When Madison Police Officer Chris Masterson isnâ??t working his State Street beat, he bikes the highways of Dane County, training for triathlons.Masterson, 27, is among the departmentâ??s new generation of bike officers seeking to maximize the tactical potential of their two-wheelers. After UW-Madison student Brittany Zimmermann was killed in her West Doty Street apartment in April 2008, Dexheimer and other members of the community policing team went out on bikes to distribute fliers and talk with neighborhood residents.