This article presents a comprehensive investigation into the non-destructive testing (NDT) of bicycle frames made from carbon fiber reinforced polymer (CFRP). These frames are popular for their excellent properties, but their manufacturing process is prone to the formation of inhomogeneities that could affect the mechanical properties of the frame. An active thermography method with ultrasonic excitation was used to verify the integrity of the frame. Experimental measurements on the frame were performed using the Edevis UTvis system and the thermal response to this excitation was recorded by a FLIR SC7500 infrared (IR) camera and processed using the lock-in method. The detection of inhomogeneities in the frame and their subsequent processing and evaluation in MATLAB software is presented in this work. Although these defects may not represent critical points in the bicycle frame (as they do not compromise the overall frame integrity), their early identification and prevention by modifying the manufacturing technology are important to guarantee the quality and reliability of the bicycles.