The big difference here is culture. Amsterdam, along with the rest of Europe, mostly avoided the post-WWII personal auto boom that occurred in the US. They grew up without the car whereas we grew up (and built up) around the car. If we want to increase bicycle ridership, we should start at the beginning by finding out what it would take for someone like the above "Commuter" to consider biking (Although that person is probably not the best example).

Better infrastructure will help as will higher gas prices, but the true change will happen when people start asking themselves "Why couldn't I?" instead of "Why I can't". Once a person gets on a bike for the first time, the former question follows automatically. But this can only happen by finding out what the impediments are and breaking through them. For example I know of at least 3 people who would bike commute if only they had access to showers at work.

As far as geography, Portland is a hilly town east and west (try going east on SE Salmon between 11th and 30th). It gets you in shape quick. Fortunately, any way you hit downtown, you are dropping in elevation. I used to bike commute from Tigard and really didn't sweat on the way in since it is mostly downhill. And FYI to "Commuter" because of the downhills, I was able to cover 7 miles in about 25 minutes. Don't fear the hills, enjoy them.

Thanks to Linda for the detailed post, it was very interesting. Portland has a lot to learn.