Hi Henry,
I have been motorizing bicycles for a living for 3 years now, over 70 of them of just about every type there is and having the time of my life 'working' from my home shop hehehe ;-}
I don't really build bikes in advance to have for sale, I work with customers to select the bike they like first, then work out how they want it motorized which is really fun.
Although about half of my builds are just your run of the meal boring 48 or 66cc 2-stroke direct drive kit bicycles, it's the other half that are the most rewarding and I can sum them up with two words, Custom Geared.
With the handy 'shift kit' from an outfit called Sick Bike Parts I jackshaft gas motor power over to the pedal side which I replace with a special 2 sprocket free-wheel pedal and bottom bracket assembly.
In short the bikes pedal system is shared with the the motor power but when under motor power the pedals just ratchet in place.
This limited production Cadillac Fleetwood bicycle came with a NuVinci NV 370S CVT hub that was just begging for some motor power help.
The top was too pretty to put a tank on so I went with a custom 'beer keg' style.
The front fork was replaced with a Springer with a C-brake that attaches to a self adjusting 'teeter-totter' dual pull brake lever with the back disc.
Legal 48cc Skyhawk motor with an expansion chamber exhaust, CNS carb and upgraded ignition wiring with an Iridium plug that bumped it to about 3HP.
With the NuVinci's infinitely variable hub you could putt around at 2 MPH or wind it up to over 35 MPH.
This Felt was a fun one, 66cc with X-chamber and a 3-speed hub.
I do 4-stroke shifters as well like my Big Red personal ride, Macargi Pantera 7-S with the rear wheel replaced with an internal 3-speed and a 49cc 4-stroke jackshafted engine added.
I like 4-strokers, centrifugal clutch, pull start, and no gas/oil mix.
My newest thing is Electric Shifting Adult Tricycles.
I won't go into the specs on that just now, I made a special web page for that but that's what I do with with bicycles ;-}
