If Ryan Adams is rock’s most prolific current artist, with three releases planned for 2005, it’s also true that his work sometimes bears the mark of simple exercises — the kind of music he churns out because he can. Cold Roses, the first of the ’05 album trio and the debut of Adams’ new band the Cardinals, is a handsomely wrought roots-rock set that would seem to deserve a place in that category. Even when he’s partly showing off, however, Adams can’t help revealing pieces of himself. He pokes through the ashes of romance (“a dream that’s not worth havin’,” he sings of one affair, while admitting in another song to leaving the women “who try to love me”). The music also sometimes pulls surprises (the atmospherics of “Rosebud”) and at times works up a real head of steam, as on “Let It Ride.”