Additional notes about the simulation

This section contains some theoretical issues regarding the simulation. If you have doubts interpreting something you may find useful information here, besides the basic terms section.

Coordinate systems
Linkage has two modes regarding coordinates. This depends on the option “Horizontal Mode” in the project window.
When Horizontal mode is inactive, a fixed coordinate system is used, which is defined by the initial positions of the wheel axles and the direction perpendicular to it. Horizontal mode switched on means a moving coordinate system that is transformed for every displayed image, to the direction given by the actual wheel contact points with the ground.
In both cases the coordinate system origin is the reference point, which is a freely selectable point of the project.

Pedal-kickback calculation
There are two values displayed for "pedal-kickback" or "pedal-feedback". They are measured as the difference between the current and the zero-travel crank angles.
The first value is measured relative to the horizontal ground. The second value shows the crank rotation relative to the main frame.
If you are standing out of the saddle you will probably feel the amount of pedal feedback of the first value. While riding seated, the second value represents better the feedback to your legs. The pedal-kickback values are shown positive counter-clockwise, since this what you really feel as "kickback".
Also see this pdf document about the topic here.