Bicycle Turn Indicators




About: I'm a full stack web developer focusing on security and privacy.

Being a bicyclist in the East Bay is a hard task at times with drivers who don't know how to signal and being yelled at to "get out of the street and on to the side walk" (even though it's illegal),

Whats even harder is attempting to warn drivers when you are going to turn. You could throw your hand out, but this can make you loose stability and most people don't remember the ways to put your hands. This instructable seeks to make warning drivers and other cyclists that much more easier, and make your more visible while doing it especially at night.

Alas this is the premise for the Bicycle Turn Indicators, another pal in the "Make Your Bike Into A Car Series"

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Step 1: The Flashing Circuit

When first considering this project i thought of all kinds of ways to make lights flash from using an arduino to a 555 circuit to the circuit Kipkay uses for his LED Fan Sign My Friend and coworker JacobAziza mentioned that he had to change out his mechanic relay on his car and motorcycle to run it of LEDs. PERFECT! why build a circuit from scratch when the circuit already exists for automobiles?

A note about flashing circuit relays for cars, There are two kinds electrical and mechanic. Make sure you pick up an Electrical one, i made this mistake, and got the right one off ebay. Below are some pictures.

Step 2: Choosing Battery

Choosing a battery for this project was an issue of weight vs. cost. If cost was not an issue i'd be throwing a Li-Ion pack on here and it wouldn't be a issue. It's much the case that good priced rechargeable batteries are low in amps, so they discharge quickly. My suggestions for this project are the following:

A few D (8000mAh) NiMh batteries equaling 12v (Slightly Expensive but will last quite a while)
12v Lead Acid (Heavy as hell, really cheap)
2 Lantern Batteries at 6v each (Not Rechargeable, boo)

for this project's longevity, go with a rechargeable option. If you have a lot of amps you could also run a car horn or a small sound system.

Step 3: Supply List

To get you started here is the supply list:

1 LED flasher (Electrical NOT Mechanical)
1 12v battery (Choose Wisely)
20 Yellow 10mm LEDs (yellow is the standard on cars, you could use anything but blue, blue is illegal on vehicles)
4 82 OHM resistors (Based on the calculator here
A way to Case it (i'm using Beta cases due to their flatness)
Connectors to allow the cases to be removed from the bike (i'm using auto cables)

Step 4: Test Circuit #1

First off to test my idea i threw together a quick test circuit, this allowed me to see how the flasher works and how bright the lights are. I strongly suggest breadboarding it out first so you can catch any mistakes.

Step 5: Test Circuit #2

After the simple circuit worked, i decided to breadboard the circuit i got from the LED calculator....

Step 6: Creating the Blinker Cases Step 1

Next after all the prototyping is done, you want to make the cases. I used Beta tape cases just because they are a nice size and have a small profile. you could use almost anything for this.

Step 7: Creating the Blinker Case Part 2

Next you want to mark where you want to drill the holes for your leds, and then drill the holes. This was not too hard, i used a power drill.

After that, check the leds and see if they fit, if they don't drill out the hole a bit more, I made my holes just small enough for the leads but not the whole bulb.

Step 8: Creating the Blinker Cases Part 3

Once you push all the LEDs through, you can start soldering them together, In series. Then attach the Resistor to one end of the series (i did the negative end).

Last use a connector and solder that on so you can plug it in with the rest of the system. Use hot glue to make it all stay put.

Repeat 3 times.

Step 9: The Switch

Once you are done with the cases for the LEDs you need a way to swtich them. I'm using an on-off-on switch and a small project box. I will be hooking up each side of the leds to each on switch so i can turn on the side i am turning towards.

I dremeled out a plastic case and attached zip ties so it can be attached to the handlebars.

Step 10: The Relay Case + Batteries

The wiring just hanging out all over the bike would have looked really messy and probably get broken so i cased all the wire connections and the relay in a 5th Beta tape case. The wires get really confusing at the point, be sure to keep track of what side is left and what is right so you hook them up right.

The Batteries on the other hand are a bit to big to go in this case so they are getting strapped the bike with zip ties

Step 11: Installation

After you are done with all the parts, install the cases and the batteries to the bike, i used zip ties. Once all the cases are on you can wire it up.

The first step it too attach the light cases, i drilled holes about the size of the fork and down tubes and attached them with zip ties.

next attach the switch and solder 3 wires to the switch which will control the direction of the turn indicators.

Lastly solder it all together, remembering which size goes to which switch, i used a little piece of tape to remind me.

After all the wires are soldered, do a battery check to see if everything works, if not check your connections. Once that is done you can attach the batteries and hook that up with the rest of the system.

This step takes about 2 hours. Be prepared and it also makes your bike unoperational for that period.

Step 12: Test Ride!!!!!!

Once you're done, TEST IT OUT!!!

I was really impressed with the brightness level and it seemed to help maneuvering around automobiles.

The first problem i encountered was that i hit the back light fixture with my foot, Also the general size of the light fixtures are a bit big, a smaller container could be used.

The zip ties also proved to not to have a good enough grip from preventing the light box from moving from side to side, this could be fixed by using hose clamps, which i will get in the next few days.

