# My Ebike Plan



## firewater49 (Sep 29, 2008)

The Following Was an Email snet to TNCSCOOTERS.COM



> Dear TncScooters.com,
> I am looking into converting a standard pedal bike into an Electric one using scooter parts. I have never owned a scooter before so I am wondering if the following are all the parts I need.
> 
> 
> ...


As you can see that outlines my basic plan. They have great prices on everything but motors so here is the one I want to use.

MOTOR

Also The batteries; they sell some 12V 20AH batteries for 25$ each!
I know this is insanely low, but they are out of stock.

Link (Scroll down till you find them)

Since I am a highscool student I am aiming for about 150-200$ for this project. How did you guys attach the motor to your rear wheel? Do you see any other parts that I'll need? Lastly but not least, some calculations:

2600RPM*/60 =43.33 Rotations Per Second
43.33 * 1/5(Gear Reduction) * 26 in. (size of wheel) * pi = 707.54 Inches Per Second
707.54 / 12 (To give me Feet per second, not inches) * 0.61 (Approximate MPH Conversion) = 36 MPH

36 MPH * 85%(Inefficiencies) = 30.57 MPH

I'm aware that this will give low torque with poor acceleration, but there are no hills and I'm willing to pedal the first bit. Also for the charger/receptacle I had no Idea so I guessed.

Any comments on how to hook up to bike? What wires do I need to buy or anything else?

Thanks,

Sam


----------



## TX_Dj (Jul 25, 2008)

If you have a 26" diameter tire (true diameter, not the size of the wheel rim), a 5:1 reduction, and 2600 rpm, my calculations say your road speed will be 40 mph, not 36. Small error. 

2600 RPM / 5 (gear) = 520 wheel rpms
26" diameter = 81.68" circumference
520 * 81.68 / 12 = 3539.46 feet per minute.
There are 88 feet per minute per mile per hour.
3539.46 / 88 = 40.22 MPH


----------



## JohninCR (May 6, 2008)

Sam,

The main thing you're missing is how to get the power from the motor to turning a wheel. The motor needs #25 chain, so you need chain, a large sprocket, and a freewheel to attach the sprocket to the wheel and allow you to coast without spinning the motor. 

The easiest is to go to the front wheel, which means mounting the motor somewhere on the front forks. In the motor mount you'll need adjustability to ensure a tight chain, otherwise you'll need some type of spring loaded mechanism on the chain that goes on the return side, not the pulling side. You'll need a rear wheel to put on the front, so you have a threaded hub that the freewheel screws on for attaching the sprocket. Be sure to consider spacing in your fork to accomodate the sprocket on the hub and routing for your chain.

Rear wheel mount is possible, but more involved. The easiest is left side for the motor, but you'll need to fabricate a wheel hub with thread on both sides. Can be purchased, but expensive. I made one by cutting 2 hubs in half and welding the halves with threads together to give me double threaded. The left side would unscrew from motor torque, so I put epoxy on the threads when I screwed it on. Right side is called a bottom bracket mount. You'll also need some kind of freewheel for your crank sprocket too, and engineer a shaft and sprockets that has both a #25 chain sprocket connecting to the motor and a bicycle chain sprocket inserted into the drive chain.

When ordering your throttle and controller, make sure the type is matched. ie Pot throttle or hall type throttle. Also, for that motor make sure the controller is for brushed motors, and that it can handle the voltage and amperage you run. For a 350W motor, I'd plan on peak power at least double, so at 24V I'd get a 30 amp controller. 

With that little motor don't try to gear for more than 20-25mph, say 25 at the listed rpm, which is probably no load rpm. Then you can pedal for a bit more top speed.

If fabrication isn't easy, you might consider one of the geared motors at TNC, since they already gear the motor speed down for you and the output sprocket uses bicycle chain, so it will end up about the same total cost and less work unless you go with a front wheel solution.

Good luck with it!

John


----------



## firewater49 (Sep 29, 2008)

Thank you for all of your help guys. I think I will purchase a geared motor to make it simpler, then I will attach that to the front wheel, using a 7 Speed Sprocket (To give me some gearing). The motor already has a 1/7 gear reduction. So with the 9 tooth sprocket, and a similar gear on the other side I should reach a speed of about 27 MPH. Then With a large sprocket on the 7-Speed I may have only 8 MPH, maybe enough torque to peel out! I appreciate all the help you guys have given me. The last thing to do now is to email them again with new parts making sure that they are compatible!.... Thanks!


----------

