New project – electric bike

This past Saturday morning I was surfing Youtube before I was ready to get up and came across a nice electric bike add-on. I thought about it and I have all of the components needed. I have a treadmill that isn’t being used (and won’t be any time soon due to my wife’s foot issues which are what are prompting the desire to make this), a couple kids bikes they have outgrown (not to mention the two adult bikes), an Arduino and a variety of components including a high amperage MOSFET knowing at some point I’d want to control a high draw device. I started disassembly on Saturday and some machining of a pulley and rod, though after I did the math and saw full power would be 40 miles per hour and figured I’d need to re-do this work and use a larger step-down pulley. Part of that math was finding out the RPM of the motor using a strobe disk from here¬†and then calculating the RPM using the gear ratios.

The metal working is a bit time consuming since I don’t really have the lathe set up for using, plus everything in the garage is jam packed towards that end so there is barely room to move from one spot to another and half the things I need are still in random boxes. Last night I got to a good point though and have a larger aluminum pulley mounted on a smaller steel shaft. Next step is to thread the shaft to take the bearing retainers so I can mount this shaft where the pedals go. Then I’ll need to make a motor mount and figure something out for power (for now I’m thinking I’ll use a drill battery, but that won’t be long term). I’ll use an arduino to do pulse width modulation so things won’t go too fast, though for testing at first it’ll probably just be a button and make sure to not put all the weight on the drive wheel! My son had a good idea to use the bars from the rear wheel and put them on the front to use for resting feet on.

If this thing works out I may decide to mount it on a larger bike, we’ll see. I have another night or two to get the pulley and shaft fitted, though I think the motor mount may be a bit more difficult and time consuming. I am hoping that we’ll be able to use this for my wife to putter around the woods at the very least. It may or may not be practical to use it for going on bike trips, but maybe it’d be good enough for that.

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