Uncle Joe (or others) could have seeds, or self instantiating objects. In this case, AI DOG might give Joe a dirt bike seed, which is basically a miniature dirt bike which he can plant, piss on and then with a great gout of dirt, a full sized motorcycle would appear, which he could then ride to the next adventure.
The gout of dirt would be swiped from American Astronaut, a bucket of dirt and roots thrown at Joe off camera after he finishes pissing, as if an explosion from the ground. There could be a rubber worm that he picks off himself.
This flips the trend of devolution which is part of the pedal bike ride at the start. Technology getting more primitive. The AI DOG has already begun to trend technology towards non instrumentality. She offers him the dirt bike seed as a way to get to the bio DOG more quickly. At the end of it's 600 mile range it will self compost.
The seed idea was stolen from Neal Stephenson's Diamond Age.