Introduction: Regenerative Braking for Bicycle Safety

Picture of Regenerative Braking for Bicycle Safety

If you have always wanted to generate electricity on your bicycle but wished for a way that would not add extra work and resistance to your bike ride, then this project is for you. 
We will build a regenerative brake for a bicycle, based on 2 geared motors which will power a functional ultra bright LED stop light/safety flare for your ride.
The intention of this project is to create an elegant mix of sustainability and personal transportation safety.
We wish to enhance bicycle safety by alerting visually all vehicles around you, that you are braking, making them aware of a possible change in your trajectory,  whether it is because you wish to make a turn or just slow down or stop.

It will require no extra pedal stroke effort as we will be harvesting the energy that usually gets released as heat from friction.
It will require no extra buttons, or switches as we wish to keep the cockpit of the bicycle the same, and maintain the mode of operation.
No batteries required.

This tutorial requires some soldering, light dremel work and basic circuitry (i.e connecting LEDs in parallel).
Lets go to the next page for materials.

Step 1: Materials and Tools

Picture of Materials and Tools

Here are the materials sourced.

2 mini gear motors(24:1) from
Aluminum Mounting Hub for 3mm Shaft Pair, 2-56 Holes from Pololu
Mini Metal Motor bracket from Pololu
Various nuts and bolts 

Architectural Aluminum (alloy 6063), Rect Bar W/ Rounded Edge, 1/8" Thk X 5/8" W X 6'l
from McmasterCarr

Plexiglass 1/4 in at 10x10 in 
UltraBright LEDs (Radioshack)
Speaker wire( Radioshack)
Heat Shrink (Radioshack)
Electrical tape (Radioshack)

hex set
Socket wrench
Drill, some bits,
Soldering iron,
Lasercutter (optional)
Dremel + various bits
Wire stripper

Step 2: Assembling the Assembly

Picture of Assembling the Assembly

1.Take your aluminum flat bar and measure with your micrometer/ruler how long the arms need to be from the center of the brake pad.
    For us it was 4 inches long.
    Mark where you need to drill holes to mount it to the brake assembly and at what angle you will need to mount the motor to make      contact with the tire. For us it was 120 degrees.

2. Once you have all the measurements, take your Dremel and cut the aluminum bar as you marked earlier.
    Drill the holes and dry fit the assembly to make sure it all fits. Both pieces act symmetrically so they will need to be the same lengths.
    Remember that the holes for mounting the motor mount will be much smaller than the holes needed to mount it to the brake so use       the appropriate drill bits for each.
    Be safe and use cutting fluid, goggles and gloves for all of the above.

3.If everything fits than bolt on each motor mount bracket to each of the cut aluminum bar.
   Insert each motor into the mount and make sure they are facing the correct direction in order to make contact with the tire.
   Use the provided bolts to secure the motor in in the mounting bracket.

4. Now that everything is mounted you should have 2 aluminum bars with a motor attached to each. Take the aluminum hubs,
    place them snuggly in a vice and notch each very gently with a Dremel and a cut off wheel so that they have a little grab to the tire.
   Avoid making it too sharp if you value the life of your sidewalls.

5. Once that is done, place the hubs onto the motors and gently tighten down with the worm hex nut. Be careful with this as it is prone    to stripping.

Your assembly is now complete. 

Step 3: Electrical

Picture of Electrical

Ok in the previous step we assembled the motors to the aluminum bars.
Now it's time to solder wires to the motors, run the wires on the frame and connect the LEDs.

1. Take 2  lengths of 12- 48in double stranded speaker wire(Radioshack) and strip the ends. Add some heat shrink, cut to size to make      sure it covers all exposed wire and insert into the wire.

2. Solder to the motor leads and use a heat gun/hair dryer to shrink around the connection.
    Check continuity and that everything works and is making contact. Do this to both motors.

3. Take your LEDs and solder them together in parallel. We put one in front and 3 in the back. Extend a connection for later

We didn't use any capacitors or resistors as we didn't see them as necessary in this circuit.

Step 4: Putting It All Together

Picture of Putting It All Together

1. Attach your ready assembly to the brake calipers.
It is advisable that you keep your brake pads in case you need to make an emergency stop at some point. 

2. Run the wiring under the frame with all the gear cables etc that exist, using either electrical tape or coiling it around the cables to avoid any problems or entanglements.

3. Connect the left generator to the front light and the rear LEDs to the right generator.
Test the assembly and make sure there is no drag when the brake is not depressed. The main point of this mechanism is to hack the pre-existing brake and turn the brake lever into a sort of self generating switch. 
Adjust your brakes for the necessary clearance.

Congrats, you should be all done now.

