The blog streetsblog.net has a video on the “Indianapolis cultural trail in the USA (“an eight-mile biking and walking path through the heart of the city”) which shows what can be done with cycling infrastructure. There is a Youtube video showing bike congestion in Copenhagen, Denmark here to show the other side of the picture.
On the same topic (bike congestion), an article in the English language edition of Germany’s Der Spiegel last August (see here) quotes a traffic planner talking about growing use of bicycles in Berlin, Germany. “There is a lack of space on the roads. The bike paths are too narrow. Sometimes 30, 40 people will be waiting at a traffic light.”
The article says that there have also been conflicts between fast and slow cyclists, because many bike paths — especially older ones — don’t offer space for overtaking other bikers. The same traffic planner also said: “We need to reallocate space for bicycles. That is inevitable. The space will be taken from cars.”