Perhaps the best way to experience Chapel Hill’s Spider Bags is still on the stage. But it speaks volumes about the strength of the set that Shake My Headthe group’s third and best album to datecasts that assumption in serious doubt.

At its foundation, Shake My Head is a collection of straightforward bar-rock songs. Walking (well, staggering) rhythms lend a vintage R&B swing behind overdriven guitar lines that mine ’70s rock and pop. Recorded quickly and piecemealat a record store and a house in Memphis, Tenn., then at Warrior Sound in Chapel Hillwith a gang of friends sporadically stopping by to lend extra vocals, play guitar or just hang out, the record offers an off-the-cuff feeling, without sacrificing clarity or intention. Check the laughter and chatter between songs; notice how strong the songs themselves are.

Onstage and on record, Spider Bags are established as a preeminent bar-band, mostly on the basis of Dan McGee’s songwriting and his lovable-lout persona. Here, during “Friday Night,” McGee proclaims, “All my friends are leavin’ town/ I’m the only jerk that sticks around.” In “Keys To The City,” he confesses, “I’ve been living in the city my whole life/ Now I’m cheating on my girlfriend with my ex-wife.” Even as Shake My Head finds the band playing fast and loose with their previously mastered mix of defiant garage-rock and dry-wit country, McGee remains a stalwart guide, delivering his advice and admissions in his dry near-deadpan. His chief asset as a frontman is the ability to relate via self-deprecation, a lyrical quality he shares with Paul Westerberg.

Even in the band’s mostly stable trio formation, Spider Bags shows often feel like a gamble: Will they race through a tight, tense 30 minutes or drag out a wild, crowd-baiting lysergic sprawl? One suspects the persistent turnover in the Bags’ personnel has lent McGee a certain flexibility of presentation. On Shake My Head, the joining of both approaches and units somehow makes for Spider Bags’ most cohesive and thrilling LP to date. The foundation, mind you, remains strong; this time, so does the presentation.