Those sure are great pictures! It makes me really really appreciate the bikes we have today. Some of the stuff I think might be kind of tough pales in comparison to some of the adventures these guys had.
I have an old video tape of my step-dad doing similar type riding back in the late 50's early 60's. He's riding up on the shoulders of someone who is riding the motorcycle, smoking a cigarette... nobody wearing helmets. And the bikes have 1" suspension and looked like they weighed 400lbs.
I'll have to bring it up to TF and play if for the group. Classic...