Bike Dynamo




'A simple bike dynamo using a motor as a generator.

WARNING becareful not to get any of the parts from this project caught up in your bike. This dynamo can put out more than 12 volts becareful with your parts or they could get blown.

1 motor 4v (higher voltage is better)
strong plastic lid
hose clamp looks like a metal circle which can be loosend and tightend. choose one to the size of your motor and the size of the bar on your bike.
something electronic like a bulb or buzzer you can test your dynamo on.

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Step 1: Attatching the Hose Clamp.

Attatch the hose clamp around the bar of your bike put your motor in so it is touching either the tyre or rim. Make sure it stays firmly. If not try wedging something imbetween the motor and bar. See below for more details.

Step 2: Testing and Troubleshoot

Test your dynamo conect the motor wires something you want to power. Then start riding. See below for more details.

This is my first instructable. Sorry about not having real pictures but that is what it looks like except for the crappy bike drawing.

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    47 Discussions


    4 years ago on Introduction

    U can alter the gearing by the size of the lid U use.The smaller the lid, the faster the shaft will spin.


    Reply 5 years ago on Introduction

    The computer fan is hard to get spinning from pure wind,

    but then...
    I do go pretty fast on my bike....
    maybe... Just maybe.....


    8 years ago on Step 2

    Download SketchUp at for a quick way to draw your bike- and your dynamo! Good luck and Thank you!

    Definition of generator:
    Engine that converts mechanical energy into electrical energy by electromagnetic induction. So you see, if you turn the motor it becomes a generator.

    Also in many cases you have to initially spin the electric motor a little faster than what it turns when you give it power to sort of "kick start" the generation of electricity. But not always.


    12 years ago

    Very good. I can see how it might be a problem to fine-tune one of these, though. I was going to make one of these, but I couldn't figure out how to attach it. Did you get your idea from Tetranitrate's Lego motor generators too?

    3 replies
    Fat Bagelpyrokid

    Reply 12 years ago

    Hi Thanks for replying. The hose clamps work quite well but yes they don't keep the motor attatched firmly, i think you can use radiator clips or something like that you'll probably be able to work out a good method. Tetranite's Lego generators gave me some help but only with the comments other people added really, like adding some rechargable batteries so the light won't run out when you stop.

    pyrokidFat Bagel

    Reply 12 years ago

    Yeah, I basically meant the comments too. you have a very good idea clamping it there with something, i was trying to figure out how to attach it but i had no idea how to. this gave me some very good ideas. Again, great instructable.


    11 years ago on Introduction

    is there a way of telling how much power you get out of it? like with a 3v motor will you only get a max of 3v?

    2 replies

    Reply 10 years ago on Introduction

    the higher rating a generator has, the more voltage you'll get out of it, but you'll probably never get 3v out of a 3v generator, unless you can rotate the axle as fast as 3v of power can turn the axle. i hooked up a 3v generator from a hand-held fan to my bike, and could only get about 1v power even at top speed. if you want the axle to turn faster, you'll need a series of gears.