In case you’re still looking for inspiration, imagine the red block is the bike:
It’s a self-correcting value affected by another, larger value - the leaning factor. With no leaning input, Tick will correct Target Roll to 0; but leaning to a side makes Target Roll a much juicer target for the fInterpTo.
You could also tie the leaning factor to the bike’s velocity, making it harder to lean when the speed is great. And to make it even neater, you could sample an external velocity based curve - perhaps some bikes are easier to handle than others.
And the Target Roll can also be tied to velocity, a bike that is standing still & leaning will fall over, there should be no correction added. But a fast moving run-away machine will self-correct even with no rider. Playing with that x0.1 multi will also affect how hard it is to counter the self-correction for the player.