Two days after wiping out on a dirt bike, Madison Bumgarner’s arm is in a sling and he is able to walk under his own power. Giants manager Bruce Bochy said that Bumgarner briefly left the team hotel here Friday night and went to Coors Field to meet with head athletic trainer Dave Groeschner. Bochy did not believe that Bumgarner would be at the ballpark Saturday. The left-hander is due to travel home with the club after Sunday’s game, and not expected to make any comments over the weekend. Bumgarner has bruised ribs and a Grade 1 or 2 sprain of the AC joint in his left shoulder, and while the Giants are withholding any kind of timetable for Bumgarner’s return from the disabled list until he can be evaluated in San Francisco, Bochy said he has not heard surgery mentioned as a necessity. “As far as I know, there’s no surgery,” Bochy said. “I’ve never heard it discussed that it’s needed or required.” But Bochy reiterated that not all the facts are in. This much the manager knew for certain: Bumgarner was lucky that he didn’t sustain more significant or even life-threatening injuries. Bochy knows from experience, because he crashed an Indian Chief motorcycle in the mountains east of San Diego shortly before opening day in 2001. He was riding with Ryan Klesko and they had finished shooting a commercial when Bochy took a turn too fast and didn’t see a roadblock ahead.