Abstract: The bicycle with adjustable pedaling resistance using magnetorheological-based fluid is a bicycle that includes a pedaling resistance member. The pedaling resistance member is optionally used to increase the resistance of the bicycle pedals when in use. The pedaling resistance member is integrated into the frame of the bicycle, and includes a hollow cylinder that is partially filled with a magnetorheological fluid. A paddle is affixed to a crankshaft that extends between the bicycle pedals, and across the hollow cylinder. A powering member is in wired connection with an electromagnetic coil, which is in fluid connection with the magnetorheological fluid. The powering member is able to apply electricity to the magnetorheological fluid, which in turn increases viscosity of the magnetorheological fluid thereby increasing pedaling resistance to the bicycle pedals via the paddle rotating within the hollow cylinder.