Abstract: The invention is to provide a chainless transmission mechanism comprising a first shaft connected to a pedal of the bicycle; a first bevel gear connected to the first shaft; a second shaft perpendicular to the first shaft, two ends of which are connected to a second bevel gear and a third bevel gear, respectively, the second bevel gear being matched with the first bevel gear to drive the second shaft; a fourth bevel gear mounted on an axle of a rear-wheel hub of the bicycle to engage with the third bevel gear; a ratchet clutch connected between the rear-wheel hub and the axle; and a connection member connected between the fourth bevel gear and the rear-wheel hub. A bicycle with the chainless transmission mechanism of the invention is of a simple manufacturing process and a lower cost.