Sukispop wrote: "As far as a lack of a seatback is concerned, yes, of course the bike would be more comfortable with one...but I don't think that a seat back would work with this bike's geometry. And, in fact, I don't miss the seatback at all on this bike. It's set up so that you're sitting comfortably erect. There's no body weight on your wrists or hands...there's a lip at the rear of the tractor sized seat so that your butt won't slide off the back. When you're cruising, you can extend your arms, and lean back for some real cruisin' comfort!"
The Beleize, Y3K, & Revive have seatbacks showing the feasibilty of seatbacks on semi-recumbents. Evox has a very small seatback as well. Vision R70 (RIP), Giant Bachetta, and Stingray omitted seatbacks, suggesting the intemdiate upright-bent position seems to present it as an accessory rather than a necessity.