Daily commute on bike has proven to be an economical way of transportation in many countries. Muscle fatigue significantly contributes to lower back pain and injuries, particularly among motorbike riders. This study focuses on investigating the phenomenon of muscle fatigue utilizing electromyography (EMG) to analyze and understand the impact of muscle fatigue on two major muscles responsible for maintaining posture while riding a bike. The mean power frequency is used as a measuring index, which indicates muscle fatigue. To evaluate the influence of different factors, the study focuses on two distinct trunk orientations: 90° and 60°. These orientations are chosen to simulate common riding positions adopted by motorbike riders. Additionally, the study examines the impact of vibration on muscle fatigue by comparing conditions with and without vibration. It is observed that the vibration and the 60-degree trunk angle are significant factors in inducing fatigue, as evidenced by a greater slowdown of mean power frequency for both the erector spinae and multifidus muscles (P<0.05). These findings highlight the importance of considering trunk angle and vibration exposure when addressing muscle fatigue in motorbike riders. Understanding these specific factors can inform the design of ergonomic interventions, such as optimizing riding postures and incorporating vibration-dampening mechanisms, to minimize the detrimental effects of muscle fatigue.