Brad Pitt Motorcycle Touring Iceland, Pax's Accident Fresh in His Mind

Brad Pitt's getting back on the horse, or in this case, a hog -- taking a motorcycle adventure just weeks after an e-bike accident landed his son Pax in the hospital.

TMZ got video and pics of Brad in Iceland, prepping for his ride and covering his face with a black ski mask for warmth -- it's summer on the Nordic island, but far from balmy -- then slipping on his helmet and mounting up.

Check out the video -- he pulls out of the parking lot and throttles up his speed, rolling out through the city.

BP leaves the lot accompanied by a couple other bikers ... unclear where exactly they're going, but they don't exactly seem like a fearsome motorcycle gang.

Pitt's motorcycle trip comes just a few weeks after Pax's nasty accident while riding an electric bike in Los Angeles. TMZ broke the story ... Brad and Angelina Jolie's son slammed full force into a stopped car in rush hour traffic.

Pax wasn't wearing a helmet at the time, and was briefly hospitalized with a minor brain bleed before doctors released him.

Sources with direct knowledge told us Brad was very worried about his estranged son ... and, while they didn't have any direct contact, people around Pax gave Brad consistent updates.

Of course, there's a big difference between father and son's ride locations and equipment -- but Pax's ordeal has to be on Brad's mind.