project I should do

deacon · #1 07-19-2009, 12:54 PM

But probably won't.... Take one of those 350 watt 24volt bicycle motors from tnc...

hook it to a 36v 500 watt controller... also from tnc

remove the crank from a multi speed bike. Replace it with the motor. Run the chain through the rear rear gears.. Yes all of 6 of them.

I wonder if I could get it to start that way. Probably not on a hill and the range would be terrible without any pedal assist.

Stubby79 · #2 07-19-2009, 02:40 PM

Throw a "freewheel" jack shaft into the mix(just use an old single speed rear wheel hub) and you can keep the crank/pedal assist(as I just happened to state in my last post in my ideas thread). Crank drives the sprocket on the freewheel, immediately behind the crank. A sprocket welded/bolted on to the hub where the spokes were for the output to the rear wheel and its derailleur. Weld/bolt a sprocket on the other side of the hub where the spokes were, run a chain from it to your motor.

Now you can still pedal, the motor can "pedal" for you without pushing your legs too, you can shift gears, and you have a jack shaft to change the gear ratio from the motor output, if you need to change it. Only worry is see is clearance between your jack shaft and your crank arms.

Or somehow turn your crank into the jack shaft while freewheeling at the same time. (I have some ideas on that too). Just don't get your pants caught in it while the sprocket is spinning!

deacon · #3 07-20-2009, 12:46 PM

Someone said a tandem bike has a freewheel in the rear crank. Maybe in the front as well I have never ridden a tandem. If that is the case it's all you really need.

Stubby79 · #4 07-20-2009, 06:25 PM

Look on the crank arm in that photo...they have a free-wheel mounted on it, and sprockets up above to bolt on to it. I think I could mount the same freewheel to a regular set of cranks (save buying theirs for $30) or even mount a single-speed bmx style freewheel the same way, mounting a larger sprocket to it. Having the threaded part the bmx hub would make it easier, if I had one...and if I decide I need to go this route for my own projects.

deacon · #5 07-20-2009, 07:01 PM

an electric scooter has a threaded freewheel. actually a couple it looks like TNC Scooters (Scooter Sales and Service)... I have no idea how big a crank set is but I have one or two laying about. not sure how to mount it though.

Stubby79 · #6 07-20-2009, 11:51 PM

Yep, they're about the same price...probably the same freewheel!