I realize this seems like a pretty simple issue of drawing a free body diagram, but I just can't seem to figure it out.
If a bike leans, then it must have had a torque that made it lean. I considered the centripetal force, in this case friction, as a possible source for this torque, but that would create torque in the opposite direction. The only remaining torque causing force in my FBD is weight. But weight was there before the leaning, and would only cause a torque after leaning.
If anything, because of centripetal acceleration, observing from an inertial frame of reference, the bike should lean in the opposite direction because of the introduction of the centripetal force. So the question is, what force causes the bike to start leaning?