Putting in a way for both lights to be flashed at the same time would improve this project thus allowing for a "warning light"

Here is video for the final product:

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    30 Discussions


    5 years ago on Introduction

    Have a LED set but only for the rear to put on the front I NEED TO TURN Up side down..but the PC HAS SOME THING TO STOP THE UNIT WORKING WHEN UPSIDE can only put on the rear the correct way...can i find and fix what ever it is that controls the switching.

    y not just program an ic to flick the led set u have picked much more quiet and powered by a tun of coils on the wheel all spinning arround a magnets on the fork and have a shape on the indicators so u can tell with is witch when its dark ok bye

    2 replies

    i mean for the coils they would be on the inside of the case close enough to the magnets on the spokes with black paint on a clear peice of plexi glass for the light to go through so u dont get confused with the sides ok bye again...

    I'm all for learning how to make some bike turn signals, but your opening is absolutely horrific. "Being a bicyclist is hard." What? No it's not. If you can ride a bike, you're a bicyclist. Not hard. "Whats even harder is attempting to warn drivers when you are going to turn. You could throw your hand out, but that make you loose stability and who wants to remember all the "proper" ways to put your hands?" If you have that much difficulty signaling without loosing stability, then yeah, you probably should be in traffic. For that matter, if you can't keep straight for a few seconds with only one hand, you should probably give up cycling. If you're unwilling to learn the correct ways to pilot a vehicle, you shouldn't use it. That's like saying "Who wants to learn pesky driving laws." I understand a common way to advertise something is to create a need in the reader, but painting the picture that cycling is difficult and dangerous is not going to convince someone to start riding a bike. Much less build blinkers for it. Sorry to come off as crazy, but I'll go out on a limb and ask you to revise your opening. It's really just inaccurate, bad advertising.

    4 replies

    Well thats the old way. All the signs are done on the left side because the signs were originally used for people when they were in their tractors.


    Reply 5 years ago on Introduction

    It is actually still used today on motorcycles, because you are supposed to use the front brake for most of your stopping power; and since it is on your right it leaves the other hand free for signaling.


    Reply 10 years ago on Introduction

    on most city streets cycling can be and is a harder task than most would appreciate. this is what i ment by "being a bicyclist is hard". I'm sure anyone who has been yelled at while biking (and getting the famous doppler complaint) or anyone who has been hit can agree with this. This instructable seeks to make cycling a little more easier for both cyclist and driver. being a bicyclist in most cities takes skill and practice. But i don't agree that less able bicyclists should just be banned outright from cycling in traffic. I think that with technological advances we can allow anyone to ride a bike. I know many older bicyclists who are a little uneasy in busy traffic, and do take side streets, which i greatly encourage. I also ride with taller handle bars than most which at very low speeds, like when coming to an intersection waiting to turn left, the handlebars are a little harder to control. I did change the opening a bit to be more clear. thanks for the input


    7 years ago on Introduction

    So I see that you only used 1 flasher, how did you wire the left from right?


    8 years ago on Step 12

    Great instructable, was exactly what I was looking for. The only adjustment I'd suggest is to have the beta cases on the back flipped horizontally because it's not easy for a car following to tell which direction you'll be turning because the right and left turn signals are only a few inches away from eachother.


    9 years ago on Introduction

    Hi frenzy I like the setup you built all be it with beta boxes which I am sure were cheap but I am interested in estetetics(I know I probably spelled that wrong) and design. they appear to function well and as designed and do add to the experience of riding with confidence and a greater sense of security while sharing the road with people who should be able to see you and anticipate where you are going by using the signals is a major perk for all onlookers too! beside that I think it makes as much sense to have turn signals on bikes as it does for motorcycles and cars in our fast paced world of road travel. I am a 47year old kid at heart and love to ride my chopper styled bike downtown for coffee and a people fix and wish I had a setup like yours for my bike. and I am looking into finding the blinker and leds locally and soon to see if I can build a setup like yours with one difference being to orient the lights in a horizontal plane to better define the direction intended when blinking and to create a visual buffer zone between myself and surrounding traffic. I like keeping my hands on the bars next to brakes and shifters and it just seeme natural to have blinker switches there too! If I get mine setup I will send you pics or video .Thanks for the inspiration ! nice work!

    IS there a way to circut a Small INdcator LIght by the switch so u know which is on when its night time?


    9 years ago on Introduction

    I've always wanted to do this, but wanted to find a way to not deal with programming all those expensive chips that vanish all so easily. I also would like to look into charging the lights off a dynamo...


    Reply 9 years ago on Introduction

    The seat is a Derri-air basic model; I know because I have one ( . They also have a sheep's wool cover for it. Very comfortable compared to a standard seat, but you have to become accustomed to it.


    9 years ago on Introduction

    I have signals similar to this, incandescent in the front, LED in the rear. You should watch some of my youtube videos, I show mine working as hazards.


    10 years ago on Step 5

    I Love this Instructable!  going to build my own soon.
    Quick question though.  If you split your array of 20 in two for 10left turn and 10 right, doesn't that mean you really have 2- 10 LEDarrays? So all 12volts go through whichever side is activated. Whichmight necessitate a recalc of the resistor value. Am i wrong?

    Also I'm not clear on how you wired up the switch and flasher circuitany way you could diagram that out?

    thanks again, awesome instructable!


    10 years ago on Step 2

    Some of the 6-Volt lantern batteries have 4 non-rechargeable D size batteries inside them, particularly the Energizer metal jacket lantern batteries...I converted one to rechargeable once, by taking the old D cells out, and putting new, rechargeable ones in...