Supporting Online Material

A Bicycle Can Be Self-Stable Without Gyroscopic or Caster Effects
J. D. G. Kooijman, J. P. Meijaard, Jim M. Papadopoulos, Andy Ruina, A. L. Schwab

Supporting Online Material

This supplement contains:
Materials and Methods
SOM Text S1 to S11
Figs. S1 to S19
Tables S1 to S4

This file is in Adobe Acrobat PDF format.

Other Supporting Online Material for this manuscript includes the following:

Movie s1
The Experiment. The video Video1BasicExperiment.mp4 shows a typical experimental run. In order to effectively capture the experiment on film many different camera positions were tried. The main objective was to show that the bicycle once released follows a straight line. When it is perturbed, it stabilizes and then continues on a straight line in a new direction. The difficulty was finding a viewing position from where clearly can be seen that the bicycle actually goes through these three stages. Multiple fixed positions were tried, with both zoom and panning motions, however the most effective camera position turned out to be mobile, on a skateboard that closely followed the bicycle. One person carried out the experiment with the bicycle, the cameraman stood on the skateboard and only concentrated on filming the bicycle while a the third person pushed the cameraman forward and ensured that the distance between the bicycle and camera stayed roughly constant.

Movie s2
Counter rotating wheels. The video Video2CounterSpinningWheels.mp4 demonstrates the working of the front counter rotating wheel when the front wheel is rotated.

Movie s3
Measuring trail. The video Video3MeasuringTrail.mp4 shows how the small negative trail on the experimental two-mass-skate (TMS) bicycle is measured. A piece of paper is placed underneath the front wheel and stuck to the ground with tape. The front wheel is lowered and now touches the paper. The rear frame of the bicycle is clamped to prevent it from moving. The handlebars are then turned either way a number of times and the wheel marks the paper. The bicycle is removed from the clamp and the mark on the paper is examined. The mark follows an arc, a line is drawn tangentially to either end of the mark. The point where the two lines cross indicates the point about which the wheel rotates. Next the arc traversed by the middle of the contact 'point' is drawn on the paper. The distance from the center point to the arc is approximately the trail. When we measured the trail this way it turned out to be —4 mm, that is, the contact point is 4 mm ahead of the intersection of the steer axis with the ground.

Movie s4
Slow motion experiment. The video Video4SlowMotion.mp4 is a high speed video (300 fps) of one of the experiments where we measured the lateral motions with a wireless inertial sensor (Philips Pi-Node) and forward speed by post-facto counting frames.

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