lithail said:
This is what I am thinking.
trike design.jpg
I once built a trailer very much like the back end of that; it worked ok, but I found a better way to use large diameter (26" in this case) wheels, that lets you have a lower deck for better CoG, more space back there, etc. Also, since the wheels are *above* the tubing, you can take a wheel off to work on it without tipping the trike on it's side or jacking it up (helpful if it's loaded up on the roadside).
My Raine Trike design started with a simillar rear end of dual bike frames, but changed to the present design that's proven to work on a big trailer (that can haul a piano):
https://endless-sphere.com/forums/viewtopic.php?f=2&t=80951
Basic frame:
Mostly finished, seat not bolted on yet
works, although I'm working on a way to run the pedal chain up to the front wheel without a twisting chain (like the CycleTruck used by UPS), which would eliminate the long somewhat complicated chainline to the rear wheel that it presently has. Then ti will be 3WD, pedals on the front and geared hubmotors on the rear.
You don't have to use the cambered rear wheels, they can be vertical isntead, but the camber gives it a wider track for better stability in turns.
BTW, a larger front wheel will give you a much better ride quality.
The SB Cruiser trike is a better front end thru rider section design, and some day I'l change out the rear end deck frame for the style of the Raine Trike, with larger wheels, but this is a major change to the whole backend, so it won't happen soon (and probably not until I can make a middrive to drive the rear wheels, and pedals run the front wheel, rather than pedals to the left rear wheel only and heavy hubmotors in the rear wheels).