It would be easier just to describe how I built it.
Body is a 2x2 frame with a bit of 3/8 plywood for the deck. You can make it any size. The lawnmower wheels have 1/2 inch holes. I bought some 1/2" bots with the unthreaded part to use as the axle.
put on a large washer then the wheel, then another large washer, the ran it through a 1/2" hole I bored into the 2x2 frame another washer then two 1/2 inch nuts to lack the bolt (axle) but not tightened down completely... Then I put a electical 1/2 pipe clamp over the nuts to keep them and the axle from turning. The wheel runs free on the bolt (axle) I did put a lot of grease on when I assembled it.
I found that the bike tires were too unstable since it was a lot of weight too high up. The smaller wheels are much much more stable. I don't even notice they are with me. Get yourself a good thick L bracket and saw off some of the part you hook to the bike so it won't be so long. I also have to enlarge the hole to fit over the axle.
Have you gotten to ride the hub bike yet.
I just put a controller and throttle on my diy electric and It rained last night so I haven't had a chance to test it yet. I did run it around before it started to rain and the throttle works fine. I was hoping to squeeze a little more range from it but I don't know. One thing is the darn hill around my house. On the flats it sings, I can just feel the power drain as I run it up the hills though.
I like the idea of the battery drain meter with your kit.
The tongue is a large shelf L bracket bolted to a 1/2" or so bit of tubine. Used a triangle brace on the L bracket.
