Kickbike - Relative Geometry

Continuing the previous thread:

The objective is to figure out how to adjust the relative Kickbike geometry so that we optimize the riders (kicker's) experience. Of course, the specific solutions will vary depending on what the kicker is trying to accomplish. Optimum geometry for a casual, weekend kicker might be horrible for a kick racing competitor, and vice versa. And the solutions will vary depending on the size, flexibility, and physical condition of the kicker.

That being said, is there anything helpful we can learn by comparing the Kickbike to a road bike?

No seat: The standard road bike frame fitting approach assumes that the rider will be seated, or at least that the solution to the general problem is to assume the rider will be seated. This constrains the number of degrees of freedom, and makes it much easier (though never simple) to arrive at a reasonable fit. The Kickbike, in contrast, has no seat, and makes no assumptions whatsoever about the relative position of the kicker's 'seat' compared to the Kickbike frame.

• What does this imply about the application of force to the frame, if anything?
• Does the provide additional freedom in changing the handlebar setup, angles, and the like?
• How is the overall steering and stability impacted - do we have the same concerns as a road bike over maintaining the relative handlebar positions?

Foot position: The road bike pedals are a fixed distance on each side of the frame that never varies. The kicker, in contrast, places one foot on the footboard while the other leg/foot is actively doing the kicking. The kicker frequently changes active feet after three to ten kicks.

• Are tall, or long legged, kickers more likely to experience interference with the frame?
• How can we adjust to minimize this?
• Some kickers use a style that results in their knees being raised quite high as their kicking leg moves forward. In this situation, is interference with the handlebar a problem for tall kickers?

Forward thrust: The road bike rider applies force to the wheels via the pedals, chain, and to the rear wheel. The weight of the rider is applied through both the pedals, and if seated, down through the seat, seat post, and frame. The kicker applies force through direct contact with the ground, up through the body, and through the hands and feet to the frame. The kickers weight is carried by the resting leg to the frame. Thinking about a simple force vector diagram, it would seem that the motive force in a road bike is applied along the horizontal axis of the frame, while with a Kickbike with a tall kicker the force vector would be coming from above the horizontal axis pointing down at an angle.

• Is this actually the case?
• Some gung-ho tall kickers have commented about the rear wheel bouncing. Is this something that can be easily corrected by changing their style, or by changing the handlebar selection and positioning, or a combination of both?