTR20 around to a proper position as you see fit. This is an important advantage for me personally, with the flashlight, as I go in the drops when riding, my head tends to drop along with the beam, and I either have to nudge my helmet back or raise my head, which frankly gets annoying.
Bike Mount
Here I show how I usually mount the BTR20 onto my bike:
The cable is long enough to give full range of steering without stretching or being placed under stress. For my handle bars, I use one of the large-sized o-rings.
I had attached the pressure switch originally at the top of the handlebar, but quickly realized it was much more comfortable and accessible at the bottom.

 Part 5
Outdoor Beamshots

---Many thanks to my little sister that accompanied me and served proudly and enthusiastically as a young photographer, without her I don’t think we would have been able to have these pictures---

Before we begin, I want to mention that you may notice in a few of these pictures I shift positions. I kept the same distance, the only difference is that because of the cars that would be driving around, we were forced off the road several times onto the sidewalk, and so the camera position isn’t consistent. We took these shots in front of our house located in a residential neighborhood and somewhat lighted to give a balanced representation for both urban and rural cyclists.

Also, there are four brightness levels on the BTR20, low-med-high-turbo. In these beamshots, I’ll simply refer to them as level X.


Helmet-mounted flashlight (my little sister as the model in this shot)

Level 1 Output

Level 2 Output

Level 3 Output

Level 4 Output

Area # 2 - Same area, just facing the other way

Helmet-mounted flashlight

Level 4 Output

Olight M20 (XM-L2 equipped flashlight) to show normal XM-L2 flashlight

Personal Experience

I can tend to abuse some types of my equipment. My bicycle and related accessories have the unfortunate honor of falling in this cursed category of equipment-cruelty. I usually take my road bike, which is clearly designed for roads, on off-road excursions, from bumpy grass, to over sharp rocks and even patches of loose sand (loose sand is a blast to ride in, although you bleed speed very quickly, it’s fun to try and not drift into a high lateral angle of attack as the wheels lose traction and start sliding. Of course, falling is inevitable sometimes, but even then it is extremely entertaining). Obviously, I don’t think road bikes are meant to be ridden on such hard terrain, but that doesn’t stop me. In the several weeks that I’ve had so far using the BTR20, I’ve had countless of these off-road journeys, and got to see how the BTR20 fares in a highly jarring, jerky, and rough environment. It was subjected to many sudden blows and high g-forces.

Admittedly, the BTR20 rattles – a lot. Maybe it may be attributed partially to the road bike, which has no form of suspension or shock-absorbing components and the fact that I ride it over hard terrain, but bottom line is that it has survived without any problems.
On the intense shocks, the BTR20 rarely, but has, shifted position.

Other than that, I’ve noticed that high and turbo are simply way too powerful for slow speed and urban riding. These high outputs, as you can see in the beamshots, are comparable to car headlights, packed into a tiny one inch reflector, and blinds incoming drivers. I’ve had a few instances where drivers put on their high beams to let me know I’m too bright. Medium is fine for moderate speeds. I don’t have a bike computer, so I don’t know how fast I go, but moderately speeds to me are speeds faster than slow cruising but not activating your twin turbos (ie – pedal to the metal, literally). When I sprint on my bike (gears are 46X16), I go quite fast, and at high speeds bumping the output up to high or turbo really gives life to the road, usually I can keep up with cars and in a rare instances overtake slow cars, which here in Miami we call “turtles”. Those freedom sprints feel perfectly safe at night, with a light that lights up the road relatively far and well illuminated, makes riding really enjoyable. When I reach a populated area I usually slow down and lower the brightness to the proper level according to my speed, I don’t want to increase the risk of drunk drivers “following the light”.

Closing Remarks

The BTR20, as shown in the beamshots, is a fairly powerful bike light. In cycling applications, it is a superb performer considering the different technologies that were integrated into the final product, from the well-thought out neutral white tint, to the specially engineered lens to put wasted light back on the road – this light seems to have been made from the ground up with the sole purpose of providing cyclists with a reliable and critical piece of equipment for when the sun goes down.

Off-road, the light appears promising, it is hardy, and resilient. However, the rattling may be a deal breaker for some, it boils down to personal preference.
If you guys have any questions or requests feel free to post them or send me a PM, I am always eager to help and answer any questions.

Regards and ride safe,


---The BTR20 was kindly provided by Fenix for review---


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