About a 20inch wheel ought to do it?
I'll be going out to round up the parts in a
little bit ...the other little steppers that
Ghurd gave me are also likely candidates.
Ever think of making a low friction chain
gear drive (notice I said
chain gear drive? and not chain drive?)
This is where the only sprocket is the driven
one....

Tricky part getting the circumference for the
chain just right....hence the carboard template.
Here is where you can have the sprocket pretty
loose....less friction.
Well for now I'll just use the bicycle wheel....rubber band tensioner to hold the motor drum against the bike tire?
Are you using plastic cans?
Out of time for tonight a little more tomorrow.....
( ;>) Norm.