In classic iCarly fashion, the show went the over-the-top ridiculous route explaining why Sam isn’t hanging out with her best friends.
Sam was always billed to be a tough character on the original series, so the idea that she’d be traveling the nation with a biker gang is totally on-brand for the character.
Plus, Sam got a motorcycle in the original iCarly finale on Nickelodeon, so the series did a great job at keeping with continuity, while also showing a little sympathy for any bikers standing in Sam’s way.