## 2 Materials and Methods
### Procedures  
The measurements of a completed bike setup were performed using specified parameters. These measurements included the effective seat tube angle (denoted as A in degrees), the distance from the proximal stem end to the ground (D1 in meters), the distance from the saddle's contact point to the ground (D2 in m), the distance between the saddle's contact point and the proximal stem end (D3 in m), the distance between the saddle's contact point and the top of the bottom bracket (D4 in m), and the distance between the seat post mounting point and the saddle's contact point (D5 in m). These specific measurements were chosen from a broader array of potential options to ensure that the data could be utilised to support individual users, bike fitters, and bike designers. At the preliminary stage, the research project concentrated on a detailed anthropometric analysis of cyclists to elucidate how variations in physical parameters influence cycling biomechanics. Initial measurements were taken using a professional medical scale with an integrated stationeter, including body mass (kg) and height (m). These measurements facilitated the calculation of Body Mass Index (BMI, kg/m\({}^{2}\)), which served as a gauge for physical fitness and a basis for tailoring the bicycle setup to individual cyclists' characteristics. Subsequent advanced measurements included lower limb length (m), femur length (m), shank length (m), inseam height (m), upper limb length (m), arm length (m), and forearm length (m). Additionally, a physiotherapeutic assessment and interview, alongside evaluations of perceived effort and comfort, were conducted to assess rider comfort in various bicycle configurations. The questionnaire was utilised to establish the individual comfort-oriented position. Flexibility was assessed through a forward bend test, where participants, standing with feet together and knees extended, bent forward to reach towards their toes. The fingertip reach distance (recorded in centimetres) indicated flexibility, with positive values showing distances beyond the toes and negative values indicating shortfall. These comprehensive assessments enabled the creation of a personalised and optimised bicycle setup for each participant. Furthermore, the flexibility test was utilised to determine if the optimal bike settings were suitable for individuals with limited mobility. This study's measurement of muscle activity followed the SENIAM (Surface Electromyography for the Non-Invasive Assessment of Muscles, Seniam.org) recommendations to ensure accuracy and consistency. Each subject was comfortably positioned, and the skin was cleaned and prepared for electrode placement to minimise impedance. S-EMG electrodes were placed according to the SENIAM recommendations for each specific muscle. Each muscle's Maximal Voluntary Isometric Contraction (MVIC) was determined by asking the subject to perform a maximal contraction against resistance. During each MVIC test, S-EMG signals were recorded for 3-5 s and repeated three times with rest intervals in between to avoid muscle fatigue. The highest recorded value was used as the MVIC for that muscle. The preselected muscles (from muscles that take a major role in cycling [35]) studied in this research, essential for cycling performance, stability, comfort and health (minimising lower back pain), included:  
* Right Tibialis Anterior (RTA): responsible for dorsiflexion (lifting) of the foot during the transition from the pulling to the pushing phase of pedalling. The sensor was placed at one-third the distance between the medial and lateral ends of the tibia on the right side. MVC involved the subject performing dorsiflexion of the foot against resistance. * Right Vastus Lateralis Obliquus (RVLO): as an outer part of the quadriceps group, extends the knee and generates significant power during pedal pushing. The sensor was located at two-thirds the length of the thigh from the top of the iliac crest towards the lateral side, on the right side.