Heads up riders-  Madison Police say a person in a mask stepped in front of a rider on the bike path near Sargent Street and Dennett Drive around 10:30 Saturday night.  Police confirm they are investigating the incident where the masked man stepped in front of the bike rider, pointed a gun and demanded his bicycle.  The victim got off the bike, the suspect rode away and there were no injuries in the incident. MPD quickly set up a perimeter but did not find the suspect.