I don't have anyone to play with so I tried playing solo and it is hard! lol but a cool little idea. It follows the theme very well with the "only one button" to control your character and it brings a certain level of difficulty since it sort of removes some of the control away from you forcing you to think ahead and not being able to respond sharply do to the limitations of movements. It is definitely a unique idea that I've seen this far.
I tried to solo it a few times during development and it's basically impossible. I think the only thing you can really do is always press the buttons in sync, which makes the bikes drive a symmetric path as long as no items are collected (since the steering wheels stay in sync). I have some ideas for how to make single-player mode viable, but they were way beyond what we could've accomplished within the jam. Thanks for playing!