Convert from marathon to bicron

Unit Definition (marathon)
A long distance event based on an ancient Greek event, run over a distance of just over 26 miles.

Unit Definition (bicron)
The Bicron is an obsolete metric unit of distance, which was defined as 10e-12 meter or 10e-6 micron. This distance is now called a picometer or picometre (pm). The name is a reference to the double prefix "micro-micron".