Cyclists ride on urban freeways (similar to the DC beltway) out west? What cities?
Most urban freeways have interchanges every mile or so, and the 4+ lanes of traffic mean there is a near continuous stream of full speed traffic on the ramps.
I doubt they ride the "urban" freeways. I can't quite pix a cyclist pedaling in the emergency lane on I-10 through downtown LA. However, I do know that when they do the ride across America, which launches out of the Huntington Beach area, they make their way to I-10 and ride the shoulder in order to get through the mtns and desert, taking it nearly all the way to Arizona.
Here in the MW, cyclists riding on a freeway is something not often seen. I do not know if it is legal here -- sort of doubt it.