I've got a Sun EZ1 with a front hub motor. Due to the small size of the wheel you need a "fast wind" motor that can assist up to say 25mph. I'm using the "no-longer-available-in-North-America" Crystalyte 404 hub motor, which is very quiet, fast and well-matched in power. If you can find one of these motors used, or a Crystalyte 405 motor (typically in a 20" wheel), either could be used, the 405 would need to be respoked into the 16" wheel. Another possibility is a fast wind Nine-Continent motor - typically designated a 2805, but the spokes would be incredibly short from the rim of the motor to the 16" rim, might not work - those motors (and the Goldens and Conhis direct drives) are much bigger than the Crystalyte 400x series. You could also get a 20" geared hub motor from emissions-free.com - they are a reliable supplier, and have a variety of fast wind motors as well. The 16" wheel is a challenge - if you don't want a slow moving torque monster - but a fast-moving wheel. You could also run a small non-fast-wind motor at a higher voltage, to get the rpm up. Another possibility is a direct drive Aotema motor - about the same size as the Crystalytes, used at a higher voltage to get the rpm on. You will have to do some research on small, fast wind motors. The geared motors have nice torque but the mini-geared types are not that fast wind, and running them at higher voltages to get the no-load speed up could burn them out (or burn out an overvolted controller), without tuning down the controller shunt to reduce the amperage accordingly.
I'm using Cute 100 mini-motors on my 20" wheels, but I'm having issues finding controllers that are matched to those at 48V.
I often run two 48V 15Ahr Ping packs in parallel, carried low under the seat on a mid-rack (easily available). That's well balanced, and a good spot for them on the EZ-1 - about 30 pounds of battery. That will put you many many miles down the road - I peddle moderately at all times, and I'm good for 85-90 miles with that much battery, in low-moderately hilly conditions.
Last edited by chvid; 09-10-13 at 12:40 PM.