I am working on a design for an upright tadpole cargo trike, along the lines of the Haley and Christianias...

http://www.haleytrikes.com/trikes.html

http://www.christianiabikes.com/english/uk_main.htm

I intend to use 20" wheels and was wondering about hub options for the front(s) and/or the rear that would provide the torque for heavy loads. Top speed is about 15mph so I don't need to go fast.

TIA

John