For example, here the Oregon version of Politfact looks at how many bicycles can fit in a single parking place (for a car).
The Oregon Politfact analyst doesn't care for the citation that Congressman Blumenauer's office used - somehow that seems like a less important question than whether the statement is factually accurate or not.
So 12 is the highest number of bicycle anyone will see in an area the size of a parking space. Two-tiered bike racks are available online but are primarily designed for commercial storage and retail bike storage and display. Several commercial racks hold as many as 20 bikes in 20 feet, but they need to be mounted to a wall or ceiling and aren’t really designed for outdoor use.Actually there is no particular reason why this discussion should be limited to outdoors - the question is how many bicycles can fit into the same space that would be taken up by a car, not whether it is indoors or outdoors.
Public parking in the Netherlands that provide high density with two levels of bikes parked in space where there would be one level of cars
There is nothing that technologically complex about this, but it does reflect a recognition that in the Netherlands there are so many bicycles to be parked that it makes sense to have such parking available. Whether that makes sense in the US or not is separate from whether it is possible.
An example from Brazil - a managed facility using simpler technology that is nevertheless fairly high density (although perhaps not 20 per space)
I was surprised to see a blog post from the Seattle Bike Blog extolling the virtues of a new segment of bike lanes near where I used to live (before 1990) - really, this is a big advance?
This isn't very impressive, Seattle
At 10 seconds in, the cyclist in the picture looks over his shoulder with great attentiveness since he must change lanes - the bike lane on this portion of roadway is ending and to continue with the bike lane (that from here is about three blocks away) he has to switch lanes to the left while traveling uphill with zippy car traffic coming up from behind. Then he travels a long block on 75th that is described in the video as "not bike-friendly" which is accurate (I have been back riding there since 1990~), finally turning onto Roosevelt to enter the new segment of bike lane. Which the video notes has been labeled by NIMBY residents as an effort to destroy that neighborhood - with all of ten blocks of bike lane!
OK, I'm being overly negative - but it is somewhat deflating that Seattle that is supposed to be advanced in this area still has struggles over improvements that are not terribly impressive. But that's a partial picture - I am particularly impressed (at a distance) by the implementation of dedicated bicycle "greenways" such as one in Ballard (a neighborhood in northwest Seattle).