#Learn tricks
Learn tricks
There is a load of entertaining and useful tricks, that a person with a bike can learn. Ken might know none or all of them, but there is always still room for improvement. Ridding at a steady, slow pace, should be the perfect environment to learn a half meter high bunny-hop or a 2km wheelie.
Only downside is that Barbie could think of this as being arrogant and showing oneself off, so they should have this cleared beforehand.