DIY Bike Brake Light And Turn Signals

If you ever take your bike out and share the road with large automobiles, you know that sometimes it can get a little hairy. As a biker, you will stand no chance in a collision with a vehicle. Communicating your intentions, i.e. turning and braking, can certainly reduce your risk of getting in an accident. [Mike] didn’t like the traditional idea of taking a hand off the handlebars in order to signal to traffic so he did something about it, he built turn signals and a brake light for his bike.

The business end of this project is the rear-facing light bar mounted under the rider’s seat. It is made from Radio Shack project boxes and mounted to an off-the-shelf L bracket. A bunch of LEDs were installed in the project boxes, the yellow turn signal LEDs are arranged in the shape of arrows and the red brake light LEDs are in an oval. Inside the project boxes you will find the 9v battery that powers the circuit and also a breadboard that is home to the circuits responsible for blinking the turn signals.

DIY Bike Turn Signals

Check out the switch assembly that is mounted to the handle bars. It was built using an old reflector bracket which was already the correct size to mount to handle bars. As you would expect, there is a toggle switch for turning the turn signals on and off. A little bit more interesting is the brake switch. It is a hinge-lever style limit switch and positioned in a manner such that it is activated when the brake lever is pulled. There is no additional thought or effort required on the cyclist’s part!

Something that is certainly not expected on the switch assembly is the headphone jack. [Mike] likes to listen to music while he rides and a cord dangling around from a backpack or bike bag gets in the way. On the rear light bar, there is a headphone jack that allows an MP3 player to be plugged into. The audio signals travel up the same CAT5 cord used for the turn and brake signals. This allows only a short run of headphone cable from the handlebars to [Mike’s] ears.

65 thoughts on “DIY Bike Brake Light And Turn Signals

  1. I love the idea of bike safety and it’s wonderful that Mike decided to step up and make something *from scratch* that will help keep him out of harm’s way. The brake switch solution is quite nice and every bit as robust looking as the one I have on my BMW.

    I expect we’ll see more sophisticated hacks from Mike in the future.

  2. Worried enough to make your own turn signals, but also willing to listen to music at the same time?
    Personally I like a complete sense of what’s going on around me when riding in urban areas but whatever.
    Well executed none the less, good work.

    1. I like both music and awareness when cycling. So I dropped a couple battery-powered speakers and an A2DP receiver in a top tube bag, and got both. :p

      I’ve meant to add a turn/brake signal unit (the cheap chinese ones seem like complete crap, DIY is definitely the way to go here), but haven’t yet got around to it. I do like this one, but as others have said, it would be good to add front/side visible turn signals — I rode flat bars, so my plan was to put hemispherical lights sticking out the ends of the bars; it’s less obvious how to do this with drop bars, but I suppose mounting another assembly much like what he has (sans brake light, of course) to the headtube or fork crown would work well.

      Anyway, I recently got a tadpole trike, and have all but abandoned the bike, so I’m substantially reworking my plans — at this point, I’m thinking about using motorcycle/scooter turn signal stalks in back, and mounting front/side visible signals on the front wheel fenders.

    1. thinking the same thing here… on average, i narrowly avoid hitting two or three headphone wearing cyclists every day. they are totally oblivious to anything that happens behind their back which endangers themselves and other traffic.

      1. For the record as someone who cycles every day it’s almost impossible to hear traffic behind you over the sound of traffic in front of you and wind rushing through your ears. You’re almost hitting oblivious cyclists, the ear-buds aren’t doing much either way.

    1. We use hand signals too here in London, but they’re less informative about the cycle and more about our view of other motorists and their personal inclinations towards self-pleasure etc.

      1. Google it if you don’t believe it, but to merely say “[Citation Needed]” is a lazy attempt to cast emotional doubt upon someone’s statement. If you don’t believe him, say “I don’t believe you.” Don’t try to hide behind a facad of intellectualism. Besides, citing a source means nothing more than “Someone else also said this.” The value of a citation only comes from the value of said source, which must be measured as well. Relying on the presence of a citation is just as foolish as taking uncited statements at face value. Go back to posting “first” on 4chan threads, it’s not much different.

        1. Did you read the post he replied to? “studies show ….” without actually mentioning what studies deserves a [citation needed], because it already means nothing more than “Someone else also said this”, and expects me to believe it without even mentioning who also said it.

          It’s an attempt to argue from authority, without the work of establishing the authority, thus putting the “lazy” in “fallazy”

      2. Or you could put flashing lights on trees, to test and to clear the road of drunken drivers >:)

        Incidentally, police and emergency vehicles and road maintenance and construction warning lights all use flashing lights when standing on highways. So it seems they all didn’t read that study. Or are slow to respond. Or are all dead.

    1. People also drive closer to cyclists who are wearing helmets.

      On the other hand if you wobble a bit as you ride, people will pass you at a greater distance.

      Maybe the two cancel each other out.

      Here’s another one; when you are driving along and first spot another vehicle coming towards you, you steer at them. A bit like target fixation that causes a lot of accidents (where you spend so much time looking at the thing you trying to miss you actually run into it).

