For each day of the calendar year 2014, I use a GPS mobile phone app to draw my bicycle routes during the course of any excursions. Note that the resulting lines (aggregate tracks) are a machine-calculated and machine-drawn average between all GPS data points detected by the device during the course of the route.
Neither the timing of the excursions nor the particular routes are planned in advance, but determined by any daily activities that require bicycle transportation—all these become part of the drawing performance.
By the nature of their interaction during a ride, the front and rear wheels of a bicycle necessarily leave different tracks. For each daily trip, I make a discrete drawing that marks the track of the front wheel and that of the rear wheel. My method is to use the computer to choose at random two GPS points along the route (these typically have margins of error of 5 to 15 meters). I determine the direction of the front wheel by hand drawing it as I imagine it between the selected points. Simultaneously, the computer marks the track of the rear wheel in accordance with axioms of the calculus of bicycle wheels:
- Front and rear wheels remain a fixed distance apart.
- The rear wheel always points toward the front wheel.
- The line tangent to the rear wheel track always intersects the front wheel track at a fixed distance.
For each day that I do not ride — due to illness, extreme weather conditions, or travel — the color reserved for that day’s discrete tracks covers the entire image field, since for that day, every track is possible in my imagination.
I do not preconceive the duration or the appearance of the drawing of tracks. But I do vary routes.
In order to efface each drawing’s potential as functional diagram, I delete from the drawing field all underlying maps of Berlin streets or satellite images the device provides. For every excursion, I have the device assign a distinct color in accordance with the range of the spectrum, so that each discrete trip is distinguishable within the drawing of aggregate trips.