Thinking about the twitchy steering on recumbents mentioned by neptropix
NB that at speed the steering angles through which you want to turn the front wheel are small.
It's only at low (feet down type) speeds that you want very large steering angles on the front wheel.
Look at my sketchy diagram depicting a recumbent from (almost) above:

NB: No change in belt or chain etc length at any angle, even if one of the pulleys/sprockets is circular...
= no chain/belt/etc going slack issues.
NB that as you don't need those ellipses to rotate more than 180 degrees; you don't need teeth on the ellipses:
You could use anchored wires of the type used in brake cables, or similar.
You also get your handlebars closer to where you can reach them without extending them backwards and ending up with that clumsy 'handlebars move off to the right when turning left' issue.
That solves a lot of issues for recumbents, space constricted velos, trikes etc.
(The world would be a better place if people didn't 'own' other people's ideas: What are the chances of further idea sharing when that shit happens?)
NB that at speed the steering angles through which you want to turn the front wheel are small.
It's only at low (feet down type) speeds that you want very large steering angles on the front wheel.
Look at my sketchy diagram depicting a recumbent from (almost) above:
- For near staight travel, as used at high speed: For a large handlebar angle change; you get a small front wheel angle change. (= no twitchyness)
- But at the low (feet down type) speeds at which you want large steering/wheel angles to maneuver or turn a sharp corner; the elliptical steering drive changes that to the opposite and you get a large wheel angle for a small steering angle.

NB: No change in belt or chain etc length at any angle, even if one of the pulleys/sprockets is circular...
= no chain/belt/etc going slack issues.
NB that as you don't need those ellipses to rotate more than 180 degrees; you don't need teeth on the ellipses:
You could use anchored wires of the type used in brake cables, or similar.
You also get your handlebars closer to where you can reach them without extending them backwards and ending up with that clumsy 'handlebars move off to the right when turning left' issue.
That solves a lot of issues for recumbents, space constricted velos, trikes etc.
(The world would be a better place if people didn't 'own' other people's ideas: What are the chances of further idea sharing when that shit happens?)