Instructables

Electric Bike (Assisted - not full electric) Step one

Step 6: Other 3

Picture of Other 3
Last build.
I mounted the batteries in the frame. There is a voltmeter on the handelbars. The steel frame is held by steel bars (black) now. And a rear derailer spring-slack absorber was added.
 
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First what type and model batteries did you use second how did you put the gear on the motor you found?

I have a motor with a 3/8 inch X 1.25 inch shaft and a 10mm inner shaft?
What does inner shaft mean also could normal bike freewheel be put on it how would that work

Thanks
mark101 (author)  randomness72.53 years ago
Re:Battery?
I used six 12 volt lead-acid batteries. They were relatively cheap.
I had a two stage switch. The first switch stage was 36 volts (or three batteries in series), when the bike got moving to a decent speed I then went to the full power of all six batteries. 72 volts total. Had to stop when the batteries got too low, if you drain the batteries too low, they might not recharge or be damaged. Then you flushed your money down the toilet.

This is only a for fun project, reliability is very low. I can not depend on it for regular travel.

RE how did you put the gear on the motor shaft?
It was very difficult.
There is a freewheel removing tool.
http://www.parktool.com/uploads/images/blog/repair_help/fr-1w-freewheel.jpg

I mounted it to the axle of the motor, and used a bolt and large washer to hold the freewheel on. The bolt fit inside the shaft on the motor.

To glue I used this epoxy designed for metal.

If the fit is the tiniest bit off, the freewheel will wobble, and you cant have any wobble if you want the chain to stay on.

Motors can be very different.
You can have a high amperage 24 volt motor, or like I had a high voltage motor with lower current. Both add up to high wattage.
24 volts times 15 amps = 360
72 volts times 5 amps =360
You need a minimum of 300 watts to push the average person.