  3. Great idea for version 1.
    Here’s a tip. Upgrade to 12V system and led’s designed for automotive/motorcycle use.

    http://www.amazon.com/Amjimshop-Motorcycle-Daytime-Running-Backup/dp/B00K7XIH0U/ref=sr_1_2?ie=UTF8&qid=1410707088&sr=8-2&keywords=3W+red+LED

    This will get a drivers attention far faster than the little discreete leds. and you can get them in yellow as well so 2 center red and a left and right yellow will be perfect, smaller, and waterproof. Plus dramatically brighter to make sure the dumb car drivers will look up from their cellphones to figure out what is blasting them with a massive amount of light.

  4. Genius!
    Also re. headphones one is fine, leaving the other free for hearing traffic.
    Maybe someone should make a selective unit that alerts the user when someone hoots, or gets too close via an ultrasonic sensor?
    Automated brake lights aren’t that hard, using an accelerometer..

          1. On a bike braking while turning is generally a bad idea.

            On motorcycles the microswitch is positioned so that you only need to pull the lever slightly for the brake light to come on.

            The turn switch (toggle) is also positioned so it’s pointing towards you (flat, not up) so you can activate it with your thumb. I’m not sure how he does it. (They’re also push-to-cancel, but anyway.)

            I think the builder may have seen pictures of motorcycles, but never ridden one.

    1. But you have to hit the marks too ;) I know I drilled a whole bunch of holes for a control panel I made. I had done just as you said and glued a drill guide to the panel. Once I was done I saw how terribly I had done. I blame being in a hurry and using poor quality drill bits, yeah… :P

  5. “…a cord dangling around from a backpack or bike bag gets in the way.” Why not put the player in a cellphone holder on your belt or an arm band or in a belt/bum/fanny pack?

    Seems to me as if running a cord out of a backpack to under the seat, then the headphone cord down to one handlebar would be much more in the way, and if you have to bail there’s two wires attaching you to the bike.

    1. This is what I was thinking too. You should never tether yourself to a bike in any way. I would have gone for bluetooth headphones or maybe even put some of those tiny aluminum dome speakers (like the kind you find in a soundbar) in the handlebars.

      There is something really cool about plugging in, though.

      1. Never tether yourself? I hope you don’t include cleats in that. You should Always tether yourself to the bike, when I ride clipped in the bike becomes an extension of my body. I feel like a baby animal when I ride without bike shoes. Its been said all up and down here but headphones on a bike is a good way to get killed. Even a pedestrian wearing headphones got killed here a while ago, but when you see people wear phones AND fail to Look for cars when they step onto the road it is kind of frustrating. We teach two year olds to look, listen, look and walk.

        1. I agree with the other guy, don’t tether yourself to a bike.
          Yes professional speedbikers clip their feet down – and that’s why when they get in a crash things are ugly. And they don’t have to worry about large trucks or bus crushing them anyway.

  6. I know that certainly where i’m from you need a minimum distance of 400-500mm between directional indicators on a vehicle depending on its width. Its not appliccable to pedal cycles but its certainly a good idea to separate them as much as possible to make other road users aware of your intentions. It’s hard to say how useful the arrow shape would be in every day use. I wouldn’t even like to drive anywhere where people are so inconsiderate that you would need a brake light on something as slow as a bicycle, but i must say i do like the switch even though i did chuckle at calling a microswitch a ‘hinge-lever style limit switch’
    I’m afraid to say however that i really do hate this project and all bike light projects because of all of the obnoxiously bright, flashing and ultimately distracting and annoying lights that cyclists seem to enjoy adorning themselves in.

    1. Indeed. In my motorcycle training class they said that insurance companies have found headlight modulators (motorcycles with headlights that “blink”) cause people to subconsciously steer towards you rather than the intended effect of being more aware and cautious. Something about “target fixation” when drivers are tired. We were cautioned to not install them, thought the topic remains controversial in the community.

      1. blinking lights are obviously no good on their own, as the cyclist needs to be able to see properly rather than a looming effect caused by strobing. the purpose then must be to make other road users aware. The problem is that your attention is drawn when sometimes it is unecessary, if the cyclist is in your periphery and in no danger from you directly,having your attention drawn away from the road ahead only serves to cause problems.

        a decent reflective bib or jacket i think is a much better solution, if you have ever driven past a police speedcheck after dark its incredible how far away you can be and still be aware of a body from just the reflection of your own headlights. of course the sensible solution isn’t as good as skin tight lycra and showing off your genitals to everyone you work with.

        what i find even more annoying than flashing lights is people who attach lights to the helmet. Certainly can’t be good for your spine or your head in a crash and what’s worse as soon as you turn your head you can end up suddenly showing white light to the rear and red to the front which can give others a real shock if they misinterperit it.

        sorry this has gone off topic a bit

  7. Hey, what a huge step up from the average random idiot cyclist around here. This guy put actual thought into communicating his intentions to other users that he’s sharing the road with. He beats out 98% of bicycle users and 50% of automobile users.

