My first bike was electric, it was cheap and utilized a rear hub motor, they were ok but melted... due to the cave man builders not knowing heat will destroy the internal wiring.. Now in the year 2009 a newer motor is available that has the "guts" to pull 350 pounds up a steep hill and not overheat even in hot weather!!!!!!!! it is self contained, and only needs small batterys hooked together to form 48 volts, to run for a long time. I bought one and used it on my very heavy bike and it has already prooven itself for long rides. I love this motor and it is very cheap! you get a black box, throttle, and hub motor, a rack for the batteries, and a full support from a "California" seller.. that it will satisfy you the first day!!!!. get one, and mount it in place of your front wheel. they send it in any size you ask 24' 26" 20" 0r 700, any size.
the cost isless than 300 bucks without batteries......... you simply hook together 4 12 volt batteries and create 48 volts of power.. it will propel your bike at 35 mph on flat, and 7mph on steep hills. it will take you ten or more miles on it's own power. and could easily be a "add on" for a pre- built motor bike, since it has just a "thumb throttle" to add to the handlebars. it is silent, and it is super designed to "run" no matter what!!!!!!!!!!!!!
check out "www.campsolution.com" a web site that has them listed on the second page under an old picture that looks cheap, and scares everyone away, but I bought that $239.00 model, and it is a "new 2009 motor" designed to run without fai look into the"48 volt" model, it is the state of the art type and is shipped disguised as a painted hub motor..You get a beautiful three phase three wire motor that "Wilderness Energy" sells for 500 plus....

it is the perfect motor I recomend it