Custom Daytime Visible Tail Light with Side Markers Lights

Have you ever felt invisible on your bike or find cyclists hard to see? I’ve felt that way before which is why I built a custom 7.5W tail light.

I felt that my previous bike light setup wasn’t enough because of a recent near-miss. The driver of a van behind me didn’t slow down and even started accelerating. I decided to move into an empty parking spot in case he wouldn’t slow down. Fortunately, I was safe.

It actually happened on the Off-Broadway bike route in Vancouver near Granville St. Close calls should never happen on bike routes. I try to find the safest bike routes. Now I feel that it’s not a bad idea to use a custom tail light on traffic calmed bike routes.

Whenever I experience a near-miss or drivers making mistakes, I feel that if the driver had enough time to decide, they can be prevented or be made less scary. You can give them more time to react by using brighter bike lights because they can see you further away. More time to make decisions shortens stopping distances, and reduces the likeliness and severity of a crash.

If a bike light is effective, you should feel that people drive more safely around you. You should see them giving you more space when passing, changing lanes sooner, and leaving more space in front of them, all of which makes cycling feel safer.

The bike light was built to improve visibility by:

  • Using two 45° amber side marker LEDs pointed 45° from the rear
  • Using two 45° amber side marker LEDs pointed 90° from the rear
  • Using 45° amber rear-facing side marker LEDs
  • Using 15° red rear-facing LEDs
  • Spacing the LEDs
  • Attaching the side marker LEDs close the the sides of the bike
  • Mounting it unobstructed by panniers and racks


The light has a custom made circuit. It has a micro-controller programmed with strobe patterns for daytime, nighttime, and power saving. Using strobe increases its battery life and visibility. The micro-controller also remembers your last setting and monitors the battery voltage. If the battery is low, the LEDs will dim to let you have enough time for visibility before recharging its batteries. It has a circuitry for stepping up the battery’s 13.2V to power a string of LEDs which require at least 20V.

It might seem like a lot of work to build the bike light when you could just go to the bike shop to get bike lights. The advantage of the custom made bike light over store bought bike lights is that:

  • Only one battery pack is needed for all 10 LEDs
  • One button controls all 10 LEDs which is useful for frequent stops
  • There’s no need to dismount the light every time you park it, saving you time
  • You can customize its strobe patterns and other features
  • It’s brighter than store bought tail lights
  • There’s side visility which may be important for road curves, junctions, and traffic outside your lane

The bike light may be more effective when there’s plenty of space for passing. If a four-lane road is quiet, you might see many drivers behind you using the inside lane and few using your lane within one block. It should reduce the chance of passing too closely when there’s an available lane next to your’s. If the lane is too narrow to share safely, you may still have to ride in a position that controls the lane. There’s no guarantee that it will work all the time.

The bike light was installed a week ago. My goal is not just to avoid crashes but also avoid close calls. Sometimes I get comments about the light from other cyclists. They often liked the design. Some people thought it was over done. To me, commuting safely and stress free is worth the investment.

I would still recommend using a backup light, a front light, and a helmet light.

In the future, I plan to convert the bike light into a turn signal light and possibly a brake light. Cree LEDs are recommended for higher efficiency and power ratings.

I plan on including this bike light in one of my future Instructables. Feel free to subscribe.


One thought on “Custom Daytime Visible Tail Light with Side Markers Lights

  1. deyong99 April 3, 2016 / 4:30 pm

    Great article & a must read for all cyclists ;))


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