Prototype rear/brake light for bicycle

My goal for this project was to create a brake light system for my bike which did not require anything more than minor adjustments to the existing bike – I did not want to have to drill holes or change parts. In addition, as I use my flashlights for other activities other than biking, I wanted to be able to easily switch out my flashlights for some other use, or to a different bike.

Here’s the parts I used:

  • Solarforce PTS-3 pressure tape switch and tailcap
  • 2x Solarforce L2P P60/D26 modular flashlight
  • 1x Nailbender (Customlites) P60 drop-in: 2.8V-6V Red XPE2, OP reflector, single mode (high)
  • 1x Nailbender (Customlites) P60 drop-in: 2.8V-6V Red XPE2, OP reflector, 5 mode (low/med/high/strobe/SOS)
  • 2x Diffuser lens (to widen viewing angle)
  • 2x Twofish LockBlock flashlight mount
  • Topeak bar extender
  • Some standard copper 18AWG multi-core wire
  • Standard tools: soldering iron, solder, zip ties, heatshrink tube

I already had most of the parts before even considering this project, except for the drop-ins and pressure switch. Here is the result, with both lights turned on in high mode.


As you can see, I have wires running along the frame of the bike and soldered to the PTS-3 which I cut in half and extended. At this end is the tail cap connector


At the handlebar end is the tape switch, which I have zip-tied, but could easily glue on. At least with my riding style, my thumb is near the tape and I can easily press it when braking with my other fingers.


Here’s a short video demonstrating the brake light with the lights set at medium & high, and then strobe & high:

I considered modding the actual brake lever to toggle a switch, but decided against for a couple of reasons:

  • It sounded too complicated for my liking, and again I wanted to avoid modding the actual bike
  • I might change my brake levers, which would require a whole rework
  • There are times when I only use my rear brake (the right lever) but would still want the light to toggle on.

I will admit that having the switch there makes it awkward at times as gripping the handlebar turns on the flashlight, but as most of my riding is done in the city with my fingers always over the brake lever ready to stop, it’s not a huge deal. For others, of course, this solution may not work.

In my estimates, on high mode, the lights are probably putting out about 300 lumens each. They work great for daytime visibility, but at night, I definitely have to turn it down to medium (I also have a slightly blackened diffuser lens to lower output), if not, it’s extremely blinding for drivers. I also avoid strobe/flashing modes at night as I believe it just makes it more difficult for drivers to judge distance.

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