Motorcycle stunt: sliding under semis

It’s a fairly staple moment in action flicks: good guy is on a bike and raced by bad guys, a semi truck pops into frame from a garage or sideroad, hero does a quick 90° slide turn, slides the bike almost horizontal under the semi, does another 90° to get back on course and rides away in the sunset while the bad guys either crash into the semi or stop before it.

My question is this: how do stuntmen do it without completely shredding the leg that ends up under the motorcycle and against the pavement during the slide part of the stunt ? Do they simply wear like 3 inches thick kevlar pants, or is there a trick to it I’m not figuring ?

Well, aside from camera angles and editing to make the entire thing look more extreme than it really is, most motorcycle stunters have crash cages on the sides of the bikes, which protect them from exactly those kinds of injuries.

Like Nametag said, the bike probably has an engine guard which is not only there to protect the engine, but also so you can’t set the bike down on your leg. I would assume there would be one at the back as well. Remember, the bike will slide further if it’s sliding on steel as opposed to leather (or whatever the rider is wearing). Beyond that, perhaps instead of kevlar, I could see them using a piece of steel under their pants to protect their leg from the asphalt.

As others have said, frame sliders and crash bars.