In the Netherlands the cities are basically flat and worldwide this is the exception rather then the norm. Ride your bike on a slope and you can easily reach 6

In the Netherlands the cities are basically flat and worldwide this is the exception rather then the norm. Ride your bike on a slope and you can easily reach 60 km/h. Also 20 km/h or 15 km/h is still enough to produce serious injury. On my first fall this year, when I hit my helmet-protected head, I must've had no more than 10 km/h.