This paper presents an experimental investigation of the vortex shedding characteristics of two circular cylinders with differing diameters in representing a simple riser configuration. The smaller of the two cylinders is located at varying positions around the circumference of the larger cylinder. Measurement of forces on the cylinders and the associated shedding frequencies are recorded and analyzed for five different flow velocities and orientations of the riser in the Emerson Cavitation Tunnel of Newcastle upon Tyne University. The Reynolds number corresponding to the test conditions varies from 9.64×104 to 4.82×105 for the large diameter of the cylinder and from 3.5×104 to 1.75×105 for the small diameter cylinder. The experiments were split into two distinct phases: the first was flow visualization using the hydrogen bubble technique and the second phase was force and shedding frequency measurements.