 The Bike Itself
Underneath all the whiz-bang
gizmology is a bicycle. It's not a normal bicycle, to be sure, but it
has all the same requirements as any other bike with the added
challenge of handling a gross vehicle weight of about a quarter-ton.
This complicates everything.
The recumbent itself is based on a
custom frame built by Jack Trumbull (Franklin Frames) of Columbus,
Ohio. It is not a commercial product, but should be.
One of the most obvious problems is
gearing -- with this kind of load, the standard 18-speed setup is
useless. BEHEMOTH has 105 speeds, ranging from about 7.9 to 122
gear-inches. This was accomplished by retrofitting a third derailleur
to the tandem-like crossover drive assembly on the left side of the
bike.
A 7.9-inch gear with a comfortable
pedal cadence of 60 RPM yields about 1.2 mph. While this is necessary
for getting a heavy bikeasaurus up steep hills, it does introduce the
problem of balance. To address this, we added a set of pneumatically
deployed "landing gear" that can be used under low-speed conditions --
or as a parking brake or service stand while stopped.
The rest of the gearing range yields
more traditional speeds, and I find that a comfortable cadence on level
ground yields 10-12 mph depending on my attitude and what I had for
breakfast.
Stopping power is every bit as
critical as
gearing, and the system is designed to carry four separate braking
systems...
First, a pair of Magura hydraulic
brakes controlled by hand levers to take care of "normal" braking
requirements.
Second, a hydraulic disc brake on
the rear wheel allows speed regulation on downhills without rim heating
effects,
Third, a mechanical parking brake is
immensely useful when stopped -- and also as an emergency
backup.Fourth, and unfortunately never completed but quite desirable,
another pair of hydraulics on the trailer wheels to be automatically
actuated by hitch compression.Steering has always been accomplished by
a single lateral bar under the seat, linked by a coupling rod and a
pair of rod-ends to the front fork crown. With the change from the
Winnebiko II to BEHEMOTH, we modified the bars to allow the hands to
rest in a more natural ergonomic position for typing.
These handlebars (and the nearby
seat frame) carry much more than the normal bicycle controls, of
course. There are three shift levers, the parking brake lever,
hydraulic brake levers, and 7 keyboard buttons on each side. The right
thumb has a button for the twin air horns; the left has push-to-talk.
Safety is a primary concern, as
evidenced by the mega-air-horns and their dedicated pressure tank.
Lighting is critical as well -- there are two separate beams, spot and
flood, mounted on the helmet (Night- Sun). These put light where I'm
looking, not just where the bike happens to be pointing. There is also
a 4" sealed-beam quartz-halogen headlight, a 7" yellow flasher behind
the seat, a red taillight on the RUMP, a strobe on the antenna mast,
and high-brightness LED taillights & turn signals on the trailer.
Various reflectors help insure that the bike is easily visible from all
angles, and there are a couple of bright flags just to be sure.
All bearings are sealed, of course,
and the rear wheel is a 48- spoke undished unit built around a sealed
hub. This intrinsically strong wheel design has never failed me in
17,000 miles -- I've never broken a spoke, and only rarely needed minor
tweaks to the truing. Some other components have not fared as well in
the past, specifically the headset bearing, which on the Winnebiko II
typically lasted about 500 miles. On the new system, I not only
switched to the much more robust Chris King headset, but also
shock-mounted the entire console to filter out the worst of the
high-frequency vertical acceleration.
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