I found a simple way to add a brake light switch to a bicycle brake lever. Specifically, this is for a mountain bike lever that pulls a cable for the brakes although it's possible it could work on other levers. I would not try this on super lightweight brake levers as the metal might not be thick enough to tap threads into and it might weaken the lever excessively.  The switches I used can be found at radio shack and are mini momentary pushbutton switches that are normally closed (N.C.). The tools you will need are: allen and/or box wrenches/sockets, duct tape, half round metal file, pencil, tape measure, center punch, drill and bits, 7mm fine tap and tap holder, wire, solder, soldering pencil, heat shrink tubing, heat gun and electrical tape.

Step 1: Prepping the Brake Lever

The first thing you will need to do is remove the reach adjustment screw from the body as shown in the first three pictures. This can be done using a small allen wrench. Next you need to remove the lever (silver part) from the body (black part) if possible. This is usually accomplished by removing a pivot screw and nut or a pivot pin and clip. Pay careful attention to how it goes back together and set the lever and small parts aside. Next you want to wrap the body as shown in the picture with a layer of duct tape to protect the finish when you clamp it in the vise.
<p>You could save yourself a lot of time, effort, and aesthetic appeal by simply buying a universal brake switch for $2-$10 dollars. Certain to be more reliable than this method.</p>
I'm finding big chunky ones for motorcycles, are there smaller universal brake switches for bicycles?
<p>Great idea, I will feel so much better running down cyclists now ;-)</p>
does it?
<p>If you look at what is happening mechanically, the brake lever is pressing against the switch when not being used and when you apply the brakes the lever pulls away from the switch which closes the switch, sending electrical current to the brake light to light it up. So no, the normally closed switch does not make it more complicated.</p>
<p>so the pivot point is in the center of the lever?</p>
using normally closed switches makes it more complicated.
when i press the brake lever i want the leds/light to go on and when i leave it they go off <br>anyone know how or know a source where i can find a project like that or similar? <br> <br>and by the way Great project!
<p>That would be this project; the switch used here is normally closed (so when it's not being pressed current runs through, when pressed it breaks the connection) so while the brake lever is released (you're not squeezing it), it pushes the switch to break the circuit connection.<br><br>From that point, use the wires running from the switch in whatever brake light setup you make.</p>
<p>Thank you so much it all makes sense now :) just one more question how can i make a Mandtory switch at home? or what are the alternatives for the switch ? thanks !!!</p>
Nice Job. I followed these steps to the letter, on both my front and rear mountain bike brake levels for my brake light and wired the two switches together. So no matter which brake level is pulled, it turns on the brake light. Thank you.
What a great idea and instructable! I volunteer as a fireman and EMT, and I am paranoid about my eight year old riding her bike, even when I'm riding with her. I have the motion-activated rear blinking lights, but this will be something I add on to her bike very soon. I think that I will try doing it with a magnetic reed switch. It should be easier to assemble and probably won't require drilling. Thanks again for posting it! Ken
Next stage of the hack - use the brake cable as the positive conductor and the frame as the ground. so you don't need to run electrical wires.
It would be next to impossible to insulate the brake cable from the frame ground.
Looks good.<br>You might want to show/explain how the thing works on the inside, with the (I assume) normal closed) operation.<br>The brake lever keeps the button pushed in which breaks the circuit. When the brake is pulled, the button is released, completing the circuit.<br>I think I'll do this for my motorized bike project.
@dangthelad and thrawn1<br>I completed the brake light wiring on a motorized bike that I made for a friend but didn't document the install with photos. In reality, it's the whole wiring system including headlight, alternator, regulator with supercapacitors, and horn.I am installing it on my bike as well so I plan on documenting it with another instructable. I think I could have a whole series of instructables for this bike! The next instructable will probably be the installation of the 4 stroke Blitzen alternator for the Honda GXH50 and Huasheng 142F engines on the bike. <br>
This looks like a great project abikerider. Good work! You've got me curious about what the rest of the bike brake light system consists of. Any chance you're gonna post the whole thing when it's done?
I would agree with this. I am curious about the entire completed project. It would nice to see how everything works together.
Nice instructable, well set out with clear photos and good flow. Good to see you are using decent engineering techniques with attention to detail. While functional, a large number out there are using 'duct tape' type methods.
Thanks, this is my first instructable. I really tried to make it a step by step instruction. I try to do quality work.<br>

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More by abikerider:Strange Brakes by StrangeCycles: Installation and Adjustment Add a brake light switch to a bicycle brake lever 
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