A pedal for a bicycle or an exercise bike contains: a body. The body includes a road-bike stepping assembly, a connection assembly, two positioning protrusions secured on two sides of the connection assembly, respectively, and a plurality of locking orifices defined on the connection assembly. The connection assembly is screwed with a mountain-bike stepping assembly by way of multiple screws, the mountain-bike stepping assembly includes two engaging trenches mating with the two positioning protrusions, individually, and the mountain-bike stepping assembly also includes a plurality of through apertures cooperating with the plurality of locking orifices, respectively. The connection assembly is screwed with a coupling plate by using the multiple screws, the coupling plate includes two retaining grooves mating with the two positioning protrusions, respectively, and the coupling plate also includes multiple openings cooperating with the plurality of locking orifices, respectively.