Get hurt?, heck yeah, all the time. That's why they had bactine.
BOL. Our sons kept their big wheels after we moved to our current home in the late 1970's. We didn't find out why until later. They would take them up the hill that started as they went out of our driveway. They went up 350' and 350 yards on the road on a big wheel.
One of them stayed down on the flat of the street and told the other on their walkie talkies, when the road was clear. Then, the one on the big wheel would haul ashes all the way down. Their way of stopping was to run the big wheel into the curb and go head over heels over the big wheel on to a neighbor's yard.
They built ramps like the one in your picture for their dirt bikes on a vacant 40 acres behind the house.
They had an arroyo right across the road for dirt biking, hunting small game and just being out there. Sometimes they bike back in with pup tents and spent the night. That stopped when a mountain lion moved into the area.
In the 50’s we loved a broken thermometer, since the mercury was cool when it broke up into little balls. Then we’d use it to polish nickels to look like new. Should have all long ago dropped dead from such exposure.
That’s it right there!