[more_original]

I think you're right that this is a factor. What it doesn't quite explain is the decline of car usage in European cities that have always had sidewalks and good public transportation and where cycling isn't much easier now than it was 30 years ago. There seems to be a cultural change in attitude too. Cars are not as cool anymore as they used to be.

[tonfa]

I think many European cities have seen changes in the past twenty years. Better cycling lanes, easy bicycle rental, increased public transit density and availability (eg late at night).

[semi-extrinsic]

Not to mention lots of financial discouragement (i.e. tolls and taxes) for driving inside the city.

[more_original]

Yes, I forgot about petrol prices, which have increased substantially.

I'm not so sure about infrastructure improvements, at least here in Germany. I have been cycling for more than 20 years, and the infrastructure has not changed that much. Some places have improved a bit (especially in the last 5 years), but some are worse too. I feel that the experience is largely the same here. It may be different in places like Paris or London, though.

[dasil003]

I lived and cycled in London the last 3 years, and there is a steady drumbeat of cycling improvements at all levels. Whether it's the congestion charge, cycle hire scheme, bike lanes, or even physically reconfiguring junctions with an explicitly stated goal of improving bicycle safety, there are major changes happening there.

I'm not sure how much change is happing on the continent, but based on some stories I've seen, there are many cities pushing the envelope, I think even within Germany (probably depends on the city?).

[semi-extrinsic]

Even with the improvements you mention, London is still not exactly the most bicycle-friendly city in Europe, which is a little surprising since it's flat as a pancake. You should try cycling in Amsterdam or Copenhagen for a comparison.