(YouTube link)
I never bought a wheelie bar, but this ad from 1966 brings back memories of doing stunts on my old spider bike, like standing on the seat... Then my mother instincts kicked in. Hey! These kids aren't just riding without helmets, they aren't even wearing shoes! And who encourages their kids to do wheelies, anyway? Things sure have changed in 45 years! -via Nag on the Lake
That would be parents who want their kids to live a little and have some fun. Doing wheelies is probably safer than a lot of things parents traditionally encourage their kids to do, like playing contact sports for example. Lame, killjoy parents seem to have a real problem distinguishing real danger from perceived danger that has more to do with personal prejudice. I never did more than get a little gravel rash doing stunts on my bike or skateboard - on the other hand I broke bones playing rugby. Guess which of those my parents encouraged me to do.