**Non-technical summary** This paper compares the biomechanics of the knee while cycling with the bike seat at different heights (low, medium, high, and preferred). The paper shows that the movements of the knee that are most likely to contribute to overuse injuries are considerably more pronounced when the seat is placed low than when it is placed high. >*These results suggest the importance of adjusting saddle height for safe performance and injury prevention during cycling for recreational cyclists who rides daily for recreation, fitness, or transportation purposes, especially for people who ride from a bicycle-sharing system.* **Highlights** (taken from the paper) - The study aimed to compare different saddle heights on frontal plane knee biomechanics during cycling. - The knee may repeat thousands of abduction and adduction movements during cycling, and relatively low magnitudes of force and moment may cause injury if they last for a long time. - For this reason, it is not only the magnitudes of knee joint force and moment, but also their durations that are very important for understanding overuse injury. - Compared with Low saddle height, High saddle height reduced both knee moments and time duration, which suggest the importance of adjusting saddle height for safe performance and injury prevention during cycling for recreational cyclists.