Bike Turn Lights




About: I guess that the best way to describe me is unpredictable... I am into computer programming, and many other things that don't really matter that much... I'm not really telling you too, but if you reall...
This is my first instructable, and I will show you how to make yourself safer by having turning lights pointing left or right so that the drivers know which way you want to turn when riding your bike, especially at night. I made this instructable when I first discovered this website and saw the contest. It also looks pretty cool in the dark. So if you're interested, keep on reading... 

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Step 1: The Materials and Tools

- 18 red LEDs 2.6 volts
- 2 green LEDs 2.1 volts
- 6 resisters 1/4 watts, 220 Ohms
- Wire
- A plastic box approximately 4.5x9x1 inches
- Cardboard
- Aluminum foil
- One 9 volt battery
- 1 battery holder
- 2 flip switches
- 1 switch
- Duct tape
- Electric tape
- Multi-purpose ties

- Solder
- Soldering iron
- Pliers
- Wire stripper
- Scissors
- Exacto knife
- Ruler
- Pen
- Super glue

Step 2: Building the Base

O.K., let's get started.Take a piece of cardboard and draw a triangle so that it fits in the box and so that both triangles still have about 3 inches in between them. Measure about a 1/2 inch away from the triangle. Then cut the cardboard with an exacto knife and trace it to make a second piece. Cut very shallow on the line where the triangle is to bend the cardboard pieces so that they can "stand up". (Look on the picture because it might be confusing.) Then put the triangles in the box and adjust it if it doesn't fit.  

Now, once you're done with that, glue aluminum foil to the triangles (not the parts that bend!) and let it sit overnight. I added aluminum foil so that it acts as a reflector for the LEDs. Make sure that you leave plenty of room around the triangles so that when you're done, bend the aluminum foil to make a border around the triangle.

Poke 9 holes in each triangle so that they aren't too close to the ends.
I did it a bit differently, but this way's probably easier.

Step 3: Attaching the LEDs

Put the red LEDs in each of the holes on the triangles. Divide them into three groups (for each triangle). Each group contains 3 LEDs connected in series. Attach 1 resistor to each group. Test it with a battery to check if your connections are correct. Then test it with the three groups in parallel. Look at the picture for details.
When you are done testing, solder the LEDs and resistors in series and then solder all of the pieces together. (Use wire in between the LED and resistor because you need it longer.)
Put the triangles in the box and tape them with electrical tape. Make sure that you don't short the circuit.

Step 4: Attaching the Flip-switches

Tape a green LED to the side of the flip switch with electrical tape. Then solder it to the switch. I did this because you know when which arrow is on or off. The green LED shines with the red ones.
Attach the LED to the switch as it shows on the picture. Then tape it to the handlebars. You can put it wherever you want, but its easiest to have it at the end.

Step 5: Putting It on the Bike

When you attach the wires to the switches, measure out about how far it is from where the switch is to behind the seat. Use multi-purpose ties to stick the wires to the bike.

Cut a hole in the side of the box for the main switch to go in and connect all of the wires as shown on the schematic diagram. Then just attach the box to the back of your bike. I can't exactly tell you where because everyone has a different bike but if you have a basket, put it on the basket; if you have a bag, put it on the bag; and if you don't have either, you can either duct tape it underneath the seat or make a wire holder.

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    29 Discussions


    8 years ago on Introduction

    Nice one ! i was thinking of putting a light for stop on mine :P every time i press the brakes haha but i thought it would be kinda funny


    9 years ago on Step 5

    i think this is kool but a small improvements you could make is use a brighter led or a different resistor like a 1/4 watt 680 ohm. also you could add flasher and a tail light in the center to use as a indicator. don't make its as bright but bright enough that they can see. you could also move the switches under the handle bars by the wheel almost the sideways "v". if you do i would use plastic and zip ties. also to make it look better drill a hole in the frame run the wires through the bike and cover the two holes with a small rubber grommet or something to seal the hole from rust and stuff.

