D: terrific primer.
D: to get yer ergonomics, just use cardboard to replicate your hip/knee/ankle joints. Pin it all together. Make sure your bike suits your ergonomics.
Seat back (ergo hip tilt) will also affect performance.
A look at nice finished bikes.
D: I wish to create a variant Greenmachine.
My bud Fern in London is an accomplished welder.
I plan to use the Python's choice of material - 16gg square tubing. Stainless for me.
The cuts for square tubing are simpler, with only a slight weight penalty.
By the time paint coats and gloss finish are considered, the weight savings of a carbon steel frame are partly gone. Plus I can just satin the stainless - no paint chips.
D: it won't be monotube though.
I want to parallel pipes. I plan to run the whole rear-wheel-drive chain through them.
With gear hubs, this will mean the chain is totally sealed away from the outside world.
I don't imagine that is really true- I'd need hermetic seals v.s. moisture.
Still, it should keep rain off, and dirt out.
I'm intrigued by placing all valuable hub drives in the bike frame.
The wheels, if stolen, are cheap and easy to replace.
Alternatively, they can house fancy stuff like a hub motor or a SON dynamo hub.
What would be very nice for a rear-drive is if those kevlar belt products were made in a more useful length.