A health assessment study was conducted in response to complaints of groin numbness in a bicycling police unit. Seventeen male cyclists were compared with 5 nonbiking men. The cyclists rode an average of 5.4 hours per day, and 91% indicated they experienced groin numbness on occasion. Each man wore the RigiScan Plus Rigidity Assessment System for one normal sleep session. Pressure measurements were also taken between the cyclist and the bicycle saddle. The percentage of sleep sessions that recorded an erectile event was significantly lower in the cyclists than it was in noncyclists (cyclists 27.1%; noncyclists 42.8%; P =.008). This duration percentage is negatively correlated with average hours a day that cyclists rode their bikes (r = -.41; P =.05), the number of days a week they rode (r = -.55; P =.009), and the average pressure exerted on the nose of the bike saddle (r = -.39; P =.08). The other measures of erectile quality (tumescence activity units [TAUs] and rigidity activity units [RAUs] of both the base and tip of the penis) were lower in the cyclists, but did not reach statistical significance. The number of hours cyclists rode during the day of RigiScan Plus assessment was negatively correlated with penis tip RAU (r = -.41; P =.04), and tip TAU (r = -.45; P =.04). These data suggest that prolonged bicycle riding may have negative effects on nocturnal erectile function and indicate a need for innovative bicycle saddle designs.