Check the torque on your handlebar binder bolts
I was just swapping out the stock stem riser on my new Swift for an extra-long riser (sold by Xootr for $22.95 plus shipping) in order to take some weight off my ailing wrist with a more upright riding position.
In the course of doing so, I discovered that the foremost 5mm bolt in the handelbar binder had become very (i.e. ready-to-fall-out) loose. Park Tool recommends 120 inch-pounds (13.5 Nm) for a 6mm bolt at this location, and I torqued the Swift's 5mm bolts to 80 inch-pounds (9 Nm) for now.