A preliminary field study of optimal trunk flexion by subjective discomfort in recreational cyclists

This study attempts to find the optimal trunk flexion (TF) of a recreational cyclist's subjective discomfort rating while cycling. Two hundred and fifty cyclists were sagittally filmed while cycling on a cycle-way, and their subjective body discomforts were rated. The cyclists also responded to a brief questionnaire. Results show that the TF is positively related to the discomfort on neck/shoulders and is contrary to that on the buttocks. The bike owner cyclists’ (n = 144) trunks were more flexed than the bike rental cyclists’ (n = 106), with a difference of about 11°. This study also found that the cyclists may subjectively perceive the minimum discomforts of both the buttocks and neck/shoulders regions when the trunk was nearly flexed to 38°. This finding serves as a reference for ergonomic consideration in bike design to avoid extreme discomfort while cycling.