buckyllama wrote:
I'm not sure what you mean by variable seat recline. I'm planning on
making the seat adjustable within a reasonable range (approx 30 +/-5
deg abovr horiz for the hip-shoulder section of the seat, upcurved top
to limit neck/upper shoulder strain) using a similar system to a
t-bone. My current drawing puts the BB center at about the same level
as my hip joint when seated (a few inches above the seat base)....

By variable seat recline I mean a seat where the angle of the seat back
can be changed while riding. This is complicated by needing to have the
seat base move forward to keep the rider's leg extension constant while
pedaling. The Forte lowracer I posted a link too is one example of such
a bike. [1] The variable seat recline allows for an upright seat back
for more sprinting and climbing power, and a reclined seat back angle
for minimizing frontal area on flat and downhill sections.

Further testing is needed, but variable seat recline could potentially
improve overall climbing ability of recumbent bicycles by allowing
changes in position. [2]

[1] The only other I am aware of is the one ridden (and built?) by John
"Rocketman" Williams which reportedly has a seat recline angle
adjustment from 10 to 40 degrees from the horizontal. [3]
[2] Studies have shown the fastest way to climb longer grades on an
upright bicycle is to alternate between sitting and standing.
[3] By convention, recumbent seat back angles are measured from the
horizontal.
--
Tom Sherman - Fox River Valley
"Abnormal would be a mountain lion speaking English." - M.V.