I've just got one of these things; it's not actually a
Trail Gator but a similar German device called Profex.
Unfortunately the instructions are in German, which I
don't read
The bar is attached to the seat post of the adult bike. I'm
not sure whether it's supposed to pivot around the bar. It's
almost impossible to stop it doing so, but the effect is
that the child's bike then moves off centre, and tries to
pull the adult bike off to one side. I was wondering whether
perhaps the joint should be quite loose, so that if the
child's bike does wander off centre, it will quickly wander
back again.
I have actually managed to get it so it doesn't move, by
strapping it to the bike rack. This feels OK, but you can't
turn in a tight circle.