From Oscar Peterson, Bill Evans, and Ahmad Jamal to Keith Jarrett, Marcus Roberts, and Brad Mehldau, pianists and their working trios have been among the most beloved groups in jazz. Founded in 2003, Vijay Iyer’s band with bassist Stephan Crump and drummer Marcus Gilmore has rapidly ascended toward a similar status with critics and grassroots fans alike. On Accelerando, the threesome’s second album, one hears comrades ready to explore shifts in tempo and time signatures together, while pushing the expressive potential of their own instruments. An examination of rhythm through popular songs, lesser-known compositions, and Iyer’s own pieces, it’s evenly split (including the iTunes bonus track) between sharp originals and bold interpretations. “Human Nature” starts off sounding faithful to the Michael Jackson version before delving into sublime feats of syncopation. Flying Lotus’ “Mmmhmm” is given a delicate reworking, while Iyer’s title track first rhythmically hesitates then explodes.