BC21R Fenix Bike Light

Rated 4.00 out of 5 based on 3 customer ratings
(3 customer reviews)

This rechargeable bike light is design for both mountain biking and urban settings. For the commuter, the BC21R features two side red lights and a flashing mode for additional rider safety. Its quick release mount makes it easy to detach the light, ensuring the light won’t be stolen. Mountain bikers will love the light’s dual beam system for up-close and extended visibility.

$96.00 $74.95

4.00 out of 5
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Max Lumens: 880
Modes: 5

Length: 4.4” (113mm)
Width: 1.6” (40.5mm)
Height: 1.7” (42mm)

Weight: 2.4 oz. (67g) excluding battery

Batteries: 18650 3.6V/2300mAh rechargeable battery with Micro-USB charging

Included: Bike mount, mounting shim, mounting strap, spare O-ring, 18650 3.6V/2300mAh battery, USB charging cable

Warranty: Limited Lifetime Guarantee from Fenix Lighting U.S.

MODE Lumens
Impact Resistance
Low - 2300mAh 100 12h
Low - 3400mAh 100 15h 50min
Medium - 2300mAh 200 6h
Medium - 3400mAh 200 8h 30min
High - 2300mAh 380 3h
High - 3400mAh 380 4h 30min
Turbo - 2300mAh 880 1h
Turbo - 3400mAh 880 1h 20min
410ft (125m) - 1m IPX-6 water resistant
Additional Features
  • Uses one Cree XM-L2 T6 neutral white LED with better color rendition
  • Powered by one 18650 rechargeable Li-ion battery or two CR123A Lithium batteries
  • Optimized Dual Distance Beam System
  • Micro USB direct charging
  • Built-in over-charge, over-discharge protection
  • Battery Level Indication
  • Low power warning reminds when battery replacement needed
  • Over-heat protection to avoid high temperature of the surface
  • New-type quick-release bike mount for easy and secure adjustment of the light direction
  • Four brightness levels and one flashing mode
  • Digitally regulated output maintains constant brightness
  • Made of aluminum alloy with excellent heat dissipation design
  • Waterproof to IPX-6 standard


  1. The Flash mode will flash at 380 lumens and 100 lumens alternately.
  2. The bike light is equipped with red side lights, it will be activated simultaneously by default. This side red light will be constant-on as the main light on and flashing red when main light flashes.
  3. The above-mentioned parameters (lab tested by Fenix using one Fenix ARB-L2-2300 18650 rechargeable Li-ion battery) are approximate and may vary between the bike lights, batteries and environments.

*The runtime of the Turbo brightness level is the accumulated time. The runtime can be longer when uses 18650 battery of larger capacity.


Operation Instruction

Press and hold the light button for 0.5 seconds to turn ON/OFF the light.

Output Selection
With the light on, click the light button to cycle through Low→Mid→High→Turbo→Flash.


  1. As with any performance light, the bike light builds up heat when runs for an extended period. Intelligent circuitry in the bike light downshifts the light to lower brightness level to guard against overheating.
  2. The bike light retains the last-used brightness level.
  3. When the battery power level is critical, higher brightness levels can not be activated, the bike light is programmed to cycle through lower brightness levels.

Battery Level Indicator
With the light off, single-click the light button, the side light will indicate the battery power level conditions, and then go out after 5 seconds.

  1. Side light constant-on (sufficient power level): 60%-100%
  2. Side light slow flashing (low power level): 20%-60%
  3. Side light quick flashing (critical power level): 1%-20%

Low Power Warning and Intelligent Output Downshift
Low Power Warning: With the light on, when the battery level is lower than 20%, the light button will blink red constantly, to remind you to downshift to a lower brightness level to extend runtime or recharge the bike light.

Intelligent Output Downshift: If non-stop use is needed, the light will downshift to a lower output level to extend runtime. When it downshifts to the flashing mode, the bike light will go out soon. Please stop riding and replace the battery or the bike light.


Operation Points: Remove the anti-dust plug at the bottom of the bike light to reveal the charging port, and plug the Micro USB end of the USB cable into the light’s charging port, then connect the other end of the USB cable to a USB power adaptor.

Charging Indicator: The indicator light in the bike light blinks red to indicate the charging process has begun. The indicator light turns solid green when the battery is fully charged.


  1. Turning on the bike light under charging state is not recommended by Fenix. But it will be okay if under emergency situations, the bike light can light up Low and Mid output.
  2. Once charging is completed, disconnect the USB cable from the light and be sure to secure the anti-dust plug cover.
  3. Fenix recommends using a power adaptor with output over 5V 1.5A. It takes about 4 hours to fully charge the bike light.
  4. The bike light can be connected to the USB cables for digital products such as mobile phones with standard Micro-USB charging port.
Reviews (3)

3 reviews for BC21R Fenix Bike Light

  1. Rated 4 out of 5

    Sproule Love

    This light is excellent and makes me feel safer bike commuting in NYC. The 2017 Gear Institute pick is definitely merited. However, as mentioned in the Gear Institute review, the ladder rubber band is not a solid way to attach the light to handlebars. I have to adjust it often after going on bumpy roads. I don’t have a lot of confidence that it will last.

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  2. Rated 3 out of 5

    Chris (verified owner)

    buyer beware: the light duration times as of 8/21/16 are NOT correct for the battery that ships with the light. They ship it with a 2300 mAh battery and then post times for a 3400 mAh battery.. which is kinda shady to me. I am going to email them about correcting this. Until they correct this, I will leave my review at 3 stars to try and make sure others read this

    Was this review helpful to you?
    • Fenix Lighting U.S.

      Chris-I think you were the one that alerted us to a change by the factory. Thanks. We have now corrected it.

  3. Rated 5 out of 5

    Daniel Hadley (verified owner)

    Excellent handlebar light for night riding and as a emergency light to keep in the saddlebag. It is plenty bright enough and very easy to mount.

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