    1 reply

    10 years ago on Step 5

    Is it possible to make the left turn signal red and the right turn signal green? Just for emphasis, because a bike is so small compared to a car or delivery truck.

    1 reply

    10 years ago on Introduction

    cool you could of used flashing leds for this and wired them up to a center pole Flip switch and control them with one switch or two small momentary push switches


    10 years ago on Introduction

    not bad, you could add an automotive flasher to this and have the turn signals blink as well. You'd probably need to re-wire them to run on 12v though. Running it on 9v would probably work, but the blink time would be longer and it'd probably eat 9v batteries pretty quickly.

    10 replies

    Reply 10 years ago on Introduction

    i don't thing so. thermal flashers require quite a bit of load, so if u wire it up to the LEDs, it wont flash at all


    Reply 10 years ago on Introduction

    An arduino (while seemingly the lifeblood of almost all i-bles involving LEDS) is a bit of overkill here. Maybe if you wanted to program it to have an increasing blink rate and then turn off after X seconds, or maybe even have it automatically turn on the blinker when it senses the bike slow down and the handlebars turn past a threshhold rotation... but here, just find one of those blinkerbulbs and put it in series with the LEDs... instablink...


    Reply 10 years ago on Introduction

    I meant the blinker-bulbs from the X-mas light strands... it's heat dependent, so your blink rate would go down with temp... but it's easier and cheaper than a microcontroller....


    Reply 10 years ago on Introduction

    With all those sensors for heat and speed, that's a bit too complicated but I think that the X-mas lights (that blink) is a good idea. And why would I need a heat dependent sensor anyway? What if you just happen to be riding your bike on a really cold day and you still want the blink rate to be fast?


    Reply 10 years ago on Introduction

    No, the blinker bulbs are by their nature heat-dependent. The main mechanism inside them is actually a bi-metal flap. When it heats up because of the current flowing through it, one metal expands more than the other, and causes the flap to bend away from the contact. Once it bends enough, the contact is lost, and the flap cools down. The cooling down unbends the flap, reconnecting the contacts... which causes current to flow... which heats the flap... [ad nausaem (*sp)]

    Environmental temperature would play into this b/c the rate of cooling of the flap after it's been heated is directly related to the ambient temperature around the bulb. The colder it is, the faster the flap cools... the faster it can cycle... the faster the blink rate. Not many people notice this... well, because they're frickin x-mas lights. I'm just odd like that.

    I wasn't saying that it was heat-based by design, just de facto due to the choice of components.


    Reply 10 years ago on Introduction

    O.k., thanks. Just with the speed/turning sensor, what if you wanted to have the light turn on automatically, but if it were to turn on after the handlebars turned past a threshhold rotation, don't you want to turn the light on before you start turning but without changing direction because you want to inform the drivers that you're going to turn? And when you ride a bike, you often turn the handlebars to avoid rocks, for instance, or the path you are driving on is squiggly, so you can't go straight. So for that reason, having the turning sensor doesn't make much sense.


    Reply 10 years ago on Introduction

    it was an example... because explaining "how to use an arduino to read the specific brainwaves that are emitted when a human wants to turn a bicycle a certain direction" was too long and would require an instructable in itself... Essentially, it's impossible to have the bike KNOW when you WANT to turn without you actually giving it a hint (the easiest being the turn signal lever). I actually took a comp sci class from a guy who was working on the Pilot Assistant programming for the F-22. It was supposed to be able to predict what the pilot needed based on his actions (ex: IF plane turns TOWARDS enemy aircraft, ENGAGE WEAPONS, IF plane turns AWAY from enemy aircraft, READY COUNTERMEASURES)... it required a bank of 12 or 16 computers (doubled for redundancy) to make it run... so while not impossible, it's bloody difficult. With the limited processing of the aruidino, the most logical alternative would be to program it to make generalities, such as "Every time A is X, then B..."


    Reply 10 years ago on Introduction

    I wasn't exactly talking about the bike KNOWING what to do, just that the turning sensor wouldn't work.