Even the best street skateboarders wipe out over and over and over again — the board zipping away like a pup let off a leash while the skateboarder hits the pavement, sustaining yet another scrape or bruise or blow to the ego.

And then, just like that, he picks himself up, dusts himself off, retrieves his board and gets right back to it.

The three skateboarders featured in the extraordinary documentary “Minding the Gap” are skilled practitioners of their craft, zigging and zagging through the streets and parking garages and parks of Rockford, Illinois (and other similarly depressed towns), with beautifully improvised precision.

They also fall down, a lot. And as this gritty and raw film by Bing Liu takes us deeper into the lives of these three friends (one of whom is the director himself), we see them falling even harder in their lives — and doing their best to learn from those stumbles, pick themselves up and carry on.

Bing Liu, Keire Johnson and Zack Mulligan have been friends since middle school — and almost from the start, Liu has been videotaping their skateboarding feats as well as their lives away from the pavement.

Keire and Zack are so comfortable with Bing’s camera that it never feels like an intrusion, even when he keeps rolling as Keire breaks down while coming to terms with the memory of his abusive father, or Zack and his girlfriend, Nina (the mother of his child), get into a heated, vicious argument.

Eventually the director turns the focus on the heartache in his life as he interviews his mother about his monster of a stepfather, who abused Bing, his brother and his mom.

Time and again, we see how domestic abuse has been a common theme in all of their lives.

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Keire is working as a dishwasher and doing everything he can to support his single mother, but he bears the emotional scars of the abuse he suffered, and he struggles to control his anger issues, whether he’s getting into a fight with a neighborhood bully or smashing a skateboard to pieces.

Zach has the crooked smile and charisma and sharp wit of a bad-boy character in a teen movie, but he grows surly and mean when he’s drunk and/or high, and he’s woefully unprepared to be a parent.

When Bing learns a fight between Zack and Nina resulted in physical violence, he sits down with them separately and gets a “he said/she said” account of events. But there is no doubt Zack has physically abused Nina — and when he says he knows a man can’t hurt a woman, but sometimes “b—-es“ have to be hit, it’s a sobering and sickening moment.

And then there’s Bing’s interview with his immigrant mother, who speaks in halting English and sometimes seems incapable or unwilling to fully acknowledge what happened in at the hands of Bing’s stepfather. She can’t go back in time, she tells her son. There were two sides to this man, she tells her son. She wishes she had been more aware of things, she tells her son.

The score by Nathan Halpern and Chris Ruggiero is sparse and beautiful and perfect. The editing is brilliant, as we jump back in forth in time, seeing these three as kids and then as young men, marveling at their skateboard moves and smiling at their rebellious spirit, and wondering if there’s any hope for any of them given all they’ve been through in their young lives.

We hold our breath, hoping maybe we’ll get a “Minding the Gap Again” 10 years from now, and maybe we’ll find out all three men are doing all right.

Director Bing Liu, now a Chicagoan, is scheduled to appear for audience discussion at screenings Aug. 31 and Sept. 1, 2, 5, 8 and 9.

‘Minding the Gap’

1⁄2

Hulu presents a documentary directed by Bing Liu. No MPAA rating. Running time: 93 minutes. Now showing on Hulu, and opens Friday at the Gene Siskel Film Center.