    Also, in before “Idaho Stop” by some guy who doesn’t live in Idaho.

    US bikers, do what I did and swap rear and front brake levers. So when you squeeze your right brake, you brake your front wheel. The front wheel does 95% of your braking, and this way you can keep near your hand near it at all times.

    Continue to signal your intentions with your left hand, which is now considerably safer to take off the handle-bar for a moment.

    Ditch the headphones.

    Add a bell, or at least shout a warning when overtaking pedestrians. Stop being an asshole and share the mixed-use path.

    1. If you are making some speed a sudden front braking can flip you over your head, or near to it. I know this from experience when I was a kid. So if you use only one brake I advise to use the rear one.

  8. The #1 excuse given by automobile drivers involved in crashes with bicycles is “I DIDN’T SEE THEM” Well of course it’s a tacit admission of guilt, but nevertheless you should read it at face value. If you are SEEN by the drivers then there is much less chance of getting hit. This is the purpose of garish clothing, lights, etc. is so that the driver will notice you instead of hitting you. So BE SEEN!

    Obey the law! Every single bit of it! Read the laws for where you ride and make sure you are obeying all of them when you ride. If you get into an accident and you are obeying the law 100% then there is a much better chance that others will be held responsible instead of you. Cops HATE bicyclists and will use ANY excuse to pin the whole thing on YOU.

  9. This is pretty cool and fairly well executed, plus makes good use of off the shelf components. It’s nice to see a hack that doesn’t require a laser cutter, CNC mill, 3D printer and a homemade metal forge! ;’)

    I do have one concern. That being the legality of yellow indicator lights. In most places colour is strictly regulated and I think Amber for indicators is fairly universal.
    Orange LED’s are available, but I wonder about simply using an orange sharpie?

    1. Bicycles don’t have 12v though, and batteries for 12v are either bulky or relatively expensive in my experience. Although you could mod a 12v system to run at lower voltage, or use a boost convertor I guess.

  10. caveat: >100K lifetime miles, 22 nations on 4 continents.

    Good idea, interesting implementation. Hope it works for the guy who rides the bike, but ditch the headphone plug.

    At night, the general idea is to be a light-bulb.
    During the day, the general idea is to be so visible that the driver cannot do anything other than pull over into the passing lane to avoid motion sickness.

    My gear. At night/dusk, the lights are on, but otherwise no different during the day: reflective vest, blinking tail-light and a reflector, spoke side-lights and reflectors, two headlights – a blinking one so drivers can see me, and a steady one so i can see them and reflectors, 3M reflective tape/silkscreen on my helmet, gloves and shoes. Speedplay ‘Frog’ cleats to protect my knees.

    At night, hand-signals are useless, which is why I have silkscreen reflective arrows on the backs of my gloves.

  11. A comment made on a recent TV programme was that not being able to observe the indicators (glove-mounted in that case) reduced confidence. It would seem prudent to add repeater indicators on the control box where the rider can see. This would also help reduce the chance of leaving them on for a long period after the indicated manoeuvre.

    1. I often see scooters (the motorbike type) and motorbikes that have indicator lights and a good 50% of the time if they have such it’s blinking without the person riding the bike being aware, which is annoying as hell when you expect them to turn, and it makes the 50% where they are used as intended useless since you can’t tell if it’s on on purpose or not.
      So yes you need an indication of activation I agree.

  12. Nice make, but wrong color arrow-shaped lights on the bike seems to me like a quick way to the problems with the law. And also, if you try to make something waterproof, you do not put cables on the top of the case, and you do not make your waterproofing with hotglue.

    1. Yes and no on the waterproofing, it really doesn’t matter that much if some moisture occasionally gets on passive components like wires and resistors, so hotglue added will be enough really, many classic wiring for lighting systems on bicycles is exposed to the elements and it seems to not cause a huge amount of issues.

      That PCB though has small copper pads that might not stand up to corrosion, but even if they get loose the legs of the components being soldered together should keep things functioning.

      Still though, I think many of use would try a better protection and as you say not put the wires on top.

  13. I don’t think it’s a good idea to have the turn and brake lights in a single bar where they are close to eachother since it makes it unclear which is which in various circumstances.
    I would advise putting the indicators on the side of the rear of the bike. Maybe near the screws of the rear axle.

    As for automatic break detection, that only works for handbrakes and unfortunately outside the US many bicycles have the rear-movement of pedals braking systems. Which is rather vexing to detect since it is located inside the rear wheel. And a simple detection of rotation is a flaky detection because you might not be braking at all, system so that doesn’t work either really.

    I once read that in various parts of the US they have/had a requirement for 2 brakes and that’s why the handbrake system was used more often since that ‘naturally’ comes in 2 brakes form. I cannot guarantee that information is correct though.

  14. Where I live signal lights on bicycles have to be at least 500 mm apart.Why is it so hard to find signals like this already built Also a good combo tail brake light coombo

  15. At the end of the day, for all the energy that went into it, it in the end mike was never able to convert potential energy into kinetic and he never would be able to feel like the pretty girl because tater gonna tate

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