Why and when
Along about 1995 I decided to build a short wheelbase recumbent.
I sent away for plans for the Econobent, but decided that I could
do better just using some of the ideas but going my own way. For
one thing, the chain routing and gear system on the Econobent looked
overly complicated.
Left side of the recumbent with flag folded
Left side of the recumbent with flag erect
How it's constructed
The frame
The frame is constructed out of parts of the frames of three
side-of-the-road bicycles. The steering stem, forks, and the
tubes back to the seat post and rear idler location are from
a 20" BMX bike. The seat post and chain stays and tubes back
to the rear axle are from a 27" diamond frame. The crank and
boom supporting it are from another 27" diamond frame bike,
extended using some scrap square cross section tubing.
Detail of the crank
The steering stem has been extended by clamping a length of
hardware store thin wall aluminum tubing to a cut off steering
stem, with another stem inserted in the top.
The Seat
The seat was arguably the hardest part to get right. The bottom is part of a plastic chair, mounted to some electrical conduit clamps. The conduit clamps have some inner tube on them in an attempt to keep them from sliding about on the top frame rail. The idea was to make the seat position adjustable, though this hasn't worked out all that well.
The seat bottom padding is a piece of closed cell foam. The knee pads used by gardeners are an excellent source for this material.
The seat back is a piece of 1/2 inch plywood, with foam rubber
attached to it and wrapped in some scrap vinyl to hold it together.
The upper part of the seat back is supported by an old seat post,
stuck in a seat clamp cut off and turned 90 degrees so that the
seat back can be adjusted along the major axis of the bike.
Right side of the recumbent
After using the recumbent a little, I discovered that the seat
had a tendency to twist around the frame tube, so I added the
struts from the seat sides down to the rear idler (old crank
location). These tubes are made of scrap aluminum flat stock,
thin wall aluminum tubing, and some hard copper plumbing line
that nests inside the aluminum tubing. Thus the struts are
adjustable for length.
The Chain Idlers
The rear idler is cobbled up from an old derailleur idler
and some scrap metal.
The front idler is actually off of another store-bought
recumbent, a present from a co-worker at Bell Labs (Thanks, Romano).
Detail of front idler
Detail of rear idler
How well does it work?
After I built it, I completed several metric centuries on it. After the first one, I upgraded the cranks and chainwheels from the old two-ring unit from the old salvaged bicycle to a new three ring one. This gave me the low granny I need to climb (mild) hills. Fortunately it's very flat here in Central New Jersey, so hills are not usually a problem.
The seat is comfortable, but would be better if it had some
ventilation. On a long ride, my back gets very sweaty where
the vinyl seat back covers it.
Front-left side of the recumbent
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