I am building a prototype which is similar but I am using the front axle and steering mechanism off of an old riding mower, and it will only seat one person. I too am using the rear end of a motorcycle for the drive wheel and the brake. My first build is designed for lower speeds and on a budget, hence the lawn mower axle for steering. My first prototype will use a wooden frame to save money. I had a junk motorcycle and riding lawn mower to canibalize for the first experiment.
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