Bob Weir and RatDog | RatDog.Org

Bob Weir was speaking by phone from his home in Marin County, Calif., on an early October afternoon, less than two weeks before his 60th birthday. He was already becoming reflective in the days leading up to the milestone, wondering how he got there.

"Looking back, I think it had to have been viewed as somewhat unlikely, but it somehow happened," said the guitarist who came of age with The Grateful Dead at the height of the sex, drugs and rock 'n' roll era. "I find myself asking, 'What did I do wrong?'"

He survived the '60s, outlived his famous Grateful Dead band mate Jerry Garcia, and for much of the past dozen years has been touring with his group RatDog. Weir and his jam-flavored successor to the Dead return to Burlington for a show Friday night at Memorial Auditorium.

RatDog is making this tour without guitarist Mark Karan, who is recovering from throat cancer. Weir said Karan will be "chomping at the bit" to return quickly, something Weir will try to quell.

"I'm the boss here, and I'm probably going to -- I hate to say it because it's not my normal way -- I'm going to have to err on the side of caution," Weir said. "There's every opportunity for him to come back at least as strong if not stronger."

In the meantime, veteran guitarist Steve Kimock is filling in for Karan. "He's different; he goes different places; he's a different player than Mark is," Weir said. "When we do end up working Mark back, we're going to have to have him listen to what Steve did particularly well and see if he can cop that, and then there's stuff that Mark does that Steve doesn't do at all.

"In terms of soloing, Steve is basically a stem-winder," Weir said. "He develops a solo more slowly. Sometimes it's best to just go straight to the point, but he has a way when he does one of those long stem-winding solos so that nobody in the room misses his development. Every step of the way all the colors are filled in. It's picture-perfect; there's no ambiguosity of where he is or what he's doing. When he gets to where he's going, it's generally like Christmas."

It's moments like that that keep Weir going as he's evolved musically from the 1960s to his 60s. He's nowhere near thinking his performing days are over.

"It's a real simple matter: It's what I'm here to do. I wouldn't know what else to do with myself," he said. "I don't play golf. I'm saving that for my golden years, and I don't think I'm there yet.

"As my drummer pointed out awhile back and I took stock in that, what great musician ever retired? I don't number myself among them, but it's a good point."