Thank you for the replies.
I created a rough draft if the design in my 3D program.

Images to show the placement of things.

The possibility of using thumb friction shifters or other friction shifters manually might work.

And, thanks for the sync info. I totally didn't think of rotation speed on each rear tire.

And, those parts now on my to order list once I can.

The center frame is from a weight bench I have, and is 16 guage steel 2x2 diameter. Should serve well as the frame.

Width will be about 30 inches wide. Just a few inches wider than my manual wheelchair.


I may add outer side rails for strength I'd needed.
They would be garage door steel rails.

The forked out front, I think this will turn still based on the shape if the tires being U shaped when tilted should track along the smaller inner diameter of the front wheels.

Open to design changes also if mine aren't the best.

And, thanks again for the help.