I was going to buy a recumbent but then I came across the flevobike design and some aspects of it really stuck out to me, including the variable geometry with the rear fork pivot, and the center pivot steering allowing for a front wheel drive without twisting the chain. I want to build a composite one eventually, but im starting by hacking up a frame from trash steel bikes to test and fiddle with geometry and get a feel for the steering before I invest too heavily.

I came up with a frame geometry based around a standard headset, of the style where your legs and the frame go around the front wheel rather than over the top. I haven't locked in the geometry for holding the bottom bracket, I have my leg measurements and crank measurements etc and I need to figure out what gives the most amount of seat and bottom bracket adjustment before hitting the wheel on either side. What I'm mainly focused on here is achieving the steering and aero characteristics I want. In the picture, the top row is the geometry I drew from first principles, with the aim of having the rear fork adjustment allow for transition from an upright, low trail geometry to a lowrider, high trail geometry.

Beneath that row is an equivalent copy of the geometry of a racing flevobike I found plans for on the internet, which in reality has the front frame go over the front wheel with a dog leg. I will post some more pics to show this difference.

For now, I have begun construction of something close to my geometry in the top row of the image. I do not know what happens with such a shallow steering pivot. I have only read that mechanical trail (the perpendicular riser from the wheel contact to the steering axis) is important, so I have tried to have that range between common racing bike and touring bike values. Perhaps having such a shallow pivot will not work well - the racing flevobike geometry has a sharper pivot than my drawing. I was wondering if anybody had any more insight into the steering.