Hi I have done about 4000 miles in the last 18 months, mainly hilly touring and hilly day rides on my 2 e bikes. One has a Dapu 250w motor and the other an Oxydrive 350w motor. Range is fine on both bikes if I keep the power assist low but i usually end up climbing hills at 6/7 mph.The motors whine and feel laboured and I know they are not very efficient at this speed. I can crank up the level and ride at 10/11 mph but this shortens the range to much for the 110+ kilo load. So I am thinking of building a Xiongda 2 speed set up with a 18Ah battery that will give me the range and low speed grunt,but before I do thought I would ask advice here. Any motors out there that achieve max efficiency at low speeds or is there a better 2 speed alternative to the Xiongda ?