Bicycling back pain may be caused by acute lumbar sprain, lumbar disc herniation, ankylosing spondylitis and other causes. 1. Acute lumbar sprain: it can be caused by the stimulation of local lactic acid and other metabolic products, causing aseptic inflammatory manifestations such as edema and oozing of muscles, fascia and other soft tissues, which leads to pain, swelling and limitation of the activities of the lumbar back. 2. Lumbar intervertebral disc herniation: degenerative changes in the lumbar intervertebral discs cause the bulging nucleus pulposus to irritate and compress the nerve roots, resulting in discomfort such as swelling and pain in the lumbar back, and can cause radiating pain and numbness in the lower limbs. When riding a bicycle, the weight of lumbar spine increases, causing pain or aggravation. 3. Ankylosing spondylitis: Heredity, infection, environment, immunity and other factors lead to chronic inflammatory changes in the sacroiliac joints, spine and other joints, which are mainly manifested as pain and stiffness in the lower back or buttocks. When riding a bicycle, it can cause the spine to bend forward and fight against the already straight spine, thus causing pain to arise. Bicycling back pain may also be caused by chronic strain injury and other causes, it is recommended to seek medical attention to clarify the diagnosis, under the guidance of the doctor for targeted treatment.