Bicycle Directional Lights - Simple, Low Cost, and Solar Powered

I use my bike to commute to work, and as the fall season progresses I find myself riding home in the dark. While my bike is equipped with running lights (and I with a reflective vest) I'm not particularly worried about being seen while I'm peddling along. However, hand signals in the dark have a tendency to be missed. So to improve the situation I decided that some directional lights would be just the thing. In eastern Massachusetts we call them Blinkahs.

This Instructable covers the process and materials I used to make the Blinkahs. Don't be intimidated by the number of steps in this Instructable. Each step is short and concisely worded. Nearly all have a photo to make things clear. The action steps are preceded by a hyphen - and written in Bold font. Commentary and clarifying descriptions are written in normal font. The parts on the parts list are also in Bold font.

Let the project begin!

While contemplating how I should go about it, I decided that whatever I ended up with had to meet four key objectives:
1. The power source had to be renewable i.e. I didn't want to change batteries - like ever.
2. The project had to be low cost. (ok cheap).
3. No 3rd objective.
4. The end product shouldn't look like a geek engineer's science fair project.

- Solar Powered Lights: Need 2 for $6.00. Photo from Amazon website. Objective 1 is satisfied!

- 1 inch PVC Tee: Need 1 for $0.86 from Lowes (or any equivalent store). You'll see a lot of references here to Lowes. I don't have any affiliation with them. There just happens to be one nearby. These photos are from their website.

- 1 inch PVC elbow: Need 2 for $1.32 from Lowes (or any equivalent store).

- 1 inch PVC pipe (10 ft.): Need 1 for $4.48 from Lowes (or any equivalent store). You'll have plenty left over!

- 2 pack of 3/4 -1.5 inch stainless steel clamps: Need 1 pack for $1.88 from Lowes (or any equivalent store).

- Wire Sheathing and a 3/8 inch Barbed Tee: Need approximately 10 ft. of sheathing and 1 Tee from Lowes for approximately $5.00 total. I already had these and couldn't find a photo from Lowes. This photo was taken on my work bench.

- Jacketed Fiber Optic Cable: $1.60 per linear meter. You'll use about 5 meters for a total of around $8.00. I can't actually vouch for this product. I was able to scrounge some remnants from a job we did at work. This photo from Amazon looks like the fiber cable I used. It's not like you'll be communicating bits and bytes through it. In this application we'll only use it to view transmitted light.

- Terminal block: Purchased from an electronics supply store. I had this in stock, but I'm estimating that it was around $2.

- Solderable breadboard: I already had one, but you can purchase one from any electronics store or website for about $1.

You'll also need some miscellaneous supplies like wire, electrical tape, solder, etc. and I'll assume that you already have those things.

So the total is estimated at $29.88 or just under $30. Objective 2 -Check!

- After removing the attached bracket, remove the screws from the base of
the light.

This will allow you to remove the clear top cover over the solar panel.

- Turn the light over and remove the solar panel cover.

This will expose the screws holding the solar panel to the base.

- Remove the screws holding the solar panel.

The disassembled light should look like this photo.

- Pop the button cover out.

- Turn the solar panel circuit over to expose the button.

- Unsolder the button terminals and remove the button from the board.

It will be helpful to use a flat screw driver to gently pry under the unattached end of the button.

- Solder leads to the terminals on the board where the button once was.

Set this board assembly aside for now. We are going to attach a terminal block to the base cover.

- Cut a 3 segment piece off the terminal block.

- Mount the 3 segment terminal block on the side of the base cover.

I used a small sheet metal screw and drilled a pilot hole. Placement isn’t critical, but make sure you don’t cover the light assembly hole. Note that I re-attached the mounting bracket. I found it easier to hold while drilling and applying torque to the screw.

- Thread the newly soldered leads on the board assembly through the button hole in the base cover.

- Strip the wire ends and attach to the terminal block.

Leave the board assembly unattached from the base cover for now. Later you’ll thread the fiber optic cable through the third terminal and into the red lens. The screws in the terminal block will hold the cable in place.

- Slide the red lens cover into place.

- Look through the lens and mark where the led bulb comes to.

You are going to drill an angled hole to this position and thread the fiber optic cable inside the lens to the bulb.

- Remove the lens and carefully drill the hole through the lens at an angle that will allow the fiber cable to be inserted.

You have some freedom here as the fiber cable bends. The plastic is polycarbonate which is brittle, so to reach the cable diameter I used a 1/16 inch bit for a pilot hole before switching to a 3/32 inch final bit. You may want to do the same depending on the size of the cable you use.

- Re-assemble the light and set it aside for now. (No photo)

This switch preparation process is based on building and mounting the switch assembly to the handlebar bracket that holds the hand break lever. And I used the switch that I unsoldered from the circuit board. You may choose a different approach, and that’s perfectly fine. If you choose a different switch pick something like a doorbell i.e. it is “on” only when fully depressed.

- Cut two pieces of plastic flat stock.

The larger piece is 22 x 45 mm and the smaller is 22 x 35 mm. These sizes worked well on my bike. It may vary a little on yours depending on how you want to attach it to the handlebars. I used 1/8 inch PVC but any plastic will do. It is important, however, that the larger piece be fairly rigid as this is what will hold the switch in position as you push it.

- Loosen the screw from the handlebar bracket and slide the large PVC piece into place so that it bottoms out against the handlebar. We'll call this piece the button support.

- Mark the position with a pencil as shown.

- Remove the screw completely and mark the center of screw hole on the button support.
You will be drilling a hole with this spot as the center.

- Remove the button support and draw a straight line across the piece where you marked the top of the bracket.

- Drill a hole through the button support at the center dot.

I used a small bit first to drill a pilot hole then used the larger bit. The hole has to be at least as big as the diameter of the screw.

