As Henry from Workcycles put it
Moving from Silicon Valley to Groningen in 2000 and suddenly becoming part of the incredible flow of bike riders is what eventually inspired me to begin Workcycles. Have a look this film by my friend Clarence Eckerson Jr. to understand just how bike oriented a city can become. Even for an Amsterdammer the number of cyclists in Groningen is staggering.
It is staggering with 50% of the citizens riding bikes. If you’re not familiar with Henry, get to know him in this post and in this interview at his shop in Amsterdam. Also see what’s going on in Uppsala, where cyclists have colonized the road.