Bikes rule in Amsterdam, they’re everywhere and the riders come fast and furious. For the unaware visitor, it’s a bit hairy. Many of the riders seem to have left their brains at home before taking off. Come to think of it, this applies to many motorists too. Anyway, it’s sort of OK to be wary when crossing bike paths but the riders go everywhere and expect the way to be cleared when they come.
To be fair, the bike is a convenient form of transport in many European cities. The inner cities were built long before the motor car was even thought of and the congestion (and pollution!) would be utterly hopeless if people would rely on their cars for transport.