Parallel side stick steering controls

With the steering axis almost between the rider's feet, some kind of remote steering linkage was required to bring the controls closer to the rider's hands. My solution was to connect the fork by means of link rods to a pair of parallel side sticks. These pivot independently of each other in a vertical fore-aft plane, with the fulcrum located horizontally directly beneath the seat. The 'U' shaped assembly, minus the link rods, is shown lying flat in the photograph below. Spherical joints ("Heim" or "Rose" joints) at the ends of the link rods connect to the brackets visible in the photograph.

Click on the diagram for a larger view.

Each stick is grasped by the vertical segment which also hold the brake levers, and has a short horizontal shaft mounted on ball bearings, as shown in the drawing below.

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Ball bearings, as opposed to plain bushes, were found to be necessary. The steering must respond to a lateral forces exactly as a normal upright bicycle. This is called tilt-yaw coupling, in which steering torque in the direction of tilt results when an external force causes the bike to lean over. Good handling, also called "no-hands stability", depends on this effect. It also makes a bicycle responsive to the rider's "body English". Stiffness at any point in the steering mechanism cancels this effect and makes a bicycle difficult to ride. The bike as shown in the illustrations here is very responsive and handles easily.

Updated: 15 June 2000