On mu commute I average around 19 kph incoming and 18 kph overall (more uphill when going home). This is 16.5 kmh round trip with some traffic, traffic lights and pedestrians on MUPs. I did some 60 km on rolling/flattish road at around 20 kph average with a friend. We weren't pushing it, but we couldn't have gone that much faster either. I never was a fast rider.