OBJECTIVE : To describe the incidence and patterns of injury and illness of male and female participants during a 94.7 km distance cycling event. DESIGN : Descriptive study. SETTING : Momentum 94.7 Cycle Challenge 2014. PARTICIPANTS : Participants: All 23 055 race starters (males = 17 520, females = 5236, not specified = 299). MAIN OUTCOME MEASURES : The incidence and type of all medical complaints and difference between sexes. RESULTS : Incidence (per 1000 race starters) of all medical complaints was 38.69 (males = 36.52, females = 38.39), adverse medical events 11.88 (males = 10.73, females = 16.42) and serious adverse events 1.3 (males = 0.86, females = 2.67). The incidence of nontraumatic medical complaints was 32.49 (males = 33.39, females = 31.32) and of traumatic injuries was 3.99 (males = 3.14, females = 7.07). Females compared to males had a higher risk of sustaining traumatic injuries (P < 0.001), central nervous system, (P = 0.0062) and eye complaints (P = 0.0107). Most complaints (80.6%) were reported for the musculoskeletal system. Males 10-15 years (P = 0.0013) and females 23-39 years (P = 0.0336), and older than 50 years (P = 0.0002) had a higher than expected risk for traumatic injuries. CONCLUSIONS : Medical complaints ratio reported was 1:26 (males = 1:28, females = 1:26) in all starters during the cycling event. Cyclists that did not finish the race (adverse events) were 1:84 (males = 1:93, females = 1:61). Serious adverse events that required hospitalization were 1:769 (males = 1:1163, females = 1:374). The majority of admissions were for traumatic injuries, followed by cardiovascular complaints. Results from this study indicated that a wide spectrum of medical complaints can be expected during such an event with a higher risk for females to sustain traumatic injuries and to encounter central nervous system and eye complaints. Information regarding the pattern and type of medical encounters can prove useful during planning and management of similar future events.