Step 5: Some Video and Final Thoughts

Picture of Some Video and Final Thoughts
We find it a very successful project and hope that you do as well.
Its a simple way to add much more visibility and safety to your biking without sacrificing the quality of your ride or having to add batteries.
The added weight was negligible at around 150 grams.

Here is a video of the in action.


swaxman made it! (author)2015-03-20

Very Impressive bracket design and overall nice job youve done robot, ! Such an elegant seamless simple solution youve designed. Funny that you and I had the same idea, picture attached is
sWaxmans own design system tested and constantly re designed using only recycled printer parts , EWALBB , Early Warning Anti Lock Bicycle Brake,

WEDimagineer (author)2015-02-10

I am building a new type of vehicle and this seems like the perfect design for powering brake lights, but I need to know two things: What is the wattage/amperage and can the motors withstand braking at around 35+ mph?

lucas.r.muniz (author)2014-10-07

cool! but how can i do that on a disc brake? my bike has no support for v-brakes. i know it's possible, since i've seen some electric bikes with regenerative disc brakes, but i didn't find any information on how to make one.

MichaelTylerTrammell (author)2013-01-09

Simple, brilliant, and a benefit to humanity and mother Earth alike, a true winner in my book. GREAT JOB BRO!

wolfgang64 (author)2012-11-16

This is impressive. I also would like to know the outputs and if it would be worth hooking it to an electric bike with a lipo battery. I live in very hilly terane and wonder how much energy could be recovered on long downhill. Thank you.

kprakasan (author)2012-11-15

This is just Brilliant , U will become a good inventor in the future,Works like these give me Frustration and depression Lol , Why the hell dint the Idea come in my mind or others mind , may be we should try harder , Good luck and all the best for ur future

jarvallmighty (author)2012-08-21

Love this project !! Hope you can get production going.

Noblenutria (author)2011-08-10

This is really cool. How much electricity does it generate? Do you know how much volts, amps, watts?

BillBiker (author)2011-07-07

Simply Brilliant!!! I always wanted brake lights :) . To the person wanting to know if they would wear out your tire faster, answer about the same as if you are riding it! Message me I may want to order one from ya. (I'm a very busy person with not alot of time :( ).

lovelikerobots (author)BillBiker2011-07-17

Thanks BillBiker. We are gearing up to do a kickstarter campaign and will let you know once we have some in production.

wobbler (author)2011-07-17

Brilliant lateral thinking! (No pun intended)

lovelikerobots (author)wobbler2011-07-17

Haha thanks for the compliment wobbler!

spange (author)2011-06-20

Does this not wear out your tire more quickly?

husamwadi (author)2011-05-31

hey if you dont want those monkey lights.....heh heh heh :)

AngryRedhead (author)2011-05-22

I'm not a cyclist, but I love the photos in steps 4 and 5.  Very nice!

Lovely. Thanks for the compliment!

Lelamat (author)2011-05-23

Very good idea, possible add something like this to my bike. Thanks for sharing.
Good luck on the contest !

lovelikerobots (author)Lelamat2011-05-27

Apppreciate it. Much luck adding this to your bikes!

rainger (author)2011-05-24

This is great! Going to add this to my bikes ASAP!

lovelikerobots (author)rainger2011-05-27

Thanks so much rainger!

dwebb5 (author)2011-05-26

Great project. Thank you for putting in the weight of it.
Can you give a cost, what you paid, and what it might cost if you had to purchase all of the parts.?
This might make more electricity than you need if it is in stop and go city traffic.

lovelikerobots (author)dwebb52011-05-27

Hi dwebb5
The cost with the current parts is somewhere between $40 and $50. I don't doubt it could be done a bit cheaper. Good luck.

Fabio M (author)2011-05-27

Very good idea.

If you use an incandescent light bulb instead of LEDs the load on your generators will increase, helping to slow down your bicycle..

lovelikerobots (author)Fabio M2011-05-27

Thanks Fabio M. I will try. The resistance is pretty decent as is.

LorienD (author)2011-05-23

I'll be sure to shop elsewhere. Thanks for the annoying SPAM.

lovelikerobots (author)2011-05-22

Kiteman thanks for your feedback. The idea is to have a direct relationship between pressing the brake levers and external light output. The design could easily charge batteries and it's an iteration we are working on but we really like the direct "safety flare" relationship.

Rimar2000. Very happy to hear :)

rimar2000 (author)2011-05-22

Very interesting. I think that should be mandatory brake lights on bicycles. I also ride a bike, you gave me a good idea.

Kiteman (author)2011-05-22

Am I right in thinking the only loads on the generators are the LEDs? No resistors?

Oh! Why not use this to charge batteries to run the normal lights?

(Legal point - in the UK, rear cycle lights and reflectors must be red.)

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