We often forget that great bike cities were not always so. They all had to start somewhere, work hard at it, and build up the infrastructure and bike culture, sometimes from a very low base. Even a great bike city like Portland had to evolve and grow into its current state, as these maps from the Portland Bureau of Transportation (PBOT) show. This should give hope to other cities that aren't yet bike-friendly enough: It might be hard, but it can be done!
Below is an animated version, made by the awesome Jonathan Maus of Bike Portland, but if it goes by too quickly, I've also provided the original slides (they're a bit out of order - the fifth one is on top, and then they are chronological, as you can see from the dates in the bottom right of each slide).
The dark lines are bikeways, and the different colors represent biking's model share (ie. how many percents of trips are done on a bike in each area). As you can see, most bikeways were built in the first 10 years, and then the modal share of bikes kept going up and up.
Another similar animated map of Portland can be seen here: Portland's Bikeways: 30 Years of Evolution in 1 Map.
Via Bike Portland