At the start I thought the balancing should be in opposite direction. I thought that, for example if the biker was falling left, you turn left as well to counter the fall using centrifugal force. And rotating to left helps turning left as well.
But then when I imagine that the player is not biker, but someting like plate on a stick it all maked sence (also because it is easier for people to understand what it would be like balancing plate on a stick, than understand what it would be like beeing a bike:)
After my change of thinking about the movement the game was fun, challenging but fair. So good job.
The minimalistic style also looked good.