As I was moving at low speed, I had a very pronounced front wheel wobble, but the rear wheel showed no noticeable deflection: that is to say the tangent from the rear wheel did not always intersect the track of the front wheel.

I don’t think the distance between the front and rear wheels was changing noticeably: though the speed of rotation of the two wheels relative to each other may have been changing. The wobble may have been timed to match my down-strokes on the pedals. My winter tires do have chevrons, but it is trivial to install the tire backwards! In snow or mud slippage is probably the best indication of direction: The “knobs” (whether directional or not) on the tires will make a track the “points” (or drifts) in the direction of movement (during side to side slipping). Wheel spin will deposit debris behind the point where the tire spins (which shows up as a smooth spot).

A better way to draw the lines would be to run the wheels of a model bicycle through ink, then run that across a sheet of paper. The problem is that such a model would not balance like a real rider. Then there is the more tricky and bandwidth hungry method of photographing actual tracks.

The fact is unless we have atleast 2 sharp curves it will be difficult to assess the direction. Lets say, a very skilled rider going very fast on a smooth terrain will produce no curves and hence no way to judge the direction.

I did my best with the drawing…if I find a better way to draw it I will update the pictures.