Tour de France 16th stage under way

PAU, France (AP) - Riders have set off on the Tour de France's 16th stage, as new doping allegations emerged against RadioShack Nissan Trek rider Frank Schleck.

Schleck is not among the starters for Wednesday's 122.4-mile mountainous ride from Pau to Bagneres-de-Luchon in the Pyrenees, having pulled out overnight after being informed by cycling authorities of a positive doping test after Saturday's stage.

Riders face four of the longest and steepest climbs in cycling, including the nearly 2,100-meter Tourmalet, a course that will push race leader Bradley Wiggins' Team Sky to its limits to defend the yellow jersey.