Effects of a Professional Objective Bike Fit on Power Output and Comfort

This is a prospective, interventional crossover study evaluating the impact of professional bike fitting on cycling performance and comfort in recreational cyclists. All participants must engage in structured physical activity at least twice per week (≥30 minutes per session), own a road or gravel bicycle, and are available for two laboratory visits within a 96-hour period. All participants must complete the PAR-Q+ and a health history questionnaire. At Visit 1, participants will undergo baseline testing. Their current bike setup will be replicated on a Wattbike ergometer. Participants will complete two performance tests: a six-second peak power test (PPT6) and a 20-minute Functional Threshold Power (FTP) test. For the PPT6, participants perform a seated sprint from a dead stop following a five-minute warm-up and two-minute rest. Metrics collected include peak power (W), relative peak power (W/kg), cadence (rpm), and leg imbalance (%). The FTP test will be conducted on each participant's personal bicycle mounted to a Wahoo KICKR MOVE smart trainer. Power, cadence, and torque are recorded, along with physiological data captured using a Polar H10 heart rate monitor and a COSMED Quark CPET system to measure VO₂, VCO₂, and RER. Following these assessments, participants will receive a professional bike fitting using the id match Smart Bike system. The id match system (Casella d'Asolo, Italy) uses 3D motion capture, static anthropometric scans (e.g., limb length, lumbar flexion, foot dimensions), and machine learning algorithms to optimize rider positioning. The fitting process adjusts variables such as saddle height, saddle setback, handlebar reach and drop, and cleat position. A certified id match fitter will perform each fitting, which is guided by participant-reported cycling history and pain ratings by body region on a 1-10 scale. Between 48 and 96 hours after the initial visit, participants will return for Visit 2 and repeat both the PPT6 and FTP tests using their updated bike configuration. All equipment, testing protocols, and data collection methods remain consistent between visits. Primary outcome measures include peak power and relative peak power (W/kg) from the PPT6, and FTP (W), relative FTP (W/kg), and average torque (ft-lb.) from the 20-minute FTP test. Secondary outcomes include perceived exertion (Borg RPE 6-20 scale), discomfort (Likert scale 1-20), region-specific pain, and biomechanical changes to bike setup (e.g., saddle height, setback, cleat position, joint angles).