Iliac artery endofibrosis (IAE) is a rare cause of leg pain in young, healthy endurance athletes, particularly in male competitive cyclists. The prevailing hypothesis suggests that it is due to mechanical trauma of the iliac artery from long-standing hip flexion. In this case, a 40-year-old male endurance cyclist presented with bilateral thigh pain and worsening leg fatigue upon maximal exertion. Yet, the physical exam at rest was negative for claudication and peripheral pulses were intact. For this reason, IAE is poorly recognized and remains a difficult diagnosis as it requires testing at near-maximal exertion to reveal symptoms. After the patient was referred to the vascular clinic, imaging revealed intimal thickening of the left common iliac artery but with no evidence of stenoses bilaterally. Management typically begins conservatively but true resolution of symptoms can necessitate vascular intervention.