Note that the hole is a little off center. That’s the beauty of handmade craftsmanship - it ain’t perfect!

- Cut a piece of breadboard and insert the switch that you unsoldered from the circuit earlier.

- Turn it over and solder leads to the switch pins.

I also soldered the pins that aren’t connected to better hold the switch in the board.

- Take the smaller of the two PVC rectangles and mark the center. We'll call this the switch holder.

- Draw a square around the center mark with a pencil that is about the same size as the square outline of the button.

- Drill a hole that is the same diameter as the length of one of the sides.

- Cut out the corners to make the square.

I used a Dremel for this part. The hole doesn’t have to be perfect. You’ll seal the gaps later.

- Insert the switch through the square hole so that the round button protrudes from the surface of the switch holder.

- Place the switch holder on top of the button support.

Line up the tops. The bottom of the switch holder should end just above the line you drew earlier. This is important since if it’s below the line the hole in button support will not line up with the screw hole in the handle.

- Attach the two pieces together with screws.

I used sheet metals screws but drilling a though hole and using machine screws with nuts will work, too. You now have a complete switch assembly.

With the light and switch assemblies complete you have finished the hardest parts of the project. Before you move on to the next phase you’ll need to complete the step below.

- Have celebratory beer.
(If you’re of age, of course) It’s important to enjoy your accomplishments. Make sure it’s in a nice cold mug with a big foamy head!

I mentioned that I commute to work on my bike, and I have those nerdy wire baskets that straddle the rear wheel. They’re great for carrying laptops, clothes, my lunch, and now tail lights! If you don’t have saddle baskets I’d recommend getting some. You won’t regret it, and the neighbors only laugh at you for a little while.

- Cut the pipe and fit the elbows and tee as shown in the photo. We'll call this the light fixture.

The overall length should be just inside the outer width of the baskets. The pipe fits very tightly in the sockets of the fittings. I decided not to use any pipe glue. We’ll see how that works out.

- Mount the fixture to the baskets using the pipe clamps.

Notice that I turned the Tee 90 degrees so that it faces front. The wire sheathing will slide into the open end.

- Measure and cut the wire sheathing so that it runs from the Tee to the handlebar stem.

- Thread the wire and the fiber optic cable through the sheathing.

Remember to pull two pairs of wire and one pair of fiber to feed both tail lights.

- Thread the wire and fiber through the Tee and elbows on each side of the light fixture.

- Connect the wire leads to the terminal block on the light.

- Thread the fiber optic cable through the terminal block and into the hole in the lens.

- Tighten the screws on the terminal block to hold the fiber in place. Not too tight, though.

- Slide the light mounting bracket on the elbow and tighten it down.

- Swing the light into the proper orientation and tighten it down.

- Tie the wire sheathing to the bike frame for support.

Allow enough slack in the sheathing by the fork to allow the handlebars to rotate fully in both directions.

- Pull the wires and fiber through the barbed Tee and insert the Tee into the sheathing.

- Fasten the Tee to the sheathing by wrapping with electrical tape.

- Cut a short piece of sheathing to cover the wire and fiber from the barbed Tee to a point near where the switch will be mounted.

- Thread the wire and fiber cable through the sheathing.

- Insert the barbed Tee into the sheathing and wrap with electrical tape.

You’re in the home stretch now!

- Mount the switch assembly to the hand brake handlebar bracket.

I originally mounted the switch assembly in the upright position as shown on the left. This proved to be a problem since I’ll often flip the bike over and rest it on the handlebars to do repairs or maintenance, and I can’t very well do that with the plastic switch assemblies in the upright position. So I ended up unsoldering and removing the switches, flipping them over and remounting and connecting on the opposite handlebars. Now the switches were under the handlebars and still easily accessible with my thumbs. You may want to consider this as well.

- Connect the wires that you pulled through the sheathing in the step above to the wire leads on the switch.

I twisted the wires together and soldered the connection in place. Then I covered the connection with shrink wrap. Just remember to thread the shrink wrap over one of the wires before you make the connection. You can use electrical tape instead of shrink wrap. I’d never used shrink wrap before so I wanted to try it. It’s very effective and fun to watch shrink up!

- Drill a hole through the switch assembly just under where the wires come out for the fiber optic cable. (no photo).

The hole should be just large enough so that the fiber fits snuggly.

- Push the fiber optic cable through the hole.

- Cut the fiber off with a utility razor leaving about 1/8 inch protruding.

- Sand the end of the fiber with fine sandpaper.

I used 220 then 400 grit. You may not need to go that fine.

- Tape the wire connections and the fiber optic cable to the handlebar.

- Click the button and stand back!

The fiber optic cable is there for safety and the “cool” factor. You’ll see what’s happening with the tail lights by looking at the fiber optic cable on your switch assembly. This makes it unnecessary to turn your head to see whether the light is on, off, blinking fast, or blinking slow and will help keep you in your lane!

- Seal around the edges with a sealant.

Use acrylic or Quad since you’ll be painting it.

- Paint the switch assembly with latex exterior paint.

This will help prevent damage due to the elements. Paint carefully around the switch itself. You’ll want to get paint into any gaps between the switch body and the PVC to make a good seal but not on the button itself.

- Go for a nice bike ride around town.

If you live near a tourist area or city then pick a Saturday and go for a pub ride. My favorite place to do this is Newport, R.I. The pubs are close together and filled with friendly denizens - local and otherwise - and the sidewalks are heavily populated. This will maximize your bike’s exposure. I’m usually good for about 5 or 6 pub stops before I have to resort to pushing the bike if you catch my drift ;)

I hope you enjoyed reading this Instructable as much as I enjoyed writing it, and may your bike ride home always be sunny, downhill, and above all safe! Oh, and as for that 4th Objective – I’ll let you decide!