hour movie, so writer/director Jeff Nichols created a storyline and populated it with characters. Lyon (played by Mike Faist) still appears, but the film extends the storyline from 1967 (when the book was published) to 1973, when the fictional Lyon, no longer a club member, conducts follow-up interviews.

The film version of “The Bikeriders” is largely a series of scattered episodes. A woman named Kathy’s occasional interviews with Lyon provide the film’s narration. The movie begins with Kathy (Jodie Comer) meeting a girlfriend for a drink at a bar frequented by the Vandals (the club’s name in the film). She is attracted to Benny (Austin Butler, who is channeling James Dean), a Vandals member playing pool. When the bar closes, she accepts a ride home with Benny, only to find her boyfriend sitting on the curb waiting for her. He’s not happy, and he’s even less happy when Benny spends the night across the street from their house, standing next to his motorcycle. The following day, the boyfriend walks out on Kathy, and she and Benny marry a few weeks later.

According to Kathy, the Vandals grew from a group of guys who raced their motorcycles on weekends. Johnny (Tom Hardy), influenced by Marlon Brando in “The Wild One,” organized the group into the Vandals. These men had families and full-time jobs; the Vandals offered a chance to dress up and party on weekends. With success, the Vandals’ fame spread, and other chapters opened in other cities. Benny was different from the other Vandals because the club became his entire life. He wore the colors full-time (which resulted in a brutal beating that nearly crippled him for life). Johnny viewed him as the son he wanted to take over the club, but Benny wasn’t interested.

The best dialogue scenes in “The Bikeriders” feature the club members sitting around a bar table or a campfire swapping stories. Their characters emerge, especially guys like the garrulous Zipco (Michael Shannon), an unhinged man who laments that he couldn’t go to Vietnam because the draft board realized he was unhinged. Then, there’s Cockroach (Emory Cohen), so named because he likes to eat cockroaches. (Cockroach’s ultimate fate is one of the pivotal moments in the movie, although not in a way viewers might expect.) Boyd Holbrook, Damon Herriman, and Norman Reedus also make distinct impressions as fellow gang members.

But for all the acting talent and well-written dialogue scenes, these skilled character actors do little in “The Bikeriders” except swap campfire stories and ride alongside Benny and Johnny. Kathy tells us they had jobs and families, but we don’t see their “real” lives to know how the Vandals filled a void in those lives. The only scene in which real life intrudes on the boys’ biker club is a funeral for one member who died in an auto accident. The Vandals, wearing their colors, line the entrance to the funeral parlor. As the dead man’s parents (looking like a couple straight out of “American Gothic” in their Sunday best) climb the stairs to enter, his mother stops and spits in Johnny’s face, and his father tells the Vandals to leave. I wondered what the family dynamic was when the son was alive, but we’ll never know. Even the romance between Kathy and Benny gets short shrift. We get almost no interaction between the two, and I honestly don’t know what Kathy saw in him other than he was a dreamy hunk who looked like Austin Butler.

The most fully developed character in “The Bikeriders” is Johnny, who is the shaping force behind what the club does. Johnny establishes rules, some of which seem silly until viewers realize they involve grown men fighting each other with fists and knives to determine their club rankings. Tom Hardy has one of his best performances here. He knows how to play over-the-top villains, but Johnny is quiet and succeeds because he knows how to get people to agree with his ideas. In another environment, Johnny could have been a superb manager. Here, he’s a father figure to a group of 30-somethings who have never quite grown up.

You’ll notice that I refer to the Vandals as a “club,” not a “gang.” The choice is deliberate. Much as films like “Boogie Nights” and even “The Godfather” depict the descent of similar “business enterprises,” here, the Vandals recruit new members who are not given names in the film and appear as near-clones of each other, with no personalities. These new members often served in Vietnam and came back hardened, with criminal histories and a liking for taking drugs rather than drinking beer. As they become more involved in the club, the Vandals turn into a street gang, running drugs and women and executing enemies. The film’s climax represents Johnny’s efforts to keep control of his club.

“The Bikeriders” struck me as half of a brilliant film. All the material is there, but neither Danny Lyon nor screenwriter Jeff Nichols reveals it. Understandably, a coffee-table book with 50 photos and a few interview transcripts isn’t a novel or a history. However, Nichols had the opportunity to turn “The Bikeriders” into an epic tragedy like “Boogie Nights”, but failed to do so. Most gang members, even Benny, are moving photographs with funny names. The movie brilliantly captures the look and feel of the parties and the open road. It’s worth watching for several scenes with no dialogue or real action. As a group biography, however, the movie feels incomplete. Viewers can enjoy Tom Hardy’s performance and the poetry of the club members on their bikes. However, the movie idles too often when the engines should be roaring.