The one and only 2WD Prone bicycle

current design

previous design

previous previous design

Now that my friend Hanan has dug up some carbon fiber and kevlar from the aircraft industry I am obliged to take the next step. The previous designs, as Elder Brother Nathan has pointed out, will not work due to the 'steering problem'.

What's needed is some way to steer and pedal with the hands, not necessarily simultaneously. The handbike for people who prefer biking with hands solves this problem by using an 'eigen-crank' which has both cranks at the same angle instead of opposed. This isn't so good ergonomically for the usb since a swimming motion is the most elegant and beautiful solution to the particular locomotor challenge of fastest human-powered vehicle.

Current candidate solutions:

'Slide-steer' where the front crank is moved along its axis of rotation to one side or the other (first picture on page). Its movement is restricted to this translation plus the regular crank rotation, eliminating effects of 'unwanted torque'. Hand crank slides left-right which steers by turning front fork. Chain remains in same plane always, and front gears are attached to front wheel by flexible 'roto-rooter' type connection (i.e. cable that is flexible to bends but rigid to torques). Bigger pic here

Hand eigen-crank and leg eigen-crank 180 or perhaps 90 degrees out-of-phase. There is a fancy english horse gait like this I beleive. The gallop is close but I think there is an 'anti-trot' with full synchrony of front legs and full synchrony of back. In any case the swimmer's buttterfly stroke, it should be remembered, is faster than the crawl.

Locking the steering axis with a ratchet-pawl, releasing it with a switch on the pedal. This allows steering when you want it, with a series of locked positions for steady turns.

Eigen-crank rotating twice for every foot-crank rotation (or vice versa)

'Tilt-steer' (i.e. no explicit steering mechanism)

Check out .dxf file if you have a 3d modeler, this apparently is a somewhat standard format. A library of decently modeled bike parts has yet to be found; if anyone has some, send them along mach schnell.

Ultra-Super-Bike original rendering

The four documents below comprised my entry for the 2002 international bike design competition.


Orthogonal diagrams

Rendering with fairing


Some interesting links

Prone Page full of various prones including my friend Hezi's creations

Practical Page for builders

The 'ultra-bike' - I found this page after I had already been calling my bike the usb - a weird confluence of name and concept.