Sofirn BS01 Bike Flashlight Review
The Sofirn BS01 bike flashlight is USB-C rechargeable and has a shaped beam perfect for bikes! With four modes and a simple user interface, it’s a great choice!
Official Specs and Features
Here’s a link to the Sofirn BS01 bike flashlight product page.
Versions
There’s just one version.
Price
The going price for the Sofirn BS01 bike flashlight is $31.99.
Short Review
This is a nice dedicated bike flashlight. There are only four modes and the user interface is simple enough. The attachment to the bike works well too. At $32, it’s a good-priced choice.
Long Review
The Big Table
| Sofirn BS01 bike flashlight | |
|---|---|
| Emitter: | Cree XHP50.1 |
| Price in USD at publication time: | $31.99 |
| Cell: | Internal |
| Runtime Graphs | |
| LVP? | ? |
| Switch Type: | E-Switch |
| Quiescent Current (mA): | ? |
| On-Board Charging? | Yes |
| Charge Port Type: | USB-C |
| Charge Graph | |
| Power off Charge Port | All modes |
| Claimed Lumens (lm) | 2000 |
| Measured Lumens (at 30s) | 880 (44% of claim)^ |
| Candela per Lumen | |
| Claimed Throw (m) | 277 |
| Candela (Calculated) in cd (at 30s) | 432lux @ 4.822m = 10045cd |
| Throw (Calculated) (m) | 200.4 (72.3% of claim)^ |
| Claimed CCT | 6000-6500 |
| Measured CCT Range (K) | 6900-7100 Kelvin |
| Item provided for review by: | Sofirn |
| All my Sofirn reviews! | |
^ Measurement disclaimer: Testing flashlights is my hobby. I use hobbyist-level equipment for testing, including some I made myself. Try not to get buried in the details of manufacturer specifications versus measurements recorded here; A certain amount of difference (say, 10 or 15%) is perfectly reasonable.
What’s Included
- Sofirn BS01 bike flashlight
- Charging cable (USB to USB-C)
- Bike mount
- Manual etc
Package and Manual
Build Quality and Disassembly
Size and Comps
Size: 32 mm × 30 mm × 112.8 mm
If the flashlight will headstand, I’ll show it here (usually the third photo). If the flashlight will tailstand, I’ll also show that (usually in the fourth photo).
Here’s the test light with the venerable Convoy S2+. Mine’s a custom “baked” edition Nichia 219b triple. A very nice 18650 light.
Also above is the light beside my custom engraved TorchLAB BOSS 35, an 18350 light. I reviewed the aluminum version of that light in both 35 and 70 formats. I also reviewed that specific edition, the “Oveready BOSS FT Collector Vintage Brass” 35. I love it!
Retention and Carry
The Sofirn BS01 is a dedicated bike flashlight. There’s really no mistaking that! The beam has a specific shape to prevent blinding oncoming traffic. Along with that, there’s a nice bike mount.
The pieces are sort of puzzle-like, so I’ve tried to present the order of attachment. It’s nice that this is simply a grabby attachment, with nothing permanently attached to a bike.
I will say that when mounted in the direction it’d be in on a handlebar, the strap sort of gets bunched up against the body. You can see that below. Hooking the strap into the hook might be a bit problematic. But once done, it does seem very secure!
It’s not a bike, but you can get the idea of how the light attaches to something…
Owing to how the strap works, it’s possible to tilt the BS01 very easily, for the exact positioning of the flat-top beam.
Power and Runtime
The Sofirn BS01 bike flashlight runs a single 21700 cell, but it’s built-in, so I don’t have any pictures of it. It’s unclear if the 21700 is soldered in or if it’s just in position with springs. Unfortunately, that not being clear usually means that the cell is soldered in…
The switch does give an indication of cell voltage, too, as follows:
Green: 50-100% power
Red: 25-50% power
Red flashing: <25% power
Charging
Charging of the built-in 21700 of the BS01 is by way of a USB-C port.
A USB to USB-C cable is included.
Charging is fine and quick at nearly 3A!
Modes and Currents
| Mode | Mode Claimed Output (lm) | Claimed Runtime | Measured Lumens |
|---|---|---|---|
| Turbo | 2000 | 3h | 880 |
| High | 500 | 3.5h | 273 |
| Medium | 150 | 14h | 118 |
| Low | 50 | 38h |
Pulse Width Modulation
Every mode uses PWM.
Here you can see a “baseline” – a chart with almost no light hitting the sensor. Then there’s the Ultrafire WF-602C flashlight, which has some of the worst PWM I’ve seen. It’s so bad that I used a post about it to explain PWM! Here are multiple timescales (10ms, 5ms, 2ms, 1ms, 0.5ms, 0.2ms) to make comparing this “worst” PWM light to the test light easier. That post also explains why I didn’t test the WF-602C at the usual 50us scale.
User Interface and Operation
A single e-switch controls the BS01. It’s a big switch and quite nice, really. It also has an indicator feature and can be lit in red, green, or blue.
Here’s a user interface table!
| State | Action | Result |
|---|---|---|
| Off | Click | Battery indicator for 5 seconds (Same information as above in the runtime section) |
| Off | Hold | On (Mode Memory) |
| On | Click | Mode advance (ascending) |
| Any | Double Click | “Strobe” (it’s a very slow strobe) |
| Strobe | Click | Mode memory (Manual says “previously used mode” which is accurate, but glosses over the fact the light will not return to the previous state) |
| Any | Click 3x | Iterate Smart Mode^ The light blinks once to indicate entering Smart Mode. The light blinks twice to indicate exiting Smart Mode. |
^ Smart mode is essentially a motion sensor for the BS01. When enabled, the light will turn off if no motion is sensed after around 30 seconds. If there’s motion, the light will turn back on. This is a nice feature! The switch is lit in blue to indicate Smart Mode.
LED and Beam
I’m not sure what the emitter here is. I was sure (and it looks like) a Cree XHP50 HI but I can’t find that in any documentation. Anyway, you can see how it tests below.
The BS01 has an interesting reflector made specifically for vehicles like bikes.
Below you can see the emitter. It’s sort of on the top, so it points downward anyway (toward the ground) and that light is spilled out by the reflector.
LED Color Report (CRI and CCT)
The claimed CCT is 600K and this light is definitely cooler than that. The beam has areas of somewhat different CCT though, but this is representative of essentially the middle. CRI is low, at around 70.
CBeamshots
These beamshots always have the following settings: f8, ISO100, 0.3s shutter, and manual 5000K exposure. These photos are taken at floor level, and the beam hits the ceiling around 9 feet away.
Tint vs BLF-348 (KillzoneFlashlights.com 219b version) (affiliate link)
I keep the test flashlight on the left and the BLF-348 reference flashlight on the right.
I compare everything to the KillzoneFlashlights.com 219b BLF-348 because it’s inexpensive and has the best tint!
Conclusion
What I like
- Smart Mode is neat!
- Simple user interface
- Good USB-C charging
- Nice bike mount
- Low cost
What I don’t like
- Built-in 21700 doesn’t seem to be serviceable (and definitely not in-the-field swappable)
- Very cool white
Notes
- This content originally appeared at zeroair.org. Please visit there for the best experience!
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21700 cell is replaceable!