When i was doing research on adding a motor to our Calfee i contacted Calfee and had a very detailed phone and email conversation with Rob Baird who at that time was the tech at Calfee. He recommended the mid drive motor rather than a front wheel or rear hub motor. The mid drive produces more torque and does not tax the wheels like hub motors. He told me what to buy and provided complete technical assistance with the installation.
We are close to the 2 year mark with our conversion and are still EXTREMELY happy with the results. Wind, hills, faster riders, starting from a standstill, starting on an incline all taken in stride.